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A-1331 (EB-25 Revised)<strong>Sunflower</strong><strong>Production</strong>SEPTEMBER 2007


ForewordThe first edition of “<strong>Sunflower</strong> <strong>Production</strong> and MarketingExtension Bulletin 25” was published in 1975.This publication provided general information forgrowers, seedsmen, processors, marketing agenciesand Extension personnel. Revised editions followed in1978, 1985 and 1994. Interest and knowledge aboutsunflower production and marketing in the U.S. hasincreased greatly in the past 30 years. Marketing andprocessing channels have stabilized and have becomefairly familiar to growers since 1985, but pest problemshave shifted and new research information hasbecome available to assist in production decisions.This publication is a revision of the “<strong>Sunflower</strong> <strong>Production</strong>and Marketing Bulletin” published in 1994.The purpose is to update information and provide aproduction and pest management guide for sunflowergrowers. This revised publication is directed primarilyto the commercial production of sunflower, not to marketingand processing. It will attempt to give specificguidelines and recommendations on production practices,pest identification and pest management, basedon current information.unless otherwise specified. This publication containscertain recommendations for pesticides thatare labeled ONLY for <strong>North</strong> <strong>Dakota</strong>. The users ofany pesticide designated for a state label must havea copy of the state label in their possession at thetime of application. <strong>State</strong> labels can be obtainedfrom agricultural chemical dealers or distributors.USE PESTICIDES ONLY AS LABELED.AcknowledgementsThe editor is indebted to the contributors for writingsections of this publication. The editor also appreciatesthe efforts made by previous contributors, asthese previous sections often were the starting pointfor current sections.This publication also is directed primarily toward sunflowerproduction in the northern Great Plains of theU.S. However, much of the information is relevant toother production areas. All pesticides recommendedhave a U.S. Environmental Protection Agency labeli


ContributorsiiRoger Ashley, Area Extension Agronomist, DickinsonResearch Extension Center, Dickinson, ND 58601Duane R. Berglund, Professor Emeritus and FormerExtension Agronomist, <strong>NDSU</strong> Extension Service,<strong>North</strong> <strong>Dakota</strong> <strong>State</strong> University, Fargo, ND 58105Carl Bradley, Former Extension Plant Pathologist,<strong>NDSU</strong> Extension Service, <strong>North</strong> <strong>Dakota</strong> <strong>State</strong>University, Fargo, ND 58105Gary Brewer, Former Department Chair and Professor,Department of Entomology, <strong>North</strong> <strong>Dakota</strong> <strong>State</strong>University, Fargo, ND 58105Lawrence Charlet, Research Entomologist,ARS-USDA, <strong>North</strong> <strong>Dakota</strong> <strong>State</strong> University,Fargo, ND 58105Greg Endres, Area Extension Agronomist, <strong>NDSU</strong>Research Extension Center, Carrington, ND 58421George Flaskerud, Extension Agricultural Economist,<strong>NDSU</strong> Extension Service, <strong>North</strong> <strong>Dakota</strong> <strong>State</strong>University, Fargo, ND 58105Dave Franzen, Extension Soils Specialist, <strong>NDSU</strong>Extension Service, <strong>North</strong> <strong>Dakota</strong> <strong>State</strong> University,Fargo, ND 58105Thomas Gulya, Research Plant Pathologist,ARS-USDA, <strong>North</strong> <strong>Dakota</strong> <strong>State</strong> University,Fargo, ND 58105James Hanzel, <strong>Sunflower</strong> Breeder, Proseed Inc.,Harvey, ND 58341Kenneth Hellevang, Extension Agricultural Engineer,<strong>NDSU</strong> Extension Service, <strong>North</strong> <strong>Dakota</strong> <strong>State</strong>University, Fargo, ND 58105Vernon L. Hofman, Professor Emeritus and FormerExtension Agricultural Engineer, <strong>NDSU</strong> ExtensionService, <strong>North</strong> <strong>Dakota</strong> <strong>State</strong> University, Fargo, ND58105Larry Kleingartner, Executive Director, National<strong>Sunflower</strong> Association, Bismarck, ND 58503Jan Knodel, Extension Entomologist, <strong>NDSU</strong>Extension Service, <strong>North</strong> <strong>Dakota</strong> <strong>State</strong> University,Fargo, ND 58105Greg Lardy, Extension Beef Cattle Specialist,Department of Animal and Range Sciences,<strong>North</strong> <strong>Dakota</strong> <strong>State</strong> University, Fargo, ND 58105George Linz, Wildlife Biologist, USDA-APHIS,Bismarck, ND 58501Sam Markell, Extension Plant Pathologist, <strong>NDSU</strong>Extension Service, <strong>North</strong> <strong>Dakota</strong> <strong>State</strong> University,Fargo, ND 58105Jerry Miller, Retired <strong>Sunflower</strong> Breeder, USDA-ARS,<strong>North</strong> <strong>Dakota</strong> <strong>State</strong> University, Fargo, ND 58105John Sandbakken, Marketing Specialist, National<strong>Sunflower</strong> Association, Bismarck, ND 58503Tom Scherer, Extension Irrigation Engineer, <strong>NDSU</strong>Extension Service, <strong>North</strong> <strong>Dakota</strong> <strong>State</strong> University,Fargo, ND 58105Don Tanaka, Soil Scientist, ARS-USDA, <strong>North</strong>ernGreat Plains Research Laboratory, Mandan, ND58554Richard Zollinger, Extension Weeds Specialist,<strong>NDSU</strong> Extension Service, <strong>North</strong> <strong>Dakota</strong> <strong>State</strong>University, Fargo, ND 58105Former Editors: David W. Cobia, David E. Zimmer,Marcia McMullen and Duane R. BerglundFormer Contributors: Ron R. Allen, William S. Ball,James Bauder, Al Black, David W. Cobia, WilliamDanke, Alan Dexter, Carl Fanning, Gerhardt N. Fick,Basil Furgala, Phil Glogoza, James Helm, HarveyJ. Hirning, Edna T. Holm, David H. Kinard, ArthurLamey, Darnell Lundstrom, Dean McBride, HughMcDonald, John Nalewaja, Berlin Nelson, David M.Noetzel, William K. Pfeifer, Lyle Prunty, Charlie E.Rogers, LeRoy W. Schaffner, Albert Schneiter, Robertand Jay Schuler, John T. Schulz, Tommy E. Thompson,Sebastian Vogel, Howard D. Wilkins, David E.Zimmer and Joseph C. Zubriski


<strong>Sunflower</strong><strong>Production</strong>Edited and Compiled byDuane R. BerglundProfessor Emeritus andFormer Extension Agronomist<strong>North</strong> <strong>Dakota</strong> <strong>State</strong> UniversityExtension ServiceExtension Publication A-1331(EB-25 revised)September 2007<strong>North</strong> <strong>Dakota</strong> AgriculturalExperiment Stationand<strong>North</strong> <strong>Dakota</strong> <strong>State</strong> UniversityExtension Service<strong>North</strong> <strong>Dakota</strong> <strong>State</strong> UniversityFargo, <strong>North</strong> <strong>Dakota</strong> 58105ContentspageForeword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iAcknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iContributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iiI. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Historical perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Taxonomy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Growth stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Growing degree days . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3II. <strong>Production</strong> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6World production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6U.S. production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Acreage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Seed yields/acre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Pounds of seed production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Processing plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Prices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8<strong>Sunflower</strong> marketing strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9III. Hybrid Selection and <strong>Production</strong> Practices . . . . . . . . . . . . . . 10Hybrid selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Oilseed (NuSun), traditional and confectionary . . . . . . . . . . . . 11Criterial for hybrid selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Semidwarf sunflower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12<strong>Sunflower</strong> branching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13<strong>Production</strong> practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Seed quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Soil fertility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Fertilizer recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14Fertilizer application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Water requirements for sunflower . . . . . . . . . . . . . . . . . . . . . . . . . . 15Soil water management for dryland sunflower . . . . . . . . . . . . . 16Irrigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Tillage, seedbed preparation and planting . . . . . . . . . . . . . . . . . 18Crop rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Pollination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24IV. Pest Management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54Weeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80Birds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85Other . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88V. Hail Injury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91VI. Herbicide Drift and Chemical Residue . . . . . . . . . . . . . . . . . . . . 95VII. Harvesting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101Maturity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101Harvesting attachments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101Combine adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103VIII. Drying and Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105IX. Feeding Value of <strong>Sunflower</strong> Productsin Beef Cattle Diets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109X. U.S. Grades and Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112XI. Other Information Sources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115Appendix 1. Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117iii


IntroductionIntroduction(Duane R. Berglund)Two primary types of sunflower are grown: (1) oilseedfor vegetable oil production and (2) nonoilseed forhuman food and bird-food markets (Figure 1). The oilseedhybrids may be of three fatty acid types: linoleic,mid-oleic (NuSun) or high oleic. They are usuallyblack-seeded and have a thin hull that adheres to thekernel. Seed of the oilseed varieties contains from 38percent to 50 percent oil and about 20 percent protein.Some black-seeded oil types go into the hulling marketfor birdseed. Nonoilseed sunflower also has beenreferred to as confectionery sunflower, and is usuallywhite striped and/or comes in large-seeded varieties.1Nonoilseed sunflower generally has a relatively thickhull that remains loosely attached to the kernel, permittingmore complete dehulling. Seed of the nonoilseedhybrids generally is larger than that of the oilseedtypes and has a lower oil percentage and test weight.<strong>Sunflower</strong> is a major source of vegetable oil inthe world. Worldwide production of sunflower hasincreased since the last revision of this publicationand peaked during the 1998-1999 period. The formerSoviet Union remains the highest producer, followedby Argentina and then the U.S., which is third inproduction worldwide. Domestic use and exportationof nonoilseed sunflower also have increased. The majorityof U.S. production of sunflower oil is exported,although domestic use is increasing.The following chapters provide a historical perspectiveand background of the sunflower as a viableeconomic crop and provide the current informationon worldwide and U.S. production, U.S. productionpractices, current pest identification and pest managementpractices, hail injury, herbicide use and damage,harvesting, drying, storing, and U.S. grades andstandards for market.2Historical Perspective<strong>Sunflower</strong>, native to <strong>North</strong> America, is the stateflower of Kansas and grows wild in many areas ofthe U.S. <strong>Sunflower</strong> has a long and varied history asan economic plant, but the time and place of its firstcultivation is uncertain. <strong>Sunflower</strong> was used by <strong>North</strong>■ Figure 1. The two classes of sunflower based on seedcharacteristics: (1) oilseed hybrids grown as a sourcefor oil and meal, and (2) nonoilseed hybrids-grown forhuman and bird food. Wholeseed and kernel types forboth are shown. (Gerhardt Fick)1


American Indians before colonization of the NewWorld. Spanish explorers collected sunflower in <strong>North</strong>America and by 1580, it was a common garden flowerin Spain (Figure 2). Early English and French explorers,finding sunflower in common use by the AmericanIndians, introduced it to their respective lands. Itspread along the trade routes to Italy, Egypt, Afghanistan,India, China and Russia. <strong>Sunflower</strong> developed asa premier oilseed crop in Russia and has found wideacceptance throughout Europe. Oilseed sunflower hasbeen an economically important crop in the U.S. since1966. Before 1966, sunflower acreage in the U.S. wasdevoted primarily to nonoilseed varieties.The center of sunflower origin has been identifiedas limited to the western Plains of <strong>North</strong> America,but whether the domesticated type originated in theSouthwest or in the Mississippi or Missouri Rivervalleys has not been determined. The wild form of thecultivated sunflower is well-known, which is not truewith most of our cultivated crop species today.The American Indians used sunflower as a foodstuffbefore the cultivation of corn. <strong>Sunflower</strong> also was usedas a medicinal crop, source of dye, oil for ceremonialbody painting and pottery, and as a hunting calendar.When sunflower was tall and in bloom, the bison fedon it, and according to stories told, the fat and themeat were good.Cultivation of sunflower was undertaken by NewWorld settlers as a supplementary food. Later, sunflowerwas grown primarily as a garden ornament. Italso was grown as an ensilage crop in the late 1800sand early 1900s.Expanded world production of sunflower resultedprimarily from development of high-oil varieties byplant scientists and more recently by the developmentof hybrids. <strong>Sunflower</strong> is widely grown in the worldwhere the climates are favorable and a high quality oilis desired.TaxonomyThe cultivated sunflower (Helianthus annuus L.) isone of the 67 species in the genus Helianthus. Allare native to the Americas and most are found in theU.S. It is a member of the Compositae family andhas a typical composite flower (Figure 3). Jerusalemartichoke (H. tuberosus L.), another species, is grownon a limited basis for food and livestock feed in theU.S. A few species are grown as ornamentals and therest are weeds, usually found in pastures or disturbedareas.The basic chromosome number for the Helianthusgenus is 17. Diploid, tetraploid and hexaploid speciesare known. The majority of the species are perennial,with only about a dozen annual species. Plant breedershave made interspecific crosses within the genus andhave transferred such useful characteristics as higheroil percentage, cytoplasmic male sterility for use inproduction of hybrids, and disease and insect resistanceto commercial sunflower.2■ Figure 2. A 1586 drawing of sunflower.(Mattiolus from Heiser)Growth StagesThe division of growth into vegetative and reproductivestages as developed by Schneiter and Miller isshown in Figure 4. This scheme is important as itgives producers, scientists and the industry a commonbasis to discuss plant development.


Introductioncorolla tubedeveloping “seed”petalray fl owerdisk fl oretsreceptaclebractsinvolucralbract■ Figure 3.Details ofthe head of asunflower andselected parts.(J. Miller andChristian Y. Oseto)Table 1. Growing Degree Days: <strong>Sunflower</strong> Growth and DevelopmentAve. days and GDD** unitsaccum. from planting<strong>Sunflower</strong> PlantGDDStage Description units DaysVE Emergence 167 10V4 4 True Leaves 349 20V8 8 True Leaves 545 28V12 12 True Leaves 690 34V16 16 True Leaves 772 38V20 20 True Leaves 871 44R1 Miniature Terminal Bud 919 46R2 Bud


Vegetative StagesV-E■ Figure 4. Stages of sunflower development.(A. A. Schneiter and J.F. Miller.)True leaf — 4 cmV-2V-12Reproductive StagesV-4Lessthan2cmMorethan2cmR-2 R-3R-1 R-2R-3 R-3 Top View R-4 Top ViewR-5.1R-5.5 R-5.9 R-64R-7R-8 R-9


Description of sunflower growth stageThe total time required for development of a sunflower plant and the time between the variousstages of development depends on the genetic background of the plant and growing season environment.When determining the growth stage of a sunflower field, the average development of alarge number of plants should be considered. This staging method also can be used for individualplants. The same system can be used for classifying either a single head or branched sunflower.In the case of branched sunflower, make determinations using only the main branch or head. Instages R-7 through R-9, use healthy, disease-free heads to determine plant development if possiblebecause some diseases can cause head discoloration. Also, in a number of recently released andgrown hybrids, the stay-green characteristic is present, which means the yellowing or browning ofthe bracts may not be a good indicator of plant maturity.Growth StagesStageV (number)Vegetative Stages(e.g., V-1, V-2, V-3, etc.)DescriptionThese are determined by counting the number of true leaves at least4 cm in length beginning as V-1, V-2, V-3, V-4, etc. If senescence ofof the lower leaves has occurred, count leaf scars (excluding thosewhere the cotyledons were attached) to determine the proper stage.R-1 Reproductive Stages The terminal bud forms a miniature floral head rather than a cluster ofleaves. When viewed from directly above, the immature bracts have amany-pointed starlike appearance.R-2 The immature bud elongates 0.5 to 2.0 cm above the nearest leafattached to the stem. Disregard leaves attached directly to the back ofthe bud.R-3 The immature bud elongates more than 2 cm above the nearest leaf.R-4 The inflorescence begins to open. When viewed from directly above,immature ray flowers are visible.R-5 (decimal) This stage is the beginning of flowering. The stage can be divided into(e.g., R-5.1, R-5.2, R-5.3, etc.) substages dependent upon the percent of the head area (disk flowers)that has completed or is in flowering. Ex. R-5.3 (30%), R-5.8 (80%),etc.R-6 Flowering is complete and the ray flowers are wilting.R-7 The back of the head has started to turn a pale yellow.R-8 The back of the head is yellow but the bracts remain green.R-9 The bracts become yellow and brown. This stage is regarded asphysiological maturity.From Schneiter, A.A., and J.F. Miller. 1981. Description of <strong>Sunflower</strong> Growth Stages. Crop Sci. 21:901-903.5


<strong>Production</strong>World <strong>Production</strong>(John Sandbakken and Larry Kleingartner)The sunflower is native to <strong>North</strong> America but commercializationof the plant took place in Russia. <strong>Sunflower</strong>oil is the preferred oil in most of Europe, Mexico andseveral South American countries. Major producingcountries or areas are the former Soviet Union,Argentina, Eastern Europe, U.S., China, France andSpain (Table 2). These seven countries/areas of theworld produce about 80 percent of the world’s oilseedand nonoilseed sunflower. Historically, the former SovietUnion has been the No. 1 producer of sunflower,producing about 35 percent of the world’s productionannually. During much of the 1970s, the U.S. wasthe world’s second largest producer, but in the 1980s,Argentina became firmly entrenched in second place.U.S. <strong>Production</strong>AcreageThe first sustained commercial production of oilseedsunflower in the U.S. occurred in 1966, when about6,000 acres were grown. Total combined acreage ofoilseed and nonoilseed sunflower increased graduallyin the late 1960s and expanded rapidly in the 1970s,reaching a peak in 1979 at 5.5 million acres. The U.S.share of world production has declined in recent yearsas production in Argentina and other countries hasincreased. During the peak period of U.S. production,the U.S. produced about 15 percent of the world’ssunflower production. In 2005, the U.S. market sharewas only 6 percent.The rapid acreage increase in the late 1970s wasstimulated by a variety of factors. Favorable yields in1977 and 1978 brought about by improved hybridsand favorable weather conditions were key factors,along with excellent prices when compared with competitivecrops.Table 2. World <strong>Production</strong> of All <strong>Sunflower</strong>62006-1996- 1997- 1998- 1999- 2000- 2001- 2002- 2003- 2004- 2005- 20071997 1998 1999 2000 2001 2002 2003 2004 2005 2006 ForecastArgentina 5.45 5.68 7.13 5.80 2.94 3.73 3.34 2.98 3.75 3.82 4.20Eastern Europe 2.92 2.18 2.59 2.75 1.67 1.86 2.02 2.67 2.27 2.11 2.17European Union 3.87 4.08 3.44 3.10 3.27 3.03 3.72 4.07 4.07 3.72 4.06China, Peoples 1.42 1.17 1.46 1.77 1.95 1.75 1.95 1.82 1.70 1.83 1.85Republic offormer USSR 5.37 5.41 5.74 6.89 7.27 4.94 7.19 9.35 8.00 11.32 11.20United <strong>State</strong>s 1.60 1.67 2.39 1.97 1.61 1.55 1.11 1.21 .93 1.82 .92India 1.30 1.16 1.17 .87 .81 .73 1.06 1.16 1.45 1.50 1.43Turkey .67 .67 .85 .82 .63 .53 .83 .56 .64 .80 .90Other 1.99 1.87 2.83 2.98 3.01 3.55 2.74 3.07 3.58 3.25 3.77World <strong>Sunflower</strong> 24.63 23.89 27.60 26.95 23.16 21.80 23.95 26.88 26.39 30.16 30.49<strong>Production</strong>(million metric tons)


Changes in the 1990 government farm program, whichallowed planting flexibility while providing price support,led to an increase in sunflower acreage in 1991relative to 1990. The government program establisheda marketing loan and a loan deficiency payment forsunflower and other oilseed crops.The bulk of U.S. sunflower production occurs in <strong>North</strong><strong>Dakota</strong>, South <strong>Dakota</strong>, Minnesota, Kansas, Colorado,Nebraska and Texas. Small acreages are grownin several other states (Table 3). The majority of theacreage harvested is for oil production versus nonoiluses. In 2005, the USDA reported that 2,032,000 acresof oil sunflower and 578,000 of nonoil sunflower wereharvested (Table 4).Seed Yield/AcreAnnual average sunflower yields from 1996 to 2005ranged from 1,140 to 1,564 pounds per acre foroilseed and from 997 to 1,455 pounds per acre fornonoilseed sunflower. Average yields per acre duringthe 1996-2005 period were 1,349 pounds for oilseedsand 1,220 pounds for nonoilseed sunflower (Figure 5).Pounds of <strong>Production</strong>U.S. production of oilseed sunflower ranged from1,763 million pounds (799,700 metric tons) in 2004 to4,486 million pounds (2,035,000 metric tons) in 1998(Table 5). Nonoilseed production ranged from 286million pounds (130,000 metric tons) in 2004 to 844million pounds (383,000 metric tons) in 1999.Processing PlantsFour oil extraction plants in <strong>North</strong> <strong>Dakota</strong>, Minnesotaand Kansas process oilseed sunflower. Thesefour plants have a combined crushing capacity of1,900,000 metric tons per year, according to industryestimates. Several smaller plants are located throughoutthe main sunflower production region.<strong>Production</strong>Table 3. Total Planted <strong>Sunflower</strong> Acreage by <strong>State</strong>s 1994-20061994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006<strong>North</strong> <strong>Dakota</strong> 1,590 1,450 1,180 1,470 1,990 1,700 1,330 1,070 1,370 1,210 880 1,140 900South <strong>Dakota</strong> 940 960 700 825 940 920 720 715 640 505 435 550 535Kansas 260 300 265 200 180 280 250 335 193 215 171 300 152Minnesota 500 440 150 105 130 130 95 60 70 90 60 135 90Colorado 100 115 110 85 160 270 220 195 130 130 135 215 100Texas 34 44 31 88 47 75 60 108 35 59 41 145 54Nebraska 75 90 47 55 70 101 90 82 60 66 56 99 53Other <strong>State</strong>s 68 79 53 60 51 77 75 68 60 91 95 125 100Total U.S. 3,567 3,478 2,536 2,888 3,568 3,553 2,840 2,633 2,580 2,344 1,873 2,709 1,984Thousand AcresTable 4. Harvested USA <strong>Sunflower</strong> Acreage 1994-20061994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006Oilseed 2,943 2,829 1,934 2,212 2,897 2,695 2,116 2,060 1,815 1,874 1,424 2,032 1,587Nonoilseed 487 539 545 580 595 746 531 495 365 323 287 578 277Total 3,430 3,368 2,479 2,792 3,492 3,441 2,647 2,555 2,180 2,197 1,711 2,610 1,864Thousand Acres7


Table 5. U.S. <strong>Sunflower</strong> <strong>Production</strong> 1994-20061994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006---------------------------------------------------- Million Pounds ----------------------------------------------------Oilseed 4,223 3,398 2,844 2,986 4,486 3,498 2,910 2,804 2,070 2,260 1,763 3,178 1818Nonoilseed 612 611 716 691 787 844 635 615 420 406 286 841 295Total 4,835 4,009 3,560 3,677 5,273 4,342 3,545 3,419 2,490 2,666 2,049 4,018 2113■ Figure 5. Average U.S. <strong>Sunflower</strong> Yield 1996-2005in Pounds Per Acre.PricesHistorically, sunflower depended heavily on theexport market for either seed or oil. With the adventof NuSun and high oleic sunflower, the market hasswitched almost exclusively to a U.S. and Canadianmarket. Both of these oils are very stable and do notrequire hydrogenation as do competitive oils, suchas traditional soybean and canola oils, when used ina frying application. <strong>Sunflower</strong> prices now are moredetermined by their relationship to corn oil prices.Large domestic users tend to buy in advance, thusprices are not directly affected by the Chicago soybeanoil contract and are not as likely to be as volatile.More opportunities are available to presell a portionof the crop well before planting begins. This ensuresa domestic user of a supply and allows a producer to“lock in” a price for a portion of his production. Storageof sunflower is necessary. The domestic marketneeds a 12-month supply of oil and crushers will needa steady supply of seed. Crushers likely will have toprovide producers with storage premiums for deliveryin the out-of-harvest months. Oilseed sunflower producershave the advantage of multiple market options:the hulling market, the crush market or the bird foodmarket. Supply and demand drive prices in all threemarkets. These markets are very specific and unique,with different values associated with them. Farmersshould have samples of their crop graded to determinequality and talk directly to buyers to find out whatthey want in terms of seed specifications.Nonoilseed (confection) sunflower production isgeared to the “in-shell” markets. Today’s confectionhybrids produce a significant level of large seeds.Growers often are paid on a percentage of large seed.Quality standards for confection sunflower are highand allow little tolerance for off-color and insectdamage. Most confection sunflower is produced ona contract basis. The seasonal average price duringthe 1994/95 to 2002/03 period ranged from $5.89 to$12.30 per hundredweight for oilseed sunflower andfrom $11.90 to $15.20 per hundredweight for nonoilseedsunflower. During that period, the nonoilseedprice exceeded the oilseed price by $3.85 per hundredweighton average.8


<strong>Sunflower</strong> Marketing Strategy(George Flaskerud)<strong>Sunflower</strong> marketing strategies usually use the cashforward contract for locking in a price prior to harvest.Use of this contract may be appropriate on a portionof the sunflower crop, but so may the use of other marketingtools, such as hedging with futures or use ofoptions (puts or calls). The best marketing alternativedepends in part on the basis, which is the relationshipbetween a cash and futures price.Since a sunflower futures market does not exist, relationshipsbetween the sunflower cash price and otherclosely related futures markets need to be considered.Using the futures market of a different commodity forhedging is cross-hedging, while the cash and futuresprice relationship is the cross-basis. Two futurescontracts are examined: soybean oil futures, whichare traded on the Chicago Board of Trade, and canolafutures, which are traded on the Winnipeg CommodityExchange.Historic prices were analyzed during 1997 throughApril 2004 to identify patterns and relationshipsuseful for developing marketing strategies. Priceswere standardized in U.S. dollars per hundredweight(US$/cwt).Correlations indicate that changes in NuSun prices(40 percent oil) at Enderlin, N. D., are the most closelycorrelated with canola futures (correlation = .91). Soybeanoil futures were a distant, second-best correlation(.75). These correlations suggest that canola futuresshould provide the most risk reduction for cross-hedgingcash sunflower prices. However, with the currentsituation for sunflowers, soybean oil and canola needto be evaluated to determine which futures contractlikely is to be the most profitable.Price quotations for canola futures are in Canadiandollars (C$) per metric ton. The price quotation forNovember canola was C$352 on August 25, 2003,and the exchange rate was 1.41 C$/US$. In U.S.dollars per hundredweight, this quotation would beUS$11.32 (C$352 divided by 1.41 divided by 22.046= US$11.32).Seasonal patterns for Enderlin NuSun prices (Figure6) revealed a broad range of price behavior during individualmarketing years (October-September). Highsoccurred during August in 2000-01 and 2001-02,April in 1999-00, October in 1998-99 and Novemberin 2002-03. The distribution of prices reveals that thepattern, on average, is to decline to lows in Octoberand then increase to a peak in June before declininginto the next marketing year.The range in the monthly average, excluding the lowand the high, was only $.53 per cwt. The within-yearvariations were considerably greater. The averagewithin-year range was $3.07. During 2000-01 and2001-02, when prices trended up, the average withinyearrange was $3.98. During the other years, theaverage within-year range was $2.47.The tendency for the Enderlin NuSun cross-basisrelative to canola futures (Figure 7) was to decline to alow in September and to remain nearly as low duringOctober and November, and then to increase to a highin February-April before generally declining into theend of the marketing year. During three of the fiveyears, the cross-basis was near its low in October. Therange of the cross-basis was the narrowest during Septemberand the widest during May. During October,the average cross-basis per cwt ranged from -$1.64 to-$.16 and averaged -$.99.Relative to soybean oil futures, the Enderlin averagecross-basis showed a pattern of marketing year lowsper cwt in November (-$9.15), April (-$9.25) and September(-$9.16) and highs in February (-$8.08) andJuly (-$8.30). During October, the average cross-basisranged from -$14.47 to -$6.59 and averaged -$8.95.■ Figure 6. Seasonal Behavior of NuSun Prices atEnderlin, ND.<strong>Production</strong>9


Use of the cash forward contract or cross-hedge wouldbe appropriate on that portion of the sunflower cropthat can be safely produced, i.e., on 20 percent to 40percent of the crop. The cash forward contract wouldbe preferred if it reflects an average or better cross-basisrelative to sunflower oil futures or canola futures.A greater portion of the crop could be sold on a cashforward contract if it includes an act-of-God clause.■ Figure 7. NuSun Cross-Basis at Enderlin, NDRelative to Nearby WCE Canola Futures.Variability, as measured by the standard deviation, wasgreater for the cross-basis relative to soybean oil futuresthan for the cross-basis relative to canola futures.This suggests lower basis risk when cross-hedgingwith canola futures than with soybean oil futures.From this information, marketing strategies can bedeveloped. The seasonal pattern for Enderlin NuSunprices suggests that preharvest sales should be consideredwhen prices are above the five-year averageprice. Prices declined into harvest during two of threeyears that prices were above the average early in themarketing year.In addition to the cash forward contract or crosshedge,a call option could be purchased to preserveupside potential. In the case of the cross-hedge, thecall option would be purchased in the same futurescontract. In the case of the cash forward contract, thecall option could be purchased in either the soybeanoil futures or canola futures. The put option is an alternativeto using a cash forward contract or cross-hedgein combination with a call option.For sunflowers that are not cash forward contracted,storage is an alternative. On average, storage was profitableduring the 1998-99 to 2002-03 marketing years.However, the most profitable period of storage variedconsiderably. The most profitable sell or store strategywas to sell the 1998 crop at harvest, store the 1999crop until January, store the 2000 and 2001 crops untilAugust and store the 2002 crop for one month. Sell orstore decisions are difficult and require frequent evaluationof fundamentals, cash prices, futures prices,basis and storage costs.Additional marketing alternatives are available but beyondthe scope of this article. Further information canbe found in <strong>NDSU</strong> Extension publication EC-1270,“Managing <strong>Sunflower</strong> Price Risk.”10


Hybrid Selection and<strong>Production</strong> PracticesHybrid SelectionHybrid Selection(Jerry Miller)Selection of sunflower hybrids to plant is one of themost important decisions a producer must makeeach season (Figure 8). First, three classes of hybrids- NuSun oilseed, traditional oilseed and confectionhybrids are available,. Second, variables such as yield,quality factors, maturity, dry down, standability, andpest and disease tolerance, should be considered.NuSun <strong>Sunflower</strong>NuSun oilseed sunflower hybrids will produce an oilquality with more than 55 percent oleic fatty acid.This oil is in wide demand by the frying food industryand potentially could be a bottled oil. Some hybridseed companies are providing a grower guarantee thattheir hybrids will make the minimum oleic grade.Some processors of NuSun sunflower also are providingcontracts for producing seed of this quality. Apremium may be paid to producers for planting NuSunhybrids.Traditional <strong>Sunflower</strong>Traditional oilseed sunflower hybrids have a highlinoleic and lower oleic fatty acid quality in contrastwith the NuSun hybrids. Traditional hybrids have beengrown for their multipurpose marketability, with largeexport demand and hulling for the kernel market beingmost important.striping on the hull. New hybrids with very long, largeseed are in demand for the export market. Producersmust be careful to set their combine concave widthsproperly to avoid hull damage on these hybrids. Producersgenerally plant confection hybrids at a lowerplant population and increase insect scouting andcontrol to maintain high kernel quality. Contracts areavailable to producers interested in planting confectionhybrids.Criteria for Hybrid SelectionGrowers should use several criteria in hybrid selection.First, they should take an inventory of available hybridsbeing marketed in their area. Seed yield potentialis an important trait to consider when looking at anavailable hybrid list. Yield trial results from universityexperiment stations, National <strong>Sunflower</strong> Associationsponsoredtrials and commercial companies shouldidentify a dozen or so consistently high yieldinghybrids for a particular area. Results from strip tests ordemonstration plots on or near growers’ farms shouldConfection <strong>Sunflower</strong>Confection sunflower hybrids are used primarily forin-shell and hulled kernel markets. They are characterizedby having large seed, with a distinctive color■ Figure 8. A hybrid seed production field ofsunflower. Female and male parents are planted inalternate strips across the field. (Marcia P. McMullen)11


e evaluated. Yield results from previous years on anindividual’s farm and information from neighbors alsoare valuable. The best producing hybrids in a regionmay produce approximately 2,300 pounds per acrewith good soil fertility and favorable soil moisture, ormore than 3,000 pounds per acre in the most favorablegrowing conditions.Oil percentage should be another trait to consider inoilseed hybrid selection. Several environmental factorsinfluence oil percentage, but the hybrid’s geneticpotential for oil percentage also is important. Currenthybrids have oil percentages ranging from 38 percentto more than 50 percent. Domestic oil processors havebeen paying a premium based on market price formore than 40 percent oil (at 10 percent moisture) anddiscounts for oil less than 40 percent. Current recommendationsare to select a high-oil hybrid instead of alow-oil hybrid with the same yield potential, but don’tsacrifice yield in favor of oil content.Maturity and dry down are important characteristics toconsider when deciding what hybrid to plant. Maturityis especially important if planting is delayed, beingmindful of the average killing frost in your area. Yield,oil content and test weight often are reduced when ahybrid is damaged by frost before it is fully mature.An earlier hybrid likely will be drier at harvest than alater hybrid, thus reducing drying costs. Also, considerplanting hybrids with different maturity dates as a productionhedge to spread risk and workload at harvest.The most economical and effective means to controlsunflower diseases and other pests is planting resistantor tolerant hybrids and considering a minimumof three to four years’ rotation between successivesunflower crops. Hybrids are available with resistanceto rust, Verticillium wilt and certain races of downymildew. New hybrids may be available with toleranceto Sclerotinia head and stalk disease. Growers shouldcheck with their local seed dealer or sunflower seedcompany representative to obtain this information.Stalk quality, another trait to consider, provides resistanceto lodging, various diseases and other pests. Hybridswith good stalk quality are easier to harvest andyield losses generally are reduced, withstanding damagesfrom pests and high winds. Uniform stalk heightat maturity is another important trait to consider.Hybrid selection may include selecting a hybrid withresistance to certain herbicides not previously available.This nontransgenic resistance either was derivedfrom the wild species of sunflower or from mutagenesis.<strong>Sunflower</strong> hybrids can be sprayed with herbicidesthat control various broadleaf and grassy weeds eitherby one chemical or by a tank-mix of two chemicals.This technology will allow broad-spectrum weed controlin minimum-till or no-till sunflower production,as well as with traditional production. Growers shouldcheck with their local seed dealer or sunflower seedcompany representative to obtain information regardingavailability of these hybrids.The last item to consider is to purchase hybrid seedfrom a reputable seed company and dealer with a goodtechnical service record. This is particularly importantif producers have any questions regarding productionpractices. Companies and seed dealers provide differentservices, policies and purchase incentives, includingcredit, delivery service and returns.Semidwarf <strong>Sunflower</strong>(Duane Berglund)Semidwarf sunflower is 25 percent to 35 percent shorterthan normal height hybrid sunflower. Research resultsshow seed yield and oil content of semidwarf andnormal height sunflower are similar in some years butnot always. In drought stress years, seed yield of semidwarfsunflower was significantly less than normalheighthybrids. Most semidwarf sunflower have earlymaturity ratings, thus the potential for high yields islimited, compared with conventional-height sunflower.The semidwarf plant types appear to be less susceptibleto lodging, which could be very important duringyears of optimum plant growth or where sunfloweris grown under irrigation, in high-plant populations.Generally, the semidwarf sunflower can be plantedin narrowly spaced rows or solid seeded. Universityresearch indicates root penetration and water useto a depth of 6 feet is similar for normal height andsemidwarf sunflower. Beyond 6 feet, root penetrationof the semidwarf may not be as great as that of tallerplant types. Some sunflower breeders have observedthat short-stature plants have demonstrated limitationsin head size and ability of the plant to fill the center ofthe head. Also, slower seedling emergence has beenreported for semidwarfs.12


<strong>Sunflower</strong> Branching(Duane Berglund)<strong>Sunflower</strong> branching is an undesirable trait in commercialsunflower production. It can be caused by thegenetics of a hybrid, environmental influences andherbicide injury.Branching of various degrees can occur in sunflower,ranging from a single stem with a large single inflorescencein cultivated types to multiple branchingfrom axils of most leaves on the main stem in the wildspecies. Branch length varies from a few centimetersto a distance longer than the main stem. Branchingmay be concentrated at the base or top of the stem orspread throughout the entire plant. Generally, headson branches are smaller than heads on the main stem.Occasionally, some first-order branches have a terminalhead almost as large as the main head. In mostwild species, the head on the main stem blooms first,but generally is no larger than those on the branches.Studies on the genetics of top branching have shownthat it is dominant over nonbranching and is controlledby a single gene. <strong>Sunflower</strong> literature reports that topbranching in cultivated sunflower is controlled by asingle dominant gene, but branching in wild species iscontrolled by duplicate dominant genes.Source: Sunfl ower Technology and <strong>Production</strong>,ASA monograph number 35.■ Figure 9. Soil Tests are the most reliable meansfor growers to determine fertilizer needs to obtainprojected yield goals. (Dave Franzen)<strong>Production</strong> PracticesSeed Quality(Duane Berglund)High quality, uniform seed with high germination,known hybrid varietal purity and freedom from weedseeds and disease should be selected to reduce productionrisks. The standard germination test provides anindication of performance under ideal conditions butis limited in its ability to estimate what will happenunder stress. Accelerated aging is another methodused to evaluate seed vigor. Any old or carry-overseed should have both types of tests conducted. Seedis sold on a bag weight basis or by seed count. Seedsize designations are fairly uniform across companies.Most seed is treated with a fungicide and insecticideto protect the germinating seedling. Seed should beuniformly sized to allow precision in the plantingoperation.Soils(David Franzen)<strong>Sunflower</strong> is adapted to a variety of soil conditions,but grows best on well-drained, high water-holdingcapacity soils with a nearly neutral pH (pH 6.5-7.5).<strong>Production</strong> performance on high-stress soils, such asthose affected by drought potential, salinity or wetness,is not exceptional but compares favorably withother commercial crops commonly grown.Soil Fertility(David Franzen)<strong>Sunflower</strong>, like other green plants, requires at least 16elements for growth. Some of these, such as oxygen,hydrogen and carbon, are obtained from water and theair. The other nutrients are obtained from the soil. Nitrogen,phosphorus and sulfur are frequently deficientin soils in any climatic zone. Potassium, calcium andmagnesium are frequently deficient in high-rainfallareas. Deficiencies of iron, manganese, zinc, copper,molybdenum, boron and chlorine are uncommon butcan appear in many climatic zones.A sunflower yield of 2,000 pounds per acre requiresapproximately the same amount of nitrogen, phosphorusand potassium as 40 bushels per acre of wheat.Hybrid Selection and <strong>Production</strong> Practices13


The nutrient content of the soil, as determined by asoil test, is the only practical way to predict probabilityof a response to applied nutrients (Figure 9). A soiltest will evaluate the available nutrients in the soil andclassify the soil as very low (VL), low (L), medium(M), high (H) or very high (VH) in certain nutrients.A field classified as very low in a nutrient will give ayield response to applied fertilizer 80 percent to 100percent of the time. A yield response is not alwaysobtained because soil moisture or some other environmentalfactor may become limiting. A field classifiedas low will respond to applied fertilizer 40 percentto 60 percent of the time, a medium testing field willrespond to added fertilizer 10 percent to 20 percentof the time and a high-testing field will respond toapplied fertilizer only occasionally. Fields testing veryhigh will not respond because the reserve of nutrientsin the soil is adequate for optimum plant growth andperformance.soil test levels are shown in Table 6. For yield goalsnot shown in the table, use the formulas at the baseof the table. The data in this table are based on theamount of nitrate-nitrogen (NO 3-N) in pounds peracre found in the top 2 feet of soil, the parts per million(ppm) of phosphorus (P) extracted from the top6 inches of soil by the 0.5N sodium bicarbonate, andthe ppm of potassium (K) extracted by neutral normalammonium acetate in the top 6 inches of soilOther nutrients are not usually deficient for sunflower.On sandy slopes and hilltops, sulfur may be a problem;however, sulfur would not be expected to be deficientin higher organic matter, depressional soils. Thesulfur soil test is a poor indicator of the probability ofresponse to sulfur fertilizers. <strong>Sunflower</strong> has not beenshown to be responsive to the application of othernutrients, including micronutrients in the state.14Fertilizer Recommendations(David Franzen)Soil tests have been developed to estimate sunflower’spotential response to fertilizer amendments. The mostimportant factors in the fertilizer recommendationsare the yield goal and the level of plant-available soilnutrients. In most climatic zones, predicting yieldis impossible. Past yield records are a reasonableestimate of potential yield for the coming year. A yieldgoal for sunflower should be more optimistic than theaverage yield, and should approach the past maximumyield obtained by the grower on the same or a similarsoil type. Nutrients not used by a crop in a dry growingseason usually are not lost and can be used by thefollowing crop.From an economic standpoint, having a yield goal thatis somewhat high is much more beneficial for a growerthan having a goal that is too low. A low yield goal ina good growing season easily can mean lost income of$30 to $40 per acre. In contrast, a high yield goal in adry growing season will result in a loss of only $1to$2 in additional interest on the cost of unused nutrientssince most of the nutrients will be available to thesubsequent crop.The amounts of nitrogen, phosphorus and potassiumrecommended for various sunflower yield goals andTable 6. Nitrogen (N), phosphate (P 2O 5) andpotash (K 2O) recommendations for sunflower in<strong>North</strong> <strong>Dakota</strong>.Soil N Soil Test Phosphorus, ppmplusYield fertilizer VL L M H VHGoal N Bray-1 0-5 6-10 11-15 16-20 21+lb/acrelb/acre2 ft. Olsen 0-3 4-7 8-11 12-15 16+- - - - - - lb P 2O 5/acre - - - - - -1,000 50 20 15 9 4 01,500 75 31 22 14 5 02,000 100 41 30 18 7 02,500 125 51 37 23 9 0Nitrogen recommendation = 0.05 YG - STN - PCC(Bray-1) Phosphate recommendation = (0.0225-0.0011 STP)YG(Olsen) Phosphate recommendation = (0.0225-0.0014 STP)YGYieldSoil Test Potassium, ppmGoal 0-40 41-80 81-120 121-160 161+lb/acre VL L M H VH1,000 36 25 14 3 01,500 53 37 21 5 02,000 71 50 28 6 02,500 89 62 35 8 0(K, ammonium acetate extractant) Potash recommendation =(0.04100-0.00027 STK)YGYG = Yield GoalPCC = Previous Crop CreditSTN is the amount of NO 3-N in the top 2 feet of soilSTP, STK = Soil Test P or K, respectivelyVL,L,M, H,VH = very low, low, medium, high and very high,respectively


Fertilizer Application(Dave Franzen)Germinating sunflower seed is similar to corn in itsreaction to seed-placed fertilizer. Application of morethan 10 pounds per acre of nitrogen (N) plus potash(K 2O) in a 30-inch row will result in reduced standsor injured seedlings. Dry soil conditions can increasethe severity of injury. In row widths narrower than30 inches, rates of N plus K 2O can be proportionallyhigher. For improved fertilizer rate flexibility, starterfertilizer should be placed in bands at least 2 to 3inches from the seed row.Producers have several good reasons to apply nitrogenin the fall, such as availability of labor, soil conditions,etc. However, the general principle with respectto nitrogen application is: The longer the time periodbetween application and plant use, the greater thepossibility for N loss. In other words, use judgmentin making a decision on time of N application. In thecase of sandy soils, fall application of N is not recommended.In many instances, a side-dress application ofN when the sunflower plants are about 12 inches highmay be preferable.Phosphate and potash may be fall or spring appliedbefore a tillage operation. These nutrients are notreadily leached from soil because they form onlyslightly soluble compounds or attach to the soil. Thephosphate and potash recommendations in Table 6.are broadcast amounts. The recommendations for soilthat tests very low and low in P and K can be reducedby one-third the amount in the table when applied in aband at seeding. In minimum or no-till systems, phosphateand potash may be applied in a deeper band toreduce the buildup of nutrients at the soil surface thatoccurs with these systems. However, most comparisonsamong deep, shallow and surface applicationshave shown little difference in crop response.Water Requirements for <strong>Sunflower</strong>(Duane Berglund)<strong>Sunflower</strong> has deep roots and extracts water fromdepths not reached by most other crops; thus it isperceived to be a drought-tolerant crop. <strong>Sunflower</strong> hasan effective root depth around 4 feet, but can removewater from below this depth. Research on side-by-sideplots has shown that sunflower is capable of extractingmore water than corn from an equal root zone volume.With its deep root system, it also can use nitrogen andother nutrients that leach below shallow-root crops;thus it is a good crop to have in a rotation.Seasonal water use by sunflower averages about 19inches under irrigated conditions. Under drylandconditions, sunflower will use whatever stored soilmoisture and rain that it receives during the growingseason. When access to water is not limited, smallgrains use 2 to 3 inches less total water than sunflowerduring the growing season, whereas soybean water useis slightly greater. Corn uses 1 to 4 inches, and sugarbeets use 2 to 6 inches more than sunflower, respectively,during the growing season.These total water use values are typical for nondroughtconditions in southeastern <strong>North</strong> <strong>Dakota</strong>. Small grainsuse the least total water since they have the fewestnumber of days from emergence to maturity. <strong>Sunflower</strong>and soybean have an intermediate number of daysof active growth and corresponding relative water use.Corn ranks above sunflower in growth days and wateruse, while sugar beets rank highest in both categories.However, water use efficiency does vary among thesecrops. Comparative water use efficiency measured asgrain (pounds per acre or lb/A) per inch of water usedon three dryland sites and two years in eastern <strong>North</strong><strong>Dakota</strong> was 119, 222, 307, 41, 218, 138, and 127 forsunflower, barley, grain corn, flax, pinto bean, soybeanand wheat, respectively. These results indicated thatcorn had the highest water use efficiency, sunflowerand wheat were intermediate and flax the lowest.(Source: M. Ennen. 1979. <strong>Sunflower</strong> water use ineastern <strong>North</strong> <strong>Dakota</strong>, M.S. thesis, <strong>North</strong> <strong>Dakota</strong> <strong>State</strong>University).Fertility has little influence on total water use, butas fertility increases, water use efficiency increasesbecause yield increases. Yield performance has beenshown to be a good indicator of water use efficiencyof sunflower hybrids; higher yielding hybrids exhibitthe highest water use efficiency.<strong>Production</strong> Practices15


16Soil Water Managementfor Dryland <strong>Sunflower</strong>(Duane Berglund)Management practices that promote infiltration ofwater in the soil and limit evaporation from the soilgenerally will be beneficial for sunflower productionin terms of available soil moisture. Leaving stubbleduring the winter to catch snow and minimum tillageare examples. Good weed control also conservesmoisture for the crop. The use of post-applied and preemergenceherbicides with no soil incorporation alsoconserves moisture when growing sunflower.<strong>Sunflower</strong> has the ability to exploit a large rootingvolume for soil water. Fields for sunflower productionshould be selected from those with the greater waterholdingcapacity and soils without layers that mayrestrict roots. Water-holding capacity depends mainlyon soil texture and soil depth. The loam, silt loam,clay loam and silty clay loam textures have the highestwater-holding capacities. Water-holding capacity ofthe soils in any field can be obtained from county soilsurvey information available from local Natural ResourcesConservation Service (NRCS) USDA offices.Sampling or probing for available soil moisture beforeplanting also can help select fields for sunflowerproduction. With other factors being equal, fields withthe most stored soil moisture will have potential forhigher yields. Where surface runoff can be reducedor snow entrapment increased by tillage or residuemanagement, increases in stored soil moisture shouldoccur and be beneficial to a deep-rooted crop such assunflower.Irrigation Management(Tom Scherer)Irrigation of sunflower by commercial growers is notcommon, but sunflower will respond to irrigation.Data collected by the USDA Farm Service Agency(FSA) for irrigated crops in <strong>North</strong> <strong>Dakota</strong> shows thatan annual average of about 1,500 acres of sunflowerare irrigated each year. Data for irrigated and drylandoil-type variety trials between 1975 and 1994 from theCarrington Research Extension Center show an averageyield differential of about 500 pounds per acre.However, some years the irrigated trials yielded morethan 1,500 pounds per acre more than the drylandplots, and some years the dryland plots actually hadgreater yield than the irrigated plots.Irrigated sunflower seasonal water use averages about19 inches. With good water management, averagewater use will increase from about 0.03 inch per daysoon after emergence to more than 0.27 inch per dayfrom head emergence to full seed head development.However, during July and August, water use on a hot,windy day can exceed 0.32 inch.Research by Stegman and Lemert of <strong>NDSU</strong> hasdemonstrated the yield potential of sunflower grownunder optimum moisture conditions and the effect ofwater stress at different growth stages. <strong>Sunflower</strong> yieldis most sensitive to moisture stress during the floweringperiod (R-2 to R-5.9 reproductive stages) and leastsensitive during the vegetative period (emergence toearly bud). A 20 percent reduction of irrigation waterapplication from plant emergence to the R-2 stageresulted in only a 5 percent reduction in yield, but a20 percent reduction in irrigation water applicationduring the R-2 to R-5.9 period resulted in a 50 percentyield reduction.If soil water content is near field capacity at planting,research indicates that the first irrigation could bedelayed until the root zone soil moisture is about 70percent depleted. However, if pumping capacity is low(less than 800 gallons per minute, or gpm, for a 128-acre center pivot), a lesser depletion is advisable dueto inadequate “catch-up capacity.” Irrigations duringthe critical bud to ray-petal appearance (R-2 to R-5.0)period should be scheduled to maintain a low soilmoisture stress condition (35 percent to 40 percentdepletion). Irrigation should be avoided from R-5.1to R-5.9 because of the susceptibility of the sunflowerplant to head rot from Sclerotinia (white mold). Irrigatejust before flowering in the bud stages R-3 toR-4. Soil moisture depletion again can approach 70percent during late seed fill and beyond with little orno depression in yield.Yield increases due to irrigation depend on severalfactors. Soil water-holding capacity and precipitationare two of the most important. Research indicates thatthe seed yield versus crop water use (ET) exhibits alinear relationship with a slope averaging 190 poundsper acre-inch. This means every additional inch of


water applied by irrigation will increase seed yieldby about 190 pounds per acre. Remember that theresearch was performed on the loam and sandy-loamsoils of Carrington and Oakes, N.D. A yield increaseof 50 percent or more with irrigation may be expectedalmost every year on coarse-textured soils. However, aseed yield increase from irrigation may not always occuron soils with higher water-holding capacities andwith adequate precipitation. Adequate soil fertility isvery important in achieving the higher yield potentialunder irrigation.Management of applied irrigation water requires thecombination of periodic soil moisture measurementwith a method of irrigation scheduling. Soil moisturecan be measured or estimated in a variety of ways. Thesimplest is the traditional “feel” method that is an artdeveloped through time with extensive use and experience.For most irrigation water management applications,either the resistance block type of soil moisturemeasurement or tensiometers should be used. Theseare relatively inexpensive and require little labor touse effectively.The soil water balance method of irrigation scheduling,otherwise known as the checkbook method, ispopular and well-documented. With this method,a continuous account is kept of the water stored inthe soil. Soil water losses due to crop use and soilsurface evaporation are estimated each day based onthe maximum temperature and the days since cropemergence. Precipitation and irrigation are measuredand added to the soil water account each day. Errors inestimating water use will accumulate through time, soperiodically measuring the moisture in the soil profileis necessary. Detailed instructions for using the checkbookmethod are published (<strong>North</strong> <strong>Dakota</strong> Extensionpublication AE-792). A computer program using thismethod also is available from the <strong>NDSU</strong> Agriculturaland Biosystems Engineering Department.Another form of irrigation scheduling is to use estimateddaily water use values for sunflower (Table 7).This method, sometimes called the “water use replacementmethod,” is based on obtaining daily estimatesof sunflower water use and accurately measuring theamount of rain received on the field. Irrigations arescheduled to replace the amount of soil moisture usedby the sunflower minus the amount of rain receivedsince the last irrigation. Estimates of daily sunflowerwater use can be obtained several ways. AE-792 hasa table for sunflower water use throughout the seasonbased on weeks’ past emergence and maximum dailyair temperature. More accurate sunflower water usevalues, based on measured weather variables fromthe <strong>North</strong> <strong>Dakota</strong> Agricultural Weather Network(NDAWN), are available at the NDAWN Web site:http://ndawn.ndsu.nodak.edu/. Click on “Applications”on the left side of the home screen. <strong>Sunflower</strong> cropwater use estimates can be obtained for the currentgrowing season (between emergence and harvest)or for past growing seasons if you want to do somecomparisons.<strong>Production</strong> PracticesTable 7. Average daily water use for sunflower in inches per day based on maximum daily airtemperature and weeks past emergence. For example, during the eighth week after emergence,if the daily air temperature were 85 degrees on a particular day, sunflower water use for thatday would be 0.25 inch.MaximumDaily AirWeek After EmergenceTemperature°F 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1550 to 59 0.01 0.03 0.05 0.06 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.07 0.06 0.04 0.0360 to 69 0.02 0.05 0.08 0.10 0.12 0.14 0.14 0.14 0.13 0.13 0.13 0.12 0.10 0.07 0.0470 to 79 0.03 0.07 0.11 0.15 0.17 0.19 0.19 0.19 0.19 0.18 0.17 0.16 0.13 0.10 0.0680 to 89 0.03 0.09 0.14 0.19 0.22 0.25 0.25 0.25 0.24 0.23 0.22 0.21 0.17 0.13 0.07Above 90 0.04 0.11 0.17 0.23 0.27 0.30 0.30 0.30 0.29 0.29 0.27 0.26 0.21 0.15 0.09Bud Ray Flower 100% RayAnther PetalDrop17


18Tillage, Seedbed Preparationand Planting(Roger Ashley and Don Tanaka)<strong>Sunflower</strong>, like other crops, requires proper seedbedconditions for optimum plant establishment. Errorsmade at planting time may be compounded throughoutthe growing season. Seedbed preparation, soil tilth,planting date, planting depth, row width, seed distributionand plant population should be nearly correct asconditions permit.Tillage and Seedbed PreparationTillage traditionally has been used to control weedsand incorporate herbicides in preparation for planting.When tillage is used in low rainfall areas, producersmust take care to control weeds while leaving as muchof the previous crop’s residue intact as possible. Tillagenever should occur when soils are too wet. Soilsthat are tilled when too wet and then dry will crust,turn lumpy and generally provide for poor seedbedconditions for germination and establishment.Maintaining a moist seedbed is important if producersexpect to have uniform germination and emergenceacross the field (Figure 10). Poor germinationand emergence will influence the need for and theeffectiveness of future management practices. Excessivetillage should be avoided where tillage is usedto prepare the seedbed or to incorporate preplantherbicides. Excessive tillage will break down soilstructure, cause compaction and crusting problems,reduce aeration, restrict water movement and provide■ Figure 10. No-till one pass seeding systemspreserve soil moisture and ground cover when wateris limited. (Roger Ashley)conditions favorable for infection by downy mildew orother soil-borne diseases. Breakdown of soil structurealso causes reduced nutrient and water uptake andreduces yield.Tillage and planting equipment is available to providesystems with varying levels of surface residue forsunflower production. <strong>Production</strong> systems can rangefrom conventional-till, where the quantity of surfaceresidue covers less than 30 percent of the soil surface,to no-till, where the quantity of surface residue coversmore than 60 percent of the soil surface.Conventional-till <strong>Production</strong> SystemsConventional-till production systems usually involvetwo or more tillage operations for weed control, incorporationof pre-emergence herbicides and incorporationof the previous crops residues. Pre-emergenceherbicides may be incorporated with a tandem disk,chisel or sweep plows, disk harrow, long-tine harrow,rolling harrow or air seeders with sweeps in differentsequences or combinations. Tillage sequences aredetermined by herbicide label requirements by thequantity of crop residue present at the beginning ofthe tillage operation, and by the seedbed requirementsneeded to match planting equipment capabilities.Conventional tillage systems, with or without preemergenceor post-emergence herbicide, may includethe option of row cultivation once or twice during theearly growing season before the sunflower reaches aheight too tall for cultivation. A rotary hoe or harrowcan be used just before sunflower emergence and/or atthe V-4 to V-6 development stage. Harrowing or rotaryhoeing between emergence and the V-4 stage can resultin injury or death of the sunflower plant. Dependingon planting depth and stage of crop development,stand losses are generally less than 5 percent if thesunflower crop has at least two fully expanded leaves.Proper adjustment of the harrow or rotary hoe willmaximize damage to the weeds and minimize injuryto the sunflower crop.Minimum-till <strong>Production</strong> SystemsMinimum-till production systems use subsurfaceimplements with wide sweeps, such as an undercutter(Figure 11), or harrow systems for applicationand incorporation of herbicides. These productionsystems leave between 30 percent and 60 percent ofthe soil surface covered by crop residue after planting.Minimum-tillage sunflower production systems rely


on a good long-term crop rotation to help control difficultweeds. These systems rely on two incorporationsof granular herbicides, such as Trifluralin 10G andSonalan 10G. Herbicides can be applied in late fall(late October) or early spring (mid to late April) andincorporated with either an undercutter (at a soil depthof 2 inches) or a harrow system. A second incorporationjust before or at sunflower planting is performedwith an undercutter, harrow or air seeder with sweeps(Figure 12). The time between the application/firstincorporation and the second incorporation shouldbe at least three weeks to increase the opportunity forprecipitation to occur and rewet the treated soil layer.Rewetting the treated soil layer dissolves and activatesthe herbicide granules before the second incorporation.■ Figure 11. Undercutter sweep machine used toprepare seedbed, control small weeds and conservessoil moisture. (Al Black)■ Figure 12. Air-seeder with sweeps used forminimum till sunflower planting. (Roger Ashley)Air Drill UseSolid-seeded sunflower has become popular withproducers in some regions. Air drills commonly areused to plant solid-seeded stands. Advantages listed byproducers include 1) improved utilization of equipmentalready owned and 2) ease of changing betweencrops.Suggested adjustments to the air drill when plantingsunflower include: 1) Use the proper metering roller;2) Slow the metering roller speed; 3) Calibrate thedrill. Run through the calibration cycle10 times andthen three additional times to check for consistentlymetered weights; 4) Recalibrate the drill every timevariety or seed lot changes; 5) Reduce airflow. Providethe minimum amount of air to move seed and fertilizerto the opener so the seed is not damaged; 6) Don’tplace all of your seed in the bin after the drill is calibrated.Place a couple of bags in the bin and run untilthe low seed light appears. Then place another bag inthe hopper and run until the low seed light appears.Calculate the number of acres seeded. If you appearto be planting the correct seeding rate, place one morebag of seed in the hopper and run until the low seedlight appears. If this seeding rate is correct, fill theseed bin and plant the rest of the field.No-till <strong>Production</strong> SystemsNo-till is a production system without primary orsecondary tillage prior to, during or after crop establishment.No-till systems rely heavily on diverse croprotations and pre- and postemergence herbicides, andminimize soil disturbance to control weeds. Crop rotationsshould include cool-season grass and broadleafcrops, as well as warm-season grass and broadleafcrops. These production systems maintain at least 60percent surface covered by crop residue after planting.Crop residues protect soils from erosion, controlweeds, suppress evaporation and improve soil waterinfiltration. Pre- and postemergence herbicide choicesprovide producers options that were not available justa few years ago. Residual herbicides can be appliedin a timely manner to get adequate precipitation foractivation. Burn-down applications of glyphosate orparaquat are needed before or shortly after plantingbut before emergence of the crop to control emergedweeds and volunteer crop. Spartan (sulfentrazone), aresidual broadleaf weed herbicide, may be tank-mixedwith glyphosate to control broadleaf weeds for six toeight weeks. At the present time, postemergence herbi-<strong>Production</strong> Practices19


cides such as Poast (sethoxydim) and Clethodim provideexcellent grassy weed control and Assert (imazamethabenz)will control wild mustard. Clearfieldsunflower varieties were selected for tolerance of theherbicide Beyond (imazamox) and will allow postemergencecontrol of both broadleaf and grassy weeds.However, ALS (acetolactate synthase)-resistant kochiais not controlled with this herbicide. For current informationon registered sunflower herbicides, contactyour county agent or weed control specialist.Planting sunflower in a no-till production system mayrequire the addition of residue managers to movea minimum of crop residue from the seed row sodouble-disc openers can place seed properly for seedto soil contact. Poor placement will delay or preventgermination, emergence and establishment of thecrop. This, in turn, may lead to weed, insect and harvestmanagement problems. Single-disc openers andnarrow-point hoe openers have been used successfullyto seed sunflower. Minimizing soil disturbance is important.Soil disturbance can bury weed seed, placingthem in a favorable position to survive, germinate andestablish. Weed seed left on the soil surface is exposedto weather, insects, birds and fungi and rapidly willlose viability. Low-disturbance no-till production systemsprovide the best opportunity for adequate seedzone soil water at planting.No-till and One-pass SeedingWhen low-disturbance openers, such as the single-discstyle, are used, seed should be placed at least 2 inchesdeep. In undisturbed silt loam soils, the dry/wet interfaceusually will be found about 1 inch below the soilsurface. In coarse-textured soils, this interface will bedeeper. Planting at or just below this dry/wet interfacewill result in poor and/or uneven germination, resultingin either germinating seed running out of waterand dying before the plant has a chance to establishor seed lying in dry soil until adequate rainfall isreceived.One-pass seeding operations utilizing high-disturbanceopeners (sweeps, hoes and narrow points) canproduce uneven stands under dry conditions. Seedingdepth is more variable with these types of openers,compared with the single-disc style, and moistureconditions will be more variable. Long, dry periodsat planting do occur in western <strong>North</strong> <strong>Dakota</strong>. Soilswill dry below acceptable levels for germination tothe depth of the disturbed soil in the seedbed. Unevengermination, emergence, plant stands and plants atdifferent stages of maturity will occur unless adequatemoisture is received shortly after planting to rewet theseedbed.Anhydrous ammonia (Figure 13) sometimes is appliedin one-pass seeding operations with openers specificallydesigned for ammonia application at the time ofseeding. If moisture is sufficient and application ratesdo not exceed 50 pounds, little damage to germinatingseed will occur. However, if the seedbed is abnormallydry and/or the soil does not seal properly between theanhydrous ammonia band and the seed, damage togerminating seed will occur.More recently, no-till row planters with row cleanersahead of double-disc openers are equipped with either20■ Figure 13. This one-pass seeding operation is seeding directly into wheat stubble.Anhydrous ammonia and seed are banded through special openers. Glyphosate andsulfentrazone were applied three days prior to seeding. (Roger Ashley)


a liquid or dry fertilizer attachment. These attachmentsband nitrogen fertilizers separately from theseed band, eliminating injury to the germinating seed.Planting Dates<strong>Sunflower</strong> may be planted during a wide range ofdates. In the northern Great Plains, planting mayextend from May 1 until late June. Early maturinghybrids should be selected for late planting or replantingin northern areas. Planting may be as early as twoweeks before the last killing frost and as late as 100days before the first killing frost in the fall.Growing conditions during the season will affect yield,oil content and fatty acid composition. High temperaturesduring seed formation have been identified asthe main environmental factor affecting the ratio oflinoleic and oleic acid content. Therefore, the optimumplanting date will be dependent upon the varietyand location, as well as weather conditions duringthe growing season. Variety genetics also affect oleiccontent, so select adapted varieties for your area. Highyields may be obtained from very early planting dates,but yields may be reduced by increased pest problems.If sunflower is seeded early in narrow rows and weedsare controlled early with preplant and post-plant herbicideproducts, early canopy closure should controllate-germinating weeds, eliminating the need for herbicidesor cultivation later in the season. Also, earlyplanting provides producers the opportunity to harvesthigh quality seed earlier with less cost required forpostharvest handling. Late-June plantings often resultin lower yields and oil content. In addition, when harvestis delayed by weather, mechanical drying of seed■ Figure 14. Solid seeded sunflower standestablished using an air drill. (Roger Ashley)is required, thus adding to production expenses. Thefatty acid profile also is affected by planting date. In athree-year planting date study in southwestern <strong>North</strong><strong>Dakota</strong>, oleic fatty acid content was greatest whenthe planting date occurred around May 23 and lowestwhen the planting date was later than June 10.Soil temperature at the 4-inch depth should be at aminimum of 45 F for planting. A temperature near 50F is required for germination. Periods of soil temperaturebelow 50 F delay germination and extend theperiod of susceptibility to seedling diseases, such asdowny mildew, and to herbicide injury.Row Spacing and Plant Population<strong>Sunflower</strong> will perform well in a wide range of plantpopulations and plant spacing. When adequate weedcontrol exists, no yield differences have been detectedbetween sunflower seeded in rows and solid seeded.Fields with a row spacing of less than 20 inches areconsidered to be solid seeded (Figure 14). In 2003, theNational <strong>Sunflower</strong> Association field survey found 70percent of the sunflower fields surveyed in southwestern<strong>North</strong> <strong>Dakota</strong> to have been solid seeded. Equidistantspacing of seeds should produce a uniform sunflowerstand, which makes maximum use of resources,such as water, nutrients and sunlight. Seed spacing toachieve the desired plant population is listed in Table8. Table 8 assumes seed germination is 90 percentand a 10 percent stand reduction will occur betweenemergence and harvest. The seed spacing must beadjusted with lower or higher germination rates, andthus spacing between seed.Desired seed spacing may be calculated using the followingformula:SS = (6,272,640/RS)/(PP/(GR x SR)Where:SS = in row seed spacing in inchesRS = between row spacing in inchesPP = desired plant population at harvestGR = germination rate as a decimal. For example,if germination is 95 percent, then germinationrate = .95.SR = stand reduction as a decimal. This reductionis a result of other factors between germinationand final harvest population. For example,if a 10 percent reduction is expected,then 100 percent - 10 percent = 90 percent,or .9.<strong>Production</strong> Practices21


<strong>Sunflower</strong> plants will compensate for differences inplant population by adjusting seed and head size. Asplant population decreases, seed and head size willincrease. Oilseed hybrids generally are planted athigher populations than confection varieties, as thesize of harvested seed is less important. Plant populationsfor oilseed sunflower should be between 15,000and 25,000 plants per acre, with adjustments madefor soil type, rainfall potential and yield goal. Lowerpopulations are recommended for soils with lowerwater-holding capacity and if normal rainfall is inconsistentor inadequate. Confection sunflower shouldbe planted at populations between 14,000 and 20,000plants per acre. Preharvest dry down is more rapid inhigher plant populations because of the smaller headsize. However, higher plant populations may result inincreased lodging and stalk breakage. Producers whosolid seeded sunflower use seeding rates of 18,000 to23,000 plants per acre.Proper planting equipment adjustment and operationis one of the most important management tasks insunflower production. Plateless and cyclo air plantershave been used effectively to get good seed distribution.Double-seed drops should be avoided and planteradjustments should be made. Conventional plateplanters will provide good seed distribution by usingcorrect planter plates, properly sized seed and properseed knockers. Commercial seed companies have platerecommendations for all seed sizes. Grain drills andair seeders may be used for seeding, although uniformdepth of planting and seed spacing may be a problemunless proper adjustments and modifications are made.Postharvest TillageAfter harvest, tillage of sunflower stalks is notrecommended because snow-trapping potential isdiminished, thereby reducing soil water conservationpotential during the winter for the following crop.Also, because of the nature of sunflower residues, alate harvest followed by late fall tillage leaves the soilextremely susceptible to wind and water erosion.Table 8. Seed spacing required for various populations, assuming90 percent germination and 10 percent stand loss.PlantsRow Spacingper acre 7.5 12 18 22 28 30 36- - - - - - - inches between seeds in the row - - - - - - -12,000 56.5 35.3 23.5 19.2 15.1 14.1 11.814,000 48.4 30.2 20.2 16.5 13.0 12.1 10.116,000 42.3 26.5 17.6 14.4 11.3 10.6 8.817,000 39.8 24.9 16.6 13.6 10.7 10.0 8.318,000 37.6 23.5 15.7 12.8 10.1 9.4 7.819,000 35.7 22.3 14.9 12.2 9.6 8.9 7.420,000 33.9 21.2 14.1 11.5 9.1 8.5 7.121,000 32.3 20.2 13.4 11.0 8.6 8.1 6.722,000 30.8 19.2 12.8 10.5 8.2 7.7 6.423,000 29.5 18.4 12.3 10.0 7.9 7.4 6.124,000 28.2 17.6 11.8 9.6 7.6 7.1 5.925,000 27.1 16.9 11.3 9.2 7.3 6.8 5.6Feet per1/1,000 acre 69.7 43.6 29 23.8 18.7 17.4 14.5Highlighted seed spacings provide nearly equal-distant spacing between plants for a given rowspacing and plant population.22


Crop Rotation(Greg Endres)Having a proper rotation sequence with all crops,including sunflower, is important. Research shows thatsunflower seed yield is greater following most othercrops than sunflower (Tables 9 and 10).Growers who do not rotate sunflower fields likely willbe confronted with one or more of the following yieldreducingproblems:1. Disease and disease-infested fields2. Increased insect risk3. Increasing populations of certain types of weeds4. Increased populations of volunteer sunflower5. Soil moisture depletion.6. Phytotoxicity or allelopathy of the sunflowerresidue to the sunflower cropTherefore, producers have many valid reasons forrotating sunflower fields.Table 9. Seed yield of sunflower based onprevious crop, Crookston, Minn., 1972-78.PreviousSeed yield/acre (pounds)4-yr.crop 1973 1975 1977 1978 ave.<strong>Sunflower</strong> 852 1,338 1,852 1,781 1,456Potato 908 1,279 2,348 1,605 1,535Sugar beet 770 1,683 2,358 2,168 1,745Pinto bean 946 1,410 2,282 1,674 1,578Wheat 1,284 1,549 2,339 1,655 1,706LSD .05 240 121 292 132Table 10. Seed yield of various crops followingsunflower, Mandan, N.D., 1999-2000.Previous crop<strong>Sunflower</strong>CanolaFlaxSoybeanField peaHRS wheatBarleySeed yield870 lbs/A1,200 lbs/A22.5 bu/A35.2 bu/A41.7 bu/A49.2 bu/A70.0 bu/ARisks of sunflower disease will be greatly magnifiedby short sequencing of sunflower in a crop rotation.Sclerotinia or white mold (wilt, stem rot and head rot)is the primary disease concern with a poor sunflowerrotation. Other disease concerns with improper rotationsinclude Verticillium wilt, Phoma and prematureripening. Rotations of at least three- or four-yearspacings between sunflower or other Sclerotiniasusceptiblecrops (e.g., canola, dry bean, soybean)are recommended to help reduce disease risk. Thesunflower disease section in this publication containsspecifics on the characteristics and methods of controlfor each disease.Crop rotation may help reduce but will not preventinsect problems in sunflower. Proper rotations helpreduce populations of insects that overwinter in thesoil or sunflower plant residue. Crop rotation will notreduce damage from insects that migrate into an areafrom other geographic regions or from fields plantedto sunflower the previous year that are in proximityto current-season fields. Rotations recommendedfor reducing sunflower disease risks also will reduceinsect risks.Rotation of other crops with sunflower can reducethe buildup of many weed species. Also, proper croprotation increases weed management options, includingcultural, mechanical and chemical weed control.Consult records of previous field management todetermine if long-residual herbicides that wouldadversely affect sunflower production were used.Volunteer sunflower also can become a serious weedproblem in repeat sunflower and other crops. For additionaldetails. refer to the weed management sectionof this publication, herbicide labels and <strong>NDSU</strong> ExtensionService publication W-253, “<strong>North</strong> <strong>Dakota</strong> WeedControl Guide.”Different patterns of soil moisture utilization are importantconsiderations when planning sunflower rotations.<strong>Sunflower</strong> is a deep-rooted and full-season crop.<strong>Sunflower</strong> has intermediate water use requirements,compared with other crops (see water requirementssection in this publication). <strong>Sunflower</strong> is relativelytolerant to effects of short water-stress periods, espe-<strong>Production</strong> Practices23


cially if the moisture stress occurs before the crop is inthe reproductive stages. In limited-moisture growingseasons, sunflower following a shallower rooted andshort-season crop (e.g., small grain, canola, flax) willallow the sunflower to extract residual water from agreater depth in the soil profile.Continuous cropping of crops such as corn, wheat andsoybeans results in yields that are depressed belowthe level obtained when a crop is rotated with othercrops. The same effect is observed with sunflower,even when variable factors such as fertility, disease,insects and moisture are well-managed. This responsewith continuous cropping is known as allelopathy.Toxic materials in the sunflower residue, developmentof antibodies and the increase of soil-borne diseaseorganisms all have been suggested as causes forallelopathy in sunflower. This effect has been demonstratedrepeatedly and emphasizes a need to rotatesunflower.Suggested sunflower rotations for <strong>North</strong> <strong>Dakota</strong>will vary somewhat by geographic region, primarilybecause of different precipitation zones. For practicalpurposes, the state can be divided into east and westregions. Suggested rotations for these regions arelisted in Table 11. Rotations may be varied by substitutingother crops in the rotation, but the time spacingof the sunflower crop should be observed strictly orincreased. See <strong>NDSU</strong> Extension Service publicationEB-48, “Crop Rotations for Increased Productivity,”for additional details on crop rotation.Pollination(Gary Brewer)Native sunflower and the early varieties of sunflowerwere self-incompatible and required insect pollinationfor economic seed set and yields. However, becausenumbers of pollinators were often too low to ensureadequate seed set, current hybrids have been selectedfor and possess high levels of self-compatibility.Although self-compatible sunflower hybrids usuallyoutproduce self-incompatible cultivars, modernhybrids benefit from insect pollination.The agronomic value of insect pollinating activities tocurrent hybrids varies among hybrids, fields and years.Controlled studies indicate that in most sunflowerhybrids, seed set, seed oil percentage, seed yields andoil yields increase when pollinators (primarily bees)are present. Literature reports indicate that yield couldincrease as much as 48.8 percent and oil percentagecould increase 6.4 percent in bee-exposed hybrids.However, despite the increases in yield and oil concentrationthat occur, the benefit of insect pollinationof sunflower often is overlooked (Figure 15).Seed companies and growers who produce F1 hybridseed for planting must use bees to transfer pollen fromthe male parent to the female parent. Although nativewild bees are often better pollinators of sunflowerthan honey bees, the honey bee is the only managedpollinator of sunflower available. However, if pollensources other than sunflower are nearby, the honey beeTable 11. <strong>Sunflower</strong> rotation examples for <strong>North</strong> <strong>Dakota</strong>.Year West East1 <strong>Sunflower</strong> <strong>Sunflower</strong> <strong>Sunflower</strong> <strong>Sunflower</strong>2 Small grain Pulse crop* Soybean* Small grain3 Pulse crop* Small grain Small grain Soybean *4 Flax or small grain Corn*medium susceptibility to Sclerotinia.24


■ Figure 15. Bees and hives are occasionally placedin sunflower fields to boost the native population toassure a better seed set. (Reid Bevis)will forage sunflower primarily for nectar and will nottransfer sunflower pollen efficiently.Honey bee colonies are placed in seed productionfields at a rate of one hive per one to two acres. A beedensity of more than 20 bees per 100 heads in bloomis needed to transfer sufficient pollen from the maleline to the female sterile line. Placement of honey beecolonies will depend upon proximity and acreage ofcompeting nectar and pollen sources. With no competition,all honey bee colonies are placed at one endof the target field. With competing nectar and pollensources, placement of honey bee colonies at 800-footintervals may be necessary.<strong>Sunflower</strong> genotypes vary in their attractiveness to thehoney bee. Honey bees prefer short corolla length,unpigmented stigmas, many stomata on the nectaryand high sucrose content of the nectar. Glandulartrichomes on the anthers and ultraviolet reflecting andadsorbing pigments also may be important in honeybee preference. Although some crops, such as oilseedrape, have been selected for honey bee preference, thishas not been done with sunflower.Maximum seed yields often require the use ofinsecticides to protect the crop from insect competitors.Unfortunately, many of the major insect pests ofsunflower attack the crop when it is flowering. Thus,insecticides used to control the pest also harm pollinatingbees. If pollinator activity is decreased, yieldand oil percentage may decline. The hazards to honeybees can be minimized with adequate communicationand cooperation among beekeepers, growers and pesticideapplicators. Beekeepers must inform applicatorsof the location of apiaries and be prepared to move orprotect colonies. When insecticide spraying is justified,applicators must make every attempt to notifybeekeepers in advance.<strong>Production</strong> Practices25


Pest Management(Janet Knodel and Larry Charlet)Integrated Pest Management<strong>Sunflower</strong> can be a high-risk crop because of potentiallosses from diseases, insects, birds and weeds. Thesepotential risks require that growers follow integratedpest management (IPM) practices. IPM is a sustainableapproach to managing pests by combiningbiological, cultural, physical and chemical tools in away that minimizes economic, health and environmentalrisks to maintain pest populations below levelsthat cause unacceptable losses to crop quality or yield.The concept of pest management is based on the factthat many factors interact to influence the abundanceof a pest. Control methods vary in effectiveness, butintegration of these various population-regulatingfactors can minimize the number of pests in sunflowerand reduce the cost of managing pest populationswithout unnecessary crop losses. IPM also recommendsthe judicious use of chemical pesticides whenneeded and suggests ways to maximize effectivenessand minimize impact on nontarget organisms and theenvironment.Economic Injury Leveland Economic Threshold LevelsOne major component of a pest management programis determining when tactics should be implementedto prevent economic loss. Economic loss results whenpest numbers increase to a point where they causecrop losses that are greater than or equal to the cost ofcontrolling the pest. An economic injury level (EIL) isdefined as the level of pests that will cause economicdamage. An EIL recognizes that treatment is justifiedfor some pest population levels while others are not ofeconomic importance.An economic threshold level (ETL) is the level ornumber of pests at which tactics must be applied toprevent an increasing pest population from causingeconomic losses. Usually the ETL is lower than theEIL. The ETL has been defined most extensively forinsect pests; fewer ETLs have been established forother types of pests. The ETL varies significantlyamong different pests and also can vary during differentdevelopmental stages of the crop. Crop price, yieldpotential, crop density, cost of control and environmentalconditions influence the ETL and EIL. Generally,the ETL increases as cost of control increases anddecreases as the crop value increases.Monitoring Pest Population LevelsIn general, fields should be evaluated regularly to determinepest population levels. A weekly field check isusually sufficient, but field checks should be increasedto two or three times a week if the number of pests isincreasing rapidly or if the number is approaching aneconomic threshold level. Pests should be identifiedaccurately because economic threshold levels and con-26


trol measures vary for different organisms. In addition,when insects pests are monitored, many insects arebeneficial and may help reduce numbers of injuriousinsects; recognizing which are pests and those that arebeneficial is important.Tools of Pest ManagementTools of pest management include many tactics, ofwhich pesticides are only one. These tactics can becombined to create conditions that are the least conducivefor pest survival. Chemical or biological pesticidesare used when pests exceed economic thresholdlevels; sometimes they are necessary when control isneeded quickly to prevent economic losses.Some of the tools or components of pest managementthat can be used to reduce pest populations are:Biological ControlsBeneficial insectsBeneficial pathogensHost ResistanceCultural ControlsPlanting and harvest datesCrop rotationTillage practicesMechanical/Physical ControlsTemperatureWeather eventsTrappingChemical ControlsPesticidesAttractantsRepellentsPheromonesSummaryGrowers should examine their operations andminimize pest damage by adopting integrated pestmanagement practices based on the use of economicthreshold levels, when available, plus carefullymonitoring and combining various control methods.Significant progress with sunflower pest managementhas been made and undoubtedly will continue to bemade in the future to aid successful sunflower production.The following sections provide current informationon management of insects, diseases, weeds, birdsand other sunflower pests. A growing season calendarshows the major sunflower pest problems and time ofoccurrence in the northern Great Plains productionarea (Figure 16).Pest Management■ Figure 16. A growing season calendar indicatingtime of occurrence of major sunflower pests.(J. Knodel)27


Quick Reference Guide to Major <strong>Sunflower</strong> InsectsThe information presented on this page is designed to be a quick reference for growers, crop consultants, field scouts andothers. Since this information is very brief, the user should refer to the following pages for more detailed data on life cycles,damage, descriptions, etc.Insects Description Occurrence, Injury and Economic Threshold (ET)Cutworms Dirty gray to gray brown. ET – 1 per square foot or 25 percent to 30 percent stand(several species) Grublike larva, 0.25 to 1.5 inches in length. reduction. Appear in early spring when plants are in theseedling stage, chewing them at or slightly above ground.Palestriped Adult: 1/8 inch long and shiny black, with two white ET – 20 percent of the seedling stand is injured and at riskFlea Beetle stripes on the back. The hind legs are enlarged and to loss due to palestriped flea beetle feeding. Scout formodified for jumping.flea beetles by visually estimating population on seedlingsor using yellow sticky cards placed close to the ground.<strong>Sunflower</strong> Beetle Adult: reddish-brown head, cream back with three ET – 1 to 2/seedling (adults), or 10 to 15/seedlingdark stripes on each wing cover. Body 0.25 to 0.5 (larvae). Adults appear in early June, larvae shortlyinch long. Larva: yellowish green, humpbacked in thereafter. Both adults and larvae chew large holesappearance, 0.35 inch in length.in leaves.<strong>Sunflower</strong> Adult: wingspread 0.63 to 0.75 inch, gray brown ET – none. First generation adults appear in late May toBud Moth with two dark transverse bands on forewings. mid-June. Second generation adults appear in midsummer.Larva: Cream-colored body (0.33 to 0.4 inch) with Larvae from first generation damage terminals and stalks,a brown head.whereas second generation larvae feed in receptacle area.Longhorned Adult: pale gray and 5/8 inch (6 to 11 mm) in No scouting method or ET has been developed. Adults areBeetle (Dectes) length, with long gray and black banded antennae. present from late June through August. Larvae tunnel andLarvae: yellowish with fleshy protuberances on the feed in the petioles and stem pith and girdle the base offirst seven abdominal segments (1/3 to 1/2 inch) plants. Stalks often break at the point of larval girdling.<strong>Sunflower</strong> Stem Adult: small (0.19 inch long) weevil with a ET – 1 adult/3 plants in late June to early July. AdultsWeevil gray-brown background and white dots on the back. appear in mid to late June, with larvae in stalks fromearly July to late summer.Thistle Caterpillar Adult: wingspread of 2 inches, upper wing surface brown ET – 25 percent defoliation, provided that most of the(Painted Lady with red and orange mottling and white and black spots. larvae still are less than 1.25 inches in length. AdultsButterfly) Larva: brown to black, spiny, with a pale yellow stripe appear in early to mid-June, with larvae appearingon each side, 1.25 to 1.5 inches in length.shortly thereafter. Larvae chew holes in leaves.<strong>Sunflower</strong> Midge Adult: small (0.07 inch), tan, gnatlike insect. ET – none. Adult emergence begins in early July. LarvaeLarva: cream or yellowish, 0.09 inch long, tapered at feed around head margin and at the base of the seeds,front and rear.causing shrinkage and distortion of heads.<strong>Sunflower</strong> Seed Adults: the red sunflower seed weevil is about 0.12 ET – generally 8 to 14 adult red sunflower weevils per headWeevils inch long and rusty in color. The gray sunflower seed (oil) and one per head (confectionery). Adults appear inweevil is about 0.14 inch long and gray in color. late June to early July. Treat for red sunflower seed weevilLarvae: both species are cream-colored, legless and at R5.1 to R5.4. Larvae feed in seeds from mid to lateC-shaped.summer.<strong>Sunflower</strong> Moth Adult: body is 0.38 inch long, with 0.75 inch ET – 1 to 2 adults/5 plants at onset of bloom. Adults arewingspread. Color is buff to gray. Larva: brown head migratory and usually appear in early to mid-July. Larvaecapsule with alternate dark and light lines running tunnel in seeds from late July to late August.longitudinally, 0.75 inch in length.Banded <strong>Sunflower</strong> Adult: small 0.25-inch straw-colored moth with brown ET – See banded sunflower moth section for egg or adultMoth triangular area on forewing. Larva: in early growth sampling methods for determining ET. Sampling should beconducted in the late bud stage (R-3), usually during mid-July. Adults appear about mid-July to mid-August. Larvaepresent in heads from mid-July to mid-September.stage, off-white, changing to red and then green colorat maturity, 0.44 inch in length.Lygus Bug Adult: small (0.2 inch in length), cryptically colored ET - for CONFECTION SUNFLOWERS ONLY –insects with a distinctive yellow triangle or “V” on 1 Lygus bug per 9 heads. Two insecticide sprays arethe wings and vary in color from pale green to dark recommended: one application at the onset of pollen shedbrown. Nymph (immature stages): usually green and or 10 percent bloom, followed by a second treatmentsimilar in appearance to the adults, but lack wings. 7 days later.<strong>Sunflower</strong> Adult: metallic, black, 0.25-inch long body with a long ET – none. Adults appear in mid to late July and createHeadclipping “snout.” Larvae: 0.25 inch in length. feeding punctures around stalk just below the heads.WeevilHeads drop off.28NOTE: The insects discussed above are listed in the order that they likely are to occur throughout the growing season; however, the various insectsmay or may not appear, depending upon overwintering survival and environmental conditions as the season progresses. The table is intendedsimply as a guide to when fields should be checked for possible presence of the various insects known to infest sunflowers.


InsectsInsects(Janet Knodel and Larry Charlet)<strong>Sunflower</strong> plays host to a number of insect pests. Inthe major sunflower producing areas of the <strong>Dakota</strong>s,Minnesota and Manitoba, approximately 16 species ofsunflower insects can cause plant injury and economicloss, depending on the severity of infestation. However,during any one growing season, only a few specieswill be numerous enough to warrant control measures.The sunflower insects of major importance in thenorthern Great Plains have been sunflower midge,Contarinia schulzi Gagne'; sunflower beetle, Zygogrammaexclamationis (Fabricius); sunflower stemweevil, Cylindrocopturus adspersus (LeConte); redsunflower seed weevil, Smicronyx fulvus LeConte; andthe banded sunflower moth, Cochylis hospes Walsingham.Recently, Lygus bugs have been an economicproblem for the confection and hulling sunflower seedmarket. Populations of the long-horned sunflower stemgirdler, Dectes texanus LeConte, have been increasingin <strong>North</strong> and South <strong>Dakota</strong>.Infestation of sunflower insects must be monitoredregularly, usually weekly, to determine the speciespresent and if populations are at economic thresholdlevels. Furthermore, proper timing of insecticidaltreatment is essential to maximize control.The following sections provide information on theidentification, life cycle, damage, scouting methods,economic threshold levels and management of someof the most common insect pests of sunflower in thenorthern Great Plains. A preliminary quick referenceguide to sunflower insects is available.<strong>Sunflower</strong> pests are not distributed evenly throughouta field, and fields should be checked in several locations.Some insect pests, such as banded sunflowermoth, are concentrated in areas of a field or are moreabundant near the edge of a field than in the middle.Determining the extent of a pest population on thebasis of what is found in only one or two small areasof a field is impossible. At least five sites per 40-acrefield should be monitored to collect good informationon the nature and extent of a pest infestation.Sampling sites should be at least 75 feet in from thefield margin to determine whether an entire field or aportion of the field requires treatment. When infestationsoccur primarily along field margins, delineatingthose and treating as little of the field as needed toprovide economic control may be possible. In mostcases, 20 plants per sampling site should be examinedin the Z or X pattern as shown (Figure 17).Crop consultants who are trained in pest managementscouting may be hired. Consultants should be able toidentify pest and beneficial insects and provide informationabout pest management.■ Figure 17. The X and Z scouting patterns.29


■ WirewormsSpecies: variousDescription: Wireworm larvae (Figure 18) are hard,smooth, slender, wirelike worms varying from 1.5 to 2inches (38 to 50 mm) in length when mature. They area yellowish white to a coppery color with three pairsof small, thin legs behind the head. The last body segmentis forked or notched.Adult wireworms (Figure 19) are bullet-shaped, hardshelledbeetles that are brown to black and about ½inch (13 mm) long. The common name “click beetle”is derived from the clicking sound that the insectmakes when attempting to right itself after landing onits back.■ Figure 18. Wireworm larvae. (Mark Boetel)Life Cycles: Wireworms usually take three to fouryears to develop from the egg to an adult beetle. Mostof this time is spent as a larva. Generations overlap, solarvae of all ages may be in the soil at the same time.Wireworm larvae and adults overwinter at least 9 to24 inches (23 to 61 cm) deep in the soil. When soiltemperatures reach 50 to 55 F (10 to 13 C) during thespring, larvae and adults move nearer the soil surface.Adult females emerge from the soil, attract malesto mate, then burrow back into the soil to lay eggs.Females can re-emerge and move to other sites, wherethey burrow in and lay more eggs. This behaviorresults in spotty infestations throughout a field. Somewireworms prefer loose, light and well-drained soils;others prefer low spots in fields where higher moistureand heavier clay soils are present.Larvae move up and down in the soil profile inresponse to temperature and moisture. After soiltemperatures warm to 50 F (10 C), larvae feed within6 inches (15 cm) of the soil surface. When soil temperaturesbecome too hot (>80 F, 27 C) or dry, larvaewill move deeper into the soil to seek more favorableconditions. Wireworms inflict most of their damage inthe early spring, when they are near the soil surface.During the summer months, the larvae move deeperinto the soil. Later as soils cool, larvae may resumefeeding nearer the surface, but the amount of injuryvaries with the crop.Wireworms pupate and the adult stage is spent withincells in the soil during the summer or fall of their finalyear. The adults remain in the soil until the followingspring.Damage: Wireworm infestations are more likely todevelop where grasses, including grain crops, aregrowing. Wireworms damage crops by feeding on thegerminating seed or the young seedling. Damagedplants soon wilt and die, resulting in thin stands. In aheavy infestation, bare spots may appear in the fieldand reseeding is necessary.Scouting Method: Decisions to use insecticides forwireworm management must be made prior to planting.No rescue treatments are available for controllingwireworms after planting. Producers have no easy30■ Figure 19. Click beetle or adult wireworm.(Roger Key, http://www.insectimages.org)


Insectsway to determine the severity of infestation withoutsampling the soil. Infestations vary from year to year.Considerable variation may occur both within andbetween fields.Sometimes the past history of a field is a good indicator,especially if wireworms have been a problem inprevious seasons. Also, crop rotation may impactpopulation levels.Two sampling procedures are available. One procedurerelies on the use of a corn-wheat seed mixture used asbait, placed in the soil, which attracts the wirewormsto the site (Figure 20). The other involves digging andsifting a soil sample for the presence of wireworms.Economic Threshold: If the average density is greaterthan one wireworm per bait station, the risk of cropinjury is high and a soil insecticide should be usedat planting to protect the sunflower. If no wirewormsare found in the traps, risk of injury is low; however,wireworms still may be present but were not detectedby the traps. When digging soil samples, 12 or morewireworms in 50 3-inch by 3-inch (8 cm by 8 cm)samples, is likely to result in damage to sunflower.Management: Seeds should be treated with an approvedinsecticide for protection of germinating seedsand seedlings.■ Seedcorn MaggotSpecies: Delia platura (Meigan)Description: Seedcorn maggots are larvae of smallflies resembling houseflies. The adult is a light grayfly about 0.2 inch (5 mm) long. Larvae are white,cylindrical, tapered anteriorly and also about 0.2 inch(5 mm) long (Figure 21). Larvae can be found insidedamaged seeds or in the soil nearby.Life Cycle: After soil temperatures reach 50 F (10 C)in the spring, the flies emerge, mate and then depositeggs in soil, especially where high organic matterexists. Eggs hatch in a few days and the maggots burrowinto seeds. Infected seeds often do not emerge,resulting in stand loss. Even when infested seeds dogerminate, plants may be weakened. No effective preplantmonitoring techniques are available for seedcornmaggots. Fields with extensive decaying organic matter,such as those that are heavily manured or wherea cover crop has been turned under, are particularlyattractive to egg-laying flies.Damage: The first sign of seedcorn maggot damage isareas in the field where seedlings have not emerged.Seedcorn maggots hollow out seeds or eat portions ofseedlings. Damage is most common in early plantingswhile the soil is cool, and if organic matter is high,such as when a green plant material is plowed into afield before planting. Females are strongly attracted todecaying organic matter for laying eggs.Scouting Method: Scouting to determine the risk ofseedcorn maggot infestation has not been developed.■ Figure 20. Wireworm bait station. (ExtensionEntomology)■ Figure 21. Seed corn maggot larvae. (Ric Bessin,University of Kentucky)31


■ CutwormsSpecies:Darksided cutworm Euxoa messoria (Harris)Redbacked cutworm Euxoa ochrogaster (Guenee)Dingy cutworm Feltia jaculifera (Walker)Description: Darksided cutworm — Forewingsof the adult darksided cutworm are usually light,powdery and grayish brown with indistinct markings(Figure 22). The larvae are pale brown dorsally andwhite on the ventral areas (Figure 23 ). Sides have numerousindistinct stripes. At maturity, they are about1.25 to 1.5 inches (32 to 38 mm) long and 0.19 inch (5mm) wide.Redbacked cutworm — The forewings of the adultredbacked cutworm are reddish brown with characteristicbean-shaped markings (Figure 24). The larvae aredull gray to brown with soft, fleshy bodies and may be1 to 1.25 inches (25 to 32 mm) long when fully grown(Figure 25). Larvae can be distinguished by two dullreddish stripes along the back.Dingy cutworm — Forewings are dark brown withbean-shaped markings as in the redbacked cutwormadults (Figure 26). Hind wings in the male are whitishwith a broad, dark border on the outer margin; in thefemale they are uniform dark gray. The larvae havea dull, dingy, brown body mottled with cream color.The dorsal area is pale with traces of oblique shading(Figure 27).Life Cycles: The female darksided and redbacked cutwormmoths deposit eggs in the soil in late July andearly August. The eggs remain dormant until the onsetof warm weather the following spring. The larvae ofboth species emerge from late May to early June. Theycontinue to feed and grow until about the end of June,when fully grown larvae pupate in earthen cells nearthe soil surface. The pupal period lasts about threeweeks. Both species have one generation per year.The adult dingy cutworms emerge in August and areactive until mid-October, with peak activity in September.Eggs are deposited in plants in the Compositaefamily in the fall. The larvae develop to the secondor third instar in the fall and overwinter in the soil.Pupation occurs in the spring to early summer. Onegeneration of this species is produced per year.■ Figure 22. Adult - Darksided cutwormEuxoa messoria. (Extension Entomology)■ Figure 23. Larva - Darksided cutwormEuxoa messoria. (Extension Entomology)■ Figure 24. Adult - Redbacked cutwormEuxoa ochrogaster. (Extension Entomology)32■ Figure 25. Larva - Redbacked cutwormEuxoa ochrogaster. (Extension Entomology)


InsectsDamage: Cutworm damage normally consists ofcrop plants being cut off from 1 inch (25 mm) belowthe soil surface to as much as 1 to 2 inches (25 to 50mm) above the soil surface. Young leaves also may beseverely chewed as a result of cutworms (notably thedarksided species) climbing up to feed on the plantfoliage.Most cutworm feeding occurs at night. During thedaytime, the cutworms usually will be just under thesoil surface near the base of recently damaged plants.Wilted or dead plants frequently indicate the presenceof cutworms. Cut-off plants may dry and blowaway, leaving bare patches in the field as evidence ofcutworm infestations.Scouting Method: Sampling should begin as soon assunflower plants emerge, and fields should be checkedat least twice per week until approximately mid-June.The Z pattern should be used in scouting fields forcutworms, with sampling points one and two near themargin as indicated in Figure 17.Stand reduction is determined by examining 100plants per five sampling sites for a total of 500 plants.A trowel or similar tool should be used to dig arounddamaged plants to determine if cutworms are present,since missing plants in a row do not necessarilyindicate cutworm damage (damage may be caused bya defective planter, rodents or birds).The Z pattern should be used again to determinecutworm infestation level by examining five 1-squarefoot(30 by 30 cm) soil samples per site (in the row)for a total of 25 samples.Economic Threshold: One larva per square foot (30by 30 cm) or 25 percent to 30 percent stand reduction.Management: Several different insecticides are registeredfor cutworm control in sunflower. Postemergenttreatment with an insecticide provides quick control ofsurface feeding cutworms.■ Palestriped Flea BeetleSpecies: Systena blanda (Melsheimer)Description: The adult is about 1/8 inch (3.2 mm)long and shiny black, with two white stripes on theback. The hind legs are enlarged and modified forjumping (Figure 28).Life Cycle: The life cycle of palestriped flea beetleson sunflower fields is poorly understood. However, theadult flea beetles seem to overwinter in the field undersoil clods, field debris and crop residues. They becomeactive again in the spring, perhaps feeding first onalfalfa and weeds before moving to and feeding onsunflower seedlings in June. They have been observedfeeding on sunflower through July. Palestriped fleabeetles have a wide host range, which includes variousweeds, potato, tomato, carrot, peanut, corn, oat,cotton, pea, beans, strawberry, watermelon, grape and■ Figure 26. Adult - Dingy cutworm Feltia jaculifera.(Extension Entomology)■ Figure 27. Larva - Dingy cutworm Feltia jaculifera.(Extension Entomology))■ Figure 28. Adult - Palestriped flea beetle.(Michael Catangui, SDSU)33


pumpkin. Palestriped flea beetles are considered animportant pest of commercially grown vegetables insome areas of the U.S. Recently, palestriped flea beetleshave been observed delaying regrowth of alfalfaand also were observed feeding on soybean seedlingsin eastern South <strong>Dakota</strong>.Damage: Palestriped flea beetles chew on the cotyledons,leaves and hypocotyls of sunflower seedlings,causing them to wilt and die. Injured leaves becomeriddled with holes, giving them a “lacey” appearance(Figure 29). The sunflower plant is most sensitive topalestriped flea beetle injury from seedling emergence(V-E) through the four-leaf stage (V-4). Significantstand losses may result from heavy feeding injury bythe palestriped flea beetles.Scouting Method: Surveys may be accomplished byusing yellow sticky cards placed close to the ground(Figure 30). Sampling seedlings for beetles also canaid in estimating populations and feeding injurylevels. Palestriped flea beetles move very fast and arehard to count directly on the seedlings or catch withan insect net.Economic Threshold: Control is recommended when20 percent of the seedling stand is injured and at riskto loss due to palestriped flea beetle feeding. This economicthreshold is a guideline based on published hailinjury data that predicts potential yield loss relative toseedling stand loss.Management: Palestriped flea beetles are hard tocontrol with chemical insecticides; research has shownthat treatments may provide up to 75 percent controlof adults.■ Figure 29. Damaged sunflower leaves bypalestriped flea beetle. (Michael Catangui, SDSU)■ Figure 30. Yellow sticky trap for monitoringpalestriped flea beetles. (Michael Catangui, SDSU)34


Insects■ <strong>Sunflower</strong> BeetleSpecies: Zygogramma exclamationis (Fabricius)Description: The sunflower beetle is associatedexclusively with sunflower. Adults (Figure 31) closelyresemble adult Colorado potato beetles and may beconfused with potato beetles. However, sunflowerbeetles are smaller and do not feed on potatoes, andColorado potato beetles do not feed on sunflower. Thehead of the adult is reddish brown and the thorax (areabetween head and abdomen) is pale cream-coloredwith a reddish-brown patch at the base. Each frontwing cover is cream-colored and has three dark stripesthat extend its length. A shorter lateral stripe ends atthe middle of the wing in a small dot that resembles■ Figure 31. Adult - <strong>Sunflower</strong> beetle Zygogrammaexclamationis. (Extension Entomology)an exclamation point. The beetle is ¼ to ½ inch (6 to12 mm) long and 3/32 to 3/16 inch (2 to 4 mm) wide.Eggs are about 1/16 inch (1.5 to 2 mm) long, cigarshapedand cream yellow. <strong>Sunflower</strong> beetle larvaeare yellowish green with a brown head capsule andhumpbacked in appearance. Newly hatched larvae areabout 1/16 inch (1.5 to 1.75 mm long), and will reacha length of about an inch (8 to 10 mm) when fullydeveloped (Figure 32).Life Cycle: The sunflower beetle has one generationper year in <strong>North</strong> <strong>Dakota</strong>. The adults overwinter in thesoil, emerging in late May or early June. Shortly afteremergence, the beetles begin to feed, mate and layeggs singly on stems and undersides of leaves. Adultslive for about 8½ weeks and lay eggs for a six- to seven-weekperiod. Each female lays approximately 850eggs, with a range of 200 to 2,000 eggs. Eggs hatchinto larvae in about one week (Figure 33). The larvaehave four instars, which feed and are present in fieldsfor about six weeks. When mature, the larvae enter thesoil to pupate in earthen cells. The pupal stage lastsfrom 10 days to two weeks. Adults of the new generationemerge and feed for a short period on the bractsof the sunflower head or on the uppermost leaves ofthe plant before re-entering the soil to overwinter.Damage: Adult sunflower beetles damage plants soonafter they emerge from overwintering. Damage tocotyledons is generally slight, but the first true leavesmay be severely damaged or completely consumed.Fields may be severely defoliated if beetles are numerous.Adults feed predominately on leaf margins while■ Figure 33. Eggs - <strong>Sunflower</strong> beetle. (Larry Charlet)■ Figure 32. Larva - <strong>Sunflower</strong> beetle Zygogrammaexclamationis. (Larry Charlet)35


36larvae feed on the entire leaf surface. When larvaeare numerous, damaged leaves take on a lacy appearance.Most larval feeding occurs at night, and adultswill feed during the day. During the daytime, larvaetypically rest in the terminal growth area, where theyare easily found in leaf axils and flower buds. If larvalfeeding is severe, defoliation can reduce yield due topoor seed set or fill.The late summer generation of emerging sunflowerbeetle adults and late-maturing larvae rarely causeseconomic damage to the sunflower crop. However, insome cases, they have been abundant enough to causefeeding injury on late-planted sunflower.Scouting Method: Sampling sites should be at least75 to 100 feet (23 to 31 m) from the field’s marginswhen determining if an entire field should be treated.Adults and/or larvae should be counted on 20 plants ateach of five sampling sites along an X pattern for a totalof 100 plants. The average number of adults and/orlarvae per plant then should be determined.The average percent defoliation of plants is determinedwhen damage is evident in the field by examining20 plants per five sampling sites for a total of 100plants (Figure 34).Economic Threshold: As sunflower plants develop,they can tolerate more feeding damage. In the seedlingstage, one to two adults per seedling is the recommendedeconomic threshold. For larvae, the treatmentthreshold is when populations reach 10 to 15 larvaeper plant, or when approximately 25 percent defoliationoccurs on the upper eight to 12 leaves (activegrowing part). Management normally is advised ifdefoliation reaches the 25 percent to 30 percent levelat the late vegetative and early bud stages and it appears(based on larval size of less than ¼ inch or 6mm) that more defoliation will occur on the activelygrowing part of sunflower plant. However, if defoliationis 25 percent and the majority of larvae are about1/3 inch (8 mm) long, they have reached maturity andsoon will stop feeding. Then, management probably isnot warranted.Management: Insecticide seed treatments and foliarinsecticides are effective in reducing spring populationsof the adult sunflower beetle. Application of afoliar insecticide is recommended only when beetlepopulations have reached an economic thresholdlevel in a field. Insecticides are effective in preventingeconomic loss when applied to actively feedingadults and/or larvae. Adult and larval populations ofsunflower beetle decrease as planting date is delayed.Defoliation also is lower at the later planting dates.As a result, delayed planting is effective in preventingyield reductions caused by sunflower beetle feeding,but may make fields more attractive to later seasoninsects, such as red sunflower seed weevil. Springor fall cultivation does not reduce the overwinteringpopulations of sunflower beetle adults or influence thepattern of emergence from the soil during the springand summer. <strong>Sunflower</strong> hybrids with resistance to thesunflower beetle are not available. Natural enemies includeparasites of the eggs, larvae and adults. Generalpredators, such as ladybird beetles, carabid beetles,lacewings, stink bugs, nabids and anthocorids, destroyboth eggs and larvae of the sunflower beetle.■ Figure 34. Percent defoliation of sunflower leaves.(Extension Entomology)


Insects■ <strong>Sunflower</strong> Bud MothSpecies: Suleima helianthana (Riley)Description: <strong>Sunflower</strong> bud moths have a wingspreadof about 0.63 inch (16 to 18 mm). Each gray-brownforewing has two dark transverse bands (Figure 35).One band extends across the middle of the wing andthe second band is near the wing tip. The larva hasa dark head capsule with a smooth, cream-coloredbody and is 0.31 to 0.43 inch (8 to 11 mm) at maturity(Figure 36).Life Cycle: Two generations of sunflower bud mothare produced per year in <strong>North</strong> <strong>Dakota</strong>. Adults emergefrom overwintering pupae during the last week of Mayto mid-June.A few days after adult emergence, eggs are depositedon the terminals of immature sunflower or on the receptacleof mature sunflower. Eggs also are depositedin leaf axils. The hatched larvae begin tunneling intothe sunflower plant. The initial infestation in mid-Juneis characterized by an entrance hole surrounded byblack frass, or insect excrement.Mature larvae pupate within the sunflower plant. Pupaemove to the opening of the entrance holes formedin the stem or head tissue so that adults can emergeeasily.The second-generation adults appear in July and August.Infestation by the second-generation larvae is noteconomically important.Damage: In early planted sunflower, 65 percent to 85percent of the infestations occur in the stalks. In lateplantedsunflower, most infestations occur in the pithareas of the head.Up to 4,000 larvae per acre have been reported in<strong>North</strong> <strong>Dakota</strong> and 24,000 larvae per acre have beenreported in Texas. Despite these high populations,economic loss due to this insect has been minimal.The only time yield loss is noticeable is when larvaeburrow into unopened buds, preventing proper headdevelopment. The larvae normally do not feed ondeveloping seeds but confine feeding activities tothe fleshy part of the head. Yield loss has not beeneconomically significant, although injury by the larvaproduces malformations in both the head and stalk.■ Figure 35. Adult - <strong>Sunflower</strong> bud moth Suleimaheliathana. (Extension Entomology)■ Figure 36. Larva - <strong>Sunflower</strong> bud moth Suleimaheliathana. (Extension Entomology)Scouting Method: A field monitoring scheme forthis insect has not been established since it is not ofeconomic significance.Economic Threshold: None established.Management: Insecticide use has not been warrantedfor control of sunflower bud moth.37


■ Long-horned <strong>Sunflower</strong> StemGirdler or Longhorned BeetleSpecies: Dectes texanus LeConteDescription: The adult is pale gray and 5/8 inch (6 to11 mm) in length, with long gray and black bandedantennae. (Figure 37) Eggs are about 0.1 inch (1.9mm) long and elongate, and turn dark yellow prior tohatch. Mature larvae are yellowish and 1/3 to 1/2 inch(7 to 13 mm) in length. Larvae bear fleshy protuberanceson the first seven abdominal segments. (Figure38).Life Cycle: Adults appear in mid-June to early July inthe southern Plains. Emergence continues through August,with 50 percent emerged by mid-July in Texas.Eggs are laid four to eight days after mating and eggsare deposited singly in leaf petioles. Approximately■ Figure 37. Adult - Longhorned beetle Dectestexanus. (Extension Entomology)50 eggs are laid per female, with about one-third viable.Eggs hatch in six to 10 days. Larvae tunnel andfeed in the petioles and stem pith and finally move tothe base of the plant to overwinter. Larvae developthrough six instars. In late summer, the mature larvaegirdle the inside of the lower stalk or root crown, movebelow the girdle and pack frass into the tunnels. Stalksoften break at the point of girdling, leaving the larvaprotected in its frass-packed tunnel during the winter.The larvae are cannibalistic and stalks usually harboronly a single larva, even though several may havehatched in a stalk. This insect has one generation peryear. Host plants include sunflower, soybean, ragweedand cocklebur.Damage: Plant damage due to adult feeding appearsto be insignificant since the scars do not penetrate thecortex nor encircle the stalk. Larval feeding is apparentwhen stalks lodge at the point of the girdle, about2.5 to 3.5 inches (7 to 9 cm) above the soil surface.Scouting Method: None has been developed.Economic Threshold: None established.Management: In the southern Plains, later plantingdates and fall or winter tillage have reduced sunflowerinfestations by this pest. Perennial sunflower speciesare resistant to stalk infestation, indicating the possibilityof breeding cultivars resistant to the longhornedsunflower stem girdler. Chemical treatments onsoybean and sunflower are ineffective against larvaeand were determined to be impractical against adultsbecause of the extended emergence period. Whenlarvae are present in the stalks, plants do not alwayslodge. Utilizing lower plant populations that encouragethicker stalks may help reduce damage fromlodging. If fields are suspected to be infested, promptharvesting will limit losses from lodging.38■ Figure 38. Larva - Longhorned beetle Dectestexanus. (Extension Entomology)


Insects■ <strong>Sunflower</strong> MaggotsSpecies:<strong>Sunflower</strong> receptacle maggot, Gymnocarena diffusa(Snow)<strong>Sunflower</strong> maggot, Strauzia longipennis (Wiedemann)<strong>Sunflower</strong> seed maggot, Neotephritis fi nalis (Loew)Description: The adult forms of all three sunflowermaggots (flies) have wings with a distinct brown oryellowish-brown pattern. The name “picture-wing fly”has been given to flies of this type. While all three flyspecies are similar in appearance, they do have distinguishingdifferences.Gymnocarena diffusa - This species is the largest ofthe three, with a body about 0.4 inch (10 mm) longand a wing span of approximately 0.75 inch (19 mm)(Figure 39). The eyes of this species are bright greenand the wings have a yellowish-brown and somewhatmottled appearance. G. diffusa larvae attain a length ofnearly 0.31 inch (8 mm) at maturity. The larvae taperfrom the front to rear and are yellowish white (Figure40).Strauzia longipennis - Adults of this species have awing spread of about 0.5 inch (13 mm) and a body0.25 inch (6 mm) long (Figure 41). The wings bearbroad, dark bands that form a fairly distinct F-shapedmark near the tips. The larvae of S. longipennis arecreamy white, headless and legless, as are the othertwo species (Figure 42). They taper slightly at bothends and attain a length of about 0.28 inch (7 mm) atmaturity.Neotephritis fi nalis - This sunflower maggot is thesmallest of the three species, with the adult havinga body length of about 0.25 inch (6 mm) and a wingspan of approximately 0.28 inch (7 mm) (Figure43). The wings have a brown lacelike appearance. N.fi nalis larvae attain a length of 0.19 inch (4.5 mm) atmaturity. The small, brown pupa of N. fi nalis is foundin the face of the sunflower bud, usually surrounded bya small number of damaged florets (Figure 44).Life Cycles: Adults of G. diffusa emerge in late Juneto early July after sunflower buds reach 2 to 4 inches(5 to 10 cm) in diameter. Eggs are laid on the bracts■ Figure 39. Adult - <strong>Sunflower</strong> receptacle maggotGymnocarena diffusa. (Extension Entomology)■ Figure40. Larva- <strong>Sunflower</strong>receptaclemaggotGymnocarenadiffusa.(ExtensionEntomology)■ Figure 41. Adult - <strong>Sunflower</strong> maggot Strauzialongipennis. (Extension Entomology)■ Figure 42. Larva - <strong>Sunflower</strong> maggot Strauzialongipennis. (Extension Entomology)39


of the developing sunflower heads. Egg laying occursfrom mid-July through August. The hatched larvaetunnel into the spongy tissue of the receptacle. Damageto the head is negligible. After 30 days, the maturelarvae cut a small emergence hole on the underside ofthe receptacle and drop into the soil to pupate. Overwinteringpupae are found about 7.5 inches (19 cm)deep in the soil by August or early September. Somelarvae will pupate in the sunflower head. Only onegeneration per year occurs in <strong>North</strong> <strong>Dakota</strong>.Strauzia longipennis has one generation per year. Thisinsect overwinters as a larva in plant debris in thesoil. Pupation and adult emergence is completed inearly June. Females lay eggs in stem tissue of youngsunflower, and larvae feed in the pith tissue for muchof the growing season.■ Figure 43. Adult - <strong>Sunflower</strong> seedmaggot Neotephritis finalis. (ExtensionEntomology)Unlike the other two species of sunflower maggots,two complete generations per year of N. fi nalis occurin <strong>North</strong> <strong>Dakota</strong>. Adults of N. fi nalis emerge duringthe first week of July. Egg deposition occurs on the corollaof incompletely opened sunflower inflorescences.The total larval period is 14 days. The first generationof N. fi nalis pupates in the head; the second generationoverwinters in the soil as pupae.Damage: Damage by sunflower maggots has beennegligible.The maggots of Gymnocarena diffusa feed on thespongy receptacle tissue of the sunflower head andfeeding may cause partially deformed heads. Larvaedo not feed on developing seeds.The magnitude of damage to sunflower seeds by N.fi nalis larvae depends largely on the stage of larvaland seed development. Seed sterility occurs whennewly hatched larvae tunnel into the corolla of youngblooms. Observations indicate that a single larva feedingon young flowers will tunnel through 12 ovaries.Mature larvae feeding on older sunflower heads willdestroy only one to three seeds.While infestation levels of S. longipennis occasionallyhave reached nearly 100 percent, damage from larvalfeeding is usually light. Part of a commercial sunflowerfield next to a grassed waterway or other watersource sometimes supports a higher than usual infestation.Under these conditions, high larval numbers ofeight to 10 per stalk may be found and stalk breakagecan occur. Stalk breakage of up to 30 percent of theplants has been recorded.Scouting Method: A scouting method has not beendeveloped for sunflower maggots because of the negligibleinjury caused by these insects.Economic Threshold: None established.Management: Insecticide use has not been warrantedfor control of sunflower maggots.40■ Figure 44. Pupae - <strong>Sunflower</strong> seed maggotNeotephritis finalis. (Extension Entomology)


Insects■ <strong>Sunflower</strong> Stem WeevilSpecies: Cylindrocopturus adspersus (LeConte)Description: Adult sunflower stem weevils are about3/16 inch (4 to 5 mm) long and grayish brown, withvarying-shaped white spots on the wing covers andthorax (Figure 45). The snout, eyes and antennae areblack. The snout is narrow and protrudes down andbackward from the head. Eggs are deposited inside theepidermis of sunflower stems and are very small (0.51mm long by 0.33 mm wide), oval and yellow, makingthem difficult to see. The larvae are ¼ inch (5 to 6mm) long at maturity, legless and creamy white witha small, brown head capsule (Figure 46). They arenormally in a curled or C-shaped position within thesunflower stalk. Pupae are similar to the adult in sizeand creamy whiteLife Cycle: Only one generation occurs per year. Larvaeoverwinter in sunflower stalks and crown roots andpupate in the spring, and adults emerge in mid to lateJune, feeding on the epidermal tissue of the sunflowerfoliage and stem. This feeding does not affect plantvigor. Mating occurs soon after emergence of adults.Just prior to egg laying, females descend to the lowerportion of the plant to deposit eggs individually in thestem tissue. Approximately 50 percent of ovipositionoccurs by mid-July. Upon hatching in early July, thefirst instar (larval growth stage) larvae feed on subepidermaland vascular tissue. Feeding is concentrated inthe pith tissue as the larvae develop to third and fourthinstar stages. By the last week in August, the larvaedescend while feeding to just above the soil surface.A chamber is constructed in the stem, and the weeviloverwinters there as a fifth instar larva. Pupation ofthe overwintering larva occurs the following year inearly June.Damage: Adult sunflower stem weevil feeding causesminor damage to the stem and leaf tissue of the plant.More importantly, adult weevils have been implicatedin the epidemiology of the sunflower pathogenPhoma black stem (Phoma macdonaldii Boerma) andcharcoal stem rot (Macrophomina phaseolina (Tassi)Goid).Larval injury can cause the stem to weaken from tunneling,pith destruction and especially by constructionof overwintering chambers at the stalk base. At larvalinfestations of 20 to 25 or more per stalk, the plantsrun a risk of stalk breakage and loss of the entire capitual(head). Risk of breakage is greatest when plantsare under drought stress and/or during periods of highwinds. The breakage typically occurs at or slightlyabove the soil line, in contrast to breakage attributedto a stalk disease, which normally occurs farther up onthe stalks.Scouting Methods: Field monitoring for sunflowerstem weevils to estimate population size is important.However, adults are difficult to see on the plantsdue to their small size, cryptic color and “play dead”behavior. They are inactive on the plant or fall to theground when disturbed and remain motionless. Adultscan be found on both surfaces of the leaves, the lowerportions of the stem, in leaf axils, within the dried■ Figure 45. Adult - <strong>Sunflower</strong> stem weevilCylindrocopturus adspersus. (Extension Entomology)■ Figure 46. Larva - <strong>Sunflower</strong> stem weevilCylindrocopturus adspersus. (Extension Entomology)41


cotyledons or in soil cracks at the base of the sunflowerplant. Yellow sticky traps were unsuccessful inrelating captured adult numbers to larval infestations.Sampling for the larval stage is difficult since theydevelop totally within the sunflower plant. The onlymethod for detecting the presence of larvae is to splitthe sunflower stem, a time-consuming process.Field scouting for adults should begin when plantsare in the eight- to 10-leaf stage, developmental stageV-8 to V-10, or late June to early July, and continueuntil mid-July. Select sampling sites 70 to 100 feet infrom the field margin. Count the number of adults onfive plants at five randomly selected sampling sitesthroughout the field for a total of 25 plants. Calculatethe average number of weevils per plant. Use an Xpattern (or W pattern) to space sample sites throughoutthe entire field. When scouting for stem weevils,approach plants carefully and slowly to avoid disturbingthe adults.Economic Threshold: Average field counts of oneadult sunflower stem weevil per three plants can resultin damaging larval densities of more than 40 larvaeper stalk at the end of the season.Management: Insecticidal treatment, if needed basedon field counts, should be initiated in late June orearly July before significant egg laying has occurred.Cultural control tactics, including delayed planting,altered plant population and tillage, are useful formanaging the sunflower stem weevil. Delayed plantingof sunflowers until late May or early June has beeneffective in reducing densities of larvae in the stem.Reducing plant population results in an increasedstalk diameter and, as a result, decreases damage fromlodging. Combinations of disking to break up stalksand moldboard plowing to bury them at a depth of 6inches (15 cm) can increase larval/pupal mortality andseverely impact the emergence of adult stem weevils.Otherwise, larvae/pupae are physically protected inthe woody stalks. Survival is affected only by performingboth operations. Greenhouse and field experimentshave shown resistance to feeding, ovipositionand larval development in many native species ofsunflower. Field research for resistant sunflower germplasmis under way. Natural enemies of the sunflowerstem weevil include parasitic wasps that attack boththe egg and larval stages.■ Black <strong>Sunflower</strong> Stem WeevilSpecies: Apion occidentale (Fall)Description: Adults are black and only 0.1 inch (2.5mm) long from the tip of the snout to the tip of theabdomen (Figure 47). The snout is very narrow andprotrudes forward from the head, which is small in relationto the rather large, almost globose body. Larvaeof A. occidentale are very similar in appearance to C.adspersus, except they are only 0.1 to 0.12 inch (2.5 to3 mm) long at maturity and yellowish (Figure 48).Life Cycle: Apion occidentale overwinters as an adultin soil, plant residue, sod and weed clusters and beginsto emerge and feed on volunteer sunflower as soonas the plants reach the early seedling stage. Femalesdeposit eggs under the epidermis of the stem or leafpetioles. Larvae emerging from these eggs tunnel inthe pith area of the stem, pupate and emerge as adultsin early August. Little or no adult activity is observed■ Figure 47. Adult - Black sunflower stem weevilApion occidentale. (Extension Entomology)42■ Figure 48. Larva - Black sunflower stem weevilApion occidentale. (Extension Entomology)


Insectsfor about two weeks in late July and early August.Black sunflower stem weevil adults emerging in Augustalso feed on the leaves and stems of the plant, butas the plant matures and the leaves begin to die, theadults move under the bracts of the sunflower head,where they can be observed feeding until the plantsare harvested.Damage: Adult feeding generally is considered as insignificantmechanical injury. Like the sunflower stemweevil, the black sunflower stem weevil is suspectedof vectoring Phoma black stem disease in sunflowerfields. In situations of extremely high populationsfeeding on seedling sunflowers, stand loss has occurred.However, in most cases, populations are toolow to cause economic damage and stalk tunnelingonly results in minor injury to the plant.Scouting Method: A scouting method has not beendeveloped for the black sunflower stem weevil.Economic Threshold: None established.Management: Recommendations for insecticidal controlof this insect have not been developed.■ Figure 49. Adult - <strong>Sunflower</strong> root weevil Barisstrenua. (Extension Entomology)■ <strong>Sunflower</strong> Root WeevilSpecies: Baris strenua (LeConte)Description: Adults are rather robust-looking weevils,with a somewhat oval-shaped body (Figure 49). Theyare 0.25 inch (6 mm) long and have a short, almostblunt, downward projecting snout. Their coloration isdull black in contrast to the shiny, black appearanceof A. occidentale. Baris strenua larvae are similar inappearance to C. adspersus larvae but much larger andare not located in the sunflower stalk (Figure 50).Life Cycle: Adult root weevils emerge during the latterpart of June. They feed on sunflower foliage in earlymorning and late afternoon. About two weeks afteremergence, the adults begin to congregate around theroot zone near the soil surface. Continued feeding andcopulation occur during this period. Feeding activityduring this period produces callus tissue, underwhich the bright yellow eggs are deposited two orthree at a time. Hatching of the larvae normally occursduring the second week in July. Baris strenua larvaeare not very mobile. Most of the feeding (consistingof circular tunnels) and development to fourth instartakes place in the same area where hatching occurs. Atabout the time that the fourth larval stage is reachedin late August to early September, the plant becomessignificantly dehydrated and encapsulation of thelarvae within a “soil cocoon” begins. This “larvalcocoon” overwinters among the remaining roots in thesoil. Overwintering larvae have been recovered from adepth of 15 inches (38 cm) in <strong>North</strong> <strong>Dakota</strong>.Damage: The sunflower root weevil adult, like theother two stem weevils, causes negligible mechanicalinjury to the foliage of the sunflower plant. The destructionof root tissue by the larvae of the sunflowerroot weevil causes the plants to wilt and lodge if theinfestation is severe. The damage to fields attacked bythe weevil tends to be localized.Scouting Method: A scouting method has not beendeveloped because damage caused by this pest hasbeen minor.Economic Threshold: None established.Management: Insecticide use has not been warrantedfor the control of the sunflower root weevil.■ Figure 50. Larva - <strong>Sunflower</strong> root weevil Barisstrenua. (Extension Entomology)43


■ Thistle Caterpillar (Painted Lady)Species: Vanessa cardui (Linnaeus)Description: The body of the adult is about 1 inch(25 mm) long with a wingspread of about 2 inches(50 mm) (Figure 51). The upper wing surfaces arebrown with red and orange mottling and white andblack spots. The undersides of the wings are marblegray, buff and white. Each hind wing possesses a rowof four distinct and obscure eyespots. Eggs are small,spherical and white. The larvae are brown to black andspiny, with a pale yellow stripe on each side (Figure52). When mature, the larvae are 1.25 to 1.5 inches(32 to 38 mm) long. The chrysalis, or pupa, is moltengold and about 1 inch (25 mm) long.■ Figure 51. Adult - Painted lady butterfly Vanessacardui. (Extension Entomology)Life Cycle: The painted lady butterfly is indigenousto the southern U.S. and migrates annually to thenorthern U.S. and Canada. The painted lady breeds inthe north-central states and Canada, migrates south forthe winter and returns to the northern areas in earlyJune. Eggs are laid on Canada thistle, wild and cultivatedsunflower, and many other host plants. Hatchingoccurs in about one week. Larvae feed on sunfloweruntil they reach maturity in late June or early July.Chrysalids are formed and hang from the leaves of theplant. Butterflies will emerge in about 10 days fromthe chrysalid and a second generation begins.Damage: The caterpillars (larvae) feed on the leavesand, when numerous, may defoliate infested plants.The larvae produce a loose silk webbing that coversthem during their feeding activity. Black fecal pelletsproduced by the larvae often are found in proximity tothe webbing.The effect of defoliation by the larvae on the yield ofsunflower is similar to that described for defoliation bysunflower beetle larvae.Scouting Method: Sampling sites should be at least75 to 100 feet (23 to 31 m) from the field marginswhen collecting data to determine whether an entirefield should be treated. Infestations frequently will beconcentrated in areas of a field where Canada thistleplants are abundant. Plants should be examined carefullyfor the presence of eggs and/or larvae.The field should be monitored by using the X pattern,counting 20 plants per sampling site for a total of 100plants to determine percent defoliation (Figure 35).Economic Threshold: The threshold is 25 percent defoliation,provided that most of the larvae are still lessthan 1.25 inch (32 mm) long. If the majority of thelarvae are 1.25 to 1.5 inches (32 to 38 mm) long, mostof the feeding damage already will have occurred andtreatment is not advised.Management: Insecticide use generally has not beenwarranted for control of larvae of the painted lady.However, instances of high localized infestations haveoccurred within certain fields where spot treating maybe necessary. Disease outbreaks, indicated by dyinglarvae present on leaves, often occur when large populationsare present.44■ Figure 52. Larva - Painted lady butterfly Vanessacardui. (Extension Entomology)


Insects■ <strong>Sunflower</strong> MidgeSpecies: Contarinia schulzi Gagne'Description: The tan body of the adult sunflowermidge is about 0.07 inch (1.69 mm) long, with awingspan of about 0.19 inch (4 mm) (Figure 53). Thewings are transparent with no markings except theveins. The larvae attain a length of nearly 0.09 inch(2.42 mm) at maturity and they are cream to yellowishorange when fully grown (Figure 54). They aretapered at the front and rear, with no legs or apparenthead capsule.Life Cycle: The sunflower midge overwinters in thesoil as a cocooned larva and pupates during June andJuly in <strong>North</strong> <strong>Dakota</strong> and Minnesota. Typically, theinitial peak of first-generation adult emergence occursin early to mid-July. A second peak occurs about sevento 10 days later. They prefer to lay eggs on sunflowerbuds with a diameter greater than 1 inch (25 mm).Larvae initially feed on margins of the head betweenthe bracts surrounding the heads. Larvae migrate tothe base of the developing seeds and to the centerof the head as it develops. Presence of the larvaefrequently is determined by necrotic areas at the baseof or between the bracts. As midge larvae mature,they move to the surface of the head and drop to theground. A partial, second generation occurs in August.Second-generation adults oviposit among the seeds.Damage: Damage to sunflower is a result of firstgenerationlarval feeding in developing heads. Whenpopulations are low, damage is restricted to the baseof the bracts of the head and causes slight localizednecrosis but little if any economic loss. When manylarvae are present, feeding prevents ray petal formationand distorts the growth of the developing sunflowerhead. If the abnormal growth is severe, the backof the head overgrows the front and little or no seedproduction occurs (Figure 55). If an infestation occursin the early bud stage, the bud may be killed.Often midge damage is restricted to field marginsor small portions of fields and economic losses areminimal. However, when populations are very heavy,damage will extend throughout the field and substantialeconomic losses occur. The extent of damage fromsecond generation larvae is unknown.Scouting Method: None established.Economic Threshold: None established.Management: Because effective chemical and othercontrols are not available, sunflower midge managementrelies on cultural practices done prior to planting.If a midge infestation is anticipated, new fieldsshould be established away from fields damaged theprevious season. To minimize the risk of all plantingsbeing at their most susceptible stage at midge emergence,several planting dates should be used. If available,growers should consider using a tolerant hybrid.■ Figure53. Adult- <strong>Sunflower</strong>midgeContariniaschulzi.(ExtensionEntomology)■ Figure 54. Larva - <strong>Sunflower</strong> midge Contariniaschulzi. (Extension Entomology)■ Figure 55. Severe damage to receptacle and seeddevelopment occurs when midge infection is high.(Extension Entomology)45


46■ Red <strong>Sunflower</strong> Seed WeevilSpecies: Smicronyx fulvus LeConteDescription: Red sunflower seed weevil adults are 0.1to 0.12 inch (2.5 to 3.06 mm) long and reddish brown(Figure 56). The larvae are small, 0.10 inch (2.54 mm)long, cream-colored, legless and C-shaped (Figure 57).Life Cycle: Red sunflower seed weevil emergenceoccurs in late June and early July. The newly emergedadults feed on sunflower buds or floral tissues. Oncepollen is available, the adults include it in their diet.Females need to feed on sunflower pollen for severaldays prior to egg deposition. Eggs are depositedwithin young developing seeds. Normally a singleegg is placed in each seed, although 8 percent to 12percent of the seeds may contain several eggs.■ Figure 56. Adult - Red sunflower seed weevilSmicronyx fulvus. (Extension Entomology)■ Figure 57. Larva - Red sunflower seed weevilSmicronyx fulvus. (Extension Entomology)The small, white eggs hatch in approximately oneweek. The larvae consume a portion of the kernel, andthis feeding causes economic damage. After completionof larval development, the majority of the larvaedrop to the ground. Larval drop occurs from mid-August through September. The larvae overwinter inthe soil at a depth of about 6 inches (15 cm). Larvaepupate in late June of the following year and the pupalperiod lasts about one week. A single generation peryear is produced in <strong>North</strong> <strong>Dakota</strong>.Damage: While the kernel of some seeds may betotally eaten, most seeds are only partially consumed.The separation of undamaged from weevil-damagedseed is difficult.Most larvae drop from the head to the soil after completingtheir development, but a small percentage mayremain in the seed and are present at harvest. Growerswho encounter a seed weevil infestation may want todelay harvest to allow most of the weevil larvae to exitthe seeds to avoid having larvae in the harvest bin.Larvae that are still in the seed at bin filling time aredone feeding and can cause heating and moistureproblems. Larvae harvested with the seed cannot becontrolled until they have completed development andhave emerged from the infested seeds. Once emerged,they are susceptible to fumigation. But fumigationnormally is not recommended. However, the mostadvantageous time to initiate control of seed weevil isin the field when the adult weevils are active, but priorto egg deposition.Economic Thresholds: The economic threshold varieswith differences in plant population, the cost of insecticideapplication and the market price of sunflower.The procedure for calculating the economic thresholdis discussed in the <strong>NDSU</strong> Extension sunflower seedweevil publication (E-817). Currently, an infestationlevel of four to seven seed weevil adults per head inoil sunflower or one seed weevil per head in confectionerysunflower is the average economic threshold.The optimal period for insecticide treatment is whenat least three out of 10 plants in the field are at earlybloom (R-5.1 to R-5.4, Figure 4) and the economicthreshold has been reached. If spray application isdelayed past when more than four out of 10 plants areat stage R-5.4, many eggs already will be laid in thedeveloping seeds and those eggs and larvae cannot becontrolled. If fields are sprayed too early, reinfesta-


Insectstion may occur in areas with a high weevil population.After spraying, fields should be rechecked periodicallyto determine if reinfestation is reaching the economicthreshold. Continue rechecking until most of the headsin the field have reached the R-5.7 stage. At that stage,most eggs already will have been laid and most seedswill be too mature to be suitable for further red seedweevil egg oviposition.Scouting Method: Begin by taking samples from 12plants, three plants from each of the four field sides.Sampling sites should be at least 75 feet (21 m) infrom field borders, which often have an inordinatelyhigh number of weevils. The total number of weevilscounted should be compared to the sequential samplingtable in the most recent <strong>NDSU</strong> Extension sunflowerseed weevil publication (E-817). According tothe table, take one of three possible actions: Stop sampling,no action is needed; stop sampling and treat;or, take more samples because a decision cannot bereached. When populations are low or high, sequentialsampling allows a quick decision with few samples.If populations are near the economic threshold, moreprecision is needed to making an accurate determinationand more samples are required.NOTE: To more precisely check individual sunflowerheads for red sunflower seed weevils, the face of theheads should be sprayed with a commercial formulationof mosquito repellent containing diethyl toluamide(DEET). This will cause the weevils to moveout from between the florets where they can be moreaccurately counted. Consult the most recent <strong>NDSU</strong>Extension sunflower seed weevil publication (E-817)for a table to convert the visual counts to the absolutenumber of weevils (both counted and uncounted).Management: Several federally registered insecticidesare available for control of sunflower seed weevils inthe U.S. Early planting of sunflower reduces achenedamage caused by the red sunflower seed weevil withoutcausing a measurable reduction in oil content andachene weight.Surrounding a sunflower field with a ring of earlyblooming sunflower effectively can trap immigratingred sunflower seed weevils into a small portionof the field, where they can be controlled efficiently.The trap cropping method given in publication E-817is as effective and more cost efficient than standardinsecticide treatment for control of red sunflower seedweevils.■ Gray <strong>Sunflower</strong> Seed WeevilSpecies: Smicronyx sordidus LeConteDescription: Adults of the gray sunflower seed weevilare slightly larger (0.14 inch long) than S. fulvus andgray (Figure 58). The larvae are small, 0.12 inchlong (3.1 mm), cream-colored, legless and C-shaped(Figure 59).Life Cycle: Gray sunflower seed weevil emergence occursin late June and early July and reaches 50 percentemergence about 10 days before the red sunflowerseed weevil. The newly emerged adults feed on floralbuds. Oviposition occurs on flowers in the bud stageand before red sunflower seed weevil ovipositionbegins. Female gray sunflower seed weevils do not layas many eggs as do females of the red sunflower seedweevil.■ Figure 58. Adult - Gray sunflower seed weevilSmicronyx sordidus. (Extension Entomology)■ Figure 59. Larva - Gray sunflower seed weevilSmicronyx sordidus. (Extension Entomology)47


The larvae feed in a single achene, and infestedachenes are enlarged and protrude above surroundinguninfested achenes. The majority of the larvae dropsto the ground from mid-August through Septemberand overwinters in the soil. Larvae pupate in late Juneand a single generation per year is produced in <strong>North</strong><strong>Dakota</strong>.Damage: Seeds infested by the gray seed weevil lacka kernel and, due to their light weight, the seeds maybe lost during the harvesting process. Because of theirlow population levels and low fecundity, the gray sunflowerseed weevil usually does not cause economicdamage, especially in oil sunflower fields. In confectionfields, however, populations of the gray sunflowerseed weevil may be sufficiently high to warrant treatmentat the late bud stage (R-3 to R-4).As with the red sunflower seed weevil, larvae normallydrop from the head to the soil after completing theirdevelopment. Larvae that do not emerge will presentthe grower with the same problem as unemerged redsunflower seed weevil larvae.Scouting Method: Normally, gray sunflower seedweevil populations are too low to cause economicdamage. However, if an area has had a history of highpopulations, fields, especially confection fields, shouldbe sampled beginning at bud stage R-2 (Figure 4).Sampling should be done as for the red sunflower seedweevil and continue until plants are blooming.Economic Thresholds: None established.Management: Several insecticides are federally registeredfor control of sunflower seed weevils in the U.S.If fields are to be treated with insecticides, they shouldbe sprayed while the plants are still in early bud stage.By late bud stage, most oviposition already will haveoccurred.■ <strong>Sunflower</strong> MothSpecies: Homoeosoma electellum (Hulst)Description: The adult is a shiny gray to grayish tanmoth about 0.38 inch (9 mm) long, with a wingspanof about 0.75 inch (19 mm) (Figure 60). The hindwings are devoid of markings; however, the forewingshave a small, dark, discal dot near the center of eachwing and two or three small, dark dots near the leadingmargin of each wing. When at rest, the wings areheld tightly to the body, giving the moth a somewhatcigar-shaped appearance. The larva has alternate darkand light-colored longitudinal stripes on a light brownbody (Figure 61). The larva is about 0.75 inch (19mm) long at maturity.■ Figure 60. Adult - <strong>Sunflower</strong> moth Homoeosomaelectellum. (Extension Entomology)48■ Figure 61. Larva - <strong>Sunflower</strong> moth Homoeosomaelectellum. (Extension Entomology)


InsectsLife Cycle: <strong>Sunflower</strong> moth migrations from thesouth-central U.S. normally appear in <strong>North</strong> <strong>Dakota</strong>in early to mid-July. The moths are highly attractedto sunflower that is beginning to bloom. Individualfemale moths will deposit up to 30 eggs per day onthe surface of open sunflower heads. The eggs hatchwithin 48 to 72 hours and the newly emerged larvaefeed on pollen and florets. The larvae begin tunnelinginto seeds upon reaching the third instar (larvalgrowth stage). This tunneling continues throughoutthe remainder of larval development. Larval developmentfrom hatching to full maturity takes about 15 to19 days.Damage: The young larvae of the sunflower moth feedprimarily on florets and pollen. Older larvae tunnelthrough immature seeds and other parts of the head. Asingle larva may feed on three to 12 seeds and formstunnels in both the seeds and head tissue. Larvae spinsilken threads, which bind with dying florets and frassto give the head a trashy appearance. Severe larval infestationscan cause 30 percent to 60 percent loss, andin some cases, the entire head can be destroyed. <strong>Sunflower</strong>infested with sunflower moth has an increasedincidence or risk of Rhizopus head rot.Scouting Method: Sampling sites should be at least75 to 100 feet (23 to 31 m) from field margins. The Xpattern should be used in monitoring a field, countingmoths on 20 heads per sampling site for a total of 100heads. Scouting is most accurate in the early morningor late evening, when moths are active. Sex pheromonelures are available commercially for monitoringwith traps to indicate their arrival and local populations.Insecticide applications should be consideredwhen pheromone trap catches average four moths pertrap per day from the R-3 through R-5 growth stages.Economic Threshold: The economic threshold forsunflower moth is one to two adults per five plants atthe onset of bloom or within seven days of the adultmoth’s first appearance. If using pheromone traps,consider the threshold mentioned in the ScoutingMethod section.Management: A number of federally labeled insecticidesare registered for control of the sunflower moth.■ Banded <strong>Sunflower</strong> MothSpecies: Cochylis hospes WalsinghamDescription: The adult has a dark band across the buffor yellowish-tan forewings (Figure 62 ). The wingspanis about 0.5 inch (13 mm). Early instar larvae areoff-white; late instar larvae are pinkish to red with abrown head capsule (Figure 63). Larvae will be about0.44 inch (11 mm) at maturity.Life Cycle: The life cycle of the banded sunflowermoth is similar to that of the sunflower moth, exceptthat the adults emerge from local overwintering sitesrather than migrating into <strong>North</strong> <strong>Dakota</strong>. Banded■ Figure 62. Adult and eggs - Banded sunflower mothCochylis hospes. (Extension Entomology)■ Figure 63. Larva - Banded sunflower moth Cochylishospes. (Extension Entomology)49


50sunflower moths begin to emerge from the soil aboutmid-July and are present in the field until mid-August.Adults tend to congregate in field margins on weeds oradjacent crops during the day and then move into thecrop in the evening. Within a week after emergence,they begin to lay eggs on the outside of the bracts ofthe sunflower head. Eggs may be found through earlyAugust and hatch in five to eight days. Larvae developthrough five instars and are present in sunflower headsfrom mid-July to mid-September. After feeding tomaturity, larvae drop to the ground and spin cocoonsin the soil to overwinter. Pupation takes place in lateJune or early July the following year. The pupal periodlasts about 12 days.Damage: The newly hatched larvae move from thebracts to the florets of the sunflower head, where theyenter open florets to feed. When the eggs hatch, younglarvae feed on bract tissue before moving into thehead. A sunflower head is susceptible to infestationonly during the flowering period. The larvae feed inthe florets until the third instar. During later stagesof larval development, the insect tunnels through thebase of the floret into the seed. The larvae may consumepart or all of the contents of the developing seed.The larvae usually enter near the top of the seed andleave by way of the same opening after the contentsare eaten. Each larva may destroy several (five toseven) seeds. Small areas of silken webbing on maturesunflower heads indicate the presence of banded sunflowermoth larvae within the head.Adult Scouting Method and Economic Threshold:Sampling sites should be at least 75 to 100 feet fromthe field margins. In monitoring a field, use the Xpattern (Figure 17), counting moths on 20 plants persampling site to obtain the total number of moths per100 plants. Sampling should be conducted in the latebud stage (R3), usually during mid-July. If treatmentis warranted, it should be applied at the R5.1 sunflowerplant growth stage (when 10% of head area has diskflowers that are flowering or completed flowering.)During the day (late morning to early afternoon) themoths remain quiet, resting on upper or lower surfacesof the leaves of sunflower plants. When disturbed,they flutter from plant to plant. When sampling formoths during the day, the decision to treat or not isbased on comparing the mean number of adult mothsin the field to the EIL for moths. The EIL number isthe number of moths per head that will, if not managed,result in seed damage with a value equal to thecost of treatment. Use the following formula based ontreatment costs, plant population and market price todetermine the adult EIL for day sampling.EIL(moths per 100 plants) =[(Treatment Cost ($)/Market Price) x 582.9 – 0.7Plant PopulationThe constants in the formula simplify the calculationand include the amount of loss attributable to eachbanded sunflower moth larva produced per plant.A sample calculation of the EIL based on moth samplingfor the following conditions is given below.Insecticide treatment cost = $8/acreMarket price = $0.09/lb.Plant population = 20,000/acre[[($8/$0.09)EIL =x 582.9 – 0.720,000= 19 moths per 100 plantsFor this set of variables, an infestation of about 1.9moths per 100 plants will result in sufficient larvaeto destroy seeds in the sunflower head equal to the $8treatment cost per acre in a field of 20,000 plants peracre with a market value of 9 cents per pound. If theadult population has reached or exceeded this level,then the growner should consider the use of a chemicalinsecticide to prevent larval seed damage.Egg Scouting Method and Economic Threshold:Banded sunflower moth eggs can be counted accuratelyusing a low power magnifier. A head-mounted 3.5Xmagnifier is recommended. Egg counts should bemade when most of the sunflower plants are at stageR-3. However, buds should be selected randomly toavoid bias. Sampling for banded sunflower moth eggpopulations in commercial fields should be conductedas follows:1. Divide each side of the field to be surveyed into1,312-foot (400 m) sections.2. Sample the center of each 1,312-foot (400 m)section at 20 feet (6 m) into the field from thefield margin.3. Randomly select five buds at each sample site.4. Randomly select six bracts from the outer whorlon each bud and count the banded moth eggs.Average the egg counts from the five buds.Compare the average egg count to the EIL.[[[ [


InsectsEconomic Injury Level (EIL) is the number of eggsper six bracts.TCEIL =V x PP x 0.00078V = Market value per lbPP = Plant population per acreTC = Treatment costExample: TC = $8, V = $0.10, and PP = 16,000The EIL is 6.4 eggs per six bracts.Economic Distance (ED) is the distance into a fieldfrom a sample site on the field edge where an economicallydamaging population is expected to extend.ED gives you the capability to diagram the extent ofthe EIL within a field. Economic Distance:ED = e[EIL – 1.29(E)– .194[E = Average six bract egg count at 20 feet (6 m)*EIL based on eggs per six bractsEconomic Distance Example:Field Size: 800 m by 800 m with average eggcounts of 15 per six bracts per sample site.The EIL is 6.4 eggs per six bracts.The ED is 280 feet.In this case, only 37 percent of the field wouldneed treatment, resulting in a savings of 63 percent.Management: Deep fall plowing of sunflower stubblein Manitoba has reduced moth emergence the followingseason by about 80 percent; however, this is notpractical for areas practicing conservation tillage. Researchin <strong>North</strong> <strong>Dakota</strong> has demonstrated that delayingplanting of sunflower until late May or early Junehelps reduce infestation levels of the banded sunflowermoth. Parasitic wasps attack both the eggs and larvaeof the moth. Predators also consume eggs and larvae.Since banded sunflower moths have a tendency tocongregate around field margins, perimeter sprayinghas been used with some success. This will minimizeinsecticide treatment costs and impact on pollinators.■ Lygus bugsSpecies: Tarnished plant bug, Lygus lineolaris (Palisotde Beauvois) and other Lygus speciesDescription: The most common species occurring insunflower fields is the tarnished plant bug. It attacks atleast 385 different plant species and occurs in 39 U.S.states and five Canadian provinces. Adults (Figure 64)are small, cryptically colored insects with a distinctiveyellow triangle or “V” on the wings and 0.2 inch (4 to5 mm) in length. They vary in color from pale green todark brown. The immature stages, or nymphs (Figure65), are similar in appearance to the adults, but lackwings and are usually green in color. They often areconfused with aphids, but lygus move much morerapidly.■ Figure 64. Adult - Lygus bug (Tarnished plant bug)Lygus lineolaris. (Scott Bauer, http://www.ars.usda.gov/is/graphics/photos/insectsimages.new.htm)■ Figure 65. Nymphs - Lygus bug Lygus lineolaris.(Scott Bauer, http://www.ars.usda.gov/is/graphics/photos/insectsimages.new.htm)51


Life Cycle: Adults overwinter in plant debris alongfield margins and shelterbelts. Populations probablymove to sunflower from alfalfa, canola or othercrops when those plants either have senesced or beenharvested. Sticky trap catches in <strong>North</strong> <strong>Dakota</strong> showedthat lygus bugs were present throughout the reproductivegrowth stages of sunflower. These insects produceat least two generations per year in the northernPlains. The biology of other Lygus species is similar.Damage: Oilseed sunflower are not believed to beat risk to damage from Lygus feeding at this time.The presence of scarring on confection or nonoilseedsunflower seeds, known as kernel brown spot (Figure66), is caused by lygus bugs feeding on the developingseed. The quality issue is significant because processorsdiscount the finished product with only 0.5 percentdamage. The incidence of damage in 2006 rangedbetween 1 percent and 5 percent in some productionareas of the northern Plains. Lygus feed preferentiallyon either the developing reproductive organs or on theapical meristematic and leaf primordial tissue, causinga necrosis around the feeding site due to the injectionof enzymes. This tissue destruction causes the brownspot on the sunflower kernel, resulting in a bitter tasteto the seeds. Greenhouse and field studies showed that33 to 38 seeds were damaged per adult lygus bug, andthat all reproductive growth stages (R-4 to R-5) werevulnerable to attack. Damage was reduced if headswere infested after flowering was completed (R-6 toR-7).Scouting Method: A scouting method has not beendeveloped for lygus bug in sunflower.Economic Threshold: Approximately 36 seeds aredamaged by each adult. Therefore, 0.5 percent damageon heads with 800 seeds would occur with feeding ononly four seeds per head. Thus, populations of adultlygus at levels of one per nine heads could result ineconomic loss to the producer through the reductionof seed quality.Management: Lygus can be treated at the same timeconfection sunflower is treated for other insects, suchas the seed weevil and banded sunflower moth. Twotreatments are recommended to sufficiently protectconfection sunflower heads from insect feeding: oneapplication at the onset of pollen shed, or approximately10 percent bloom, followed by a second treatmentseven days later. This program should controlinsects adequately on confection sunflower throughoutflowering, minimizing the potential feeding damage.■ Figure 66. Kernel brown spot caused by Lygus bug.(Larry Charlet)52


Insects■ <strong>Sunflower</strong> Headclipping WeevilSpecies: Haplorhynchites aeneus (Boheman)Description: The sunflower headclipping weevil adultis shiny black (Figure 67). The weevil is about 0.31inch (8 mm) long from the tip of the snout to the rearof the abdomen. The area behind the head and thoraxis large and “squared” in relation to the narrow andprolonged head and snout.Headclipping weevil larvae are cream-colored, somewhatC-shaped and grublike and 0.16 to 0.24 inch (4to 6 mm) long (Figure 68).Life Cycle: Adults emerge in mid-July and are activefor a two- to three-week period. The females feed onpollen and nectar of flowering heads. In preparationfor egg laying, the female makes one nearly completerow of feeding punctures around the circumference ofthe stalk just below the head and then lays an egg inthe head. The girdled head subsequently falls to theground, where larval development and overwinteringoccur.Damage: Head clipping by H. aeneus is the mostapparent type of damage caused by this weevil andfrequently occurs along field margins. The percentof “clipped heads” in a field is normally very low (1percent to 3 percent). However, losses up to 25 percenthave been reported in individual fields (Figure 69).Scouting Method: The weevils’ presence is determinedusing the X scouting pattern. If the adults areencountered only periodically throughout the samplingsites, controls should not be necessary.Economic Threshold: None established.Management: Insecticide use has not been warrantedfor control of the sunflower headclipping weevil.■ Figure 67. Adult - <strong>Sunflower</strong> headclipping weevilHaplorhynchites aeneus. (Extension Entomology)■ Figure 68. Larva- <strong>Sunflower</strong> headclipping weevilHaplorhynchites aeneus. (Extension Entomology)■ Figure 69. <strong>Sunflower</strong> headclipping weevil damage.(Extension Entomology)53


Diseases of <strong>Sunflower</strong>(Carl Bradley, Sam Markell and Tom Gulya)<strong>Sunflower</strong> (Helianthus annuus) is unique in that itis one of the few crop plants that are native to <strong>North</strong>America. The genus Helianthus comprises more than60 annual and perennial species, with one to severalspecies found in every state. Since wild sunfloweris a native plant, a native population of diseases andinsects that can attack cultivated sunflower also ispresent in most areas of the U.S. <strong>Sunflower</strong> is alsounusual in that it is both a field crop, with two distinctsubtypes (oil and confection), and is grown as agarden flower and for the cut-flower industry. At least30 diseases, caused by various fungi, bacteria andviruses, have been identified on wild or cultivatedsunflower, but fortunately, only a few are of economicsignificance as far as causing yield losses. When consideringsunflowers as an ornamental plant, even smallspots on the foliage are enough to reduce marketability,and thus proper disease identification is necessaryto decide upon appropriate disease management. SeeAppendix 1 for a listing of all known sunflower diseasesthat occur in the world.The most important diseases in the northern GreatPlains are Sclerotinia wilt, Sclerotinia head rot anddowny mildew. Rust, especially on confection sunflowers,and Phomopsis stem canker are important insome years, but are of less overall concern. Phomablack stem is almost universally prevalent, but is notthought to cause yield losses. Leaf diseases caused byAlternaria, Septoria and powdery mildew, head rotscaused by Botrytis and Erwinia, and Verticillium leafmottle are diseases that either are observed infrequentlyin the northern Great Plains or have not occurredwith sufficient intensity to be considered serious.The most important sunflower disease in both thecentral Great Plains (Kansas, Nebraska, Colorado,Texas) and California is Rhizopus head rot. Sclerotiniahead rot and wilt, downy mildew and Phoma blackstem are of sporadic importance. In the central GreatPlains, rust can be severe on sunflower grown undercenter pivot irrigation, and Phomopsis stem canker hasbeen of concern in years of plentiful rainfall. Underdrought conditions, charcoal rot is also of concern inthe central Great Plains. In California, rust, followedby various stalk rots, are the most prevalent diseasesafter Rhizopus head rot. For complete details on theincidence and severity of sunflower diseases, visit theNational <strong>Sunflower</strong> Association Web site (www.sunflowernsa.com),where the proceedings of the annual“<strong>Sunflower</strong> Research Workshop” are posted.The production of ornamental sunflowers in the U.S.is scattered across at least 41 states, and includes bothfield and greenhouse production. Greenhouse-grownsunflower is prone to Pythium and Phytophthora rootrot and Botrytis blight, as well as the range of sunflower-specificpathogens. Field-grown ornamentalsunflower, especially in the Midwest, is prone to thesame pathogens that attack oilseed sunflower. Sclerotiniawilt, rust, powdery mildew, Rhizopus head rot,southern blight and root knot nematodes are cited asthe major diseases. Since cosmetic appearance is soimportant on ornamental crops, even diseases consideredas minor on an oilseed sunflower crop are ofconsequence to ornamental sunflower. Thus, obscurediseases, such as leaf smut, cocklebur rust and petalblight, have been cited as causing losses to ornamentalsunflower in the U.S. and abroad.Effective control measures for most sunflower diseasesare:• Planting resistant hybrids• A minimum rotation of four years between successivesunflower crops• Seed treatment for control of downy mildew anddamping-off• Tillage to bury crop residue that may harborpathogens• Foliar fungicides for rust and other foliar diseases54


DiseasesMany sunflower diseases are controlled by singledominant genes for resistance (e.g., downy mildew,Verticillium leaf mottle). Most sunflower hybrids inthe U.S. have resistance to Verticillium leaf mottle,several races of downy mildew and several racesof rust. Unfortunately, the rust and downy mildewpathogens continue to evolve and new races are foundperiodically. This requires commercial seed companiesto add new genes to their hybrids so their hybrids canremain resistant to the ever-changing pathogens. Someother disease organisms, such as Sclerotinia, requiremultiple genes for resistance, which makes developmentof resistant hybrids much more difficult. Greatstrides have been made in making sunflower hybridsmore tolerant of both Sclerotinia wilt (root rot) andSclerotinia head rot. No current hybrids can be consideredimmune to either type of Sclerotinia infection,but then again, breeders have so far been unable todevelop immune varieties for other Sclerotinia-susceptiblecrops. Disease reaction varies widely amonghybrids, and growers are encouraged to consult seedcompanies and Extension or public research personnelfor recommended disease-resistant varieties. Producersalso should remember that disease response ishighly influenced by environment. Disease evaluationsmade in only one location may not accurately predict ahybrid’s performance in all areas.Crop rotation helps reduce populations of many importantsunflower pathogens in the soil. Most sunflowerdiseases are caused by pathogens specific to sunflower.Sclerotinia, however, attacks many crops, andsusceptible crops (such as mustard, canola, crambe,soybean and dry edible bean) should be interspersedin rotation with corn and cereals, which are nonhostsof Sclerotinia. Rotation time away from sunflower isinfluenced by the occurrence and severity of diseasesnoted in the current year. Regular monitoring of fieldsand maintaining accurate records are also importantin determining rotation practices. Rotation will havea minimal effect on foliar diseases since the pathogenspores may be carried by wind from distant fields.Currently, only two fungicides are employed for foliardisease control, with several others in the registrationprocess. Consult state Extension publications for moredetails.The arrangement of the sunflower diseases in thefollowing section is based on time of appearanceduring the growing season and the plant part affected.Early season diseases (e.g., downy mildew and apicalchlorosis) are covered first, followed by foliar diseases(including virus diseases), stalk and root infectingdiseases (including nematodes) and finally, head rotsand other diseases of mature plants.For additional information and photos of sunflowerdiseases, visit the National <strong>Sunflower</strong> AssociationWeb site (www.sunflowernsa.com) and the Website of the USDA <strong>Sunflower</strong> Research Unit inFargo, N.D. (www.ars.usda.gov/main/site_main.htm?modecode=54420520), as well as the heavily referencedchapter on sunflower diseases in “<strong>Sunflower</strong>Technology and <strong>Production</strong>” edited by A.A. Schneiterand published by the Agronomy Society of Americaas Monograph No. 35. For current information onthe disease resistance of commercial hybrids, pleaseconsult <strong>NDSU</strong> publication A652, “Hybrid <strong>Sunflower</strong>Performance Testing,” available in hard copy or onthe Web at www.ext.nodak.edu/extpubs/plantsci/rowcrops/a652.pdf.55


I. Early Season Diseases■ Downy MildewDescription: Downy mildew has been observed oncultivated and wild sunflower throughout the U.S.and was quite common before the advent of resistanthybrids and the use of fungicides as seed treatments. Itis most serious in areas with flat topography or heavy,clay soils that foster waterlogged conditions conducivefor disease development.Typical systemic symptoms in seedlings includedwarfing and yellowing (chlorosis) of the leaves(Figure 70) and the appearance of white, cottonymasses (fungal mycelium and spores) on the lower andsometimes upper leaf surface during periods of highhumidity or dew (Figure 71). Most infected seedlingsare killed, but those that survive will produce stunted■ Figure 70. Dwarfing and discoloration of sunflowerresulting from infection by downy mildew.(D.E. Zimmer)plants with erect, horizontal heads with little, if any,seed (Figure 72). When seedlings are infected severalweeks after emergence, or a fungicide seed treatmentinhibits rather than prevents infection, the plants usuallystart showing symptoms at the four-, six- or eightleafstage. This situation is referred to as “delayedsystemic infection.” These plants are characterized bysome degree of stunting, with typical downy mildewleaf symptoms starting at some level in the plant (withlower leaves appearing normal). If susceptible plantsare exposed to the mildew pathogen after the seedlingstage, they also may develop a thickened, clublikeroot and become stunted, but may not show foliarsymptoms. All infected plants serve to perpetuate thepathogen in the soil and are more prone to droughtstress and lodging.<strong>Sunflower</strong> plants also display localized foliar lesionsdue to airborne downy mildew spores. The infectedspots are generally small, angular lesions (delimitedby veinlets) with white sporulation on the underside ofthe lesion. These local lesions may coalesce into largerlesions, but they rarely result in a systemic infection,and thus have minimal impact upon yield.Dwarfing and distortion of leaves also are symptomstypical of herbicide drift damage, especially from2,4-D and related phenoxy compounds, and may beconfused with downy mildew symptoms (Figure 73).Herbicide damage, however, never will exhibit thewhite appearance (fungal mycelium and spores) onthe underside of the leaves nor the chlorosis typical ofdowny mildew.56■ Figure 71. Lower surface leaves on downy mildewinfected plants frequently exhibit a white cottonygrowth of fungus. (D.E. Zimmer)■ Figure 72. Plants infected with downy mildewseldom produce heads; when they do, the headsdo not nod but remain erect and produce little or noseed. (T. Gulya)


Disease Cycle: Downy mildew is caused by the obligatefungus Plasmopara halstedii, which is soil-borne,wind-borne and seed-borne. <strong>Sunflower</strong> plants are susceptibleto systemic infection before the seedling rootsexceed 2 inches in length. This short period may rangeup to a maximum of two to three weeks, depending onsoil temperature and moisture. Cool, water-saturatedsoil during this period greatly favors infection. Thefungus may persist in the soil for five to 10 years aslong-lived oospores. While this downy mildew fungusdoes not infect any crops other than sunflower andJerusalem artichoke, weeds in the Compositae family,such as marsh elder, are susceptible, and thus mayserve as reservoirs for the fungus.<strong>Sunflower</strong> planted on land with no previous sunflowerhistory occasionally has shown downy mildew infection.There are three principle ways downy mildewmay occur in fields with no previous history of sunflower.Windblown and soil-borne spores account forthe majority of such infections. Spores of the fungusoccurring on volunteer sunflower or wild annualsunflower, even a few miles distant, may be blown tonewly planted fields and result in substantial infectionunder favorable conditions of cool, water-logged soils.Spores also may adhere to soil particles and move toneighboring fields during dust storms. Water runningthrough an infested field also may carry mildewspores into a previously disease-free field.Modern seed production practices, coupled with stringentinspection of certified seed, virtually eliminatethe possibility of introducing downy mildew into a“clean” field via infected seed. Seed from infectedplants is generally either nonviable or so light inweight that it is separated during seed processing.A slight possibility remains that viable seed may beproduced on infected plants. These seeds may producehealthy plants, systemically infected seedlingsor plants with latent infection in which the fungus islocalized in the roots and does not produce symptomson the leaves. These latent infections, however, willhelp perpetuate the disease in the field.Damage: Severely infected plants may die before orshortly after emergence or in the seedling stage. Thefew plants reaching maturity seldom produce viableseed. Heads on these plants typically face straight up,rendering them extremely vulnerable to bird feeding.Yield losses from downy mildew can be substantial,depending on the percentage of infected plants andtheir distribution within the field. If infected plantsare scattered randomly throughout a field, yield lossesprobably will not be observed unless infection exceeds15 percent. <strong>Sunflower</strong> have excellent compensatingability when healthy plants are adjacent to infectedplants. When the disease is in a localized area, suchas a low spot in a field, and all plants are infected, theresultant yield loss is much greater.Management: The continued discovery of new downymildew races and the occurrence of mildew strainsresistant to Apron XL (mefenoxam) and Allegiance(metalaxyl) seed treatment have altered managementstrategies. When these seed treatments were effective,seed companies had no need to develop resistantvarieties. Now most seed companies are developinghybrids that use multirace immunity, which should beeffective despite the development of new races. Notall hybrids in a company’s lineup will have downymildew resistance, however. At least two dozen racesof the fungus have been identified in the U.S., but annually,usually two to three races make up the majorityof races. Fortunately, lines released by the USDA areavailable that confer resistance to all known races.With the appearance of downy mildew strains thatare insensitive to metalaxyl and mefenoxam fungicideseed treatments (Apron XL, Allegiance), effortsare under way to find replacement seed treatments.The fungicide azoxystrobin (Dynasty) recently hasbeen labeled for use on sunflower as a seed treatmentDiseases■ Figure 73. Damage to sunflower from 2,4-D orgrowth regulator type herbicides may be mistakenfor downy mildew symptom. (D.E. Zimmer)57


for downy mildew suppression. As other effectivechemicals are registered for use as sunflower seedtreatments, the most effective management strategywould be to use two fungicides at the same time. Atwo-fungicide treatment will improve disease controland probably be less costly, in addition to delaying thedevelopment of fungicide resistance in downy mildew.Seed-applied fungicides will protect against root infectionby all races, and thus will augment protectionoffered by resistant hybrids.Seed applications, however, will not protect againstfoliar infection. Since the fungicides are water-soluble,they can be washed off shallow-planted seed withexcessive rainfall, resulting in poor disease control.Selection of downy mildew-resistant hybrids is themost effective way of controlling downy mildew.Seed companies are actively incorporating genes thatcontrol all known races, and these hybrids will beimmune, at least until a new race emerges. Additionalmanagement practices that minimize downy mildewproblems include extended crop rotations, eradicationof volunteer sunflower, avoiding poorly drained fieldsor those with excessive low areas and delaying plantinguntil warm soil temperatures foster rapid seedlinggrowth.■ Apical ChlorosisDescription: Apical chlorosis is the one of two bacterialdiseases of sunflower that is noticed with anyregularity in the U.S. The causal organism is Pseudomonassyringae pv. tagetis. Apical chlorosis is strikingand seldom goes unnoticed. The major symptom ofthe disease is the extreme bleaching or chlorosis ofthe upper leaves (Figure 74). Apical chlorosis may bedistinguished from iron chlorosis or nitrogen deficiencyby the complete lack of green pigment and theuniformity of the chlorosis. With mineral deficiencies,the veins characteristically remain green. In addition,the white leaves affected by apical chlorosis neverwill “regreen,” while those due to mineral deficiencieswill.Disease Cycle: Apical chlorosis occurs only duringthe vegetative growth stage when leaves are activelyexpanding. It is most severe in young seedlings duringcold weather and in water-logged soils.Damage: Plants affected by apical chlorosis usuallywill produce new green leaves in several weekswith little discernible effect other than striking whiteleaves in the middle of the plant. Thus, yield reductionsdue to apical chlorosis are minimal. However,if long periods of cold spring temperatures coincidewith water-logged soils, seedlings affected by apicalchlorosis may die. Yield losses still will be minimal ashealthy neighboring plants should compensate for thedead seedlings.Management: No hybrids are completely immune toapical chlorosis. The only control recommendationat present is to follow a four-year rotation to avoidincreasing the population of the bacteria in the soil.Roguing (identifying and removing) infected plantsin seed production fields will eliminate the diseaseand minimize the possibility of infected seed. Thissame bacterium will produce apical chlorosis on otherCompositae weeds, such as thistles, ragweed, otherHelianthus species (including cultivated Jerusalemartichoke), marigold and zinnia. Thus, controlling volunteersunflowers and Compositae weeds, as potentialdisease reservoirs, will help minimize soil populationsof this bacterium.58■ Figure 74. Apical chlorosis is characterized by anextreme bleaching or chlorosis of the upper leaves.(William K. Pfeifer)


II. Foliar Diseases■ RustOn most crops, rust refers to a single fungal species.On sunflower, the main fungus causing rust is Pucciniahelianthi, which is worldwide in distribution andcauses economic losses. In <strong>North</strong> America, four otherPuccinia species are found on wild and cultivated sunflower:P. canaliculata (nutsedge rust), P. enceliae, P.massalis and P. xanthii (cocklebur rust), plus one rustfrom another genus, Coleosporium helianthi. The followingdiscussion will deal mainly with P. helianthi,with minimal descriptions of the other rust fungi.Description: Rust occurs in all sunflower productionareas of the U.S. and Canada and also is widespreadon wild sunflower. Most oilseed hybrids havehad good resistance to the prevailing rust races, butchanges in the rust population in the last decadehave resulted in greater rust severity and occasionallyin substantial losses in seed yield or seed quality.Confection hybrids are generally more susceptibleto rust (and other diseases) than oilseed hybrids. Atleast 25 different rust races have been identified inthe U.S., which makes breeding for rust resistance achallenge. Rust, incited by the fungus Puccinia helianthi,is characterized by cinnamon-colored spots oruredial pustules, which primarily occur on the leaves(Figure 75) but also on the stems, petioles, bracts andthe back of the head under severe infestations. Theinitial appearance of rust is determined by adequaterainfall and warm temperatures, so the disease usuallyoccurs in late summer in the northern Great Plains.The uredial pustules turn black with the advent of cooltemperatures as the brown urediospores are replacedby black overwintering teliospores.Disease Cycle: This rust completes its entire life cycleon sunflower and does not require an alternate host, asdo some cereal rusts. Puccinia helianthi overwinterson plant debris as teliospores (thick walled, restingspores). These spores germinate in the spring toproduce basidiospores that infect volunteer seedlingsor wild sunflowers. This initial infection results in theformation of pycnia (generally on the underside ofleaves), which, in turn, leads to aecial pustules, generallyon the upper surfaces of leaves or cotyledons. Theaecia are small (1/8 inch), orange cup-shaped pustulesthat may occur singly or in small clusters (Figure 76).The aeciospores are spread by wind to other sunflowerplants, where they initiate the cinnamon-brown uredialpustules. The uredial stage is the repeating portion ofthe rust life cycle. Rust multiplies rapidly under favorableconditions of warm temperatures and either rainor dew. Thus, even in dry years, if night temperaturesare low enough to promote dew formation on leaves,this minimal amount of leaf wetness will be sufficientto initiate rust infection. Excessive rates of nitrogenfertilization and abnormally high seeding rates resultin excessive foliage, which increases humidity withinthe canopy and favors rust development.Damage: Rust not only reduces yield, but also reducesoil, seed size, test weight and kernel-to-hull ratios.Late-planted fields of susceptible hybrids are generallymore severely damaged by rust than earlier-plantedfields. Irrigated fields also are apt to have more severeinfection as the constantly wet leaves provide an idealenvironment for the rust fungus to multiply.■ Figure 75. Rust occurs most commonly on leavesand after flowering. The cinnamon-red pustulesproduce summer spores; the black pustules occur latefall and produce overwintering spores. (D.E. Zimmer)■ Figure 76. Aecial cups of Puccinia helianthi.(T. Gulya)Diseases59


Management: The most effective way to avoid lossfrom rust is by planting rust-resistant hybrids. Withsunflowers grown under center pivot irrigation, nightirrigation fosters more rust infection since the sporesgerminate best in the dark. Headline (pyraclostrobin)and Quadris (azoxystrobin) are registered for controlof rust on sunflower, and additional fungicides maybecome registered. Refer to the most current editionof the “<strong>North</strong> <strong>Dakota</strong> Field Crop Fungicide Guide”(PP-622) available from the <strong>NDSU</strong> Extension Serviceto view fungicide products registered on sunflower.The injury threshold (i.e., disease severity abovewhich fungicide spraying is warranted to minimizeyield loss) developed for using tebuconazole is whenthe rust severity on the upper four leaves is 3 percentor greater. High rust severity on lower leaves hasless impact upon seed yields, as the upper leaves arethe ones supplying most of the photosynthate for thedeveloping seeds.<strong>Sunflower</strong> rust, like cereal rusts, occurs as many different“physiological races,” which constantly change.Thus, hybrids selected for rust resistance eventuallybecome susceptible as rust races change. Seed companiescontinually are testing their hybrids in differentlocations to determine rust resistance against thevarious races from region to region. Rust evaluationsmade under conditions of natural infection or withartificial inoculation of specific races also are doneby university research centers, and this informationfrequently is found in the <strong>NDSU</strong> publication “Hybrid<strong>Sunflower</strong> Performance Testing” (A652). A few othermanagement practices, besides rust-resistant hybrids,that can minimize rust are available. Destruction ofvolunteer plants and wild annual sunflower occurringin the vicinity of commercial fields as early in thespring as possible will reduce sources of inoculum.High rates of nitrogen fertilizer and high plant populationsboth foster dense canopy development that inturn create ideal conditions for rust infection, and thusshould be avoided if rust is of concern.Other Rusts: As mentioned previously, four otherPuccinia species and one Coleosporium species ofrust can infect sunflower in parts of the U.S. Noneof them have yet to be reported to be of economicsignificance on cultivated sunflower, but they mightbe considered potential nuisance foliar pathogenson ornamental sunflowers. As sunflower productionexpands into new areas, especially in the south-centraland southwestern U.S., the possibility of other Pucciniaspecies attacking cultivated sunflower increases.Puccinia xanthii, commonly known as cockleburrust, is easy to distinguish from P. helianthi based onpustule size. This rust is microcyclic, with only teliaand basidiospores, and does not exhibit the five sporestages of a full-cycle (macrocyclic) rust such as P.helianthi. On sunflower, the telial pustules are few innumber, range from 1/4 to 3/8 inch in diameter, aredistinctly puckered (convex) and bear a layer of darkbrown spores only on the underside of leaves. As theteliospores germinate in place, the spore layer changesfrom brown to gray. As little as two to three hours ofdew at temperatures of 68 to 77 F is sufficient for P.xanthii infection. <strong>Sunflower</strong> is minimally susceptibleto this rust. The main host for this rust is cocklebur(Xanthium species), with some authors also listingragweed (Ambrosia). This rust has been seen onlyonce on sunflower, and only in <strong>North</strong> <strong>Dakota</strong>.Puccinia enceliae and P. massalis are two ruststhat are recorded on wild Helianthus species in thesouthwestern U.S. and have been shown to infectcultivated sunflower in greenhouse tests. No reportsof them being identified on or causing yield losses tocultivated sunflower are known. Puccinia massalis isreported only on Texas blueweed (Helianthus ciliaris)in the Rio Grande Valley of Texas and New Mexico.Uredial pustules are indistinguishable from those of P.helianthi. Positive identification of P. massalis requiresmicroscopic examination of teliospores for the placementof germ pores. Puccinia enceliae occurs on wildHelianthus and dessert shrubs in the genera Viguiera(goldeneye and resin bush), Encelia (brittlebush) andTithonia (Mexican sunflower) in the desert regions ofwestern U.S. and northern Mexico. Uredial and telialpustules of P. enceliae on sunflower are similar inappearance to those of P. helianthi. Positive identificationof P. enceliae requires microscopic examinationof teliospores. Neither of these two Puccinia specieshas been observed on sunflower in the northern GreatPlains.Puccinia canaliculata is a full-cycle, heteroecious rustthat has its aecial stage on sunflower and cocklebur(Xanthium strumarium), and its uredial and telial stage60


on sedges of the genus Cyperus. This rust had beenconsidered as a possible mycoherbicide for control ofthe noxious weed yellow nutsedge. On sunflower, theaecial pustules look very similar to the telial pustulesof P. xanthii in shape, with the main difference that theP. canaliculata aecia on the underside of the leaf areorange, as compared with the dark brown of the teliaof P. xanthii. This rust has been observed in Kansas ina sunflower field infested with nutsedge. Since the rustrequires both hosts to complete its life cycle, eliminationof the nutsedge effectively will limit this rustinfection of sunflower.Coleosporium species are commonly referred to aspine needle rusts and are heteroecious rusts (requiringtwo different hosts to complete their life cycle).Coleosporium helianthi has its uredial and telial stageson sunflower, and the remainder of its life cycle ontwo- and three-needle pines, such as Jack pine, Virginiapine and loblolly pine. The rust is of minimal economicimportance in pine plantations and never hasbeen observed on cultivated sunflower. On Jerusalemartichoke (and other perennial Helianthus species), C.helianthi infections can be quite severe and potentiallycause yield losses. Preliminary greenhouse tests haveshown that cultivated sunflower is susceptible, withlittle differences between commercial hybrids. Themost effective way to prevent C. helianthi infectionon sunflower is to avoid planting near shelter belts orareas with two-needle pines.■ Albugo or “White” RustDescription: White rust is one of the rarest sunflowerdiseases in <strong>North</strong> America, but is considered apotentially serious disease in countries such as SouthAfrica and Argentina. Despite the word “rust” in thecommon name, this disease is caused by a pathogenmore closely related to downy mildew. White rust hasbeen recorded on sunflower in <strong>North</strong> America onlyin western Kansas, eastern Colorado and adjacentNebraska during the late 1990s and seldom is seenin this area. In <strong>North</strong> <strong>Dakota</strong>, it has been recorded onragweed (Ambrosia spp.), various sage and sagebrush(Artemisia spp.) and goatsbeard (Tragopogon). Whiterust has not been recorded on either wild sunflower orcultivated sunflower in the northern Great Plains or inCanada on sunflower.Foliar lesions, consisting of raised, chlorotic pustulesup to 3/8 inch in diameter, are the most commonlyseen symptom on sunflower in the U.S. (Figure 77). Adull, white layer of spores forms in these pustules onthe underside of the leaf, which could be mistaken forlocal lesions caused by downy mildew. If the Albugopustules are numerous enough, they will merge as theyenlarge, and entire areas of the leaf will turn necroticas secondary fungi colonize the pustules.One striking feature often seen with Albugo is that asingle horizontal “layer” of leaves in the crop canopyusually is affected, with a sharp demarcation ofhealthy leaves above and below the affected leaves.This delimited layer of infected leaves suggests thatenvironmental conditions and Albugo spores wereDiseases■ Figure 77. Albugo lesions on upper leaf surface (left) and lower leaf surface (right). (T. Gulya)61


present for a very short time, thus only one layer ofleaves shows symptoms. Albugo also can cause lesionson stems, petioles, bracts and the back of heads. Thelesions on stems (Figure 78), petioles and the back ofthe heads are much different from those on leaves, andappear to be dark, bruiselike lesions. This appearanceis due to the presence of black oopsores just beneaththe epidermis. No white sporangia ever are seen inthe stem or petiole lesions. Stem lesions often arecolonized by other fungi and may lead to stalk rot andlodging by the secondary fungi. Petiole lesions maygirdle the petiole and cause the affected leaf to wilt,thus causing considerable damage and yield loss.Disease Cycle: The causal agent of white rust is theobligate fungus Albugo tragopogonis, which recentlyhas been reclassified as Pustula tragopogonis. Inaddition to sunflower, this fungus infects cocklebur(Xanthium), groundsel (Senecio), marsh elder (Iva),ragweed (Ambrosia) and several other weedy Composites.The fungus appears to have host-specific races,however, so white rust occurring on one host genusmay not infect other genera or cause only minimalinfection. Albugo overwinters as oospores in infectedplant debris. Rain splashes the oospores onto nearbyseedlings, where they germinate to form motile zoosporesthat enter through stomates. The pustules thatdevelop contain masses of dry, white asexual sporangia.The pustules rupture to release sporangia that arewindblown to other plants to continue leaf infection.Sporangia also can initiate infection on stems, petiolesand bracts. Optimal conditions for Albugo infectionare cool nights (50 to 60 F) with rain or dew, but lesiondevelopment is favored by warm days (70 to 80F).Damage: Foliar infection by Albugo seldom causesyield loss, although the symptoms are quite noticeable.Lesions on stems and petioles, which fortunatelyare seen seldom in the U.S., are much more serious.Petiole lesions lead to defoliation, with significantyield losses, and stem lesions may become colonizedby other fungi and result in lodging. Albugo infectionson the head may result in seed infection, which wouldbe of concern in seed production fields.Management: Field trials have shown that sunflowerplants can tolerate a high proportion of foliage infectionby Albugo before yield losses are observed. Stemand petiole lesions caused by Albugo are more serious,as stem lesions can result in lodging and petiolelesions will result in defoliation. In countries whereAlbugo is serious, commercial seed companies havemade the effort to develop resistant hybrids. In theU.S., no information is available regarding the reactionof hybrids to white rust. Evaluations of USDA breedingmaterial have shown that resistance probably iscontrolled by several genes, each governing infectionof leaves, stem, petioles and heads. Since Albugo is anOomycete, like downy mildew, the same fungicidesthat control downy mildew have been effective againstwhite rust. Thus, seed treatment with metalaxyl ormefenoxam will offer protection against both systemicinfection and foliar infection for a limited time. Rotationis of limited use with Albugo, as the spores can bewindblown from adjacent fields.62■ Figure 78. Albugo lesions on stems. (T. Gulya)


■ Alternaria Leaf and Stem SpotDescription: Alternaria leaf spot is a ubiquitousdisease on senescing leaves and generally of littleconcern, but under warm, humid conditions it can be aserious defoliating disease. The Midwest has two mainspecies of Alternaria: A. helianthi and A. zinniae, ofwhich A. helianthi is the more prevalent and moreserious. In addition, several other Alternaria specieshave been reported on sunflower, including A. alternata,A. helianthicola, A. helianthinfi ciens and A. protenta.Alternaria helianthi and A. zinniae both producedark brown spots on leaves. These spots are irregularin size and shape with a very dark border and a graycenter (Figure 79). The spots on young plants mayhave a yellow halo. Leaf lesions may coalesce, causingleaves to wither. Stem lesions begin as dark flecksthat enlarge to form long, narrow lesions (Figure80). These stem lesions often coalesce to form largeblackened areas, resulting in stem breakage. Stemlesions are distributed randomly on the stem and arenot associated with the point of attachment of the leafpetiole. Brown, sunken lesions also may form on theback of the head, especially following any mechanicaldamage such as that caused by hail or birds. Theleaf and stem lesions caused by the various Alternariaspecies are similar and thus not diagnostic. Therefore,microscopic examination is required to distinguishwhich Alternaria species is present.Disease Cycle: All Alternaria fungi overwinter ondiseased stalks. They can be seed-borne at low levels,although seed is a relatively unimportant source ofthe inoculum under most conditions. Seedling blightscaused by Alternaria may develop when sunflowerplants emerge in rainy weather on Alternaria-infestedsoil. However, plants at the flowering to maturingstage are more susceptible than plants in the vegetativeor budding stage. Safflower and cocklebur also can bealternate hosts of A. helianthi.Disease development in A. helianthi is favored by77 to 82 F temperatures and at least 12 hours of wetfoliage. Extended wet periods of three to four days cancause serious losses as the spots enlarge.Damage: The primary damage that all Alternariaspecies cause is the leaf blights that lead to defoliationwhich increases the potential for yield loss. Inthe northern Great Plains, the climate is usually notconducive for Alternaria epidemics, and Alternariagenerally affects only the lower, senescing leaves.However, in warmer climates with plentiful rainfall,the potential for defoliation by Alternaria speciesand subsequent yield loss is much greater. In additionto the direct yield loss caused by foliar Alternariainfection, this fungus also has been noted to causeblemishes on the achenes. While this damage may beonly superficial, if the achenes are on confection sunflowersdestined for human consumption, the impactof “achene blemish” can be significant. This acheneDiseases■ Figure 79. Leaf lesions caused by Alternariahellanthi. (B.D. Nelson)■ Figure 80. Stem lesions caused by Alternariahellanthi. (T. Gulya)63


lemish, currently noted only on sunflower grownin Israel, looks very similar to “kernel black spot,”which is caused by feeding by the tarnished plant bug(Lygus), with no involvement from Alternaria.Management: Alternaria leaf blights are considered amajor disease in subtropical sunflower growing areas,where yield losses may range from 15 percent to 90percent, but are much less serious in temperate areasof the U.S. However, severe epidemics have beenobserved on sunflower in the eastern and southeasternportions of the U.S. Management practices to minimizeAlternaria problems include crop rotation andburying of infested crop refuse to hasten decomposition.Consult university Extension publications, suchas <strong>NDSU</strong>’s PP-622, “Field Crop Fungicide Guide,” forcurrent recommendations of foliar fungicides registeredfor use on sunflower for Alternaria control. Seedtreatments with metalaxyl or mefenoxam offer nocontrol of Alternaria seedling blights.■ Septoria Leaf SpotDescription: Septoria leaf spot develops first on thelower leaves and spreads to the upper leaves. The spotsbegin as water-soaked areas (greasy green in appearance).The spots become angular, with tan centersand brown margins (Figure 81). A narrow yellow halooften surrounds young spots. Mature leaf spots maycontain tiny black specks, the fungal fruiting bodies(pycnidia), which are visible with a 5X to 10X handlens. The presence of pycnidia is the best means ofdistinguishing leaf spots caused by Septoria fromthose caused by Alternaria.Disease Cycle: Septoria leaf spot can be caused bytwo Septoria species, S. helianthi. and S. helianthina,of which the former is the major species in the U.S.Septoria can be seed-borne and also can survive oninfected sunflower crop refuse. Septoria leaf spotmay appear anytime during the growing season and isfavored by moderately high temperatures and abundantrainfall. As such, the disease potentially is moresevere in southern growing areas, compared with thenorthern Great Plains.Damage: In the temperate climate of the Midwest,Septoria leaf spot usually causes little damage. SevereSeptoria infection may cause some defoliation, but ifthis affects only the lower leaves on mature plants, theimpact upon yield will be minimal.Management: Crop rotation, incorporation of sunflowerresidue and clean seed are the best means ofmanaging Septoria leaf spots. Although resistance toSeptoria has been identified in breeding material, theinfrequent occurrence of Septoria has not warrantedthe development of resistant hybrids.■ Figure 81.Septoria leaf spot. Note small blackpycnidia in lesions. (T. Gulya)64


■ Powdery MildewDescription: Powdery mildew, caused by the fungusErysiphe cichoracearum, can be found in most fieldsafter full bloom. The symptoms are distinctive andeasy to recognize: a dull white to gray coating of theleaves, starting as individual circular spots and eventuallymerging to cover the entire leaf (Figure 82). Thiscoating is the scant mycelial growth of the funguson the leaf surface. Severely infected areas senesceprematurely and dry up. Normally the lower leaves aremore heavily infected than the upper leaves. In othercountries, two other powdery mildew fungi have beendocumented on sunflower: Sphaerothecia fuligineaand Leveillula taurica. These both exist in the U.S.,but to date have not been documented on sunflower.Disease Cycle: Powdery mildew seldom is seen untillate in the growing season, as senescing leaves aremost susceptible to infection. While leaves are themost common plant part affected, powdery mildewalso will form on bracts and the backs of heads. Thepowdery coating seen is a combination of scant myceliaand spores of the asexual stage, which is referred toas Oidium. As the season progresses, the fungus formssmall (pinhead-sized) black cleistothecia, the sexualfruiting bodies.Damage: Powdery mildew generally occurs lateenough in the season that control measures are notneeded. <strong>Sunflower</strong> cultivars differ widely in reactionto powdery mildew. On ornamental sunflower, especiallythose grown in the greenhouse, powdery mildewis common. Although the main impact of the diseaseis cosmetic, this alone can cause economic losses.Management: Powdery mildew is seldom a problemon cultivated sunflower in the Midwest, but may beof concern in more humid areas and on the southernPlains states. On ornamental sunflowers, powderymildew can be minimized by adequate air movement,allowing the leaves to dry, and by the use of registeredfungicide sprays specific for powdery mildew.■ Diseases Caused by Viruses andPhytoplasmasDescription: Several viruses have been reportedon sunflower from other countries and the warmerregions of the U.S. (Florida), but no reports of virusesoccurring on sunflower in the northern Great Plainshave been confirmed. Wild sunflower is a host ofTobacco ring spot virus in the Rio Grande Valley, andCucumber mosaic virus has been reported on sunflowerin Maryland. Viruses reported on sunflower outsidethe U.S. include Tobacco streak virus, Tomato big budvirus, Sunfl ower rugose mosaic virus, and Tomatospotted wilt virus. Confirmation/identification of avirus as the causal agent is based on observation of theviral particles using an electron microscope, detailedchemical analysis of the viral components or serologicalidentification.The only well-documented virus found on sunflowerin the U.S. is Sunfl ower mosaic virus (SuMV), currentlyfound only in southern Texas on both cultivatedsunflower and wild Helianthus species. Symptoms ofSuMV are a mottled pattern of light green and normalgreen areas on the leaf, referred to as mosaic (Figure83). Affected plants may die in the seedling stage orlive to maturity, with all leaves affected.Aster yellows is a disease at first believed to be causedby a virus but which has since been identified as aphytoplasma. Phytoplasmas are living cells, in contrastto viruses, and are intermediate in size betweenviruses and bacteria. Symptoms on sunflower includeyellowing of leaves and/or the head, which often occursin sectors. A characteristic symptom is a wedgeshapedportion of the head that remains green andbears small leaves rather than floral parts (Figure 84),a condition termed “phyllody.”Diseases■ Figure 82. Powdery mildew with fungus producingwhite, powdery spores on leaf surface. (Reu V. Hanson)65


■ Figure 83. <strong>Sunflower</strong> mosaic virus. (T. Gulya)■ Figure 84. Aster yellows. Note wedgedshaped portion of head which remainsgreen. (Donald Henne)Disease Cycle: SuMV is spread primarily by aphidsbut is also seed-borne to a small extent. Seedlings lessthan a month old are the most susceptible, and mosaicsymptoms appear within a week after aphid transmission.Affected leaves will retain the mosaic pattern forthe life of the plant, but no stunting due to the virus isdiscernible.The aster yellows phytoplasma is transmitted only bythe aster leaf hopper (Macrosteles quadrilineatus) andoccurs on a wide variety of plants. Symptoms generallyappear at flowering, and affected heads will showthe symptoms for the remainder of the summer.Damage: SuMV, which currently is found only inTexas, can substantially reduce yield in individualplants. No fields have been observed with high incidence.This disease is also of quarantine significance,and many countries will not accept seed from fieldswith any level of SuMV. Aster yellows, which occursthroughout the Midwest, is sporadic in occurrenceand is generally more of a novelty than of economicconsequence.Management: As both SuMV and aster yellows arespread by insects, the easiest means of minimizingboth diseases is to control their insect vectors. Varietaldifferences to aster yellows have been noted. In contrast,no resistance to SuMV is available in commercialhybrids, although resistance has been found inwild Helianthus species from Texas.■ Other MiscellaneousFoliar DiseasesThe diseases mentioned above are the most likely leafdiseases to be encountered in the main sunflower-producingareas of the Midwest. As sunflower productionexpands into other areas, a possibility exists of otherfungi causing leaf spots. Some of the fungi recordedto cause leaf spots on wild sunflower in other areas ofthe U.S. include Ascochyta compositarum, Cercosporahelianthi, C. pachypus, Colletotrichum helianthi, Entylomacompositarum (leaf smut), Epicoccum neglectum,Itersonilla perplexans, Myrothecium roridum,Phialophora asteris (Phialophora yellows), Phyllostictawisconsinensis and Sordaria fi micola. Check outthe “<strong>Sunflower</strong> Diseases” chapter by Gulya et al. in“<strong>Sunflower</strong> Technology and <strong>Production</strong>,” published bythe Agronomy Society of America, for more details onthese minor foliar pathogens.66


III. Stalk- and Root-infectingDiseases■ Sclerotinia WiltDescription: Sclerotina wilt usually is observed firstas plants start to flower. The first symptoms include asudden wilting (Figure 85) with no other leaf symptoms,and a characteristic stalk lesion at the soil line.The length of time from the first sign of wilt to plantdeath may be as little as four to seven days. The stalklesions that form at the soil line are tan to light-brownand eventually may girdle the stem (Figure 86). Undervery wet soil conditions stalks and roots may becovered with white mycelia and hard black structurescalled sclerotia (Figure 87). Sclerotia are irregularshapedstructures which range in size and shape fromspherical and 1/8 inch in diameter to cylindrical orY-shaped and up to 1 inch in length. Sometime a seriesof dark “growth” rings produced by the daily extensionof the fungus can be observed.Disease Cycle: Sclerotinia sclerotiorum overwinters assclerotia in the soil or in plant debris. When sunflowerroots grow near sclerotia, the sclerotia are stimulatedto germinate, and the resulting mycelium infects thelateral roots. The fungus grows along the root systemto the tap root and up into the stem, and the plant wiltsand dies. Contact between roots of adjacent plantswithin rows allows the fungus to spread from plant toplant. The fungus does not move between conventionallyspaced rows. <strong>Sunflower</strong> is the only crop that S.sclerotiorum consistently infects through the roots.Other susceptible crops are infected mainly by sporeson above-ground parts of the plant.Sclerotia are formed in the decayed stem pith and onthe roots as the plant dies. These sclerotia then arereturned to the soil during tillage operations and serveas sources of inoculum for the next susceptible crop.Sclerotia can survive in the soil for five or more years,with a portion of them dying each year if they fail toinfect a host. The higher the inoculum density (i.e., thenumber of sclerotia in the soil), the longer the period a■ Figure85. Suddenwilting is acharacteristicsymptom ofSclerotiniawilt.(B.D. Nelson)■ Figure 86. Basal canker formed from Sclerotiniawilt infection. (B.D. Nelson)■ Figure 87.Dense whitemold may formon the surfaceof the basalcanker. Hardblack bodiescalled sclerotiaalso form on theoutside and theinside of stems.(D.E. Zimmer)Diseases67


field will remain infested. Soil moisture and temperatureduring the growing season are not critical factorsaffecting wilt incidence. Plant population, in the rangefrom 15,000 to 30,000 plants per acre on 30- or 36-inch rows, is not a factor affecting disease incidence,although solid seeding should be avoided. Lodging ofwilted plants, however, increases at high plant populationsdue to smaller stem diameter.Damage: Historically, wilt is the most prevalent ofthe Sclerotinia diseases, with the disease found in oneout of two fields in the <strong>Dakota</strong>s, and about 3 percentof the crop affected. Wilt occurs whenever sunfloweris planted on Sclerotinia-infested soil and can causesevere yield loss. Infected plants die rapidly, and ifthis occurs before the seed is fully mature, the result isa loss of seed yield accompanied by lower test weightand lower oil content. Since plant death occurs late inthe season, healthy adjacent plants have little opportunityto compensate for the loss of the Sclerotinia-infectedplant. On the average, infected plants yield lessthan 50 percent of healthy plants. Equally important,however, is that Sclerotinia wilt leads to increasednumbers of sclerotia in the soil, thus contaminatingthe field for all susceptible crops that would be in therotation.Management: Sclerotinia wilt is a difficult diseaseto manage for several reasons. First, the fungus has avery broad host range and basically is able to infect allbroadleaf crops to some extent. Rotation to minimizeSclerotinia is most effective with cereal grains andcorn. Second, since the sclerotia can persist in the soilfor long periods of time, long rotations away frombroadleaf crops are necessary to minimize sclerotialpopulations in the soil. This may not be feasiblebecause repeated cropping of cereal grains will lead toa buildup of cereal diseases, especially Fusarium headblight. <strong>Sunflower</strong> breeders have strived to increase thelevel of resistance to Sclerotinia wilt and tremendousimprovements have been made, but no immune hybridsare on the market yet. Based on several years oftests with artificial inoculations, commercial hybridswith extremely good levels of resistance are available.Information on hybrid ratings for Sclerotinia stalkrot resistance is found in <strong>NDSU</strong> publication A-652,“Hybrid <strong>Sunflower</strong> Performance Testing.”Lastly, chemical control is not an option since thesclerotia are low in number and scattered throughoutthe soil. The most effective chemicals would be soilfumigants used for nematocide control, and even ifthe chemicals were registered on sunflower, the costwould be prohibitive. Two management strategies holdpromise to minimize, but not eliminate Sclerotinia.One is the use of biocontrol. Various fungi, termedmycoparasites because they feed upon other fungi,have been shown to attack Sclerotinia. One suchfungus is Coniothryium minitans, which is found inthe registered product called “Contans.” If this productis applied to the soil (and preferably to the crop beforedisking), the mycoparasite Coniothryium will colonizethe sclerotia and kill the sclerotia in several monthsrather than years. This will allow shortened rotationsto be used, but replanting a Sclerotinia-infested field toa susceptible crop (e.g., dry bean, canola, sunflower)the following year still is inadvisable.Another management option is tillage, and this is atthe center of two schools of thought. One opinion isthat deep tillage (inversion of the soil profile via moldboardplowing) will put the sclerotia deep into thesoil in an anaerobic environment where they are moreprone to bacterial degradation and are out of the plantroot zone. If deep tillage is used, producers shouldpractice reduced tillage in the following years to preventbringing the buried sclerotia back to the surface.The second school of thought is to let the sclerotiaremain on the soil surface, where they are subject bothto weathering and attack by other fungi. No conclusiveevidence is available to show that either no-till or deeptillage produces significantly less Sclerotinia wilt withsunflower, although research on soybeans stronglyfavors no-till to reduce sclerotia numbers.68


■ Sclerotinia Middle Stalk Rotand Head RotDescription: Middle stalk rot is the disease least oftencaused by Sclerotinia, and is first observed in the middleto upper portion of the stalk at or before flowering.Midstalk rot begins with infection of the leaf, and thefungus progresses internally through the petiole untilit reaches the stem (Figure 88). Symptoms of Sclerotinialeaf infection are not unique enough to identifythe fungus, but once the stem lesion forms, thesymptoms are identical with the lesion formed by rootinfection. The characteristic pith decay and formationof sclerotia both within the stem and sometimes on theexterior are highly diagnostic. The stalk usually lodgesat the lesion site and the leaves above the canker die.With time, the fungus completely disintegrates thestalk, and the affected area will have a shredded appearance,as only the vascular elements of the stemremain.The first symptoms of head rot usually are the appearanceof water-soaked spots or bleached areason the back of the heads. The fungus can decay theentire head, with the seed layer falling away completely,leaving only a bleached, shredded skeletoninterspersed with large sclerotia (Figure 89). Thesebleached, skeletonized heads, which resemble strawbrooms, are very obvious in the field, even from adistance. During harvest, infected heads often shatterand any remaining seeds are lost. The large sclerotiain the heads may be 0.5 inch (12 mm) or greater indiameter and many are harvested along with the seed(Figure 90).Disease Cycle: If soil is very wet for seven to 14 days,sclerotia in the upper several inches of soil can germinateto form small mushrooms called apothecia. Theseapothecia produce ascospores for a week or more. Theascospores can originate within the sunflower field orcan be blown in from adjacent fields. Thus, sunflowerfields with no history of Sclerotinia can became affectedby head and middle stalk rot. Apothecia arenot usually observed until after the crop canopy hascompletely covered the rows. Apothecia are morelikely to form in crops with dense canopies, such assmall grains, and the resultant spores can be blown adistance to nearby sunflower fields (Figure 91). Ascosporesrequire both free water (dew or rain) and a foodbase such as dead or senescing plant tissue to germinateand infect. The fungus cannot penetrate unbroken■ Figure 88.Middle stalkrot occursvia ascosporeinfection.(B.D. Nelson)■ Figure 89. Head rot showing skeleton head filledwith sclerotia. (B.D. Nelson)■ Figure 90. <strong>Sunflower</strong> seed contaminated withsclerotia.Diseases69


Thus, lower plant populations will facilitate more airmovement and hasten leaf drying. Moderate levelsof nitrogen fertilization also will minimize excessivefoliage, but this needs to be counterbalanced withadequate fertilization to optimize yields.■ Figure 91. Apothecia in field of soybean plants.(B.D. Nelson)tissue. Midstalk infection may result from either leafinfection or infection at the leaf axil. Head infectionactually starts as ascospores colonize the dead floretsand pollen on the face of the head. Thus, when lesionsare seen on the back of the head, several weeks haveelapsed since infection took place.Damage: Middle stalk rot is the least often seen phaseof Sclerotinia diseases. Head rot incidence fluctuatesdramatically, dependent entirely upon weather conditions.In dry years, head rot is entirely absent, while inyears and locations where rainfall is frequent duringand after flowering, head rot may be present in nearlyall fields to some degree. Currently the incidence ofhead rot and wilt in the <strong>Dakota</strong>s is about equal, withapproximately 3 percent of the crop affected by eachdisease. Yield loss from head rot on an individualplant may range from minimal to total loss since theaffected head may disintegrate and drop all of the seedon the ground prior to harvest. Intact but diseasedheads will have light and fewer seeds, with lower oilconcentration, and also will shatter during harvest.The sclerotia that form in the diseased stalks andheads are returned to the soil at harvest, thus contaminatingthe field for subsequent broadleaf crops.Management: The same comments made about Sclerotiniawilt also apply to head rot management, withsome exceptions. Since ascospores that cause headrot can be blown into a field, rotation will have lessconsistent impact upon head rot, even though it mayreduce the levels of sclerotia in the field. Anythingthat can minimize the crop canopy will help modifythe environment necessary for ascospore infection.One of the most important tools for managing allSclerotinia diseases is monitoring the incidence ofSclerotinia diseases on any preceding crop. If Sclerotiniais observed on a crop, the grower then knowsthat planting any susceptible crop in that field thenext year is imprudent. The number of years necessaryto rotate away from susceptible broadleaf crops(while the population of sclerotia declines) dependsupon the initial Sclerotinia incidence. As a generalrule of thumb, most researchers suggest that fouryears away from broadleaf crops should reduce thesclerotial population to below a threshold level. Sincesunflower is the only crop prone to root infection, androot infection can happen even in dry years, sunflowerobviously would be the worst crop choice to plant ina known infested field, with dry bean and canola followingclosely behind. As stated earlier, the best cropsto break the Sclerotinia cycle are monocots (smallgrains, corn, sorghum).<strong>Sunflower</strong> hybrids do exhibit different degrees of susceptibilityto head rot, but no totally resistant hybridsare available. An extensive testing program is underway to evaluate commercial hybrids for head rot resistance.Several university research centers have establishedmist-irrigated plots, which when coupled withartificial inoculations with ascospores, have producedhigh levels of infection to accurately assess hybriddisease response. After the most resistant hybrids havebeen tested in multiple locations, this information willbe published in the <strong>NDSU</strong> publication “Hybrid <strong>Sunflower</strong>Performance Testing” (A652), also availableonline at www.ag.ndsu.edu/pubs/plantsci/rowcrops/a652.pdf. No chemical is registered for control of headrot in the U.S. Even if a chemical were registered, itwould have to be applied as a preventative becausewhen symptoms become visible, the infection alreadytook place two to three weeks earlier and the fungushas become well-established in the head.For more information on sclerotinia, consult <strong>NDSU</strong>Extension Service publication “Sclerotinia Diseaseof <strong>Sunflower</strong>” (PP-840), also viewable on the Internetat www.ag.ndsu.edu/pubs/plantsci/rowcrops/pp840w.htm.70


■ Stem Rots Caused by SclerotiniaMinor and Sclerotium RolfsiiDescription: Stem rots caused by Sclerotinia minoror Sclerotium rolfsii are very similar in appearanceand will be covered together. Sclerotinia minor onsunflower is seen in California and the southern GreatPlains, but has not been reported in the northernGreat Plains. Stem rot caused by Sclerotium rolfsii,also called Southern blight, primarily is observed onsunflower in warm climates such as California, Floridaand irrigated fields in the southern Great Plains. Sclerotiumrolfsii has not been observed on sunflower inthe northern Great Plains, but has been noted in nurserystock in Minnesota, suggesting it could becomeestablished in the northern latitudes. Both fungi havea very broad host range encompassing many broadleafcrops.The symptoms of both Sclerotinia minor and Sclerotiumrolfsii are outwardly very similar to the rootinfection and wilt caused by Sclerotinia sclerotiorum.Affected plants have a water-soaked lesion on the stemat the soil line that turns light brown. Under humidconditions, white mycelium also may be found on thelesion. In some instances, the lesion also may have aseries of dark rings due to the diurnal growth patternof the fungus. Plants infected with either fungus wiltand die suddenly, without any distinctive foliar symptoms,within a week of the onset of wilting. The majorfield sign to distinguish S. sclerotiorum from S. minoris the size and shape of the sclerotia. In S. minor, thesclerotia are always round and generally less than 1/12inch (2mm) in diameter (Figure 92), and thus muchsmaller than sclerotia of S. sclerotiorum. Sclerotia ofSclerotium rolfsii are also round and the same size (12 inches), especially ifcomplete inversion of the soil profile is possible, willremove most of the sclerotia from the root zone andplace the sclerotia where they are most vulnerable toattack by soil bacteria. Differences in hybrid susceptibilityhave not been investigated in the U.S. becauseneither disease is present in the major sunflowerproduction areas.Diseases■ Figure 92. Sclerotia of Sclerotiniasclerotiorum (left) and S. minor (right)from sunflower stalks. Ruler at top incentimeters. (T. Gulya)71


■ Charcoal RotDescription: Charcoal rot is caused by Macrophominaphaseolina, a fungus that attacks about 400plant species, including sunflower, dry bean, soybean,corn and sorghum. Charcoal rot is found throughoutthe Great Plains, but the disease is most common andsevere in southern areas such as Texas, Kansas andNebraska. Charcoal rot has been found on sunflowerin western <strong>North</strong> <strong>Dakota</strong> and north-central South<strong>Dakota</strong> recently, and also on corn and soybean in bothstates. Charcoal rot generally appears after floweringbut seedling blights have been reported. Symptoms onstalks appear as silver-gray lesions near the soil line(Figure 93), which eventually decay the stem and taproot, leaving a shredded appearance. Stems are hollowand rotted, and lodge easily. Plants show poor seed filland undersized heads. Seed yield, test weight and oilconcentration are reduced. Numerous tiny black fungusbodies, called microsclerotia, form on the outsideof the stalk and in the pith. To the unaided eye, the microsclerotialook like pepper grains; with a 5X to 10Xlens they are clearly distinguishable as black, sphericalsclerotia. Another unique characteristic of charcoal rotis the compressing of pith tissue into horizontal layers,like a stack of separated coins (Figure 94). This is adiagnostic characteristic of the disease.Disease Cycle: The primary source of inoculum issclerotia in the soil, but Macrophomina also can beseed-borne. Upon stimulation by nearby root exudates,the sclerotia germinate to form mycelium thatcolonizes the roots. Macrophomina may colonizeroots early in the season, but disease symptoms donot manifest themselves until anthesis. Once the rootsystem is colonized, the fungus enters the stem andcolonizes the vascular system, resulting in wilt andpartial degradation of the pith. Disease developmentis favored by soil temperatures above 85 F. Moisturestress during the post-flowering period greatly favorsdisease development.Damage: Post-flowering stresses due to high plantpopulation or drought coupled with heavy applicationsof nitrogen fertilizer, hail or insect damage promotedisease development and accentuate the impact ofcharcoal rot. Yield losses can be significant if diseaseincidence is high, as infected plants die before seed setis complete.Management: Crop rotation, balanced fertilizer programsand practices to reduce moisture stress all helpminimize the impact of charcoal rot. Certain hybridsoffer some resistance, possibly through drought tolerance.Since the fungus also attacks corn, sorghum andsoybeans, not growing sunflower and these crops insuccessive years on the same ground would be advisableif charcoal rot has been observed.■ Figure 93. Silver grey discoloration of lower stemcaused by charcoal rot compared with healthy greenstalk (left). (T. Gulya)72■ Figure 94. Charcoal rot affected stalk split apart toreveal characteristic compression of pith into layers.(T. Gulya)


Texas Root RotDescription: Texas root rot, or cotton root rot, is asoil-borne fungal disease found only in Texas, NewMexico, Arizona, southeastern California and northernMexico. The causal agent, Phymatotrichopsisomnivora (synonym: Phymatotrichum omnivorum) hasa very broad host range of more than 1,800 species ofbroadleaf herbaceous crops and weeds. On sunflower,as with most crops, the initial symptom is wilting followedquickly by death of affected plants. The diseasein Texas develops in late spring and usually occurs incircular spots in the field, which enlarge after rain orirrigation. No diagnostic symptoms appear on leavesor stems, but white mycelial strands on roots, visiblewith a 5X to 10X hand lens, are characteristic of thisfungus. Following rain or irrigation, the fungus mayproduce white mycelial mats up to 12 inches in diameterand up to ¾ inch thick on the soil surface.Disease Cycle: The Texas root rot fungus survives formany years in the soil as sclerotia. These germinate toproduce mycelial strands that can grow some distancein the soil until root contact is made. This ability alsoallows the fungus to spread from plant to plant in arow via overlapping root systems. The disease is mostsevere in moist, warm (80 F or higher at a 1-footdepth) soils that are high pH and high clay content.Sclerotia, at first white and turning tan to dark brown,are round and generally greater than 1/12 inch in diameter.Sclerotia may form in the soil away from plantroots. On roots, the sclerotia may form at irregularintervals, giving the appearance of a string of beads.Damage: Like other root-infecting, stalk-rotting fungi,Phymatotrichum can cause considerable yield lossesif plants are infected near bloom. Even if seed yield isnot reduced, the fungal infection will lower oil contentand result in lower test weight. In field trials in westernTexas, disease incidences up to 60 percent wereobserved, which cut yields by at least half.Management: The fungus persists in the soil for manyyears as sclerotia, which are the propagules that infectsubsequent crops. Resistance has not been observedin sunflower. The best disease management is rotationwith nonhosts, such as corn, sorghum, small grains orgrass. Planting after cotton or alfalfa, especially whereTexas root rot was observed, would be the worst-casescenario.■ Phoma Black StemDescription: Phoma black stem, caused by the soilbornefungus Phoma macdonaldii, is characterizedby large, jet black lesions on the stem, sometimesreaching 2 inches in length. In addition, the fungusproduces lesions on the leaves, on the back of the headand at the base of the stalk. The typical stem lesionsoriginate with leaf infections that progress down thepetiole to the stalk. Under favorable conditions, theleaf wilts, the petiole turns uniformly black and thestem lesions expand to form a large, shiny, black patchwith definite borders (Figure 95). Small circular fruitingbodies of the fungus are produced on the surfaceof the stem, but these are inconspicuous to the nakedeye and require a hand lens to observe.Disease Cycle: Phoma infection occurs throughout thegrowing season, although it usually is not noticed untilthe stem lesions become obvious later in the summer.The fungus overwinters in infected debris and conidiaare spread by splashing rain. Insects such as Apionand Cylindrocopturus stem weevils also can carryPhoma spores both internally and externally. Adultweevils feeding on the leaves cause leaf lesions, whilecontaminated larvae spread the fungus as they tunnelthroughout the stem. Disease transmission throughinfected seed is of minor importance.■ Figure 95. Large black lesions associated withthe point of attachment of the leaf to the stem is acharacteristic symptom of Phoma black stem.(D.E. Zimmer)Diseases73


Damage: Phoma black stem is the most widespreadstalk disease noted on sunflower in the northern GreatPlains, but yield losses attributable solely to Phomagenerally are considered minimal. Infected plants mayproduce smaller heads with reduced seed yield and oil.Phoma stem lesions are generally superficial and donot result in pith damage or lodging. However, if stemweevil larva tunneling spreads Phoma spores in thepith, extensive pith degeneration can occur.Management: No control measures are totally effective.A four-year rotation to other crops will minimizethe concentration of Phoma within the soil. Controlof stem weevils can help reduce transmission of thefungus. However, such control is not recommendedsolely for management of Phoma. No hybrids havebeen identified as being immune to the disease, butsome hybrids are more tolerant than others.■ Phomopsis Stem CankerDescription: Phomopsis stem canker, caused by Phomopsishelianthi (sexual stage = Diaporthe helianthi)is a serious disease that first was observed in Europein the late 1970s and in the U.S. in 1984. The distinguishingfeature of the disease is the large tan to lightbrown lesion or canker that typically surrounds theleaf petiole (Figure 96). Compared with Phoma blackstem, the Phomopsis lesion is much larger, reaching 6inches in some cases, is brown rather than black andtypically has a sunken border. Phomopsis also causesmore extensive pith degradation than Phoma, so thestalk may be crushed with moderate thumb pressure.Phomopsis-infected plants also are more prone tolodging than Phoma-infected plants.Disease cycle: The fungus overwinters predominantlyas perithecia of Diaporthe in infected plant debris.The ascospores released from the perithecia arerain splashed or windblown onto leaves. The infectionstarts on the margins of lower leaves. A brownnecrotic area develops and may be bordered by achlorotic margin. The infection spreads down throughthe veins to the petiole and finally to the stem. Thesesymptoms look similar to those of Verticillium leafmottle, but with Verticillium, the necrotic areas arebetween the veins. Stem lesions usually do not appearuntil flowering. Girdling stem lesions result in wiltingand make the plant more prone to lodging. The diseasemay be difficult to identify when both Phoma andPhomopsis are present, in which case the stem lesionmay be intermediate in color between the black lesionassociated with Phoma and the brown typically associatedwith Phomopsis. In these cases, microscopicidentification of the fungus is necessary.Damage: Phomopsis stem canker has been found inboth the central and northern areas of the Great Plains.Since the fungus is specific to sunflower, it likelywould not be found in areas without a history of sunflowerproduction. The disease is most severe underconditions of prolonged high temperatures and highrainfall. Yield losses result from smaller heads andlighter seed, and from lodging due to weakened stems,which can be quite extensive.Management: Since the fungus overwinters in infectedsunflower debris on the soil surface, thoroughdisking in the fall to bury plant residue and croprotation can reduce disease incidence and severity.Leaving crop residue on the soil surface would fosterthe best development of Phomopsis. Most U.S. sunflowercompanies are trying to incorporate some levelsof Phomopsis resistance into their hybrids, usingparental lines developed in Europe, where the diseaseis particularly severe. No U.S. commercial hybrids areimmune to Phomopsis stem canker, nor are any fungicidesregistered in the U.S. for control of Phomopsis.Please consult <strong>NDSU</strong> publication A-652 for informationon ratings of commercial hybrids to Phomopsis.74■ Figure 96. Phomopsis is characterized by thelarge light brown lesion or canker which typicallysurrounds the leaf petiole. (T. Gulya)


■ Verticillium Leaf MottleDescription: Verticillium wilt, or more accurately,leaf mottle, is caused by the soil-borne fungus Verticilliumdahliae. The fungus has a wide host rangeand causes wilt of several other cultivated plants andweeds. Potato is the other important crop host ofVerticillium in the northern Great Plains. Verticilliumleaf mottle typically causes necrosis between the mainleaf veins with yellow margins. The contrast betweenthe necrotic tissue surrounded by chlorosis and thehealthy green leaf tissue is striking and quite diagnostic.Symptoms begin on the lower leaves and progressslowly upward (Figure 97) and may encompass allleaves. Affected leaves rapidly become completely dry,but do not wilt to the same degree as with Sclerotiniawilt. Thus, the term leaf mottle may be more appropriatethan Verticillium wilt. Symptoms usually are notobserved until flowering, but under severe conditions,they may occur as early as the six-leaf stage. Thevascular system of infected plants may be discoloredbrown, visible as a brown ring in a cross-section of thestem. The pith of severely diseased plants is blackenedwith a layer of tiny black fruiting bodies (microsclerotia).These microsclerotia are much smaller thanmicrosclerotia of charcoal rot and are not visible witha hand lens. Under a microscope, Verticillium microsclerotiaare irregular to club-shaped (< 0.1 mm long),while charcoal rot microsclerotia are more uniformlyspherical and larger (0.1 to 1.0 mm in diameter). Anotherfungus, Phialophora asteris, causes quite similarsymptoms on sunflower. This fungus does not formmicrosclerotia, which is one way to distinguish it fromVerticillium.Life Cycle: Verticillium overwinters as mycelium ormicrosclerotia in infected plant debris. The microsclerotiagerminate in response to root contact and colonizethe root system. As the fungus reaches the taproot and lower stem, toxins produced by the fungusare translocated to the leaves to produce the chloroticand necrotic areas between the veins. Verticilliumremains within the stem tissue and cannot be isolatedfrom symptomatic leaves. The fungus is isolated mosteasily from stems and petioles of infected plants. Noinvolvement of conidia occurs in disease development,although the fungus does produce conidia in culture.Damage: <strong>Sunflower</strong>s infected with Verticillium usuallydie before seeds are completely mature, and thus yieldlosses result from smaller head size, lighter test weighand reduced oil concentration. The stems of Verticillium-infectedplants are weakened as the pith shrinks,and are more prone to lodging.Management: Resistance to Verticillium dahliae iscontrolled by a single dominant gene (V-1), and mostU.S. oilseed hybrids contain this resistance. However,a new strain of Verticillium that is able to overcomethe V-1 gene recently was identified both in the U.S.and Canada. Thus, hybrids that previously were consideredresistant have shown symptoms of Verticilliumwilt due to infection by this new strain. Confectionhybrids as a group are more susceptible to Verticilliumthan are oilseed hybrids. Verticillium leaf mottle is aserious disease on lighter soils with a history of sunflowercropping, and is seen less frequently on heavy,clay soils. This disease will cause some yield loss eachtime a susceptible crop is planted, as the fungus canpersists for five to 10 years as microsclerotia.Diseases■ Figure 97. Plants infected with Verticilliumwilt show interveinal necrosis with yellowmargins. (T. Gulya)75


■ Bacterial Stalk RotDescription: Bacterial stalk rot occurs sporadically inthe Great Plains and generally is not considered a majorsunflower disease. The pathogen is Erwinia carotovora,a bacterium that causes soft rot on potato andother vegetables. Typical disease symptoms are stemdiscoloration (dark brown to black), often centeredon a petiole axil, and a wet, slimy, soft rot of internalstem tissue. A pungent odor, reminiscent of rottingpotatoes, is also characteristic. Due to pressure fromthe gas produced by the bacteria, the stem may be splitopen. Symptoms may extend down the stem into theroots. The bacterium also can infect the head, causinga wet, slimy rot of the receptacle. Infected stems areprone to lodging, and infected heads quickly fall apart.After the plant dies, the affected stalk or head dries upand may leave little indication of prior mushy rot.Disease Cycle: The main source of the bacteria isinfested plant residue on the soil surface. The bacteriaenter the plant through wounds caused by insects, hailand windblown sand; they cannot penetrate unbrokenepidermis like fungal pathogens. Extended wetand warm periods favor disease development. Mostdiseased plants are observed later in the season. Youngplants are more resistant to stalk decay than plantsnearing senescence. Varietal differences in susceptibilityto bacterial stalk rot are reported.Damage: Bacterial stalk rot is seen infrequently. Plantsaffected by this disease will be killed and producelittle or no seed, but disease incidence within a field isgenerally low.Management: While differences in resistance havebeen observed, little information is available on theresistance of current hybrids. Control of stem feedinginsects will minimize the potential of insect transmission.■ Nematode DiseasesDescription: Nematodes are microscopic, nonsegmentedroundworms that can cause serious damage tothe roots of many crops. While many different types ofnematodes have been found in sunflower fields, theireconomic impact on the plant is undocumented orhighly variable.Genera of nematodes that have been reported on sunflowerin the northern Great Plains include Heliocotylenchus,Tylenchrohynchus, Paratylenchus, Hoplolaimusand Xiphinema; the first two genera are the mostwidely distributed in <strong>North</strong> <strong>Dakota</strong>, while Paratylenchusis the dominant nematode in South <strong>Dakota</strong>.All these nematodes are ectoparasites, meaning thatthey feed either on the root surface or burrow partiallyinto the roots. Root-knot nematodes (Meloidogynespp.), damaging pests of many crops, have beenreported on sunflower in Florida and in warm areas ofother countries but have not been recorded on sunflowerin the upper Great Plains states. <strong>Sunflower</strong> isnot a host for the soybean cyst nematode (Heteroderaglycines), making sunflower suitable for rotation withsoybean where the cyst nematode is a problem.Disease Cycle: Nematodes overwinter in the soil aseggs and colonize plant root systems throughout thegrowing season. Symptoms caused by nematodes arenot distinctive and mimic those due to drought andnutrient deficiencies. In severe infestations, the foliagewilts and turns yellow, and stunting may occur. Thepattern of affected plants in the field may have little orno relationship with topography. Examination of rootsis necessary to prove nematode damage. Identificationof nematodes to genus requires their extraction fromsoil and roots, followed by microscopic examination.Damage: High populations of nematodes have causedyield reductions in greenhouse studies.Management: Applications of nematocides in fieldtrials have produced variable yield responses. Nonematocides are registered for use on sunflower, andthe potential cost return makes their use questionable.Tolerance to nematode damage appears related to theextensive root system of sunflower.76


IV. Head Rots and Diseasesof Mature Plants■ Head Rots, Other Than SclerotiniaDescription: Several head rots (other than Sclerotinia)occur on sunflower in the U.S., and these are causedby several fungi, including Rhizopus, Botrytis and thebacterium Erwinia, covered previously.Rhizopus head rot, caused by Rhizopus arrhizus andR. stolonifera, was considered a sporadic disease inthe Great Plains, but recent surveys have shown it tobe the most widespread disease in the central GreatPlains (Figure 98). Initial symptoms are brown, wateryspots on the receptacle. Rhizopus species rot the softtissues of the head, turning it brown and mushy. Athreadlike, whitish fungal mycelium develops on andwithin the receptacle. Tiny black pinhead-sized fruitingstructures (sporangia) form within the head tissue,giving the appearance of pepper grains.Botrytis head rot is caused by the widespread fungusBotrytis cinerea, and is distinguished from Rhizopusby the gray “fuzz” on the heads (caused by myceliumand spores). Heads affected by Botrytis eventually willdisintegrate and may contain small sclerotia, similar insize to those caused by Sclerotinia.Bacterial head rot caused by Erwinia carotovora israre in the Great Plains. This disease is characterizedby a slimy, wet, brownish rot of the head with no fungusgrowth or spores in the tissues. Often such headshave a putrid odor.Disease Cycle: Rhizopus enters the head throughwounds caused by hail, birds and insects and has beenassociated with head moth and midge damage. Thesusceptibility of heads increases from the bud stage upto the full bloom and ripening stages. Disease developmentis most rapid in warm, humid weather. Oncethe head is fully colonized and all tissue killed, thehead dries up and becomes hard and “mummified.”Botrytis infects sunflower heads during cool, wetweather and requires organic debris, such as flowerparts or senescing tissue, to initiate growth. Late attacksstart from the senescent petals and head bractsand may be serious during a wet fall and late harvesting.Head rot symptoms start as brown spots on theback of the head, which is identical to the initial symptomsof all head-rotting fungi. These spots becomecovered with gray powdery Botrytis conidia, givingthe head a “fuzzy” appearance. These spores generallyform on the surface tissues and not inside the tissues,as with Rhizopus. In wet weather, the infection spreadsthroughout the tissues, and the head becomes a rotten,spongy mass.Bacterial head rot, as with bacterial stalk rot, is causedwhen windblown or rain-splashed bacteria fall onwounds in the head caused by hail, insects or birds.No fruiting structures are associated with bacterialdiseases, but the putrid odor associated with bacterialrotting is distinctive enough for identification.Damage: Disease incidence for all three describedhead rots is generally low throughout the northernGreat Plains, while Rhizopus head rot is common inthe High Plains. Individual heads affected by any ofthe head rots will have lighter test weight seed, loweroil content and reduced seed yield. In severe cases,the affected heads may be entirely lost. Seeds fromheads infected by any of these fungi or bacteria willhave higher free fatty acid content, resulting in a bittertaste. Thus, head rots of confection sunflower maycause losses due to lowered quality factors, even incases where actual seed yield losses are minimal.Management: Insect control may help minimizeRhizopus head rot, but will not offer as much diseasereduction as fungicide sprays. In the U.S., no fungicidesare registered for control of any head rot, exceptSclerotinia. No practices are recommended to controlbacterial head rot, other than to minimize head-feedinginsects that might transmit the bacterium.■ Figure 98. Rhizopus head rot is characterized bya dark brown, peppery appearance of tissues in thereceptacle. (T. Gulya)Diseases77


78Weeds(Richard Zollinger)Weeds compete with sunflower, causing poor growthand yield losses. Yield loss from weed competitiondepends on weed species, time of infestation,weed density and climatic conditions. All weeds arecompetitors. However, in the northern region of theU.S., wild mustard, wild oats and kochia, which growrapidly early in the season, appear more competitivethan foxtail on a per-plant basis.A comprehensive weed management program consistingof cultural and/or chemical controls is needed tomaximize yields. <strong>Sunflower</strong> is a good competitor withweeds. However, this competitive advantage occursonly after plants are well-established. The first fourweeks after emergence are most critical in determiningweed competition damage, so early weed controlis essential. Weeds competing longer than four weekscause important yield loss even if they are removed.All chemical recommendations for weed control havea U.S. federal label unless otherwise specified. Allrecommended herbicides have federal registration atthe time of printing, and rates listed are label rates attime of printing. Consult the current issue of <strong>NDSU</strong>Extension publication W-253, “<strong>North</strong> <strong>Dakota</strong> WeedControl Guide,” or appropriate Extension publicationsfrom other states for current labeled products, ratesand method of application.WILD MUSTARD (Sinapis arvensis) is a major weedthat infests sunflower. Wild mustard is not controlledby most of the herbicides commonly used in sunflower.Wild mustard emerges early and appears to be mostcompetitive with sunflower when the early season iscool. The cool condition favors wild mustard, but notsunflower growth. Late seeding with seedbed tillageto control early emerged wild mustard can reduceinfestations. However, wild mustard may continue toemerge with timely rains and remain a problem evenwith late seeding. Assert (imazamethabenz) is the onlyherbicide registered for use in conventional sunflowerto control wild mustard. Wild mustard can be controlledeasily in Clearfield sunflower with Beyond(imazamox) and in Express-resistant sunflower withExpress (tribenuron).Wild mustard is controlled effectivelyby herbicides used in other crops in the rotation.Wild mustard seed can remain viable in the soil formany years, so plants allowed to produce seed cancause an infestation for many subsequent years.WILD OAT (Avena fatua) is another cool-season weedthat is abundant in <strong>North</strong> <strong>Dakota</strong> and causes importantyield losses, especially in early seeded sunflower. Wildoat germinates early in the spring, and germinationand emergence generally stop when soil becomeswarm. Delayed seeding reduces wild oat infestations.Wild oat can infest late-seeded sunflower when cooland moist conditions occur at or after seeding. Wildoat is controlled to various degrees by several registeredherbicides (Table 12).GREEN FOXTAIL (Setaria viridis) and YELLOWFOXTAIL (Setaria lutescens) are the most abundantgrassy weeds in <strong>North</strong> <strong>Dakota</strong>. Both green and yellowfoxtail occur throughout the state. Green foxtail hasbeen more abundant, but yellow foxtail is the dominantspecies in many areas because herbicides givingless control of yellow foxtail have been used in crops.The two species have similar appearance, but yellowfoxtail has a flat stem with long hairs at the base ofthe leaves, a more brushlike spike and a larger seed.Green foxtail has a round stem with no hair on theleaves. Foxtail is a warm-season plant, and germinationand emergence do not occur until the soil reaches60 degrees Fahrenheit. Many sunflower herbicidesgive excellent control of foxtail species (Table 12).KOCHIA (Kochia scoparia) is considered the worstweed problem of sunflower in <strong>North</strong> <strong>Dakota</strong>. Kochiais a highly competitive weed that emerges during coolperiods early in the spring or later with warm temperaturesand adequate moisture. Most kochia has becomeresistant to ALS (acetolactate synthase) herbicides andno registered herbicides in sunflower give adequatecontrol. Beyond herbicide in Clearfield sunflower isan ALS herbicide and will not control ALS-resistantkochia. Soil-applied Spartan (sulfentrazone) controlsALS-resistant and susceptible kochia when activatedby sufficient moisture after application. Kochia seedsdo not have a long residual life in the soil. Goodcontrol of kochia in the crop prior to sunflower emergenceor control before seeding will reduce the kochiainfestation.


WeedsRUSSIAN THISTLE (Salsola iberia) is most commonin the drier western areas of <strong>North</strong> <strong>Dakota</strong>. Russianthistle germinates throughout the season. Germinationis rapid, so light rains anytime will promote a newflush of Russian thistle growth. Competition data onlosses from Russian thistle in sunflower are not available.The plants are normally small and competitionusually is not expected. However, Russian thistle isdrought tolerant and losses may be severe, even froma small number of plants under conditions of limitedmoisture.OTHER WEEDS important in sunflower are wildbuckwheat (Polygonum convolvulus), redroot pigweed(Amaranthus retrofl exus), common lambsquarters(Chenopodium album), field bindweed (Convolvulusarvensis), Canada thistle (Cirsium arvense), cocklebur(Xanthium strumarium), marshelder (Iva xanthifolia),biennial wormwood (Artemisia biennis), nightshades(Solanum spp.) and wild sunflower. Some of theseweeds are controlled partially by soil-applied triflualinor Sonalan (ethalfluralin), but these products cannotbe used in no-till sunflower production because ofTable 12. Relative effectiveness of herbicides for various weeds.HerbicideGreen/yellow foxtailWild oatWild buckwheatComn. cockle burKochiaPreplant herbicidesGlyphosate E E F-G E F-E P-E G-E E F-G E G-E G-E G-EParaquat G G F F-G G-E E G E G-E E E - PSoil-applied herbicidesEptam (EPTC) E G-E F P F F N P F G P N NProwl(pendimethalin) G-E P P N F G N N N G F-G N NSonalan(ethalfluralin) E P-F P-F N F E N N P G-E G-E N NDual Magnum(s-metolachlor) G-E P P N P P-F N P P F-G P N NSpartan(sulfentrazone) P N P-F N E E P-G P-F E E G-E G-E NTrifluralin E P P N F G N N N F-G F-G N NPOST-applied herbicidesAssert(imazamethabenz) P G-E F-G P N P N E N P P-F N NBeyond* (imazamox) E E P G-E E1 F G-E E E E G-E P NPoast (sethoxydim) E G-E1 N N N N N N N N N N NSelect (clethodim) E E N N N N N N N N N N NComn. lambsquartersMarshelderWild mustardNightshade spp.R. root pigweedRussian thistleBien. wormwoodCanada thistle* = Clearfield sunflower.1 = Herbicides will not control resistant biotypes.E = Excellent, G = Good, F = Fair, P = Poor and N = None.The ratings in the table indicate relative effectiveness, with effectiveness of each herbicide varying with environment andmethod of application.79


their soil incorporation requirement. Pre-emergenceSpartan controls most small-seeded broadleaf weedsand suppresses wild buckwheat, marshelder andfoxtail. However, no herbicides are available for selectivecontrol of wild buckwheat, Canada thistle, fieldbindweed, cocklebur, marshelder or wild sunflower.Beyond in Clearfield sunflower controls most annualgrass and broadleaf weeds except ALS-resistantweeds, including kochia, but has no activity on perennialbroadleaf weeds. Weeds for which no herbicidesare available need to be controlled in previous crops inrotation, or through tillage or the use of herbicides inor between other crops in the rotation.The sunflower yield loss from individual weeds varieswith the weed species, environment and time of weedemergence relative to the crop. <strong>Sunflower</strong> yield lossesfrom several weeds at various infestations are presentedin Figure 99. The values are averages from severalyears and losses from an individual weed would varywith conditions. A weed that emerges before the sunflowerwould be more competitive than one emergingafter sunflower establishment, and an environment thatfavored the growth of the weed would cause a greaterloss than if the environment favored the sunflower.■ Weed Management(Richard Zollinger)CulturalCultural weed control requires an integrated system oftillage operations. Weeds must be controlled in othercrops in the rotation to reduce the potential infestationlevel in sunflower. Preplant, pre-emergence andpostemergence tillage practices all must be followedfor effective weed control using only tillage. Poortiming or missing any tillage operation can reducethe effectiveness of the cultural weed control programdrastically.Preplant tillage can control one or more weed flushes.<strong>Sunflower</strong> should be planted immediately after the lasttillage operation so the crop can germinate rapidly andcompete more favorably. Weeds frequently emerge beforesunflower, especially during cool weather. Theseweeds can be controlled by pre-emergence harrowing.Postemergence mechanical weed control consistsof harrowing and cultivating. Small weeds can becontrolled by harrowing after the sunflower is in thefour- to six-leaf stage (V-4 to V-6) and can resist burialand breaking (Figure 100). Postemergence harrowingshould be done across rows and preferably on a warm,clear day to assure sufficient weed kill with the leastdamage to the sunflower. <strong>Sunflower</strong> seedlings, whichare strongly rooted, can be harrowed three to fivetimes during the four- to six-leaf stage (V-4 toV-6).The harrow should be kept free of trash. Spring toothharrows are recommended; solid spike-tooth harrowsshould not be used, as excessive damage may result.80■ Figure 99. Percent reduction in sunflower seed yield from several weeds. (J.D. Nalewaja)


Weeds■ Figure 100. This field was harrowed beforesunflower emergence and was being harrowed atabout the four leaf stage to control seedling weeds.(GTA-Farmers Union)The direction of travel during harrowing is determinedby considering the stand, weed growth and herbicidetreatment. Harrowing diagonally to the rows will givebetter in-the-row weed control than with the row harrowing.However, sunflower damage will occur fromthe tractor wheels with diagonal harrowing. Harrowingmay be necessary if a soil-applied herbicide wasnot activated by rainfall, if a field previously treatedwith a herbicide has weeds resistant to the herbicideor if adverse climatic conditions reduce herbicide effectiveness.If the herbicide is band-applied, harrowingshould be parallel to the rows to prevent dilutionwith untreated soil. A rotary hoe also is effective forpostemergence weed control, but weeds must be justemerging for good control. Setting the harrow or“weighting” the rotary hoe to do the most damageto weeds and the least damage to sunflower can beaccomplished on a “try-and-adjust” system. Postemergenceharrowing will kill some sunflower (5 percentto 8 percent loss can be expected), so if this systemof weed control is planned, the sunflower should beseeded at higher rates than normal.After postemergence harrowing, weed control forthe remainder of the season depends on the row-cropcultivator. During the first cultivation, producers musttake care not to cover the sunflower. One to three ormore cultivations may be necessary, depending onthe weed situation in the field. Lateral sunflower rootsare shallow and can be damaged easily by cultivatingtoo deeply and too closely to the plants. Cultivationshould be no closer to the row center than the leafspread of the plants. During later cultivations, soil maybe thrown into the row to bury weed seedlings andprovide the sunflower extra support.Registration of Spartan and Clearfield sunflower willallow and encourage no-till sunflower production. Notillfarming increases dependence on chemicals andincreases selection pressure for resistant weeds.ChemicalThe most effective weed management is accomplishedby an integrated system that uses both cultural andchemical control. Preplant cultural practices to reduceweed seed populations, pre-emergence tillage andpostemergence cultivation may be needed to supplementthe herbicides under adverse climatic conditionsand to control late-emerging weeds or weeds that arenot controlled by herbicides. Herbicides vary in theireffectiveness against various weeds (Table 12).Preplant and Pre-emergenceGLYPHOSATE at 1 to 2 pt/A of 3 lb/gal concentrate(0.38 to 0.75 lb ai/A) is registered for the controlof emerged weed seedlings before, during or afterplanting but before the crop emerges. Glyphosate isa nonselective, systemic, nonresidual herbicide, sotreatment must be made before sunflower emergenceand after weeds emerge. Several formulations areavailable, so follow label directions for rates, weedsizes, application volume and addition of nonionicsurfactant.PARAQUAT at 2.5 to 4 pt/A (0.63 to 1 lb ai/A) isregistered for the control of emerged weed seedlingsbefore, during or after planting but before the cropemerges. Paraquat is a nonselective contact herbicide,so treatment must be before sunflower emergence.However, application must be after weed emergence,as paraquat has no soil residual to control late-emergingweeds. A nonionic surfactant at 0.25 percent v/vshould be added to the spray solution to increase spraydroplet contact with the leaf surface and retention bythe leaf. Spray should be applied at 20 gallons peracre by ground equipment or 5 gallons per acre by air.Paraquat is a restricted-use herbicide.81


82EPTAM (EPTC) at 2.5 to 3.5 pt/A (2 to 3 lb ai/A)applied before planting or at 4.5 to 5.25 pt/A or 20 to22.55 lb 10G per acre applied after Oct. 15 controlssome annual grass and broadleaf weed species. Eptamis degraded within three weeks after application. The3 pound- per-acre rate spring applied occasionallyhas caused sunflower injury on coarse-textured, loworganic matter soils. The risk of sunflower injury canbe reduced by using lower rates on these soils. Immediateand thorough incorporation is essential, as theherbicide is volatile. A 15-minute delay in incorporationduring warm weather with moist soil may resultin significant vapor loss and poor weed control. Properincorporation can be accomplished by tandem diskingtwice in cross directions (4 to 6 inches deep) or byany other method that thoroughly mixes the chemicalwithin the top 3 inches of soil. Eptam generallygives good short-term weed control but is weak onwild mustard, Russian thistle, common cocklebur,smartweed and all perennial broadleaf weeds. Wild oatcontrol is good.PROWL or PROWL H20 (pendimethalin) at 2.4 to3.6 pt/A EC, 2.1 to 3 pt/A ACS preplant incorporatedor pre-emergence in no-till sunflower is registered forcontrol of most grass and certain broadleaf weeds insunflower. Prowl can be applied in the fall at 2.4 to4.25 pt/A and incorporated when soil temperature isless than 45 degrees. Prowl is registered only as an incorporatedtreatment for conventionally tilled sunflowerbecause of greater consistency of weed control andgreater crop safety. Prowl plus Spartan controls manygrass and broadleaf weeds in no-till sunflower. No-tillsunflower is treated with higher rates of Prowl thanconventionally tilled sunflower. The higher rates helpovercome the reduced control from pre-emergence vs.PPI treatment and from Prowl being absorbed on thecrop residue. Prowl is registered at 2.4 pt/A in no-tillsunflower for coarse-textured soils with less than 3percent organic matter and 3.6 pt/A for all other soils,including coarse-textured soils with greater than 3percent organic matter.Prowl may be applied up to 30 days before seedingno-till sunflower. Spray volume greater than 20 gallonsper acre should be used to aid penetration to thesoil in fields with high amounts of crop residue. Prowldoes not control emerged weeds, so either glyphosateor paraquat would be needed to control emergedweeds in no-till sunflower prior to planting. Prowl hasstate registration for no-till sunflower in <strong>North</strong> <strong>Dakota</strong>,South <strong>Dakota</strong> and Minnesota.SONALAN (ethalfluralin) at 1.5 to 3 pt/A (0.55 to1.15 lb ai/A) preplant incorporated in the spring isregistered for the control of annual grass and somesmall-seeded broadleaf weeds in sunflower. Thegranular formulation (Sonalan 10G) can be appliedin the spring or fall between Oct. 10 and Dec. 31 at5.5 to 11.5 lb 10G/A. Sonalan does not control wildmustard. The first incorporation into the soil may bedelayed no longer than two days after application.The second incorporation should be delayed threeto five days after the first. Sonalan has a shorter soilresidual than trifluralin and is slightly more effectivein controlling wild oats, Russian thistle and a fewother broadleaf weeds. Sonalan is registered for tankmixtures with Eptam.Recent labeling allows use of Sonalan in reducedtillagesystems for suppression of foxtail species.Sonalan 10G may be applied at 7.5 to 12.5 pounds peracre in the fall to small-grain stubble and incorporatedonce in the fall and once in the spring with a V-bladeprior to planting sunflower. Sonalan 10G may beapplied in the spring and incorporated twice using a V-blade. For spring applications, a delay of at least threeweeks between incorporations should be observedunless a minimum of 0.5 inch of precipitation occursafter the first incorporation. The delay then may beshortened to 10 days. The incorporations should bemade at approximately 5 mph using a V-blade implementwith 12- to 32-inch-wide sweeps. Both incorporationsshould be no deeper than 2 to 2.5 inches.DUAL MAGNUM (s-metolachlor) at 1 to 2 pt/A (0.95to 1.9) preplant incorporated or preplant will controlgreen foxtail and several other weeds, such as pigweedand lambsquarters. It will not control wild mustard orwild oats. Incorporation improves weed control andconsistency of control. It requires soil moisture foractivation and better weed management. Use higherrates for clay soils high in organic matter.SPARTAN (sulfentrazone) at 3 to 8 fl oz F (1.5 to 4oz ai/A) applied pre-emergence controls most annualsmall-seeded broadleaf weeds, such as kochia, pigweedspecies, lambsquarters, nightshade, smartweed,Russian thistle and biennial wormwood, and maysuppress buckwheat, mustard, ragweed and Russianthistle. Spartan may provide some grass but no peren-


Weedsnial weed control. Adjust rate based on organic matterand use higher rates if applied up to 30 days prior toplanting. <strong>Sunflower</strong> has good tolerance to Spartanon medium to fine-textured soils with organic matterabove 3 percent. Crop injury may occur on soilswith low organic matter and soil pH greater than 8.0,especially on calcareous outcropping. Do not use oncoarse-textured soils with less than 1 percent organicmatter. Closely furrow at planting to avoid injury. Poorgrowing conditions at and following sunflower emergence,cold temperatures, soil compaction or a rate toohigh based on soil type and organic matter may resultin sunflower injury. Consistent weed control greatlydepends on at least 0.75 inch rainfall shortly after applicationand before weeds emerge. Spartan is a PPOinhibitor mode-of-action herbicide in which no weedresistance has been documented.TRIFLURALIN at 1 to 2 pt/A or 5 to 10 lb 10G/A(0.5 to 1 lb ai/A) is a preplant incorporated herbicidefor grass and certain broadleaf weed control insunflower. Incorporation should be by tandem disk orfield cultivator twice in cross directions (4 to 6 inchesdeep) at about 6 mph. Thorough incorporation is essentialfor optimum, consistent weed control. Trifluralinis less volatile than EPTC (Eptam). Immediatesoil incorporation is preferred, but with cold, dry soiland low wind, incorporation may be delayed up to 24hours. The lower rate should be used on soils of coarsetexture and low organic matter. Trifluralin gives seasonlongcontrol of some annual grass and broadleafweeds. Wild mustard is not controlled, and wild oatcontrol is poor.PostemergenceASSERT (imazamethabenz) at 0.6 to 0.8 pt/A (0.19to 0.25 lb ai/A) controls wild mustard in sunflower.Assert should be applied before sunflower exceeds 15inches in height. Wild mustard should be in the rosettestage but prior to bloom. <strong>Sunflower</strong> injury may occurfrom Assert if applied during high temperatures andhumidity.POAST (sethoxydim) at 0.5 to 1.5 pt/A (0.1 to 0.3 lbai/A) applied postemergence in sunflower controls annualgrasses and suppresses quackgrass. Oil adjuvantshould be included at 1 qt/A. Poast at 0.5 pt/A controlswild proso millet; at 1 pt/A controls volunteer corn,green and yellow foxtail, and barnyardgrass; and at1.5 pt/A controls wild oats and volunteer cereals.Quackgrass that is 6 to 8 inches tall can be suppressedwith Poast at 1.5 pt/A. Quackgrass regrowth shouldbe treated at 1 pt/A. Cultivation between 14 to 21 daysafter application will improve quackgrass control. Theaddition of 2 to 4 quarts per acre of liquid nitrogensolution or 2.5 pounds per acre of ammonium sulfatein addition to the oil adjuvant may increase control ofvolunteer corn, cereal grains and quackgrass. <strong>Sunflower</strong>should not be harvested before 70 days afterapplication.CLETHODIM (several trade names) at 6 to 8 fl ozor SELECT MAX (clethodim) at 9 to 32 fl oz/A (1to 3.9 oz ai/A) applied postemergence in sunflowercontrols annual grasses, volunteer cereals and perennialgrasses, including quackgrass. See label rates tocontrol individual type of grasses. Oil adjuvant shouldbe included at 1 qt/A. oz/A. Cultivation between 14and 21 days after application will improve quackgrasscontrol. The addition of 2 to 4 qt/A of liquid nitrogensolution or 2.5 lb/A of ammonium sulfate in additionto the oil adjuvant may increase grass control. <strong>Sunflower</strong>sshould not be harvested before 70 days afterapplication.■ Herbicide-resistant <strong>Sunflower</strong>Clearfield sunflowerBEYOND (imazamox) at 4 fl oz/A (0.5 oz ai/A) appliedpostemergence to Clearfield sunflower varietiesfrom the two- to eight-leaf stage controls most annualgrass and broadleaf weeds. Apply with NIS at 0.25percent v/v alone or with UAN liquid fertilizer at 1 to2 qt/A. Beyond will not control wild buckwheat, biennialwormwood, large common lambsquarters, Canadathistle or ALS-resistant weeds, including kochia.Clearfield sunflower can be planted on land previouslytreated with Assert or Pursuit to reduce or eliminateinjury from long residual sulfonylurea herbicides.Clearfield sunflower may facilitate no-till sunflowerproduction.EXPRESS (tribenuron) at 0.25 to 0.5 oz/A (0.188to 0.38 oz ai/A) applied postemergence to ExpressSun sunflower varieties will control annual broadleafweeds, including wild mustard. It will not controlALS-resistant weeds, including kochia or grass weeds.Control or suppression of Canada thistle can be expectedat the higher rate. Apply early postemergenceto Express-resistant sunflower in the one-leaf stage83


ut prior to bud formation. Broadleaf weeds shouldbe 3 inches or less in height. Apply with MSO-typeoil adjuvants at 1 percent v/v. NIS or petroleum oiladjuvants are not prohibited.Sequential applications are allowed but observe a 14-day interval between applications and do not exceed1 oz/A during any growing season. Allow a 70-daypreharvest interval. Express Sun application may helpfacilitate no-till sunflower production.■ Preharvest ApplicationGRAMOXONE INTEON (paraquat) at 1.5 to 2 pt/A(0.375 to 0.5 lb ai/A) can be used as a harvest aid inoilseed sunflower. Application should be made whenthe backside of the sunflower heads is yellow, bractsare turning brown and seed moisture is less than 35percent. Paraquat can be used on both confectionaryand oilseed hybrid cultivars. Apply with a nonionicsurfactant at 1 to 2 pints per 100 gallon of water. Aseven-day interval must elapse between applicationand harvest. Paraquat is a restricted-use herbicide.DREXEL DEFOL (sodium chlorate) at 1 to 2 gal/A (6to 12 lb ai/A) can be used as a desiccant with both oilseedand confectionary sunflower. Application shouldbe made when the backside of the sunflower heads isyellow, bracts are turning brown and seed moisture isless than 35 percent. Apply at 20 to 30 gallons per acreby ground and 5 to 10 gallons per acre by air.Roundup Preharvest Application in <strong>Sunflower</strong>Monsanto has issued a Supplemental label allowingcertain applications of glyphosate (Roundup) for controlof annual and perennial weeds in sunflower. Applyno more than a total of 22 fl oz of the 4.5 lb. acidequivalent/gal formulation at preharvest. See label forrates suggested.For preharvest use in sunflower, apply for weedcontrol, NOT crop desiccation when sunflower plantsare physiologically mature. Apply when the backsidesof sunflower heads are yellow and bracts are turningbrown and seed moisture is less than 35%. Generallythe dry chaffy material from the disk flowers on thehead can be easily rubbed off by hand and expose theseeds at this stage of maturity. Allow a minimum of 7day preharvest interval (PHI) for sunflower followingapplication.For post-harvest weed control, the products may beapplied after harvest of sunflower. Higher rates may berequired for control of large weeds, which were growingin the crops at the time of harvest. Tank mixtureswith 2,4-D or dicamba may be used after harvest.Always follow the pesticide label when applying anyproduct to sunflower.■ Control of Volunteer <strong>Sunflower</strong>in CropsCrops following sunflower often are infested withvolunteer sunflower plants. In small grains, 2,4-Dand MCPA at rates of at least 1 pt/A are needed forconsistent control. Bromoxynil plus MCPA at 0.5 pt/A+ 0.5 pt/A has given excellent, consistent volunteersunflower control. Dicamba plus MCPA at 4 fl oz/A +0.5 pt/A has given good control. Several sulfonylureaherbicides plus 2,4-D or MCPA, and Curtail or CurtailM also control sunflower. <strong>Sunflower</strong> can emerge fromdeep in the soil, and these late-emerging plants mayescape an early herbicide application. However, delayingtreatment until all sunflower emerge may result inpoor control and some yield loss from competition.Some judgment is needed to determine the propertime for application, and two applications may beneeded in some situations.In corn, preplant Hornet (flumetsulam plus clopyralid),postemergence bromoxynil, Basagran (bentazon),dicamba, Distinct (dicamba + diflufenzopyr),Hornet, Callisto (mesotrione), Permit (halosulfuron),<strong>North</strong>Star (dicamba + primisulfuron) and Option(foramsulfuron) control volunteer sunflower. Volunteersunflower also can be controlled with glyphosate inRoundup Ready corn.In soybean, preplant Pursuit Plus (imazethapyr +pendimethalin), Gangster (flumioxazin + cloransulam),postemergence bentazon, Result (bentazon+ sethoxydim), FirstRate (cloransulam), Pursuit(imazethapyr), Raptor (imazamox) and glyphosatein Roundup Ready soybean will control volunteersunflower.Refer to the herbicide label or the most currentedition of the “<strong>North</strong> <strong>Dakota</strong> Weed Control Guide,”<strong>NDSU</strong> Extension publication W-253, for rates,adjuvants and application guidelines.84


BirdsBirds(George M. Linz and Jim Hanzel)<strong>Sunflower</strong>, due to the easy accessibility and highnutritional value of its seed, is particularly vulnerableto damage by birds (Figure 101). Seeds are exposedand the large head serves as a perch during feeding.<strong>Sunflower</strong> seed is a preferred bird food because theseed contains many proteins and fats essential to theirgrowth, molt, fat storage and weight maintenanceprocesses. Although many species of birds feed in maturingsunflower fields, the greatest losses are causedby migrating flocks of red-winged blackbirds, yellow-headedblackbirds and common grackles (Figure102). Significant losses can occur in fields near cattailmarshes.■ Migrating and FeedingHabits of BlackbirdsThe adult male blackbird is the first of his speciesto arrive in the spring. He establishes a territory andawaits the arrival of the females. As females arrive,they disperse to the males’ territories and breedingtakes place. Each female produces a clutch of threeor four eggs. Nests are built in dense vegetation, mostoften in cattails, which have an abundant food supply.Their diet throughout the nesting season includesinsects, weed seeds and waste grains.Following nesting in July, blackbirds form large flocksand begin feeding in grain fields. Blackbirds startfeeding on sunflower seed soon after the petals beginto wilt and cause most of the damage during the followingthree weeks. Peak concentrations of blackbirdsoccur in mid-September in the northern growing area(Figure 103). This period coincides with the time thatsunflower nears physiological maturity. Most often,the birds roost in the cattail marshes at night and moveto the field for feeding during the day.Blackbirds feed on insects and weed seeds in smallgrain, corn or sunflower fields before these crops arevulnerable to damage. They become used to feeding ina certain location and include sunflower seeds in their■ Figure 101. <strong>Sunflower</strong> may be depredated by birds.Birds perch on sunflower heads and pluck the seeds.(Reu V. Hanson)■ Figure 102. The red-winged blackbird is the mostserious bird pest of sunflower in the northern Plains.(Reu V. Hanson)85


86■ Figure 103. Blackbirds cause the most damage inearly to mid-September. (Reu V. Hanson, George Linz)diets as the crop matures. Efforts made by the producerto move birds from a field often are unsuccessfulbecause the birds are in the habit of feeding there.ManagementBlackbirds are protected under the Migratory BirdTreaty Act. However, Section 21.43, Title 50 CFR,provides: “A federal permit shall not be requiredto control yellow-headed, red-winged, tri-coloredred-winged, and Brewer’s blackbirds, cowbirds, allgrackles, crows and magpies when found committingor about to commit depredations upon ornamental orshade trees, agricultural crops… .” Cultural practicesin combination with mechanical and chemical harassmentpractices should be used to control blackbirds.Cultural ControlA combination of cultural practices may be used to reducethe risk of bird damage to sunflower. If possible,sunflower should not be planted near cattail marshesor woodlots. Unplanted access trails allow easier accessto fields while scaring blackbirds from the centerof the field. Planting should be done at the same timeas neighbors because earlier and later ripening fieldstake more damage.Weed and insect control should begin early. Insectsand weeds in the crop are often an attractive foodsource for blackbirds before the crop reaches a susceptiblestage. Once blackbirds have developed patternsin insect-infested or weedy fields, they will begin toinclude the maturing cultivated crops in their diet.The plow-down of harvest stubble should be delayeduntil after sunflower harvest. Crop stubble serves asan alternate feeding area for harassed birds and otherwildlife. <strong>Sunflower</strong> should be harvested as early aspossible to avoid prolonged exposure to bird damage.Desiccation to advance harvest will reduce exposureto birds.Cattail ManagementDense cattail marshes serving as roosting sites forblackbirds can be managed with a registered aquaticherbicide (e.g., glyphosate) to remove cattails usedby these birds (Figure 104). Generally, cattails mustbe treated one year before sunflower is planted in thevicinity of the marsh to allow time for the cattails todecompose. However, herbicide applications madein mid-July might reduce blackbird use of the marshin the year of application. The herbicide should beapplied from mid-July to late August to at least 70percent of the marsh with an agriculture spray planeor helicopter (Figure 105). Use 2 quarts of herbicideper acre. Managing these marshes reduces blackbirduse and improves the habitat for other more desirablewildlife, such as waterfowl. <strong>North</strong> <strong>Dakota</strong>/South<strong>Dakota</strong> Wildlife Services, telephone (701) 250-4405,is a unit within the U.S. Department of <strong>Agriculture</strong>’sAnimal and Plant Health Inspection Service. It operatesa cost-share cattail management program in <strong>North</strong><strong>Dakota</strong> and South <strong>Dakota</strong>.Decoy CropsBlackbirds can be attracted readily to small plots ofoilseed sunflower or other desirable crops planted neartraditional wetland and tree roost sites. This strategycan be effective for the protection of high-valuedconfectionery and oilseed varieties. The plots mustproduce sufficient seeds to feed the expected populationof blackbirds. Each bird can eat about 1 poundof sunflower seeds. Thus, if a grower expects 30,000blackbirds, then a 20-acre plot must produce about1,500 lb/acre to feed the birds for a season. Theseplots also provide essential food and cover for othermigrating and game birds. The <strong>North</strong> <strong>Dakota</strong>/South<strong>Dakota</strong> Wildlife Service’s National Wildlife ResearchCenter, at telephone (701) 250-4469, is developingand refining the decoy crop concept. A cost-shareprogram is available to sunflower growers.


BirdsBirds are kept out of sunflower fields most successfullyby starting methods to frighten them as soon as thebirds are seen in the vicinity, regardless of their diet.Various ways of moving birds mechanically are listed.Use of .22-caliber RifleThis method should be used only where legal and safe.One rifleman can protect 100 acres by firing from ahigh position into the midst of settling birds. Severalmore rounds fired into the lifting flock often will sendthem on their way. Riflemen must use extreme carewith the use of rifles since the bullet may carry a mileor more. Sometimes good results can be obtained withthis method if used consistently.Automatic Exploders (Figure 106)Automatic exploders or bird-scaring cannons automaticallydetonate a gas to produce an extremely loudexplosion. These devices range from relatively simplemechanisms to deluxe models with photoelectric regulatorsand programmable firing sequences. The deviceshould be operated before birds begin to arrive fromtheir roosting area at sunrise and continued as long asbirds are in the field. It should be shut off at night. Theexploder should be placed on a stand above the crop.It should be adjusted to fire slowly, about every four tofive minutes. The exploder should be moved every twoor three days, as birds will become accustomed to thenoise if operated in the same location day after day.One exploder can protect 10 to 20 acres, especially ifused with other mechanical devices and shooting.Electronic Frightening DevicesDevices that broadcast distress calls of blackbirds aremarginally effective and their application is somewhatlimited because of their high cost and limited broadcastrange. Furthermore, because they make extensiveuse of batteries, sophisticated electronic equipmentand loud speakers, they are subject to vandalism andtheft.■ Figure 104. Cattails used by roosting blackbirdscan be removed by aquatic herbicide (e.g.glyphosate). (George Linz)Pyrotechnic DevicesThese include cracker-shells, flares, whistlers (firedor pistol launched) and firecrackers. Most of theseproducts are effective in startling birds and are usedcommonly by many growers. These devices must beused with care, however, because of the potential for■ Figure 105. An aquatic herbicide such as Rodeo(glyphosate) should be applied by airplane orhelicopter. (James Hanzel)■ Figure 106. Gas exploder, when properly locatedand moved within the field every 2 to 3 days canreduce bird damage. (Reu V. Hanson)87


mishaps. Safety glasses and hearing protectors arestrongly recommended since these devices occasionallydetonate prematurely. They also may be a firehazard during dry periods.ShotgunThis tool is costly and ineffective as a direct controldevice. Killing a few birds has little if any direct effecton the rest of the flock. However, shotguns can beused to reinforce automatic exploders and pyrotechnicdevices.Airplane HazingHarassing feeding blackbirds with airplanes sometimescan be a marginally effective method of chasingflocks from sunflower fields. This technique isespecially effective if combined with other mechanicalmethods, such as shotguns and pyrotechnic devices.Check with local authorities for permits needed toconduct low-level flying.RepellentsAvitrol, a chemical frightening agent, and Bird Shield,a chemical repellent, are the only chemicals registeredfor management of blackbirds in sunflower. Avitrolis a cracked-corn bait in which one out of every 100particles is treated with the active ingredient 4-aminopyridine.The bait is applied by airplane or groundvehicle along access lanes placed in fields. When ablackbird eats one or more treated particles, it flies erraticallyand emits distress calls. This abnormal behaviorsometimes causes the remaining birds in the flockto leave the field. Bird Shield is a newly registeredproduct that is formulated with the active ingredientmethyl anthranilate. Research results to date indicatethat the efficacy of both Avitrol and Bird Shield areinconsistent.Best results are obtained by using an integrated pestmanagement system that includes controlling insectsand weeds that might attract blackbirds prior to sunflowerripening and by using a combination of harassmentdevices. Any device used must be operated whenthe birds are in the field.Other Pests and Damage(Duane R. Berglund)Several sources of sunflower injury exist. Some ofthem are confused with damage from insects or diseases.RabbitsRabbits will start foraging soon after seedling emergence,especially near the edges of fields. They willtend to concentrate on one row and apparently eattheir fill, then leave until the next feeding period. Continuedfeeding by rabbits has been observed until theplants are 8 to 10 inches tall. Rabbit feeding on suchlarge plants may be confused with deer. However, deercan be detected by their tracks.DeerDeer begin foraging on sunflower plants when theplants reach 8 to 10 inches and continue throughharvest. They feed in areas near cover, such as woodedareas. All leaves of young plants will be consumedbelow the growing point. Heads will be foraged untilnear maturity and seeds until harvest. Often deer willknock down the stalk to facilitate foraging.Gophers and MiceGopher and mouse damage usually is seen just afterplanting. It generally occurs next to overgrazed pastures,grassland recently converted to cropland andfields next to abandoned areas. The seed will be dugup, split open with the kernel consumed and the hullleft on the soil. Several seeds in a row will be eaten.Seedlings are eaten occasionally when they are 2 to 3inches tall. If the growing point is consumed, the seedlinggradually dies. Shooting or rodenticide-treatedoats will control gophers and mice.88


LightningLightning damage sometimes is mistaken for adisease. It is distinguished from disease damage bythe sudden death of the plants in the affected areaand the fact that both sunflower and weeds (not grass,however) are killed (Figure 107). Near the edge of thearea, plants are wilted but not dead, and the stalks mayhave a brown to blackened pith. The area may be aslarge as 50 to 100 feet in diameter. The affected areausually is circular and does not increase in size afterthe first two weeks. Flags may be placed at the edgesof the affected area to observe if the damage graduallyprogresses beyond the flags. If damage does graduallyextend beyond the flags, this could indicate damagefrom a source other than lightning.FloodingSoils should have good drainage for sunflower production,but the crop doesn’t differ greatly from mostother crops. In flooded sunflower, research found thatethylene increased in the stems and roots below thewater. Later, chlorophyll breakdown and leaf epinastyresulted. <strong>Sunflower</strong> plants flooded longer than threedays may not recover. Cool, cloudy days during theflooding period reduce the damage, whereas hot andsunny days may hasten the death of plants.Heat CankerWarm temperatures and sunny days can result in heatcanker injury to young sunflower seedlings growingin black or dark, moist soils. Hot temperatures at thesoil line cause cell death in the young stem and theplants will show bands of yellowing and constricting.In severe cases, the constricted area completely girdlesthe stem at the soil line and the plant topples over. Thesunflower seedling will not recover since the growingpoint is above this site. Plant populations can bereduced significantly in some cases.Frost Damage<strong>Sunflower</strong> seedlings in the cotyledonary stage (VE)can withstand temperatures down to 26 degrees Fahrenheitwhen just emerging from the soil. <strong>Sunflower</strong>in the V-1, V-2 and V-3 stages become less tolerant tofrost as they grow and develop. The terminal bud canbe frost damaged in seedlings with two, four and sixtrue leaves. This early frost damage and killing of theterminal bud can result in excessive branching as thesunflower grows and develops.<strong>Sunflower</strong> is most susceptible at the bud (R-4) andpollination stages (R-5.0 to R-5.9) of development.Temperatures of 30 F or less can cause damage to theanthers and stigmas of the pollinating disk flowers.(See Figure 108 for frost-damaged sunflower head).<strong>Sunflower</strong> has a composite type flower. Several rowsof showy yellow ray flowers encircle the head andcommonly are called the “petals,” although each is anindividual flower. The center portion of the head, andby far the greater part, is composed of inconspicuousindividual flowers, one for each seed that may develop.These disk flowers mature in circles from the outsideOther Pests and Damage■ Figure 107. Two spots in sunflower field damagedby lightening. (Terry Gregoire)■ Figure 108. Frost damage in the center third ofsunflower head. (Duane Berglund)89


of the flower head to the center, so that at variousstages, the disk flowers ready for pollination appear asa yellow circular band in the brownish or dark centerof the head. These disk flowers are sensitive to frost.The result of the frost damage in the flowering periodis circular bands of undeveloped seed that would varywith individual flower heads from a band around theoutside edge to an area in the center. Unopened budsare less susceptible to frost than the opened flowerheads. Growers can determine the extent of injury bycutting the surface of the flower head.Once pollination is completed and 10 to 14 days afterpetal drying occurs, the sunflower plants can withstandfrost temperatures as low as 25 F and have onlyminor damage. Twenty-five degrees Fahrenheit at thebud stage often will damage the stalk below the budand seeds will not develop. If hard frosts do occur,many times only the seed in the center of the head (thelast to pollinate) will be affected.When sunflower heads start to turn yellow on thebackside and the bracts are drying and turning brown,most risk of frost damage is very minimal.In nonoilseed sunflower, frost damage can cause qualityproblems by causing a dark brown to blackenednutmeat to result during the roasting process. Forthe birdseed market, light-weight sunflower seed andbrown seeds are the result of frost damage and will bediscounted.For oilseed sunflower, reduced test weight per busheland lower oil percent may result from a frosted immaturesunflower crop.90


Hail InjuryHail Injury(Duane R. Berglund)Hail storms can and will cause different types ofsunflower plant injury. Plant death, damage to theterminal bud, physical injury to the stalk and head,and defoliation are all types of injury that can influenceyield. Variables such as hailstone size and degreeof hardness, speed and density, storm duration andplant environmental status, such as whether the leavesare flaccid or turgid, influence the type and degree ofcrop injury. The stage of plant development is also animportant factor. Figures 109 and 110 illustrate twodistinct types of hail damage. As shown in Figure 109,almost all heads have been destroyed, while plantsshown in Figure 108 have a high level of defoliationwith the heads still attached.One of the major factors causing differential growthand yield response is the stage at which the injuryoccurred. Data were obtained from a sunflower dateof-plantingstudy at Carrington, N.D. Five sunflowerhybrids sown at six planting dates between May 1and June 20 were damaged by a hail storm on Aug. 6.Stages of plant development at the time of the stormwere from R-1 to R-7. Data were taken approximatelyone week after the storm. Average percent defoliationfrom all planting dates was similar at about 26.4 percent.An average of 4.7 stalk and head stone bruisesoccurred per nondestroyed plant. The percent of plantsdestroyed and the percent of the remaining plants withheads broken off or bent over but attached decreasedwith plant maturity (Table 13).Defoliation: Reduced yield as a result of defoliationdepends on the amount of leaf loss and the stage atwhich it occurs. Stages R-1 through R-6 appear tobe the most sensitive to defoliation since much ofthe photosynthate produced at this time is directed tohead development. At early and late stages of plantdevelopment, high levels of defoliation may not have amajor impact on seed yield. Approximate yield reductionsdue to varying degrees of random defoliation■ Figure 109. Heads destroyed by hail stones.(A.A. Schneiter)■ Figure 110. <strong>Sunflower</strong>s defoliated by hail.(A.A. Schneiter)91


Table 13. Effect of hail injury on sunflower at severalstages of plant development.Injury on nondestroyed plantsApprox.% Headsdevelopment % broken over %Date stage when Plants % Heads but still Attachedplanted injured destroyed broken off attached headsMay 1 R-7 19.2 7.6 14.3 78.0May 9 R-6 24.1 6.3 17.1 76.6May 21 R-5 23.9 17.1 17.8 65.2May 30 R-3 29.6 16.1 17.0 66.9June 10 R-2 55.7 36.4 23.7 39.9June 20 R-1 60.7 39.9 22.6 37.692at several stages of growth are presented in Table 14.These values are based on investigations conducted atFargo and Carrington and are the best estimates availableon the effect of defoliation for average growingconditions.Stand Reduction: Plant death as a result of hail injuryis a common occurrence, especially at early stages ofdevelopment when plants are small. At early stagesof plant development, before plants begin competingwith each other, yield losses due to stand reductioncaused by hail are not different than those that wouldoccur due to reduced seeding rates. If the amount ofstand reduction is significant and/or occurs when theplant has begun to develop and compete with neighboringplants, the remaining uninjured plants cannotcompensate enough and yields will be reduced. Lossesdue to stand reduction increase as the plant maturessince it decreases the time for remaining plants tocompensate.Approximate yield reductions from variable levelsof random stand reduction at several stages of plantdevelopment are presented in Table 15. These valuesare based on studies conducted at Carrington andFargo. These values represent direct stand reductionwhere the plants have been destroyed and no longerare competing with uninjured plants for light, water ornutrients.Injured Plants: In addition to stand reduction anddefoliation, injuries such as terminal bud removal orinjury and stem breakage or bruising may occur asa result of hail. An example of a living but severelyinjured plant is the gooseneck shown in Figure 111.Plants that are injured but living sometimes may reducetotal crop yield more than if they had been completelydestroyed since they continue to compete withuninjured plants for space, light and nutrients but donot produce an equal yield. Competition from injuredplants may reduce the ability of noninjured plants tocompensate for the hail-damaged plants.The response of plants to a hail injury, such asterminal bud removal, varies depending on the stage■ Figure 111. Goose-neck and stem bruising causedby hail injury. (A.A. Schneiter)


at which the injury occurs. When plants are injuredin this manner at vegetative (V) stages, they usuallydevelop branches that produce small seed-bearingheads. When injury to the terminal bud occurs duringthe early reproductive (R) stages, a greater percentageof the plants may die. When injury occurs near or afterflowering, the plants usually remain green and continueto live but do not produce seed. A similar type ofresponse can be evident when plants have been injuredby the head-clipping weevil; however, the injury fromthe head-clipping weevil is a straight cut across thestalk.The effect of bruising by hailstones is difficult todetermine. If the amount of stalk bruising is such thatthe plant does not weaken or break during the remainderof its development prior to combine harvest,the effects on yield may be minimal. Stalk injury ofsuch magnitude or at a specific location on the plantHail InjuryTable 14. Approximate percent yield reduction from the indicated percent total leaf areadestroyed at several stages of sunflower plant development.Percent Leaf Area DestroyedStage * 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100- - - - - - - - - - - - - - - - - - - - Approximate percent yield loss - - - - - - - - - - - - - - - - - - - -V-E to V-3 0 0 0 1 1 1 2 2 2 3 3 3 4 4 5 7 8 10 12 15(6-26 days)V-4 to V-5 0 0 0 1 2 2 2 2 3 4 4 4 5 5 7 9 12 14 17 21(27-29 days)V-6 to V-8 0 0 0 1 2 2 2 2 3 4 4 5 6 6 8 10 14 16 19 22(30-34 days)V-9 to V-11 0 0 1 2 3 3 4 4 4 5 5 5 5 7 9 11 14 17 21 24(35-39 days)V-12 to V-(N) 0 1 2 3 4 4 5 5 5 6 7 7 9 12 15 18 22 26 31 35(40-43 days)R-1 0 2 3 4 5 6 6 6 7 7 8 9 13 16 20 24 29 34 40 47(44-51 days)R-2 0 2 3 4 6 8 9 10 11 12 13 14 16 18 23 30 37 45 55 65(52-58 days)R-3 0 2 5 8 10 15 17 19 21 24 28 32 38 44 51 59 68 78 88 99(59-67 days)R-4 0 2 4 5 7 10 12 12 15 18 22 27 34 39 45 53 61 72 85 99(68-75 days)R-5 0 1 2 3 5 7 8 10 13 16 20 25 32 37 43 49 55 67 78 90(76-84 days)R-6 0 0 1 1 3 3 4 8 11 15 19 24 29 35 41 46 53 63 72 80(85-92 days)R-7 0 0 1 1 1 3 5 7 8 10 11 13 14 16 17 18 19 20 21 22(93-102 days)R-8 0 0 1 1 1 2 2 3 4 5 6 7 7 8 9 9 10 10 10 11(103-110 days)R-9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0(111-maturity)*Number of days after planting for development to a specific stage will vary significantly depending on environmental conditionsand the hybrid. Interpolating percent of loss between stages may be necessary.93


esulting in nonharvestable heads certainly would havean effect on yield. Physical injury by hailstones onthe back of a sunflower head at or near anthesis canresult in Rhizopus head rot, especially if wet or humidconditions are present. Physical injury can occur as aresult of bird, insect or hailstone damage. Increaseddead plant tissue resulting from a hail storm, especiallyon the back of a head, may increase the chanceof white mold infection.Table 15. Approximate percent yield reduction from the Indicated percent stand reduction atseveral stages of sunflower plant development.Percent Stand ReductionStage * 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100- - - - - - - - - - - - - - - - - - - - Approximate percent yield loss - - - - - - - - - - - - - - - - - - - -V-E to V-3 0 1 2 3 4 8 10 11 12 12 13 14 16 18 24 32 43 58 77 100(6-26 days)V-4 to V-5 0 1 2 3 4 8 10 11 12 12 13 14 16 18 24 32 43 58 77 100(27-29 days)V-6 to V-8 0 1 2 3 4 8 10 11 12 12 13 14 16 18 24 33 43 58 77 100(30-34 days)V-9 to V-11 0 1 2 3 4 8 10 11 12 12 13 14 16 19 25 33 44 59 77 100(35-39 days)V-12 to V-(N) 0 1 2 3 4 8 10 12 12 13 14 15 17 21 27 35 46 60 78 100(40-43 days)R-1 1 2 5 9 12 14 15 16 17 18 19 21 25 29 35 43 53 66 81 100(44-51 days)R-2 2 3 7 9 13 17 19 21 23 24 26 28 31 35 40 47 57 68 83 100(52-58 days)R-3 4 7 11 13 15 17 21 24 27 29 31 34 37 41 46 53 61 72 84 100(59-67 days)R-4 5 10 14 18 20 22 25 27 29 32 35 38 42 47 53 60 68 77 88 100(68-75 days)R-5 5 10 14 19 20 24 28 31 35 39 42 45 49 54 60 66 73 81 90 100(76-84 days)R-6 5 10 15 19 22 26 31 35 39 44 48 52 56 62 68 73 79 85 93 100(85-92 days)*Number of days after planting for development to a specific stage will vary significantly depending on environmental conditionsand hybrid. It may be necessary to interpolate percent of loss between stages.94


Herbicide Drift andChemical ResidueHerbicide DriftHerbicide drift is the movement of herbicide fromtarget areas to areas where herbicide applicationwas not intended. Herbicide drift generally is causedby movement of spray droplets or by movement ofherbicide vapors. Herbicide granules or dried particlesof herbicide may move short distances in high windsbut are not considered important sources of herbicidedrift.<strong>Sunflower</strong> is susceptible to many of the postemergenceherbicides commonly used on crops grown in proximityto sunflower. Herbicides that may damage sunflowerinclude most all ALS (acetolactate synthase)herbicides (Accent, Ally, Amber, Beacon, Express,Affinity, Pursuit and Raptor), atrazine, dicamba, bentazon,Bronate, Buctril, Curtail, glyphosate, MCPA,paraquat, Stinger, 2,4-D and Tordon.<strong>Sunflower</strong> yield may be severely reduced by 2,4-D ordicamba (Figure 112). The amount of loss varied from25 percent to 82 percent, depending on the sunflowergrowth stage when the herbicide was applied in tests.<strong>Sunflower</strong> yield loss averaged from three rates each of2,4-D and dicamba to simulate spray drift was greatestwhen the herbicides were applied in the bud stageand least when applied during bloom. <strong>Sunflower</strong> inthe V-2 to V-4 leaf stage was affected less than largerprebloom sunflower.drift than a shorter crop, such as wheat or barley. Theamount of herbicide that contacts the sunflower andthe environment during and following applicationinfluences the yield loss caused by herbicide drift. Forexample, experiments at <strong>North</strong> <strong>Dakota</strong> <strong>State</strong> Universityshowed that 2,4-D at 0.5 ounce per acre appliedto 12- to 14-leaf sunflower caused a 5 percent lossin 1973 and 93 percent loss in 1978. Low but equallevels of drift may cause very different effects onsunflower yield, depending on environment. <strong>Sunflower</strong>injury from herbicide drift will be greatest with warmtemperatures and good soil moisture.<strong>Sunflower</strong> may exhibit herbicide injury symptomswithout a yield loss. Experiments at <strong>North</strong> <strong>Dakota</strong><strong>State</strong> University indicated that sunflower heightreduction, as compared with undamaged sunflower,caused by 2,4-D, MCPA or dicamba was significantlycorrelated with sunflower yield loss. Drift of 2,4-D,Herbicide Drift and Chemical ResidueOnly a small portion of an applied herbicide driftsfrom the target area. However, some nontarget areascan receive rather high doses of herbicide since herbicidedrift can accumulate in the nontarget areas. Herbicideaccumulated in downwind areas occasionallymay exceed the rate applied to the target field. A smallportion of the herbicide applied with each sprayer passmay accumulate in an adjoining field. Also, a tallercrop, such as sunflower, may intercept more spray■ Figure 112. <strong>Sunflower</strong> yield loss from herbicidesapplied at various growth stages averaged over 2,4-Drates of 0.5, 1 and 2 oz./A and dicamba at 0.1, 0.5and 1.0 oz/A. (A. Dexter)95


MCPA or dicamba, which causes a sunflower heightreduction, also would be expected to reduce yield.However, typical injury symptoms can occur withoutheight reduction and this would not be expected toreduce yield.MCPA, 2,4-D, dicamba and Tordon are growth-regulatorherbicides and all produce similar symptomson sunflower. <strong>Sunflower</strong> exhibits epinasty, which isan abnormal bending of stems and/or leaf petioles,shortly after contact with a growth-regulator herbicide.Figure 113 shows the bending of sunflower only24 hours after 2,4-D application while Figure 114shows the abnormal twisting of leaf petioles severaldays after 2,4-D application. <strong>Sunflower</strong> growth oftenis slowed or stopped by growth-regulator herbicides.Leaves that develop after contact with a growthregulatorherbicide often are malformed. Leaves mayhave more parallel vein patterns and abnormal leafshapes (Figure 115). A higher degree of injury froma growth-regulator herbicide may stop plant growthtotally. Some plants die without further growth, somewill remain green and not grow the rest of the season,and some plants will begin growing later after theherbicide is partially metabolized. <strong>Sunflower</strong> in Figure116 did not grow for several days and then produced astalk and flower.Affected plants also may branch and produce multipleheads when growth resumes (Figure 117). Root■ Figure 113. Bending of sunflower only 24 hoursafter 2,4-D application. (A. Dexter)■ Figure 115. Growth regular herbicides may causeleaves of sunflower to have more parallel veinpatterns and abnormal leaf shapes. (A. Dexter)96■ Figure 114. Abnormal twisting of leaf petiolesseveral days after 2,4-D application. (A. Dexter)■ Figure 116. Interrupted growth of sunflower due toexposure to growth regulator herbicide. (A. Dexter)


growth may be retarded by growth-regulator herbicidesand abnormal lumps or knots may develop onsunflower roots (Figure 118). <strong>Sunflower</strong> contacted bygrowth-regulator herbicides during the bud or floweringstage may develop malformed heads or heads withsterility (Figure 119).■ Figure 117. Multiple branching and heading ofsunflower due to exposure to growth regulatorherbicides. (A. Dexter)<strong>Sunflower</strong> plants contacted with a growth-regulatorherbicide will not develop all of the symptoms shownin Figures 112 through 117. Considerable variationin symptomology can occur, depending on herbiciderate, sunflower stage and environment.Symptoms similar to those shown in Figures 114 to119 also may be produced by soil residues of herbicide.MCPA and 2,4-D have very short soil residual,but damage to sunflower could occur if they wereapplied just before planting or emergence. Tordonhas a long soil residual and can carry over from theprevious year and cause sunflower injury. Dicamba atrates used in small grains would not be expected tocarry over to the next year. Dicamba used in the fall atrates necessary to control certain perennial weeds maypersist in the soil and damage sunflower the next year.Accent, Ally, Amber, atrazine, Beacon and Pursuit arelong residual herbicides that may persist for more thanone year at levels that can injure sunflower. The lengthof persistence can be affected by pH (high pH causeslonger residue of some herbicides), application rateand soil moisture.The symptoms from these herbicides are not similar tosymptoms from growth-regulator herbicides. <strong>Sunflower</strong>affected by Accent, Ally, Amber, Beacon or Pursuitemerge and become well-established. Chlorosis startson the young leaves often with a distinct yellowing.Top growth and roots may be severely stunted. Plantsmay remain small for several weeks or they may die.Herbicide Drift■ Figure 118. Abnormal lumps and knots onsunflower roots developed after exposure to growthregulator herbicides. (A. Dexter)■ Figure 119. <strong>Sunflower</strong>s contacted by growthregulator herbicides during bud or flowering stagedeveloped malformed heads or heads with sterility.(A. Dexter)97


Low doses may cause temporary stunting and plantslater may begin to grow normally. <strong>Sunflower</strong> affectedwith atrazine emerge and look normal for a short time.Leaf burn starts on the outer edges of the oldest leavesand progresses toward the middle of the leaf. Veinalareas are the last to turn brown in an affected leaf.The risk of sunflower injury from herbicide drift isinfluenced by several factors.Spray particle size: Spray drift can be reduced byincreasing droplet size since larger droplets movelaterally less than small droplets. Droplet size can beincreased by reduced spray pressure; increased nozzleorifice size; use of special nozzles, such as “Raindrop,”“LFR,” “XR” or “LP;” use of additives thatincrease spray viscosity; rearward nozzle orientation;and increased nozzle pressure on aircraft. Researchhas shown that increasing nozzle pressure in a rearward-orientednozzle in a high-speed air stream willproduce larger droplets and less fines. This is due toless secondary wind shear, and does not happen withground sprayers.Spray pressure with standard flat-fan nozzles shouldnot be less than 25 pounds per square inch (psi)because the spray pattern from the nozzles will notbe uniform at lower pressures. The “XR” and “LP”nozzles are designed to give a good spray pattern at 15to 50 psi. Operating at a low spray pressure results inlarger spray droplets. Some postemergence herbicides,such as bentazon, require small droplets for optimumperformance, so techniques that increase droplet sizemay reduce weed control with certain herbicides. Herbicidesthat readily translocate, such as 2,4-D, MCPA,dicamba and Tordon, are affected little by droplet sizewithin a normal droplet size range, so drift controltechniques would not be expected to reduce weed controlwith these herbicides. Glyphosate is translocatedreadily, so droplet size has minimum effect on weedcontrol. However, glyphosate is inactivated partiallyby increased water volume and spray volume recommendationson the label should be followed.Herbicide volatility: All herbicides can drift in spraydroplets, but some herbicides are sufficiently volatileto cause plant injury from drift of vapor or fumes. Theester formulations of 2,4-D and MCPA may producedamaging vapors, while the amine formulations areessentially nonvolatile. Dicamba is a volatile herbicideand can drift in droplets or vapor.Herbicide vapors may cause crop injury over greaterdistances than spray droplets. However, spray dropletscan move long distances under certain environmentalconditions, so crop injury for a long distance does notnecessarily result from vapor drift. A wind blowingaway from a susceptible crop during herbicide applicationwill prevent damage from droplet drift, but a laterwind shift toward the susceptible plants could movedamaging vapors into the susceptible crop.Herbicide volatility increases with increasing temperature.The so-called high-volatile esters of 2,4-D orMCPA may produce damaging vapors at temperaturesas low as 40 degrees Fahrenheit, while low-volatileesters may produce damaging vapors between 70 and90 F. The soil surface temperature often is severaldegrees warmer than air temperature, so a low-volatileester could be exposed to temperature high enough tocause damaging vapors, even when the air temperaturewas less than 70 F.Wind velocity and air stability: Wind, or thehorizontal movement of air, is widely recognized asan important factor affecting spray drift. However,vertical movement of air also has a large influence ondamage to nontarget plants from spray drift. An airmass with warmer air next to the ground and decreasingtemperature with increasing elevation will be unstable.That is, the warm air will rise and the cool airwill sink, providing vertical mixing of air. Stable air,often called an inversion, occurs when air temperatureincreases or changes little as elevation increases. Withthese temperature relationships, very little verticalmovement of air occurs since cool air will not rise intowarmer air above. Spray droplets or vapor are carriedaloft and dispersed away from susceptible plants withunstable air conditions. With stable air (inversion),small spray droplets may be suspended just above theground in the air mass, move long distances laterallyand be deposited on susceptible plants.98


Low wind velocity in combination with unstable airgenerally will result in very little damaging spray drift.However, low wind velocity with stable air (inversion)can result in severe damage over a long distance. Cropinjury has been observed two miles or more fromthe site of application with 10 mph or slower winds,small spay droplets, stable air, highly susceptible cropsand nonvolatile but highly active herbicides. Longdistancedrift can occur with particle drift as well asvapor drift.Stable air usually can be identified by observing dustoff a gravel road or smoke from a fire or smoke bomb.Smoke or dust moving horizontally and staying closeto the ground would indicate stable air. Fog also wouldindicate stable air. Herbicide application should beavoided during stable air conditions unless spray driftis not a concern.Distance between nozzle and target (boomheight): Less distance between the droplet releasepoint and the target will reduce spray drift. Lessdistance means less time to travel from nozzle totarget, so less drift occurs. Small spray droplets havelittle inertial energy, so a short distance from nozzle totarget increases the chance that the small droplets canreach the target. Also, wind velocity often is greater asheight above the ground increases, so reduced nozzleheight will reduce the wind velocity affecting thespray droplets.Shielded sprayers: Shielded sprayers utilize sometype of shielding to protect spray droplets from wind.The effectiveness of the shields varies, dependingon the design of the shield, wind velocity and winddirection relative to the sprayer. Drift from shieldedsprayers has varied from about 50 percent to morethan 95 percent less than from similar nonshieldedsprayers in experiments with various shield designsand conditions.Herbicide drift can reduce sunflower yield severely.The risk of herbicide drift can be reduced greatlyby increasing droplet size, reducing nozzle height,using nonvolatile herbicides, avoiding spraying duringtemperature inversions, using shielded sprayersand spraying when the wind is blowing away from asusceptible crop.Chemical Residue in theTank and Sprayer CleanoutCrop injury from a contaminated sprayer may occurwhen a herbicide not registered on sunflower was usedpreviously in the sprayer. The risk of damage is greatestwhen the previous herbicide is highly phytotoxic tosunflower in small amounts. Rinsing with water is notadequate to remove all herbicides. Some herbicideshave remained tightly adsorbed in sprayers throughwater rinsing and even through several tank loads ofother herbicides. Then, when a tank load of solutionincluding an oil adjuvant or nitrogen solution was putin the sprayer, the herbicide was desorbed, moved intothe spray solution and damaged susceptible crops.Highly active herbicides that have been difficult towash from sprayers and have caused crop injury includeALS herbicides (Accent, Ally, Beacon, Express,Pursuit and Raptor), and growth-regulator herbicides(2,4-D and dicamba).Herbicides that are difficult to remove from sprayersare thought to be attaching to residues remainingfrom spray solutions that deposit in a sprayer. Theherbicide must be desorbed from the residue or theresidue removed in a cleaning process so the herbicidecan be removed from the sprayer. Sprayer cleanoutprocedures are given on many herbicide labels and theprocedure on the label should be followed for specificherbicides. The following procedure is given as anillustration of a thorough sprayer cleanup procedurethat would be effective for most herbicides.Step 1. Drain tank and thoroughly rinse interiorsurfaces of tank with clean water. Sprayrinse water through the spray boom. Sufficientrinse water should be used for fiveminutes or more of spraying through theboom.Step 2. Fill the sprayer tank with clean water andadd a cleaning solution (many herbicidelabels provide recommended cleaning solutions).Fill the boom, hoses and nozzlesand allow the agitator to operate for 15minutes.Step 3. Allow the sprayer to sit for eight hourswhile full of cleaning solution. The cleaningsolution should stay in the sprayer foreight hours so that the herbicide can befully desorbed from the residues inside thesprayer.Chemical Residue99


Step 4. Spray the cleaning solution out throughthe booms.Step 5. Remove nozzles, screens and filters andclean thoroughly. Rinse the sprayer toremove cleaning solution and spray rinsatethrough the booms.Common types of cleaning solutions are chlorinebleach, ammonia and commercially formulated tankcleaners. Chlorine lowers the pH of the solution,which speeds the degradation of some herbicides.Ammonia increases the pH of the solution, whichincreases the solubility of some herbicides. Commerciallyformulated tank cleaners generally raise pH andact as detergents to assist in removal of herbicides.Read the herbicide label for recommended tank cleaningsolutions and procedures. WARNING: Never mixchlorine bleach and ammonia, as a dangerous andirritating gas will be released.Sprayers should be cleaned as soon as possible afteruse to prevent the deposit of dried spray residues. If asprayer will remain empty overnight without cleaning,fill the tank with water to prevent dried spray depositsfrom forming. A sprayer kept clean is essential toprevent damage from herbicide contamination.100


HarvestingHarvesting(Vern Hofman)Maturity<strong>Sunflower</strong> in the northern Great Plains production areausually is ready for harvest in late September or October,with a growing season of approximately 120 days.The growing season may vary in length, depending onsummer temperatures, relative moisture distributionand fertility levels. The sunflower plant is physiologicallymature when the back of the head has turnedfrom green to yellow and the bracts are turning brown(Stage R-9), about 30 to 45 days after bloom, and seedmoisture is about 35 percent.Desiccants can be applied to the crop after physiologicalmaturity to speed the dry-down process. Thechemical compounds act much like a frost to kill thegreen tissue on the plant and accelerate its drying.After applications of a desiccant, dry down of the seedis not as rapid as the dry down of the plant. Growersoften are tempted to apply desiccants too early whenpotential loss factors are present. Application of a desiccantbefore the plant reaches physiological maturitywill reduce yield and lower oil percentage. Drying isfacilitated in most years by a killing frost, but if frostoccurs too early, yield and oil percentages are reduced.Seed shattering loss during harvest and loss from birdsmay be reduced by harvesting sunflower at moisturecontents as high as 25 percent. <strong>Sunflower</strong> seed fromthe combine then is dried in a grain dryer to 9.5 percent,which is considered a safe storage level.Harvesting AttachmentsCombines suitable for threshing small grains canbe adapted to harvest sunflower. A variety of headerattachments are available, with many operating on ahead stripper principle.The attachments are designed to gather only the sunflowerheads and eliminate as much stalk as possible.Major components of this attachment are catch pans,a deflector and a small reel. Long catch pans extendahead of the cutter bar to catch the seed as it shatters.The deflector mounted above the catch pans pushesthe stalk forward until only the heads remain abovethe cutter bar. As the heads move below the deflector,the stems contact the cutter bar and are cut just belowthe head. A small reel, mounted directly behind thedeflector, pushes the heads into the combine feeder.Catch pans are available in various widths. Theserange from narrow 9-inch pans spaced on 12-inchcenters (Figure 120) to 37-inch pans spaced on 40-inch centers (Figure 121). The narrow 9-inch pans canoperate on any row spacing, while the wider and moreefficient 30- to 40-inch spaced pans are limited to afixed-row spacing.The deflector consists of a curved piece of sheet metalthe full width of the combine head. It is attached to thereel support arms above the catch pans. The reel forthe unit is mounted directly behind the deflector andusually consists of three or four arms. The reel is usually16 to 20 inches in diameter and mounted 4 to 5inches above the catch pans, so when the heads comein contact with the reel, they are pushed back into thefeeder. The shield and reel can handle tall plants whiletaking only a minimum length of stalk with the head,allowing harvest when the seed is dry but stalk moisturemay remain above 50 percent. Cleaner threshingalso is accomplished when only the head enters themachine.101


Optional forward rotating stalk-walker shafts, introducedfrom Argentina and used mainly in the southernPlains, can be mounted under the cutter bar to reduceplugging of stalk slots between pans. The stalk-walkerpulls sunflower stalks and weeds down so that only thesunflower head is fed into the combine. Stalk-walkersare reported to be especially useful in fields with tallweeds.A rotating drum with metal projections that replacesthe deflector bar and reel often is used (Figure 122).The projections are triangular-shaped pieces of strapiron welded to its surface. As the drum rotates, theprojections pass through the slots between the catchpans to remove any stalks that may cause clogging.The smooth drum acts as a deflector bar to strip stalksuntil one of the projections catches a head and pushesit into the cutter bar and into the combine header.Row-crop units mounted on combine headers havebeen used successfully to harvest sunflower seed(Figure 123). One unit uses gathering belts, one oneach side of the row, to draw the stalk into the cuttingunit and the header. A large quantity of stalk passesthrough the machine with this unit and may increasethe foreign matter in the seed, but this unit works wellpicking up lodged sunflower and getting the heads intothe machine.Another type of header uses a short section of screwconveyor to pull the stalks into the cutter bar and thecombine header. This unit also works well for pickingup lodged sunflower.■ Figure 120. Catch pans in narrow 9 inch pansspaced on 12 inch centers. (V. Hofman)■ Figure 122. Rotating drum with metal projections.(V. Hofman)102■ Figure 121. Catch pans in wide 37 inch pansspaced on 36 inch centers. (V. Hofman)■ Figure 123. All crop header used to harvestsunflower. (V. Hofman)


Combine AdjustmentsForward Speed: A combine’s forward speed usuallyshould average between 3 and 5 miles per hour.Optimum forward speed usually will vary dependingupon moisture content of the sunflower seed andyield of the crop. Forward speed should be decreasedas moisture content of the seed decreases to reducethe shatter loss as the heads feed into the combine.Faster forward speeds are possible if the moisture ofthe seed is between 12 percent and 15 percent. Thehigher speeds should not overload the cylinder and theseparating area of the combine except in an extremelyheavy crop. Seed having 12 percent to 15 percentmoisture will thresh from the head very easily as itpasses through the cylinder.Cylinder Speed: After the sunflower heads areseparated from the plant, they should be threshed ata cylinder speed operating as slow as possible. Thenormal cylinder speed should be about 300 revolutionsper minute (rpm), depending upon the conditionof the crop and the combine being used. This cylinderspeed is for a combine with a 22-inch-diametercylinder to give a cylinder bar travel speed of 1,725feet per minute. Combines with smaller cylinderswill require a faster speed and combines with a largercylinder diameter will require a slower speed. Rotarycombines, as well as conventional machines, shouldhave similar cylinder travel speeds. A rotary combinewith a 30-inch cylinder will need to be operated at220 rpm to have a cylinder bar speed of 1,725 feet perminute. A combine with a 17-inch cylinder will needto operate at 390 rpm to have a cylinder bar speed of1,725 feet per minute.If a combine cylinder operates at speeds of 400 to 500rpm, giving a cylinder bar speed of more than 2,500feet per minute, very little seed should be cracked orbroken if the moisture content of the seed is above 11percent. Cylinder bar speeds of more than 3,000 feetper minute should not be used because they will causeexcessive broken seed and increased dockage. Excessdockage and broken seed may overload the sieves andthe return elevator.Concave Adjustment: <strong>Sunflower</strong> threshes relativelyeasily. When crop moisture is at 10 percent or less,conventional machines should be set wide open togive a cylinder-to-concave spacing of about 1 inchat the front of the cylinder and about 0.75 inch atthe rear. A smaller concave clearance should be usedonly if some seed is left in the heads. If the moisturepercentage of the crop is between 10 percent and 12percent, rather than increase the cylinder speed, thecylinder-to-concave clearance should be decreasedto improve threshing. If seed moisture exceeds 15percent to 20 percent, a higher cylinder speed and acloser concave setting may be necessary, even thoughforeign material in the seed increases. Seed breakageand dehulling may be a problem with close concavesettings. Make initial adjustments as recommendedin the operator’s manual. Final adjustments should bemade based on crop conditions.Rotary combines should be set to have a rotor-to-concavespacing of about 0.75 to 1 inch. Making initialsettings as recommended in the operator’s manual usuallyis best. Final adjustments should be made basedon crop conditions.Fan Adjustment: Oilseed and nonoilseed sunflowerweigh about 28 to 32 pounds per bushel and 22 to 26pounds per bushel, respectively. The seed is relativelylight compared with other crops, so excessivewind may blow seed over the chaffer and sieve. Seedforced over the sieve and into the tailings auger willbe returned to the cylinder and may be dehulled. Onlyenough wind to keep the trash floating across the sieveshould be used. The chaffer and sieve should be adjustedto minimize the amount of material that passesthrough the tailings elevator.When the combine is adjusted correctly to threshsunflower seed, the threshed heads will come throughonly slightly broken and with only unfilled seedremaining in the head. Cylinder concaves and cleaningsieves usually can be set to obtain less than 5 percentdockage. Improper settings will crush the seed butleave the hull intact. Proper setting is critical, especiallyfor nonoilseed sunflower that is used for the humanfood market. The upper sieve should be open enoughto allow an average seed to pass through on end, orbe set at a ½- to 5/8- inch opening. The lower sieveshould be adjusted to provide a slightly smaller opening,or about 3/8 inch wide. The final adjustments willdepend on the amount of material returning throughthe tailings elevator and an estimation of the amountof dockage in the grain tank. Some operators are ableto adjust and operate their machine to allow only 2percent to 3 percent dockage in the seed.Harvesting103


Field LossThe harvested yield of sunflower can be increased bymaking necessary adjustments following a determinationof field loss. Three main sources of loss are: (a)loss in the standing crop ahead of the combine, (b)header loss as the crop enters the machine and (c)threshing and separating loss. The loss found in anyof these three areas will give the combine operator agood estimate of sources of seed loss and the adjustmentsnecessary to minimize seed loss.Loss occurring in any of these areas may be estimatedby counting the seed on the soil surface in a squarefootarea. Ten seeds per square foot equal approximately1 hundredweight (cwt) per acre loss if seedloss is uniform throughout the entire field.The loss in the standing crop is estimated by countingthe seed in a 1-square-foot area ahead of the machineat several different places in the field. Header loss canbe calculated by counting seed in a 1-square-foot areabehind the head under the combine and subtracting thestanding crop loss. The loss in combine separation canbe found by counting the seed in a 1-square-foot areadirectly behind the rear of the combine and subtractingthe shatter loss and the header loss found under themachine. The count made directly behind the combinewill be concentrated, so an adjustment must be madeto equalize the loss over the entire width of cut. Theresult should be divided by the ratio:Width of Header Cut (feet)Width of Rear of Combine (feet)The answer is the adjusted separator loss for the widthof cut. This result must be divided by 10 to obtain thecombine separator loss in cwt per acre. The total lossin cwt per acre is determined by adding the seed lossin the standing crop, header loss and separator lossand dividing this answer by 10. The percentage losscan be found by dividing the total cwt per acre by theyield in cwt per acre.Harvest without some seed loss is almost impossible.Usually a permissible loss is about 3 percent. Loss ashigh as 15 percent to 20 percent has occurred with awell-adjusted combine if the ground speed is too fast,resulting in machine overload.104


Drying and Storage(Kenneth Hellevang)Drying and StorageHarvesting sunflower at higher moisture contentsnormally results in higher yields and less field loss.Early harvest also reduces exposure to late-season wetand cold weather. Frequently, mechanical drying isrequired so harvesting can be completed.Natural-air, low-temperature and high-temperaturebin, batch (Figure 124) and continuous-flow dryerscan be used to dry sunflower.Natural-air and low-temperature bin drying is energyefficient if designed properly and permits rapid harvestsince bins can be filled at the harvest rate. Dryingwill take three to six weeks, depending on the initialmoisture content, airflow rate and outdoor temperature.Required airflow rates and drying time for dryingoil sunflower at various moisture contents using air at47 degrees Fahrenheit and 65 percent relative humid-ity (average <strong>North</strong> <strong>Dakota</strong> conditions for October) areshown in Table 16. Drying times will be twice as longat 27 degrees due to the reduced moisture-holdingcapacity at colder temperatures. Heating the air morethan about 5 degrees normally causes overdrying.Table 16. Recommended airflow rates and dryingtimes for natural-air drying oilseed sunflower inOctober. (47 F and 65 percent relative humidity).Fan TimeMoisture AirflowContent (cfm/bu) hours days17% 1.00 648 2715% 1.00 480 200.75 720 300.50 960 4013% 1.00 336 140.75 504 210.50 672 28■ Figure 124. A high temperature column dryer usedfor drying sunflower. (K. Hellevang)Add enough heat when needed to dry the sunflower tothe safe storage moisture content. Generally, enoughheat to warm the air about 5 degrees is the maximumamount required. As a rule of thumb, about 2 kilowatts(kW) of heater will be required per fan motorhorsepower. The equation for calculating the heatrequirement in Btu is: Btu/hr = cfm x 1.1 x temperatureincrease. Convert Btu to kW by dividing by 3,413Btu/kW. Refer to <strong>NDSU</strong> Extension Service publicationEB-35, “Natural Air and Low Temperature CropDrying,” and publication AE-701, “Grain Drying,” formore information on drying sunflower.A perforated floor is recommended. Since air does thedrying, making sure air reaches all the sunflower isimperative. The uniform airflow distribution requiredfor drying is more difficult to achieve with ducts than105


with perforated floors. However, drying can be donesuccessfully if ducts are spaced no more than onehalfthe grain depth apart and the distance from theduct to bin wall does not exceed one-fourth the graindepth. Provide 1 square foot of duct or floor perforatedsurface area for each 25 cubic feet per minute (cfm) ofairflow. One square foot of bin exhaust opening shouldbe provided for each 1,000 cfm of airflow.Drying temperatures up to 220 F do not appear tohave an adverse effect on oil percentage or fattyacid composition. High drying temperatures for thenonoil varieties may cause the kernels to be steamed,wrinkled or even scorched.Column batch and bin batch dryers should be operatedat 180 and 120 F, respectively. Continuous-flow andrecirculating batch dryers may be operated at temperaturesup to about 200 F. Temperatures in excess of 110F should not be used to dry sunflower seed for seedingpurposes.Fire hazards exist in dryers used for sunflower. Veryfine hairs or fibers from the seed are rubbed looseduring handling and commonly are found floating inthe air around the dryer. These hairs or fibers or otherplant materials may be ignited when drawn throughthe drying fan and open burner. A fire hazard is presentunless these ignited particles burn themselves outbefore contacting the sunflower seed.The fire hazard is decreased if the fans of a portabledryer are turned into the wind to draw clean air thatdoes not contain fine hair or fibers and by pointingstationary dryers into the prevailing wind. A moveableair intake duct may be placed on the burner intaketo draw clean air away from the dryer. However, theduct must be large enough to not restrict the airflowbecause drying speed will be reduced if the airflow isreduced.Clean the dryer, air ducts and area around the dryerat least daily. Frequently remove the collection ofsunflower lint on the dryer column and in the plenumchamber, as this material becomes extremely dry andcan be ignited during dryer operation. A major concernis that some sunflower seeds will hang up in thedryer or be stopped by an accumulation of fines andbecome overdried. Make sure the dryer is completelycleaned out after each batch, and check a continuousflowdryer regularly (at least hourly) to see that thesunflower seed is moving.High-speed dryers are like a forge when a fire getsgoing. However, fires can be controlled if they arenoticed immediately, which makes constant monitoringnecessary. Many fires can be extinguished by justshutting off the fan to cut off the oxygen. A little waterapplied directly to the fire at the early stages mayextinguish it if shutting off the fan fails to do so. A fireextinguisher for oil-type fires should be used for oilsunflower fires. Many dryers are designed so that sunflowercan be unloaded rapidly in case of a fire, beforethe dryer is damaged. In some dryers, just the part ofthe dryer affected by the fire needs to be unloaded.Measuring Moisture ContentMeasuring the moisture content of sunflower immediatelyafter removal from the dryer results in only anestimation. As moisture is removed from the sunflowerseed, the hull dries first and the kernels dry last. Moisturetesters used by local grain elevators and farmoperators generally result in a reading that is lowerthan the actual moisture percentage when moisture ismeasured while the moisture variation exists. The initialmoisture content of the sunflower and the temperatureof the drying air influence the amount of error.A number of operators have reported that sunflowerremoved from the dryer at 9 percent to 10 percentmoisture (according to the moisture tester) would beup to 12 percent moisture later. The moisture reboundcan be estimated by placing a sample from the dryerin a covered jar and then rechecking the moisture after12 hours.Guidelines for drying sunflower are:• The area around the dryer and the plenum chambershould be cleaned thoroughly.• The fan must be fed clean air without seed hairs.• A continuous flow in all sections of recirculatingbatch and continuous-flow dryers should be maintained.Uneven flow will cause overdried spotsand increase fire hazard.• Drying equipment must not be left unattendedday or night.• The dried sunflower should be cooled to air temperaturebefore storing.106


StorageFarm structures that are structurally adequate to storeother grains are adequate for storing sunflower due tosunflower’s light test weight, Figure 125.Seed should be cleaned for storage. Fines tend to concentratein the center of the bin if a distributor is notused. Since this material tends to be wetter, this areais more prone to storage problems. Also, airflow willbe restricted by the fines, limiting cooling by aerationin the center of the bin. Large pieces of head, stalkand corolla tubes, which frequently adhere to the seed,should be removed because they are higher in moisturethan the seed.Oil sunflower should not be stored above 10 percentmoisture during the winter and 8 percent during thesummer. Nonoilseed sunflower should not be stored■ Figure 125. Structures adequate to store othergrains are adequate for sunflower. (K. Hellevang)above 11 percent moisture during the winter and 10percent during the summer. <strong>Sunflower</strong> can be storedfor short periods in the fall at 12 percent with adequateairflow to keep the seeds cool. Resistance ofoilseed sunflower to fungal infection during storage at10 percent moisture is equal to wheat resistance at 15percent stored moisture.Aeration to control seed temperature is essential.Aeration fans normally are sized to provide 0.05 to 0.2cfm/bu. (0.15 to 0.6 cfm per cwt) of sunflower (Figure126). <strong>Sunflower</strong> should be rotated between bins duringthe storage period when aeration is not available.Cooling sunflower reduces the potential for sunflowerdeterioration from insects and mold. <strong>Sunflower</strong> shouldbe cooled to 40 degrees or below before or soon afterit is put in the bin and to about 25 degrees for winterstorage. Insects become dormant and will not causedamage or multiply if seed temperature is below about40 F.Moisture and heat accumulate in the peak due tomoisture migration, which results in crusting, spoilageand increased possibility of insect infestations (Figure127). This can be prevented by cooling the sunflowerusing aeration.Bins should be checked initially every two weeksfor moisture condensation on the roof, crusting andchanges in temperatures within the pile. Any of theseconditions could indicate the presence of mold or insects.If the sunflower has started to heat, it should becooled immediately. The sunflower should be checkedat least monthly after the seeds have been cooled toabout 25 F for winter storage and a history of temperatureand moisture content has been developed.Drying and Storage■ Figure 126. Aeration is critical for proper storage. (K. Hellevang)107


Seed lots containing a high percentage of hulled seedor immature seed, such as seed resulting from anearly frost, tend to deteriorate in storage, affecting oilquality.Refer to <strong>NDSU</strong> Extension Service publicationAE-791, “Crop Storage Management,” for moreinformation on aeration and storage management.■ Figure 127. Moisture migration leads to increasedmoisture in top center of stored sunflower.(K. Hellevang)108


Feeding Value of <strong>Sunflower</strong>Products in Beef Cattle Diets(Greg Lardy)<strong>Sunflower</strong> MealNutrients in sunflower meal can vary depending onseveral factors. The amount and composition of mealis affected by oil content of the seed, extent of hullremoval and efficiency of oil extraction. The proportionof hull removed before processing differs amongcrushing plants. In some cases, a portion of the hullsmay be added back to the meal after crushing. Theamount of hull or fiber in the meal is the major sourceof variation in nutrients (Table 17).Pre-press solvent extraction of whole seeds with nodehulling produces meal with a crude protein contentof 25 percent to 28 percent, partial dehulling yields34 percent to 38 percent crude protein content andcompletely dehulled sunflower meal commonly yielding40-plus percent crude protein. <strong>Sunflower</strong> mealis marketed and shipped as meal or pellets. Proteinrequired by rumen microbes can be provided in theform of rumen-degradable protein from sunflowermeal. Heat treatment or toasting of meal from thesolvent extraction process may increase the propor-Table 17. Nutrient content of solvent-extractedsunflower meal based on amount of hullsretained.No Hulls PartiallyRemoved Dehulled DehulledDry Matter, % 90.0 90.0 90.0Percent, Dry Matter BasisCrude Protein 28.0 34.0 41.0Fat 1.5 0.8 0.5Crude Fiber 24.0 21.0 14.0Ash 6.2 5.9 5.9Calcium 0.36 0.35 0.34Phosphorus 0.97 0.95 1.30Potassium 1.07 1.07 1.07Magnesium 0.80 0.79 0.79Hesley (ed), National <strong>Sunflower</strong> Association, 1994.tion of undegradable protein. <strong>Sunflower</strong> meal is moreruminally degradable (74 percent of crude protein)than either soybean meal (66 percent) or canola meal(68 percent; Table 18).<strong>Sunflower</strong> meal has a lower energy value than eithercanola or soybean meal (Table 18). Energy variessubstantially with fiber level and residual oil content.Higher levels of hulls included in the final meal productlower the energy content and reduce bulk density.The mechanical process of oil extraction leaves moreresidual oil in the meal, often 5 percent to 6 percentor more, depending on the efficiency of the extractionprocess. Elevated oil content in mechanically extractedmeals provides greater energy density. Pre-presssolvent extraction reduces residual oil to 1.5 percentor less.<strong>Sunflower</strong> Meal in Beef Cattle Diets<strong>Sunflower</strong> meal can be used as the sole source ofsupplemental protein in beef rations. In trials comparingsunflower meal with other protein sources, equalanimal performance commonly is observed based onisonitrogenous diets from different sources.Cows consuming low-quality forages, such as winterrange, crop aftermath or other low-quality forages, canutilize supplemental degradable protein to increasetotal intake, forage digestibility and performance.Protein can be supplemented with a number of feeds,coproducts or oilseed meals. Least costly sources arecritical to profitability, and sunflower meal often isvery competitively priced per unit protein. <strong>Sunflower</strong>meal has been used widely in beef cow supplementationprograms but few research trials documentcomparative animal performance.Feeding Value of <strong>Sunflower</strong> Products in Beef Cattle Diets109


Table 18. Protein and energy fractions for sunflower meal, soybean mealand canola meal.<strong>Sunflower</strong> Soybean CanolaItem Meal Meal MealDry Matter Basis, %Crude Protein 26.0 49.9 40.9Crude Protein, %Rumen Degradable 74.0 66.0 68.0Rumen Undegradable 26.0 34.0 22.0Dry Matter Basis, %Crude fiber 12.7 7.0 13.3Neutral Detergent Fiber 40.0 14.9 27.2Acid Detergent Fiber 30.0 10.0 17.0Net Energy, Maintenance, Mcal/lb 0.67 0.93 0.73Net Energy, Gain, Mcal/lb 0.40 0.64 0.45Total Digestible Nutrients 65 84 69Adapted from NRC, 1996.<strong>Sunflower</strong> Silage<strong>Sunflower</strong> silage can make a suitable feed for beefcows; however, high moisture levels can be a challengesince sunflowers typically don’t dry down well.Consequently, dry feed must be added to the silagepile to reduce the moisture level to a point where seepageis not a major problem.Table 19 gives the estimated nutrient content of sunflowersilage produced from either low-oil or high-oilvarieties of sunflower. Depending on what other feedsare mixed in the silage pile, nutrient contents maychange.Blending corn and sunflower silages together can helpalleviate the moisture problem. Producers also mayconsider waiting seven to 10 days following a killingfrost to facilitate dry down. Blending dry forage intothe silage pile also can reduce moisture content. Tominimize seepage problems, the moisture level shouldbe 65 percent or less.Whole <strong>Sunflower</strong> SeedsWhen economical, whole sunflower seeds can be usedas a source of energy and protein in beef cattle diets(Table 19). Fat levels can be quite high in whole seeds;consequently, amounts fed should be restricted basedon fat content of the seed. Typically, no more than 4percent supplemental fat should be added to cow dietsto reduce the potential for any detrimental effects onfiber digestion. This will result in inclusion levels ofapproximately 10 percent of the diet.<strong>Sunflower</strong> Residue<strong>Sunflower</strong> residue is useful for aftermath grazing bybeef cows. Nutritional value of the head is greaterthan the stalk. Supplementation may be required ifthe volume of residue is limited and nutrient qualitydecreases rapidly after head material is consumed.<strong>Sunflower</strong> Screenings<strong>Sunflower</strong> screenings from both confection and oilseed plants are often available at competitive prices.Nutrient content varies widely with the amount ofmeats, which are high in fat and protein, and hull,which is low in nutrient content and digestibility.Screenings are best used in modest growing or maintenancediets when animal performance is not critical.The presence of sclerotia bodies does not appear to bea problem for palatability, nutrient content or animalperformance.<strong>Sunflower</strong> Hulls<strong>Sunflower</strong> hulls are low in protein and energy andshould be used only as a bedding source.110


SummaryTable 19. Nutrient content of sunflower products.That sunflower meal is a useful protein source forgrowing and finishing cattle is apparent from thelimited research. Similarly, beef cows can be providedsupplemental protein effectively with sunflower meal.<strong>Sunflower</strong> meal may be especially useful in dietswhere degradable protein is required, such as lowerqualityforage or high corn finishing rations. The increasedbulk of this relatively high-fiber meal may affectlogistics, but ruminants are positioned to be moretolerant of high fiber levels than other species. Othersunflower products can be used effectively in ruminantdiets, given appropriate performance expectations.NE m, NE g,DM, % TDN, % Mcal/lb Mcal/lb CP, % ADF, % Ca, % P, %<strong>Sunflower</strong> Hulls* 90.0 40.0 0.41 0.00 5.0 63.0 0.00 0.114<strong>Sunflower</strong> Screenings* 87.0 64.0 0.66 0.39 11.1 29.0 0.72 0.42<strong>Sunflower</strong> Seed, Confectionary* 94.9 83.0 0.93 0.63 17.9 39.0 0.18 0.56<strong>Sunflower</strong> Seeds, Oil Type* 94.9 121.0 1.42 1.03 17.9 39.0 0.18 0.56<strong>Sunflower</strong> Silage, Low-oil Variety** 30.0 61.0 0.61 0.69 11.1 42.0 0.8 0.3<strong>Sunflower</strong> Silage, High-oil Variety** 30.0 66.0 0.35 0.42 12.5 39.0 1.50 0.3*Adapted from Lardy and Anderson, 2003.**Adapted from Park et al., 1997.Feeding Value of <strong>Sunflower</strong> Products in Beef Cattle Diets111


U.S. Grades and Standardsfor <strong>Sunflower</strong>(Duane R. Berglund)112Definition of <strong>Sunflower</strong> SeedGrain that, before the removal of foreign material,consists of 50 percent or more of cultivated sunflowerseed (Helianthus annuus L.) and not more than 10percent of other grains for which standards have beenestablished under the U.S. Grain Standards Act.Definition of Other TermsCultivated sunflower seed - <strong>Sunflower</strong> seed grownfor oil content. The term seed in this and otherdefinitions related to sunflower seed refers to both thekernel and hull, which is a fruit or achene.Damaged sunflower seed - Seed and pieces ofsunflower seed that are badly ground-damaged,badly weather-damaged, diseased, frost-damaged,heat-damaged, mold-damaged, sprout-damaged orotherwise materially damaged.Dehulled seed - <strong>Sunflower</strong> seed that has the hullcompletely removed from the sunflower kernel.Foreign material - All matter other than wholesunflower seeds containing kernels that can beremoved from the original sample by use of anapproved device and by handpicking a portion of thesample according to procedures prescribed in theUSDA’s Federal Grain Inspection Service instructions.Heat-damaged sunflower seed - Seed and piecesof sunflower seed that are materially discolored anddamaged by heat.Hull (husk) - The ovary wall of the sunflower seeds.Kernel - The interior contents of the sunflower seedthat are surrounded by the hull.Basis of DeterminationEach determination of heat-damaged kernels, damagedkernels, test weight per bushel and dehulledseed is made on the basis of the grain when free fromforeign material. Other determinations not specificallyprovided for in the general provisions are made on thebasis of the grain as a whole, except the determinationof odor is made on either the basis of the grain as awhole or the grain when free from foreign material.Table 20 lists the U.S. grade requirements for sunfloweraccording to the Federal Grain and InspectionService. These requirements became effective Sept. 1,1984. The table lists the minimum limit for test weightand the maximum for damaged and dehulled seed.U.S. grades for both oilseed and nonoilseed classes ofsunflower are determined with the requirements listedbelow.Table 20. Grade and grade requirementsfor sunflower.Maximum limits ofMinimumdamaged sunflower seedtest weight Heat DehulledGrade per bushel damage Total seed(pounds) - - - - - (percent) - - - - -U.S. No. 1 25.0 0.5 5.0 5.0U.S. No. 2 25.0 1.0 10.0 5.0U.S. Sample grade – U.S. sample grade shall be sunflowerseed that:(1) Does not meet the requirements for the grades U.S.Nos. 1 or 2; or(2) In a 600-gram sample, contains eight or more stonesthat have aggregate weight in excess of 0.20 percent ofthe sample weight, two or more pieces of glass, threeor more crotalaria seeds (Crotalaria spp.), two or morecastor beans (Ricinus Communis), four or more particlesof an unknown substance(s), or 10 or more rodentpellets, bird droppings or an equivalent quantity ofother animal filth; or(3) Has a musty, sour or commercially objectionableforeign odor; or(4) Is heating or otherwise of distinctly low quality.Source: Federal Grain and Inspection Service-USDA


Other Information SourcesMajor Organizations andInformation Sources■ Public Research andNonprofit AssociationsSupporting the efforts of private companies in thedevelopment of the sunflower industry are public-supportedresearch institutions and nonprofit associations.The following is a list and brief description of thefunctions and purposes of such groups:<strong>State</strong> Agricultural Experiment Stationsand Cooperative Extension ServiceThe Agricultural Experiment Stations, which conductresearch, and Cooperative Extension Services, whichdeliver adult education programs in the major sunflowerproduction areas, are at:Colorado <strong>State</strong> University, Fort Collins, CO 80523Kansas <strong>State</strong> University, Manhattan, KS 66506<strong>North</strong> <strong>Dakota</strong> <strong>State</strong> University, Fargo, ND 58105South <strong>Dakota</strong> <strong>State</strong> University, Brookings, SD57006Texas A & M University, College Station, TX 77843(branch stations at Lubbock and Bushland)University of California, Davis, CA 95616University of Minnesota, St. Paul, MN 55108, andCrookston, MN 56716Extension PublicationsMany Extension publications giving specific informationon sunflower production, insect pests, diseases,herbicide use, marketing and food use are available.These are readily available through your county orstate Extension offices.Federal ResearchThe Agricultural Research Service (ARS) of theUSDA, working with state agricultural experiment stationsand cooperative Extension personnel in the majorsunflower-producing areas, have developed inbredlines for hybrids, conducted research and providedinformation on production, utilization and marketingaspects. The main USDA-ARS sunflower unit is at the<strong>North</strong>ern Crops Science Laboratory on the campusof <strong>North</strong> <strong>Dakota</strong> <strong>State</strong> University, Fargo, ND 58105,www.fargo.ars.usda.gov.<strong>Agriculture</strong> and Agri-Food CanadaUnit 100-101 Route 100Morden, Manitoba, R6M 1Y5 CANADAwww.agr.gc.ca/The National <strong>Sunflower</strong> Association4023 <strong>State</strong> St. N.Bismarck, ND 58502-0690Tel: (888) 718-7033 or (701) 328-5100http://sunflowernsa.com/The National <strong>Sunflower</strong> Association was organized in1975 to promote the sunflower industry and to solvecommon problems. This association is intended torepresent the interest of growers, processors and seedcompanies, including country elevators, exportersand other merchandisers. It publishes The <strong>Sunflower</strong>magazine and sponsors The <strong>Sunflower</strong> Research Forum,a meeting devoted to scientific reports and topicsof general interest.National <strong>Sunflower</strong> Association of CanadaBox 1269Carman, MB R0G 0J0Phone: (204) 745-6776info@canadasunflower.comwww.canadasunflower.com/U.S. Grades and Standards / Other Information Sources113


The International <strong>Sunflower</strong> Association12 Avenue George V75008 Paris, FranceThe objective of the International <strong>Sunflower</strong> Associationis to improve international cooperation and toexchange information in the promotion of researchof agronomics, processing techniques and nutritionassociated with the production, marketing, processingand use of sunflower. This objective is accomplishedby sponsoring and publishing the proceedings of internationalconferences and by publishing the <strong>Sunflower</strong>Newsletter, a quarterly periodical.■ Sources of Informationof General InterestGovernmental Statistical Reporting Services<strong>Sunflower</strong> production and farm price statistics arereleased by the following state and federal officesof Economics, Statistics and Cooperative ExtensionService, USDA:<strong>North</strong> <strong>Dakota</strong> Agricultural Statistics ServiceP.O. Box 3166Fargo, ND 58108-3166South <strong>Dakota</strong> Agricultural Statistics ServiceBox 31 Drawer VSioux Falls, SD 57101Minnesota Agricultural Statistics ServiceSeventh and Roberts StreetMetro Square, Suite 270St. Paul, MN 55101Texas Agricultural Statistics ServiceBox 70Austin, TX 78767National Agricultural Statistics ServiceU.S. Department of <strong>Agriculture</strong>Washington, D.C. 20250<strong>Sunflower</strong> Technology and <strong>Production</strong>ASA Monograph 35. 1997, 834 pages. Albert A.Schneiter, editor. This monograph text is the extensiverevision of the original Agronomy Monograph 19<strong>Sunflower</strong> Science and Technology. The monographhas many contributing authors addressing and reportingall the scientific work on sunflower that is in theliterature. It has become the “bible of knowledge andinformation” for all who wish to read and study aboutthe sunflower plant, its origin, development, productionand utilization.The <strong>Sunflower</strong>(by C.B. Heiser Jr. from Univ. of Oklahoma Press,Norman, OK 73069, for $10.95)This 200-page book, authored by a botanist and writtenin layman’s language, covers historical development,the distribution and interrelationships ofsunflower species. It describes sunflower as an internationalcommercial crop, as ornamentals and as weeds.The <strong>Sunflower</strong>(4023 <strong>State</strong> St. N., Bismarck, ND 58501-0690)The <strong>Sunflower</strong> magazine is published nine timesa year by the National <strong>Sunflower</strong> Association ofAmerica. It is intended for growers, merchandisers,processors, hybrid seed companies, researchers andother legitimate interests in the sunflower industry.<strong>Sunflower</strong> Directory(4023 <strong>State</strong> St. N., Bismarck, ND 58501-0690, $10)The directory includes more than 150 companies, inaddition to several trade organizations, governmentagencies and universities, which have a unique functionin the sunflower industry. More than 400 individualshaving expertise in sunflower also are listed.High Plains <strong>Sunflower</strong> <strong>Production</strong> Handbook2005, 44 pages. (Kansas <strong>State</strong> University- Agric. ExperimentStation and Cooperative Extension Service).Joint publication of Kansas <strong>State</strong> University, Colorado<strong>State</strong> University, University of Nebraska, Universityof Wyoming and USDA-ARS Central Plains ResearchCenter, Akron, Colo. Also supported by: Kansas<strong>Sunflower</strong> Commission, National <strong>Sunflower</strong> Association– High Plains Committee and Colorado <strong>Sunflower</strong>Administrative Committee.114


GlossaryGlossaryAchene — The sunflower fruit consisting of hulland “seed;” a small, dry, one-seeded fruit thatdoes not open at maturity.Apothecium (pl. apothecia) — Cup- or saucershapedfruiting structure of some fungi.Ascospore — Fungal spore borne in a structurewithin the apothecium.Annuala — Plant in which the entire life cycle iscompleted in a single growing season.Bract — Modified, reduced leaf structure beneathray flowers on sunflower head.Canker — Sharply defined dead area of tissue onstem.Corolla — Collective term for petals of thesunflower.Cytoplasmic Male Sterility — Malesterility inherited through hereditary units inthe cytoplasm, rather than through nuclearinheritance.Defoliate — To remove leaves of a plant.Dehull — Removal of outer seed coat (hull) fromthe “seed.”Depredation — A plundering or despoiling;robbery.Desiccant — A dry-down or defoliating chemical.Disk Flower — Tubular flowers that compose thecentral part of the sunflower head; produce theseeds.Fungicide — A chemical or physical agent thatkills fungi.Fungus (pl. fungi) — A group of organisms thatlack chlorophyll and that obtain food throughabsorption, frequently from plants.Herbicide — A chemical or physical agent thatkills plants.High Oleic — Oilseed sunflower that contains atrait for high oleic fatty acid content in its oil.A premium oil used in the snack food industry.Host — The organism affected by a parasite ordisease.Hybrid — The offspring of two unlike parents.Insecticide — A chemical or physical agent thatkills insects.Instar — Any stage of insect development; larvalgrowth stage.Involucral Bract — An individual bract within adistinct whorl of bracts that subtend the floweringpart of a plant.Kernel — Term used for true seed in processing,preferred to “nutmeat.” The sunflower seed isneither “nut” nor “meat.”Larva (pl. larvae) — The preadult form of an insect.Nonoilseed — Preferred term, equivalent to nonoilsunflower or confectionery sunflower.NuSun — Term that describes the new mid-oleicsunflower oil. It is lower in saturated fat (lessthat 10 percent) than linoleic sunflower oil andhas higher oleic levels (55 percent to 75 percent)with the remainder being linoleic (15 percent to35 percent)Oilseed — Preferred term, equivalent to oilsunflower.Open Pollinated — Naturally pollinated by selfingor crossing between two related strains.Perennial — A plant that continues its growth fromyear to year, not dying after once flowering.115


Petiole — The stalk of the leaf.pH — Expression of acidity or alkalinity of soil orwater.Physiological Maturity — Stage at which a seedhas reached its maximum dry weight.Pollinator — Insect that carries pollen from plantto plant.Pupa (pl. pupae) — The stage between larva andadult in some insects.Ray Flower — Flattened, ray shaped flowers onmargins of sunflower head. Commonly referred toas the petals. These are sterile and do not produceachenes.Receptacle — Fleshy, thickened part of sunflowerhead just above the stem that bears the flowerparts.Sclerotium (pl. sclerotia) — The hard, restingbodies of certain fungi.“Seed” — True seed in sunflower is the kernel;however, “seed” commonly is used to describethe kernel plus hull, which is equivalent to theachene.Self Compatability — <strong>Production</strong> of fruits andnormal seeds following self pollination.Sporea — Reproductive structure of fungi.<strong>Sunflower</strong> — The preferred term, equivalent tosunflowers.Sun Oil — The preferred term, equivalent tosunflower oil, sunflower seed oil.Variety — A subdivision of a species; a distinctgroup of organisms.Volunteer Plant — Plant arising from seeddispersed from a previous crop.116


Appendix 1Appendix 1Diseases of <strong>Sunflower</strong>(Oilseed, Confection and Ornamental)(Helianthus annuus L.)■ BACTERIAL DISEASESApical chlorosisBacterial leaf spotsBacterial wiltCrown gallBacterial stalk rot■ FUNGAL DISEASESPseudomonas syringae pv. tagetis (Hellmers) Young et al.Pseudomonas syringae pv. aptata (Brown and Jamieson)Young et al.P. cichorii (Swingle) StappP. syringae pv. helianthi (Kawamura) Young et al.P. syringae pv. mellea (Johnson) Young et al.Pseudomonas solanacearum (Smith) SmithAgrobacterium tumefaciens (Smith and Townsend) ConnErwinia carotovora subsp. carotovora (Jones) Bergey et al.E. carotovora subsp. atroseptica (van Hall) DyeAlternaria leaf blight, stem spot and head rotAlternaria alternata (Fr.:Fr.) Keissl. = A. tenuis NeesA. helianthi (Hansf.) Tub. and Nish. = Helminthosporium helianthi Hansf.A. helianthicola Rao and RajagopalanA. helianthinfi ciens Simmons et al.A. protenta SimmonsA. zinniae M.B. EllisCharcoal rotDowny mildewFusarium stalk rotFusarium wiltGray moldMacrophomina phaseolina (Tassi) Goidanich= Sclerotium bataticola Taubenhaus= Rhizoctonia bataticola (Taubenhaus) E.J. ButlerPlasmopara halstedii (Farl.) Berl. and De Toni in Sacc.Fusarium equiseti (Corda) Sacc. = (teleomorph: Gibberella intricans Wollenweb.)F. solani (H. Mart.) Sacc.= (teleomorph: Nectria haematococca Berk. and Broome)Microdochium tabacinum (Van Beyma) Arx= Fusarium tabacinum (Van Beyma) Gams= (teleomorph: Monographella cucumerina (Lindfors) Arx)Fusarium moniliforme J. Sheld.= (teleomorph: Gibberella fujikuroi (Sawada) Ito in Ito and K. Kimura)F. oxysporum Schlechtend.:Fr.Botrytis cinerea Pers.:Fr.= (teleomorph: Botryotinia fuckeliania (de Bary) Whetzel)117


Leaf smutMyrothecium leaf spotPetal blightPhialophora yellowsPhoma black stemPhomopsis stem cankerPhytophthora stem rotPowdery mildewEntyloma compsitarum Farl.= (anamorph: Cercosperella columbrina Ell. and Ever.Myrothecium roridum Tode:Fr.M. verrucaria (Albertini and Schwein.) Ditmar:Fr.Itersonilia perplexans Derx.Phialophora asteris (Dowson) Burge and IsaacPhoma macdonaldii Boerema= (teleomorph: Leptosphaeria lindquistii Frezzi)= P. oleracea Sacc. var. helianthi-tuberosi Sacc.Phomopsis helianthi M. Muntanola-Cvetkovic et al.= (teleomorph: Diaporthe helianthi M. Munt.Cvet. et al.)Phytophthora spp. P. drechsleri TuckerErysiphe cichoracearum DC. = (anamorph: Oidium asteris-punicei Peck)E. cichoracearum DC. var. latispora U. Braun(anamorph: Oidium latisporum U. Braun)Leveillula compositarum Golovin f. helianthiL. taurica (Lév.) G. Arnaud(anamorph: Oidiopsis sicula Scalia)Sphaerotheca fuliginea (Schlechtend.:Fr.) PollacciPythium seedling blight Pythium spp.P. aphanidermatum (Edson) Fitzp.P. debaryanum Auct. non R. HesseP. irregulare BuissmanRhizoctonia seedling blightRhizoctonia solani Kühn(teleomorph: Thanatephorus cucumeris (A.B. Frank) Donk)Rhizopus head rot Rhizopus arrhizus A. Fischer = R. nodosus NamyslowskiR. microsporus Tiegh.R. stolonifer (Ehrenb.:Fr.) Vuill = R. nigricans Ehrenb.Rusts(common sunflower rust) Puccinia helianthi Schwein.(cocklebur rust)P. xanthii Schwein.(nutsedge rust)P. canaliculata (Schw.) Lagerh.(unnamed rusts)P. massalis Arthur, P. enceliae Diet. and Holw.Pine needle rustColeosporium helianthi (Schwein.) Arth.Sclerotinia basal stalk rot and wilt, mid-stalk rot, head rotSclerotinia sclerotiorum (Lib.) de BarySclerotinia basal stalk rot and wiltSclerotinia minor JaggerSouthern blightSclerotium rolfsii Sacc.(teleomorph: Athelia rolfsii (Curzi) Tu and Kimbrough)Septoria leaf spot Septoria helianthi Ellis and Kellerm.S. helianthina (Petrov and Arsenijevic)Texas or cotton root rot Phymatotrichopsis omnivora (Duggar) Hennebert= Phymatotrichum omnivorum DuggarVerticillium leaf mottle Verticillium dahliae Kleb.White rustAlbugo tragopogonis (Pers.) S.F. Gray= Pustula tragopogonis (Pers.) Thines118


Misc. foliar pathogensAscochyta compositarum J.J. DavisCercospora helianthi Ell. and Ever.C. pachypus Ell and KellermanColletotrichum helianthi J.J. DavisEpicoccum neglectum Desm.Phyllossticta wisconsinensis H.C GreenSordaria fi micola (Rob. ex Desm.) Ces. and Not.Appendix 1■ NEMATODES, PARASITICDagger, AmericanPinLesionReniformRoot knotSpiralStuntXiphinema americanum CobbParatylenchus projectus JenkinsPratylenchus spp.P. hexincisus Taylor and JenkinsRotylenchulus spp.Rotylenchulus reniformis Linford and OlivieraMeloidogyne arenaria (Neal) ChitwoodM. incognita (Kofoid and White) ChitwoodM. javanica (Treub) ChitwoodHelicotylenchus sp.Tylenchorhynchus nudus AllenQuinisulcius acutus (Allen) Siddiqi■ VIRUS and PHYTOPLASMA DISEASES.Aster yellows<strong>Sunflower</strong> mosaic potyvirus (SuMV)<strong>Sunflower</strong> chlorotic mottle virus (SuCMoV)Cucumber mosaic virus (CMV)Tobacco mosaic virus (TMV)Tobacco ringspot nepovirus (TRSV)Tobacco streak lilarvirus (TSV)Tomato spotted wilt tospovirus (TSWV)119


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FeaturingBird DamageHybrid SeedWeed ControlDiseasesGrading<strong>Production</strong>Herbicide DriftStorageHarvestingHail InjuryInsectsThe <strong>NDSU</strong> Extension Service does not endorse commercial products or companies even though reference may be made to tradenames,trademarks or service names.This publication may be copied for noncommercial, educational purposes in its entirety with no changes. Requests touse any portion of the document (including text, graphics or photos) should be sent to permission@ndsuext.nodak.edu. Include exactlywhat is requested for use and how it will be used.For more information on this and other topics, see: www.ag.ndsu.eduCounty commissions, <strong>North</strong> <strong>Dakota</strong> <strong>State</strong> University and U.S. Department of <strong>Agriculture</strong> cooperating. Duane Hauck, director, Fargo, N.D. Distributed in furtherance ofthe acts of Congress of May 8 and June 30, 1914. We offer our programs and facilities to all people regardless of race, color, national origin, religion, gender, disability,age, veteran’s status or sexual orientation; and are an equal opportunity institution. This publication will be made available in alternative formats for people withdisabilities upon request, (701) 231-7881.4M-9-07

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