PCC_MayJun_2019_e

May/June 2019 

Evaluation of Nitrogen Stabilizers to Improve Corn 

Yield and Plant Nitrogen Status 

Weed Identification: A Crucial Component of Weed 

Management 

Evaluation of Grafted Tomato Plants for 

California Fresh Market Producton Systems 

Walnut Husk Fly Management 

MAY/JUNE 2019 

VINEYARD 

REVIEW 

pages 36-50 

See 

Page 15 

September 26th-27th 

Visalia Convention Center 

303 E. Acequia Ave. Visalia, CA 93291 

PUBLICATION 

Volume 4 : Issue 3 


www.progressivecrop.com 

1

Multi-Target 

Navel Orangeworm Monitoring Systems 

for California conventional and organic tree nuts 

EXCEPTIONAL FOURSOME 

Optimum detection/navel orangeworm ipm 

MONITORING SYSTEMS 

Male Attractant System: 

PHEROCON ® NOW L 2 

PHEROCON VI 

Delta Trap 

Female Attractant System: 

PHEROCON ® IV NOW 

PHEROCON IV NOW 

Egg Trap 

NEW! Predator Detection System: 

PHEROCON ® P 2 

NEW! Multi-Gender 

Attractant System: 

PHEROCON ® PPO Lure 

NOW L 2 

High Lure 

NOW L 2 

Low Lure 

• Male NOW Attractant High/Low- 

Release Pheromone Lures 

• Female NOW – Oviposition 

– Attractant, Concentrated, 

Stabilized lures 

• Detect mite predators, such as the 

Six-spotted thrips and Stethorus beetles 

• Based on the Great Lakes IPM trap 

• Used in recent university trials 

• May be used as a treatment threshold 

indicator 

• Contains easy hanger 

Note: Apply miticides based on UC-IPM Guidelines 

PHEROCON 1C Trap 

• Male/Female NOW Attractant, 

High-Release PPO Micropourous 

Gel Kairomone Lure 

More information below 

• Male/Female NOW 

Attractant, High- Release 

PPO Microporous Gel L 2 

peelable Kairomone Lure 

• Ready-to-Use, 

peelable backing 

• Duplicates USDA release 

rate standard vial at 100 

mgs per day 

• 4 to 6 week field longevity 

• Easy to use; ready-to-use 

barrier pack 

NEW! Multi-Gender Attractant System: PHEROCON® PPO ® PPO Lure 

Lure 

Precision - multicomponent 

release • 

Higher capture rates • 

Earlier detection • 

*Patent pending 

Controls the release of 

more volatile molecules 

while allowing release 

of less volatile molecules. 

• Volatile molecules 

• Less volatile 

molecules 

• Greater longevity 

Contact your local supplier and order now! 

Visit our website: www.trece.com or call: 1- 866-785-1313. 

2 Progressive Crop Consultant May/June 2019 

© 2019, Trécé Inc., Adair, OK USA • TRECE, PHEROCON and CIDETRAK are registered trademarks of Trécé, Inc., Adair, OK USA • TRE-1383, 2/19 

® 

INCORPORAT ED 

INSECT PHEROMONE & KAIROMONE SYSTEMS 

Your Edge – And Ours – Is Knowledge.

4 

IN THIS ISSUE 

Evaluation of Nitrogen 

Stabilizers to Improve 

Corn Yield and Plant 

Nitrogen Status 

PUBLISHER: Jason Scott 

Email: jason@jcsmarketinginc.com 

EDITOR: Kathy Coatney 

ASSOCIATE EDITOR: Cecilia Parsons 

Email: article@jcsmarketinginc.com 

PRODUCTION: design@jcsmarketinginc.com 

Phone: 559.352.4456 

Fax: 559.472.3113 

Web: www.progressivecrop.com 

12 

18 

26 

30 

36 

42 

48 

Weed Identification: A 

Crucial Component of 

Weed Management 

Evaluation of Grafted 

Tomato Plants for 

California Fresh Market 

Producton Systems 

Walnut Husk Fly 

Management 

ACP Control with Systemic 

Insecticides 

VINEYARD REVIEW 

Grapevine Heat Stress and 

Sunburn Management 

Grapevine Trunk Diseases: 

Current Management 

Strategies 

Pierce’s Disease and Glassywinged 

Sharpshooter: Still 

a Threat to California Viticulture 

4 

18 

VINEYARD 

REVIEW 

36 

CONTRIBUTING WRITERS & 

INDUSTRY SUPPORT 

Brenna Aegerter 

UCCE Farm Advisor for 

San Joaquin County 

Whitney Brim-Deforest 

UCCE Rice Advisor 

Akif Eskalen 

Department of Plant 

Pathology - UC Davis 

Michelle Leinfelder- 

Miles 

Delta Farm Advisor, UC 

Cooperative Extension, 

San Joaquin County 

Kevin Day 

County Director and 

UCCE Pomology Farm 

Advisor, Tulare/Kings County 

Steven T. Koike, 

Director, TriCal Diagnostics 

Emily J. Symmes 

Sacramento Valley 

Area IPM Advisor 

University of California 

Cooperative Extension 

and Statewide IPM 

Program 

José Ramón Úrbez- 

Torres 

Agriculture and Agri- 

Food Canada 

Stephen Vasquez 

Technical Viticulturist, 

Sun-Maid Growers 

George Zhuang UCCE 

Fresno County 

UC COOPERATIVE EXTENSION 

ADVISORY BOARD 

Emily J. Symmes 

UCCE IPM Advisor, 

Sacramento Valley 

Kris Tollerup 

UCCE Integrated Pest 

Management Advisor, 

Parlier, CA 

The articles, research, industry updates, company profiles, and 

advertisements in this publication are the professional opinions 

of writers and advertisers. Progressive Crop Consultant does 

not assume any responsibility for the opinions given in the 

publication. 



3

Evaluation of Nitrogen Stabilizers to Improve 

Corn Yield and Plant Nitrogen Status 

By MICHELLE LEINFELDER-MILES 

| Delta Farm Advisor, UC Cooperative Extension, San Joaquin County 

Introduction 

Nitrogen (N) is part of a balanced, 

natural cycle in the 

environment among the 

atmosphere, soil, plants, animals, and 

water. Nitrogen is the most important 

element needed by crops, and we often 

add nitrogen fertilizer to optimize crop 

productivity. Nitrogen use in agricultural 

systems must be reported for regulatory 

compliance under the Irrigated 

Lands Regulatory Program and the 

Dairy Order to help ensure that a greater 

fraction of the applied N is recovered 

in the harvested crop and not lost to the 

environment. Nitrogen management 

gives consideration to the four R’s: 

• Right source: selecting a fertilizer 

source that matches with crop need and 

minimizes losses. 

• Right rate: applying the right amount 

based on crop need and nutrient 

availability through other sources. 

• Right time: applying the nutrient 

when the crop can use it. 

• Right place: fertilizer placement that 

optimizes the crop’s ability to use it. 

The four R’s address management 

considerations (e.g. fertilizer program, 

irrigation), but site characteristics 

(e.g. soil, cropping system, weather 

conditions) also influence N recovery in 

the crop. Also important to improving 

crop N recovery is understanding 

barriers to adopting best management 

practices, such as costs or risks to crop 

quality or yield. 

While the four R’s articulate four 

principles for nitrogen management, 

the N cycle in cropping systems 

is complicated. Nitrogen can be 

introduced and lost by various paths. 

We generally add N with fertilizer or 

Keep Birds Out 

GUARANTEED 

“I’ve used Bird Gard 

for years to protect my 

growers’ crops and keep 

birds from damaging 

the irrigation. 

Bird Gard works, what 

more can I say?” 

Tim Peltzer 

Peltzer Farm Management 

Terra Bella, CA 

Bird Gard is the ONLY bird control with a 

1-YEAR UNCONDITIONAL MONEY-BACK GUARANTEE 

888-332-2328 www.BirdGard.com 

Guaranteed Bird Control for over 30 Years! 

Continued on Page 6 

4 Progressive Crop Consultant May/June 2019

They may 

be unseen, 

but they 

shouldn’t go 

unnoticed. 

Nematodes are the invisible threat to almond orchards. 

Protect your crops from nematode damage with Velum ® One. 

Protection from wide-spectrum 

nematode damage. 

Can increase yield 8.3% with an 

average of $475/bearing acre. 1 

58% average increase in canopy 

diameter in newly-planted trees. 2 

Convenient in-season application 

via chemigation. 

For more information, visit www.VelumOne.com. 

1 

Profit increase based on 2017 almond price/lb. and average yield/bearing acres with 8.3% increase in yield versus untreated over three-year trial, per trial data of five locations with a 

single application of Velum One at 6.5 or 6.85 fl. oz./A. 

2 

Velum One applied at 6.5 oz./A, spring 2017, via drip irrigation. Trees planted in January 2017. Increase in green canopy pixels based on an average of two rows of untreated trees 

compared to an average of two rows of Velum One-treated trees. 

© 2018 Bayer CropScience LP, 800 North Lindbergh Boulevard, St. Louis, MO 63167. Always read and follow label instructions. Bayer, the Bayer Cross, and Velum are registered trademarks of 

Bayer. Not all products are registered for use in all states. For additional product information, call toll-free 1-866-99-BAYER (1-866-992-2937) or visit our website at www.CropScience.Bayer.us. 



5

Continued from Page 4 

organic matter amendments—such as 

crop residues, compost, or manure. 

Fertilizers provide N in plant-available 

forms—ammonium (NH 4 

+) and nitrate 

(NO 3 -). Organic matter amendments 

must be mineralized before the 

N is available for plant uptake. 

Mineralization is a process that involves 

soil biology converting organic N to 

NH 4 

+. The timeline of this conversion 

will depend on the properties of 

the amendment, environmental 

conditions—such as soil temperature 

and moisture, and the activity and 

abundance of soil microbes. 

In the soil, NH 4 

+ has different fates. It 

can be immobilized by microorganisms, 

taken up by plants, fixed to soil particles 

due to its positive charge, volatilized to 

ammonia gas (i.e. lost from the system), 

or converted to NO 3 -—a process 

known as nitrification. Nitrification is 

a two-step process. The first step is the 

conversion of NH 4 

+ to nitrite (NO 2 -) 

by Nitrosomonas bacteria. The second 

step is the conversion of NO 2 - to nitrate 

(NO 3 -) by Nitrobacter bacteria. These 

two steps generally occur in close 

succession to prevent the accumulation 

of NO 2 - in the soil. Conditions that 

affect nitrification include soil aeration, 

moisture, temperature, pH, clay and 

cation content, NH 4 

+ concentration, 

among others. Just as NH 4 

+ has different 

THE FOUR R’s 

Right source: selecting 

a fertilizer source that 

matches with crop need and 

minimizes losses 

Right rate: applying the 

right amount based on 

crop need and nutrient 

availability through other 

sources, 

Right time: applying the 

nutrient when the crop can 

use it, 

Right place: fertilizer 

placement that optimizes 

the crop’s ability to use it. 

fates in the soil, so too does NO 3 -. Plants 

preferentially take up NO 3 -, but if NO 3 - 

is present when plants are not in need 

of it, then NO 3 - may be immobilized 

by microorganisms, volatilized to 

nitrogen gas (i.e. lost from the system), 

or leached out of the root zone (i.e. lost 

from the system). 

Technologies have been developed 

to mitigate N losses from the system. 

These technologies are collectively 

known as enhanced efficiency 

fertilizers (EFF) and include additives, 

physical barriers, and chemical 

formulations that stop, slow down, 

or decrease fertilizer losses. Nitrogen 

stabilizers, slow-release fertilizers, and 

polymerized fertilizers are examples of 

EEF. Nitrogen stabilizers are fertilizer 

additives intended to improve crop 

N use efficiency and reduce N losses 

to the environment by interrupting 

the microbial processes that change 

N to its plant-available forms. We 

developed a trial to evaluate two N 

stabilizer products with the objective 

of determining whether the treatments 

improved corn silage yield or plant 

N status compared to fertilizer alone. 

We did not attempt to measure N 

losses from the system (e.g. leaching, 

denitrification), as these are very 

challenging to quantify. 

The products in our trial were 

Vindicate (Corteva Agriscience) and 

Agrotain Plus (Koch Agronomic 

Services). Vindicate delays the 

nitrification process by inhibiting 

the Nitrosomonas bacteria that 

converts NH 4 

+ to NO 2 -. Vindicate has 

bactericidal activity, and the active 

ingredient is nitrapyrin. Agrotain Plus 

has two modes of action—reducing 

ammonia volatilization and delaying 

nitrification. Ammonia volatilization 

is the conversion of NH 4 

+ in the 

soil to ammonia gas (NH 3 ) in the 

atmosphere, and it is reduced by 

inhibiting the urease enzyme. Ammonia 

volatilization is most problematic 

when the N source is urea-based and 

not incorporated or watered into the 

soil. The active ingredients of Agrotain 

Plus are Dicyandiamide (DCD), which 

delays nitrification, and N-(n-butyl)- 

thiophosphoric triamide (NBPT), 

which reduces volatilization. DCD has 

bacteriostatic activity, which means it 

slows the metabolism of Nitrosomonas. 

We hypothesized that N stabilizers 

would improve yield and N uptake over 

the fertilizer-only treatment, providing 

growers with a tool for nutrient 

stewardship. 

Methods 

The trial took place in San Joaquin 

County on a DeVries sandy loam soil. 

The field had a winter wheat crop that 

was cut for forage in the late spring. Dry 

manure was applied to the field between 

wheat harvest and corn planting, which 

occurred on May 24, 2018. The variety 

was Golden Acres 7718. At-planting 

fertilizer provided approximately 12 lb 

N per acre (4-10-10). Sidedress fertilizer 

application occurred on June 21st and 

provided approximately 105 lbs N per 

acre (UAN 32). Four treatments were 



WE’VE GOT 

YOU COVERED. 

Join the fight against disease. 

ChampION ++ Fungicide/Bactericide has the smallest, 

most consistent copper particles of any water dispersible 

granule (WG) copper formulation. This leads to more 

thorough leaf coverage and plant absorption for 

excellent control. All this with less environmental 

load than high-dose copper products and 

OMRI listed for use in organic crop production. 

Get the copper fungicide that won’t back 

down. For more information, contact 

your Nufarm rep today or go to 

nufarm.com/us. 

For specific application rates, directions, mixing instructions and precautions, read the product label. 

Please visit www.nufarm.com/us to download a full label. IMPORTANT: Always read and follow label instructions. 

© 2018 Nufarm. ChampION ++TM is a trademark of Nufarm Americas. 12/18-61898 



7


Figure 1. Nitrogen stabilizers applied at sidedress fertilizer application. 

applied at sidedress, when plants were 

at V3-4 stage of development (Figure. 

1). The N stabilizers were applied at the 

label rates, and the treatments were: 1) 

Bring the 

heat on 

hard-to-kill 

weeds and 

insects with 

d-LIMONENE ADJUVANT 

Spreader-Activator with Citrus Extract 

R-Agent DL ® dramatically 

boosts performance. 

Use R-Agent DL with and without oil 

on agricultural, turf, ornamental, and 

non-cropland sites. 

Distributed by 

Chemurgic Agricultural Chemicals, Inc. 

P.O. Box 2106 • Turlock, CA 95381 

www.chemurgic.net 


TM 

Vindicate at 35 fluid ounces per acre, 2) 

Agrotain Plus at 3 pounds per acre, 3) 

combination of Vindicate and Agrotain 

Plus at aforementioned rates, and 4) 

fertilizer-only, no 

stabilizer product 

(“untreated”). Plots 

were 35 feet across 

(i.e. fourteen 30-inch 

rows), in order to 

adapt to equipment 

of different widths, 

by 900 feet long. 

Treatments were 

randomly applied 

in three replicate 

blocks. Aside from 

the treatments, the 

trial was managed 

100% Active 

Ingredient! 

For more information: 

email: tom@chemurgic.net 

Tom Kelm: 559 696-6558 

• Adjuvants 

• Nutrients 

• Organics 

• Formulation 

Services 

by the grower in the 

same manner as the 

field. 

We evaluated soil 

N status, plant 

N status, and 

silage yield. Prior 

to planting, 

20 soil cores 

were randomly 

collected from 

across the trial 

and aggregated by 

foot-increments, 

down to two feet. 

Mid-season leaf 

and soil samples 

were collected 

when the corn was in the R1 stage (i.e. 

silking). Soil was collected from 10 

in-row locations in each treatment, and 

aggregated by foot-increments, down to 

two feet. Leaves were sampled from ten 

plants in each treatment, sampling the 

leaf one-below and opposite the earleaf. 

Harvest occurred on September 20th. 

All fourteen rows were harvested for 

weight, and samples were collected at 

the silage pit for aboveground biomass 

N analysis. The samples were dried 

at 60⁰C for 48 hours for calculating 

dry matter (DM). Post-harvest, 10 

in-row soil cores were collected to 

one-foot depth and aggregated for 

each treatment. Laboratory analyses 

were conducted by Ward Laboratories 

(Kearney, NE; https://www.wardlab. 

com/). We used Analysis of Variance 

to detect differences in treatments and 

Tukey’s range test for means separation 

(JMP statistical software). Treatments 

were considered statistically different if 

the P value was less than 0.05. 


“ Technologies have been 

developed to mitigate N 

losses from the system. These 

technologies are collectively 

known as enhanced efficiency 

fertilizers... 

“

Calcium 

At Your Service 

Apply CaTs ® during the growing season for improved water infiltration 

and soil structure. CaTs works by displacing sodium to flocculate soil 

colloids resulting in increased water movement through the soil. 

The 100% soluble calcium and sulfur works immediately in the soil. The 

thiosulfate sulfur reacts in the soil to release additional calcium. CaTs 

convenient liquid formulation allows for easy application with irrigation. 

Crop Vitality Specialists can provide assistance regarding application, 

blending, field studies and technical data. 

Learn more about CaTs on the Crop Vitality YouTube Channel. 

Start a Conversation today with Your Crop Vitality Specialist 

Call (800) 525-2803, email info@cropvitality.com or visit CropVitality.com 

©2019 Tessenderlo Kerley, Inc. All rights reserved. CaTs ® is a registered trademark of Tessenderlo Kerley, Inc. 



9

Table 1. Plant N, yield, dry matter (DM), and N removed results for the 2018 N stabilizer efficacy trial. There were no 

significant differences among treatments. 

TABLE 1 

Treatment 

Midseason (R1) 

Leaf Total N 

(%) 

Aboveground 

Biomass Total 

N 

(%) 

Yield at 

30% DM 

(tons/acre) 

DM 

(%) 

Total N Removed at 

Harvest 

(lbs N/acre) 

Vindicate 2.97 1.12 40.4 0.37 272 

Agrotain Plus 2.97 1.11 37.7 0.34 250 

Vindicate and 

Agrotain Plus 

2.71 1.16 38.7 0.34 269 

Untreated 2.87 1.09 38.3 0.35 251 

Average 2.88 1.12 38.8 0.35 261 

CV (%) 4 2 3 3 5 

P value 0.32 0.18 0.48 0.20 0.39 


Results and Discussion 

There were no statistically significant 

differences among treatments for plant 

tissue N, yield, dry matter, or total N 

removed at harvest (Table 1). Midseason 

leaf N averaged 2.88 percent 

across treatments, and aboveground 

biomass N at harvest averaged 1.12 

percent. At mid-season, leaf N from 2.7 

to 3.5 percent indicates that the plants 

had sufficient N to carry the crop to 

harvest, and at harvest, whole plant 

N from 1.0 to 1.2 percent indicates 

that the N fertilization program was 

adequate for maximizing yield [1]. 

Calculated to 30 percent dry matter, 

average yield across treatments was 

38.8 tons/acre, and dry matter was 

35 percent. There was a trend for the 

two treatments with Vindicate to have 

a higher N removed than the two 

treatments without it, but the difference 

was not statistically significant. The low 

coefficient of variation (CV), which is a 

measure of variability in relation to the 

mean, indicates low variability among 

replicates for all of these parameters. 

The pre-plant (post-dry manure 

application) soil nitrogen status was 

17 parts per million (ppm) NO 3 -N 

and 4 ppm NH 4 -N for the 0-12 inch 

depth, and 7 ppm NO 3 -N and 2 ppm 

NH 4 -N for the 12-24 inch depth. When 

soil NO 3 -N is below 25 ppm in the 

top foot of soil, it is recommended to 

apply N fertilizer in order to prevent 

yield reductions [2]. There were no 

differences among treatments in soil 

N status at the mid-season sampling, 

but there were differences at the postharvest 

sampling (Table 2. See page, 

11). Mid-season soil NO 3 -N averaged 

32 ppm across treatments in the top 

foot of soil, and 10 ppm in the second 

foot of soil, which is an adequate 

concentration to carry the crop through 

to harvest. Soil NH 4 -N averaged 4 ppm 

and 2 ppm across treatments for the top 


Table 2. Soil N status (as NO3-N and NH4-N) at mid-season and post-harvest samplings for the 2018 N stabilizer 

efficacy trial. 

TABLE 2 

Treatment 

Mid-season 

NO 3-N (ppm) 

0-12 inches 

Mid-season 

NO 3-N (ppm) 

12-24 inches 

Mid-season 

NH 4-N (ppm) 

0-12 inches 

Mid-season 

NH 4-N (ppm) 

12-24 inches 

Post-harvest 

NO 3-N (ppm) 

0-12 inches 

Post-harvest 

NH 4-N (ppm) 

0-12 inches 

Vindicate 33 10 4 2 38 b 2 

Agrotain Plus 32 10 4 2 44 ab 2 

Vindicate and 

Agrotain Plus 

32 9 3 2 57 a 2 

Untreated 31 12 4 2 43 ab 2 

Average 32 10 4 2 46 2 

CV (%) 25 31 20 36 7 19 

P value 0.99 0.75 0.58 0.97 0.04 0.89 

foot and second foot, respectively. The 

CV was high for mid-season soil data, 

which indicates high variability among 

replicates. Post-harvest soil NH 4 -N 

averaged 2 ppm across treatments in 

the top foot of soil, but soil NO 3 -N 

was higher than at any other time 

during the season, averaging 46 ppm 

across treatments. These results may 

indicate that 

the dry manure 

mineralized 

later in the 

season, after the 

peak demand 

of the corn. 

Post-harvest 

soil NO 3 -N 

above 20 ppm is 

considered high and indicates that this 

crop was not deficient in N [2]. The low 

CV for NO 3 -N indicates low variability 

among replicates. The significant 

differences among treatments are not 

well-understood, particularly as the 

control (fertilizer-only) treatment had 

soil NO 3 -N that was not different from 

any of the treatments. Interestingly, 

Vindicate had the lowest post-harvest 

soil NO 3 -N and a trend toward higher 

N removed (though not statistically 

higher), which may indicate that 

product use made N available at a time 

that optimized N uptake. 

Summary 

N is part of a balanced, natural cycle 

“ 

N is part of a balanced, 

natural cycle in the 

environment and is the most 

important nutrient in cropping 

systems. 

in the environment and is the most 

important nutrient in cropping 

systems. Giving consideration to N 

management will help ensure that a 

greater fraction of the applied N is 

recovered in the harvested crop and 

not lost to the environment, and keeps 

growers in regulatory compliance. 

Enhanced Efficiency Fertilizers, such 

as N stabilizers, 

have been shown 

to improve 

crop yield in 

regions like the 

Midwest and 

the Northeast, 

and may help 

to mitigate N 

losses from the 

environment. In our trial, we evaluated 

the efficacy of N stabilizer products for 

improvements in corn silage yield or 

plant N status compared to fertilizer 

alone. Under the management and 

environmental conditions of this trial, 

we found no differences in yield or plant 

N status; however, plant and soil tests 

indicated that N was never limiting in 

the trial. If N was lost from the system, 

the loss was not large enough to result 

in N limitation in the control. Future 

study should test these products using 

different N sources and N rates (e.g. 

grower rate and grower rate minus 50 

lbs N/acre). It may be possible to reduce 

the fertilizer N rate without sacrificing 

yield. 

“ 

References 

1. Nutrient Management for Field Corn 

Silage and Grain in the Inland Pacific 

Northwest. https://www.cals.uidaho.edu/ 

edcomm/pdf/PNW/PNW0615.pdf. 

2. Nutrient Management Guide – Silage 

Corn (Western Oregon). https://catalog. 

extension.oregonstate.edu/em8978. 

Comments about this article? We want 

to hear from you. Feel free to email us at 

article@jcsmarketinginc.com 



11

By WHITNEY BRIM-DEFOREST | UCCE Rice Advisor, Yuba/Sutter Counties 

Weed identification is the 

foundation for weed control. 

For both cultural controls 

(tillage, weed-whacking, etc.), and 

herbicides, misidentification can lead 

to wasted time, money, and resources. 

But even for experienced weed scientists 

and botanists, weed identification 

can be difficult. Traditional keys, for 

example, primarily rely on our ability 

to distinguish between plants at flowering, 

and often require a fair amount 

of knowledge of botanic terms, and 

possibly even a microscope. Aside from 

the difficulty of using the keys, identification 

at flowering is usually too late for 

weed control, particularly for the use of 

many herbicides. 

There are many tools available to use for 

weed identification, ranging from books 

to cards, to online databases, and even 

computer programs and smartphone 

apps. The resources found below are 

just a few of the plethora of weed 

identification resources, highlighting 

some of the most relevant for California, 

and many that are free or low-cost. 

Print 

Printed materials may be a bit difficult 

to carry into the field, obviously, but 

they can be a good resource, especially 

for learning more about the biology and 

ecology of the weed species once it is 

identified. 

1) Weeds of California and Other 

Western States (DiTomaso 

and Healy, 2007) 

This 2-volume set is 

available through the 

UCANR website (as well 

as many other websites), 

and contains many, 

many weeds found in 

California, as well as 

those that may be likely 

to move into California 

from surrounding states. 

It includes over 700 

weed species, in over 

60 families. It also has 

tables to help distinguish 

between commonlyconfused 

weeds. 

2) Weed Identification 

Cards (DiTomaso, 2013) 

This set of cards is 

adapted from the Weeds 

of California and Other 

Western States book listed 

above, and contains the 48 most 

widely distributed weed species 

in California. It is available from the 

UCANR website. The weeds are divided 

into the following 8 plant groups, for 

easy searching: 

1. Volumes 1-2 of Weeds of California and 

Other Western States (DiTomaso and 

Healy, 2007). 


• Broadleaf annuals, erect 

• Broadleaf annuals, low growing 

• Broadleaf annuals, scrambling 

• Broadleaf perennials, not viney 

• Broadleaf perennials, viney 

• Grass annuals 

• Grass perennials 

• Sedges 

The cards are small and can be held in the hand while in the field. 

They are laminated, so even if they get moist, they will not be 

ruined. 

Computer Based 

There are a couple of resources available (one USB-loaded program 

and one web-based application) if you need some help identifying 

weeds, especially during early growth stages. While the USB can 

only be used on a computer, the web-based application can also 

be used on a smart-phone (in the field), although it does require 

connectivity to the web to be able to do so. 


2. Weed Identification Cards 

(DiTomaso, 2013). 



13


1) Weed ID USB (DiTomaso, 2014). 

The Weed ID USB contains identification information for 722 broadleaf species 

and 200 weedy grasses. Using the program, it is possible to identify weeds even 

at the seedling stage, using key characteristics visible to the naked eye, instead of 

requiring a microscope or hand lens. For example, key traits such as stem crosssection, 

leaf shape, hairs on the leaves, etc. It also allows the user to select the 

family, or genus, if known. After making selections, the program will, through 

process of elimination, show a list (with photos and descriptions) of all the weed 

species fitting those characteristics. Once down to a few species, the user can 

visually compare the photos of their specimen to the photos in the database. 

The USB is available through the California Invasive Plant Council Website (www. 

cal-ipc.org), or by contacting Dr. DiTomaso directly (jmditomaso@ucdavis.edu). 


2) Online Weed Identification Tool (University of Wisconsin-Madison): 

The University of Wisconsin-Madison hosts an online weed identification tool 

that is very similar to the USB drive (above). It is freely available at https://weedid. 

wisc.edu/weedid.php. Several states are available, so be sure to select California as 

the search location. There are far fewer species in this database in comparison to 

the USB drive, but the identification method is similar. The user has to select plant 

characteristics, and through a process of elimination, the possible weed species 

with those characteristics will remain. The user can then use the photos to identify 

their specimen. 

Continued on Page 16







REGISTER AT 

progressivecrop.com/conference 

You’re invited to join us for the first annual Crop Consultant 

You’re invited to join us at the first annual Crop Consultant 

Conference. The event takes place on September 26th, and 

Conference. It is taking place on September 26th, and 

27th at the Visalia Convention Center. 

27th at the Visalia Convention Center. 

This 2-day conference provides Education and Networking opportunities for PCAs, CCAs, and Ag 

This 2-day conference provides Education and Networking opportunities for PCAs, CCAs, and Ag 

Retailers from across California. Join us for our Opening Reception and Gala Dinner, the first night, 

Retailers from across California. Join us for our Opening Reception and Gala Dinner, the first night, 

followed by our seminars and Industry Lunch the next day. Attendees will learn about current issues 

followed by our seminars and Industry Lunch the next day. Attendees will learn about current issues 

impacting California’s agriculture industry, the latest technologies, and more at our workshops and 

impacting California’s Agriculture Industry, the latest technologies, and more at our workshops and 

seminars while earning 6 CE Credits (Pending DPR Approval). 

seminars while earning 6 CE Credits (Pending DPR Approval). 

powered by: 

powered WEST by: COAST NUT 

Workshops and Seminars 

6 Hours of CE Credit (Pending DPR Approval) 

Workshops Mixer and & Networking 

Seminars 

Meals 6 Hours Included of CE (Gala Credit Dinner, Lunch, (Pending Breakfast, DPR Approval) and snacks) 

Mixer & Networking 

Meals Included (Gala Dinner, Lunch, Breakfast, and snacks) 

For more information and to register visit progressivecrop.com/conference 

LIMITED 

WEST COAST NUT 

SPOTS AVAILABLE 

For more information and to register visit progressivecrop.com/conference 

May/June 2019 www.progressivecrop.com 15


Mobile Apps 

Although there are several smartphone 

applications available for both Androids 

and IPhones, testing of several yielded 

only one with enough species to make it 

worthwhile to use in the field. 

1) Pl@ntNet (www.plantnet.org) 

The Pl@ntNet app (available for both 

Android and IPhone) was created by a 

consortium of universities and public 

research institutions. It contains plant 

species from all over the world, so 

the user has to be careful to select the 

correct continent (North America). It 

does not cover only weeds, however, 

which is important to note. It also 

contains native and naturalized species. 

The app works by matching key photo 

characteristics with identified photos 

already in the database. The user 

takes a photo, then specifies which 

characteristic to focus on (leaf, fruit, 

bark, flower, habit, or other), then the 

app matches the photo with potential 

specimens in the database. The user 

then selects the species that most 

closely matches, and submits it to the 

app, where it is reviewed (seemingly 

by experts). Upon testing it, it was able 

to accurately identify several grasses, 

broadleaves, and shrubs. 

In-Person Assistance 

When in doubt, ask another person 

to assist in identification. Fellow pest 

control advisors, growers, and other 

colleagues are great resources. However, 

if it appears to be a new or unknown 

weed species in a particular cropping or 

natural system, there are other resources 

available to help as well. 

can assist in identification. Visit the herbarium website at https://herbarium. 

ucdavis.edu/services.html for collection and sample delivery protocols. The 

herbarium can identify up to five samples per person per year at no charge, and 

after that, an hourly rate for identification applies. 

There are many more tools available for weed identification beyond the ones listed 

above, including many helpful keys and online resources. In order to identify a 

weed, it may be necessary to utilize many tools and second opinions, particularly if 

it is a less well-known species, or if it is new to a cropping or natural system. While 

identification can be time-consuming, especially when we are anxious to get rid 

of a weed, ensuring proper identification before deciding on a plan for control can 

save a lot of time, energy, and money over the long run. 

Comments about this article? We want to hear from you. Feel free to email us at 


1) University of California Cooperative 

Extension advisors and specialists 

County-based advisors and campusbased 

specialists can be helpful in 

providing weed identification. Local 

offices are located in almost every 

county in California, and advisors there 

can tap into larger networks of weed 

scientists for help with identification, 

if they are unable to identify the weed 

themselves. 

2) Weed identification at the UC Davis 

Herbarium 

For really tricky cases, the UC Davis 

Herbarium has botanists on staff that 


ADVERTORIAL 

Higher Almond Yields with Luna ® 

Luna Sensation ® | Luna Experience ® 

From bloom to harvest Luna ® fungicide protects almonds from 

8 major diseases to improve plant health and ensure 

higher almond yields season after season. 

PRAY AT BLOOM 

Merivon ® 

by +251 lbs./A 

average 

Merivon 

3,102 3,353 

FOR BEST RESULTS AT HARVEST. 

LUNA ® OUT-YIELDS IN PERFORMANCE TRIALS 

Pristine ® 

by +110 lbs./A 

average 

Pristine 

2,668 

2,778 

SPRING AND EARLY SUMMER (AROUND BLOOM TIME) IS WHEN MOST DISEASES OCCUR. 

Scab 

Cladosporium 

carpophilum 

Brown Rot 

Blossom Blight 

Monilinia laxa 

Jacket Rot 

Botrytis cinerea 

Alternaria 

Leaf Spot 

Alternaria 

alternata 

Anthracnose 

Colletotrichum 

acutatum 

Almond 

Leaf Rust 

Tranzschelia 

discolor 

Shothole 

Wilsonomyces 

carpophilus 

Hull Rot 

Rhizopus spp. 

Monilinia spp. 

8 DISEASES 

THAT IMPACT 

ALMOND TREE 

HEALTH & YIELD 

How It Works 

Luna ® is a breakthrough systemic 

fungicide with uniform uptake after 

application, allowing it to effectively enter 

the buds, blooms and new tissue where 

disease hides. Make Luna a cornerstone 

of your fungicide program to control eight 

almond diseases for long-term tree health. 

Protection 

Means Profits 

Luna ® out-yields Merivon ® by more than 251 lbs./A. 

+251 lbs. = an additional 

$ 800/A * 

Luna out-yields Pristine ® by more than 110 lbs./A. 

+110 lbs. = an additional 

$ 351/A * 

* Source: Average yield gain in dollars per pound based on 

California Agricultural Statistics Review, 2014–2015, 

California Department of Food and Agriculture, page 81. 

LEARN MORE ABOUT HOW LUNA CAN HELP YIELD ABUNDANT HARVESTS AT LUNAFUNGICIDES.COM. 

© 2018 Bayer CropScience LP, 800 North Lindbergh Boulevard, St. Louis, MO 63167. Always read and follow label instructions. Bayer, the Bayer Cross, Luna, Luna Experience, and Luna Sensation are 

registered trademarks of Bayer. Pristine and Merivon are registered trademarks of BASF Corporation. Not all products are registered for use in all states. For additional product information, call toll-free 

1-866-99-BAYER (1-866-992-2937) or visit our website at www.CropScience.Bayer.us. 

17

Evaluation of Grafted Tomato Plants 

for California Fresh Market Production Systems 

By BRENNA AEGERTER | UCCE Farm Advisor for San Joaquin County 

All photos courtesy of Brenna Aegerter 

Why Graft? 

Grafting involves joining a 

fruit-producing shoot (called 

the 'scion') of a desirable cultivar 

onto the disease-resistant rootstock 

of another cultivar. For example, 

let’s say you normally grow the cultivar 

'QualiT-47' for fruit production, but 

that cultivar is susceptible to a soilborne 

disease problem in your fields, then you 

could graft the top part of a 'QualiT-47' 

seedling onto the root-portion of a 

more disease-resistant cultivar. In the 

case of tomato rootstocks, the majority 

of the cultivars are interspecific hybrids 

Additional Environmental Stress Conditions that the product is useful for: 

What is 

Anti-Stress 550®? 

When to apply 

Anti-Stress 550®? 

Frost & Freeze 

• High Temperatures & Extreme Heat 

• Drought Conditions 

• Transplanting • Drying Winds 

When is Anti-Stress 550® 

most effective? 

Beat the Heat & Care 

for Your Crops with: 

Anti-Stress 

550 ® 

A foliar spray that creates a 

semi-permeable membrane 

over the plant surface. 

Optimal application period is 

one to two weeks prior to the 

threat of high heat. 

*One application of Anti-Stress 550® will remain effective 30 

to 45 days, dependent on the rate of plant growth, 

application rate of product and weather conditions. 

559.495.0234 • 800.678.7377 

polymerag.com • customerservice@polymerag.com 

Order from your PCA or local Ag Retailer / Crop Protection Supplier 

between cultivated tomato (Solanum 

lycopersicum) and wild tomato species 

(most commonly Solanum habrochaites, 

or less often S. peruvianum or S. 

cheesmaniae). Solanum habrochaites is 

known from other published research 

to be tolerant of salinity, drought, cold 

temperatures, and resistant to many 

soilborne diseases and many of these 

benefits have been demonstrated to be 

conferred to the grafted plant when an 

interspecific hybrid rootstock is used. 

Most of us are familiar with grafting as 

a standard practice for California fruit 

and nut trees and grapevines, but it 

has experienced only 

limited commercial 

The coating of Anti-Stress 

becomes effective when the 

product has dried on the plant. 

The drying time of Anti-Stress is 

the same as water in the same 

weather conditions. 

adoption among 

annual crops in 

California thus far. 

Grafted tomato 

transplants are 

commonly utilized 

in the commercial 

greenhouse industry, 

where tomatoes are 

produced under 

protected culture 

and are generally 

grown over a much 

longer production 

cycle, often a 

10-month period. 

There are greenhouse 

producers in Southern 

California, but it is 

more common in 

British Columbia, 

Ontario, Mexico 

and other US states 

(Arizona and 

others). In many 

countries in Latin 

America, Europe 

and Asia, grafted 

plants represent a 

large percentage of 

the tomato industry. 

For example, in Spain, 50 to 70 million 

grafted plants are grown annually for 

greenhouse production systems. There 

has also been some adoption of grafting 

by high-tunnel tomato growers in the 

eastern United States. In Southern 

California, the nursery Plug Connection 

is marketing grafted tomatoes to home 

gardeners, dubbing them as a “Mighty 

‘Mato”. This allows a home gardener to 

grow an heirloom tomato variety, which 

often has little or no disease resistance, 

without worrying about rotation 

or other soilborne disease control 

measures. 

Our goal was to evaluate the potential 

for grafting standard tomato cultivars 

onto rootstock cultivars that possess 

resistance to soilborne diseases and 

nematodes. Our primary objective 

was to evaluate the yield performance 

of grafted plants in replicated trials 

in commercial fresh market (“mature 

green”) production fields in the 

northern San Joaquin Valley. Our team 

consisted of myself, Scott Stoddard with 

University of California Cooperative 

Extension (UCCE) in Merced County, 

and Michael Grieneisen and Minghua 

Zhang in the Department of Land, Air 

and Water Resources at the University 

of California, Davis. This project 

produced the first publicly-available 

research results on grafted tomatoes for 

California production systems. 

How is it Done? 

For each tray of grafted tomatoes to 

be produced, two trays of seed are 

sown; one tray of the rootstock seed 

and another tray of the scion seed. At 

approximately one month after sowing, 

the young seedlings are grafted. Both 

seedlings are cut at the hypocotyl, and 

the scion shoot is spliced onto the 



TRADITION 

At HELM, our values have a tradition of trust and partnership. 

Blending your demands with our innovations, we create crop protection with 

greater ‘grower’ value for optimized production, performance and profits. 

HELM. Delivering Solutions that Cultivate Growth. 

QUALITY • PERFORMANCE • RELIABILITY • VALUE • INDEPENDENCE 

Always read and follow label directions. HELM® is a trademark of HELM AG. ©2019 HELM Agro US, Inc. 



19

Production of splice-grafted tomato plants for our field trials. 

Step 1 

Step 2 

Step 3 


rootstock stump. The method we used 

is a commonly used splice-graft with 

small, soft, silicone clips to hold the 

scion and rootstock together during 

healing. Grafted transplants cost more 

than non-grafted transplants due to 

increased seed costs and the labor 

required to do the grafting. Thus far, 

grafted tomato plants are only available 

from a few sources in California, and 

we won’t know what the cost for grafted 

tomato transplants will be until they are 

being produced in larger volumes here. 

The use of fully- or semi-automated 

grafting robots is emerging as a way 

to reduce labor costs and improve the 

survival rate of grafted plants. This 

of course requires significant capital 

investment. About 20 seed companies 

offer tomato rootstock seeds (see list 

at http://www.vegetablegrafting.org/ 

tomato-rootstock-table/). However, for 

a nursery facility or grower considering 

doing their own grafting, building a 

Step 1. Scion and rootstock 

shoots, with stems of about the 

same diameter, are cut at 45° 

angles. 

Step 2. A soft silicone plastic clip 

is placed on the rootstock stump. 

The scion cutting is placed into 

the clip, aligning the angled cuts. 

Grafting success rates are highest 

when the diameters of the two 

stems to be joined are similar. 

Step 3. The plants are then 

transferred to a healing chamber 

with high humidity, low light 

and moderate temperatures for 

about a week to allow the graft 

union to heal. The plants are then 

transferred back to finish growing 

in the greenhouse. 

healing chamber may be a hurdle. There 

is research underway by others to look 

at conducting the one-week healing 

period inside the greenhouse. For more 

information on the logistics of grafting 

on a commercial scale, please see the 

Vegetable Grafting Manual, the link 

for which is provided at the end of this 

article under “More information”. 

Field Trials in the Northern San 

Joaquin Valley 

The trials were conducted in commercial 

production fields at six locations 

over three years from 2016 to 2018; 

three locations in San Joaquin County 

and another three locations in Merced 

County. The treatments included all 

combinations of the scions and rootstocks 

listed in Table 2 (See page 22). 

The plots were laid out in a randomized 

complete-block design with four 

replicate blocks, each block measuring 

approximately 80 by 40 feet. The 

cooperating growers managed the 

experimental plots similarly to the 

rest of their field with respect to pest 

control, fertilization, irrigation, and 

other management practices. Plants 

were mechanically transplanted into 

prepared beds at a 4- to 5-inch depth 

per normal practice; the graft union 

ended up well below the soil surface. 

In staked or trellised production 

systems in other regions, the graft 

union is typically kept above ground to 

realize the full benefit of the rootstock 

pathogen resistance. With graft union 

buried below the soil surface, soilborne 

pathogens may attack the scion crown 

tissues or adventitious roots arising 

from the scion. Due to the lack of 

significant pathogen pressure in our 

fields, we believe this was not an issue 

for these trials. 

In our trials, grafted plants were more 

vigorous and had better foliage cover of 

fruit at harvest than non-grafted plants 

of the same cultivar. We also measured 

NDVI (Normalized Difference 

Vegetation Index, a measure of the 

“greenness” or how much of the bed is 

covered with actively photosynthesizing 

foliage) and it was also slightly higher 

in grafted plots. Averaged across all 

six trials, marketable yield increased 

only 12 percent when grafting with 

‘Maxifort’ or ‘DRO138TX’ as the 

rootstock, although the results were 

better in some individual trials. At the 

San Joaquin County sites, yields of 

non-grafted vines were similar to the 

statewide average yield and grafting 

increased yield significantly (25 to 40 

percent depending on the year). Some 

scion-rootstock combinations were as 

much as 68 percent higher than the 

non-grafted plants of the same scion 

(e.g. ‘QualiT-27’ on ‘Maxifort’ at the San 

Joaquin site in 2018). At the Merced 

sites, yields of non-grafted vines were 

well above-average and grafting was 

much less beneficial. Many published 

field trials indicate that the yield 

advantages of grafted plants are greatest 

under sub-optimal growing conditions. 

Field sites with heavy soilborne disease 

pressure, or abiotic stresses may be the 

best candidates to see improvements 

with grafting. 

Fruit Size and Quality 

Many published studies have found 

that grafted plants produce a higher 



Agenda 

FREE EVENT, PRIZES, 

EXHIBITORS & MORE 

7:00 AM 

7:30 AM 

8:00 AM 

8:30 AM 

9:00 AM 

9:30 AM 

10:00 AM 

PROFSSIONAL 

Join us at our upcoming Summer Trade Shows! 

Register at wcngg.com/events 

 

 

 

 

 

 

Registration 

Trade Show CE Credits: 15 Minutes; Other 

wORKSHOPS 

Pre- and post-Planting Nematode Management in 

Panel Discussion—Got Questions on Walnut and Almond 

Perennial Crops 

Varieties—Get Them Answered Here 

Caroline Eberlein, Postdoc, UC Riverside CE Credits: 30 Minutes; Other 

Cliff Beumel, Sierra Gold Nursery, Steve Rothenberg, Dave Wilson Nursery, and Tom Burchell 

Nursery, Speaker TBA 

Research Updates on Almond Insect Pests: Navel Orangeworm, 

Walnut Board 

Leaffooted Bug, and Ants 

Jennifer Williams, Assistant Marketing Director, Walnut Board 

Kris Tollerup, UCCE Area-wide IPM Advisor CE Credits: 30 Minutes; Other 

An IPM Approach to Controlling Soilborne Diseases 

New Technologies for Irrigation Management 

Phoebe Gordon, UCCE Farm Advisor, Madera 

CE Credits: 30 Minutes; Other 

Spencer Cooper, Senior Manager, Field Outreach and Education 

Break 


10:30 AM 

11:00 AM 

11:30 AM 

12:00 PM 

12:15 PM 

1:00 PM 

Research Updates on Walnut Insect Pests: Navel Orangeworm, 

Walnut Husk Fly, and Pacific Flatheaded Borer 

Jhalendra Rijal, UCCE Area IPM Advisor, Merced, San Joaquin, and Stanislaus Counties 


Spray Applications and Preharvest Intervals 

Marline Azevedo, Deputy Ag Commissioner, Stanislaus Ag Department CE Credits: 30 Minutes; L & R 

An Effective IPM Approach to Mite Control 

David Havilland, UCCE Farm Advisor, Kern County CE Credits: 30 Minutes; Other 

Lunch 

NOW—Benefits of Mating Disruption for Almonds and Walnuts 

Brad Higbee, Field Research and Development Manager for Trécé Inc. CE Credits: 30 Minutes Other 

Adjourn 

Are You Ready for FSMAs Produce Safety Rule Inspections? 

Priscilla Rodriguez, Director of Food Safety for WAPA 

Nutrition Management—Preharvest Preparation for 

Walnuts and Almonds 

Rich Kreps, CCA 

Exploring Organics—What You Need to Know 

Nate Siemens, Organic Nut Grower 

JCS Marketing will donate $1 per attendee* to the 

Turlock FFA Chapter for a student scholarship. 

*Growers, Applicators, PCAs, CCAs, and Processors. 

7:00 AM 

7:30 AM 

8:00 AM 

8:40 AM 

9:20 AM 

10:00 AM 

10:30 AM 

11:00 AM 

11:30 AM 

12:00 PM 

12:30 PM 

1:00 PM 

SEMINARS 

What Almond Growers Need to Know About 

the Sterile Insect Program 

Houston Wilson, UC Riverside Cooperative Extension Specialist 


Registration 


WORKSHOPS 

The Ins & Outs of The Sustainable 

Groundwater Management Act (SGMA) 

Aaron Fukuda, Tulare Irrigation District, General Manager 

Best Strategies for Controlling 

Root Health and Moisture 

Mites at Hull-Split 

Management for Pre-harvest 

Kris Tollerup, Kearney Agricultural Research 

Cooperative Extension Advisor, IPM 

Devin Clarke, Crop Manager, Tree Nuts, Yara North America 


Rich Kreps, CCA 

The Latest on Canker Diseases and 

New Management Practices 

Supplemental Pollination 

Themis Mohammad J Michailides Yaghmour Ph.D., Area Plant Orchard Pathologist Systems UC 

Elizabeth Fichtner, UC Farm Advisor Tulare County 

Advisor, Kearney Cooperative Agricultural Extension Research Kern Cooperative County 


Break 


The Best Management Practices and 

What the Almond Industry Needs 

Treatments for Hull Rot in Almonds 

to Know About The Food Safety 

Themis Mohammad J Michailides Yaghmour Ph.D., Area Plant Orchard Pathologist Systems UC 

Modernization Act (FSMA) 

Advisor, Kearney Cooperative Agricultural Extension Research Kern Cooperative County 

WAPA 


Understanding the Latest Laws and 

Regulations for Almond Pre-harvest 

Best Methods for Dust Control 

John Susoeff, Ag Standard Specialist Fresno County Ag 

California Almond Board 

Commissioners Office 

CE Credits: 30 Minutes; Laws & Regulations 

Lunch 

NOW-Benefits of Mating Disruption 

Brad Higbee, Field Research and Development Manager for Trécé Inc. 


Adjourn 

Alm nd Day 

JUNE 12, 2019 

 

Fresno Fairgrounds 

 

 

CE Units Offered 

4 

4 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Questions? Call us today at 

 

 

(559) 352-4456 or visit us online at 

 

 

www.wcngg.com | JCS Marketing 

 

 

PO Box 27772, Fresno, CA 93729 

 

 

 

 

 

 

JCS Marketing Inc 

@jcs_marketing 

@jcsmarketing 

Powered by: 

May/June 2019 www.progressivecrop.com 21


percentage of fruit in larger size classes 

than those produced by the nongrafted 

scion varieties. Averaged over 

all our trials, the differences in fruit 

size distribution between grafted and 

non-grafted were fairly small. In some 

trials, however, plants on vigorous 

rootstocks did have larger fruit. Some 

published studies provide measures of 

fruit quality, such as dissolved sugars, 

pH, total dissolved solids, vitamin C, 

lycopene, or even “taste-test” data. 

Those studies indicate that the quality 

of fruit from grafted plants seems to be 

slightly inferior to fruit from the nongrafted 

plants, though still commercially 

acceptable. Our field trials focused on 

yields, and we did not measure any 

fruit quality data. However, we did 

not notice any fruit defect problems in 

grafted vines. Also, in 2018 we did cut 

open both red and mature green fruit at 

harvest to make sure that there were no 

problems inside the fruit. 

Variability From Trial to Trial or 

Field to Field 

A study in Florida with determinant 

type cultivars has shown yield 

increases of 25 to 42 percent using 

certain rootstocks, but year-to-year 

variability also increased as compared 

to non-grafted plants. This variation 

underscores the importance of 

considering variable outcomes to 

determine the feasibility of grafted 

tomatoes here. Some fields will likely 

benefit more from grafting than others, 

and this may not always be predictable 

in advance. 

Economics 

Costs of field establishment are 

increased significantly with grafting. 

Material costs for transplanting (seed 

plus nursery costs) alone might be 

$2,000 per acre or higher or more 

than with conventional transplants. 

However, we don’t yet really know what 

the costs might be if this were adopted 

commercially in California, so our plant 

costs are based on small volume sales 

prices. If we assume a cost of $0.40 per 

grafted plant, then a yield increase of 

19 percent at a market price of $6.55 

per 25-pound box would pay for the 

increased plant cost. 

On-going and Future Work 

Scion Cultivars 

(Trial Years) 

‘Bobcat’ (2016) ‘DRO137TX’ (2016-18) 

‘Dixie Red’ (2016) ‘Maxifort’ (2016-18) 

*‘Galilea’ (2016) ‘Arnold’ (2018) 

‘HM 1794’ (2016-18) ‘Guardior’ (2018) 

‘Quali T 27’ (2017-18) ‘Estamino’ (2018) 

‘Quali T 47’ (2017-18) 

‘Quali T 99’ (2017-18) 

Other research projects looking 

at grafting tomatoes are being 

conducted in California. A United 

States Department of Agriculture 

(USDA)-funded project with 

processing tomatoes is underway with 

collaboration of Gene Miyao, UCCE 

Yolo, Solano and Sacramento counties, 

Zheng Wang, UCCE Stanislaus County 

and myself, in addition to proprietary 

research being conducted by the 

industry. Rootstocks for heirloom 

tomato production are being evaluated 

by Margaret Lloyd, small farms advisor 

with UCCE in Yolo, Solano and 

Sacramento counties. 

Acknowledgements 

The California Department of Pesticide 

Regulation provided partial funding 

for this project but does not necessarily 

agree with any opinions expressed, nor 

endorse any commercial product or 

trade name mentioned. In addition, 

this project was supported by the 

Specialty Crop Block Grant Program 

at the U.S. Department of Agriculture 

through Grant 14-SCBGP-CA-0006. 

The contents of this report are solely 

the responsibility of the authors and 

do not necessarily represent the official 

views of the USDA. We also thank 

our grower-cooperators (Live Oak 

Farms and Pacific Triple E), Growers 

Transplanting Inc. for producing grafted 

Rootstock Cultivars 

(Trial Years) 

Non-grafted Control 

Table 2. Scion and rootstock cultivars used in our field trials. 

*Note: Galilea is a roma/saladette type, while the other seven cultivars are all round types; all 

but Dixie Red were developed for the Western U.S. mature green production system. 

plants, and the following companies 

that supplied the seeds: Monsanto/De 

Ruiter Seeds, Gowan Seed Company, 

Harris Moran Seed Company, and 

Syngenta Vegetable Seeds. 

For More Information 

Additional information on our field 

trials: 

https://ucanr.edu/sites/veg_crop_sjc/ 

Grafted_tomatoes/ 

Detailed information on how to 

undertake vegetable grafting is available 

at: http://www.vegetablegrafting.org/ 

resources/grafting-manual/ 

List of tomato rootstocks including 

disease resistances and where to order 

seed: http://www.vegetablegrafting.org/ 

resources/rootstock-tables/solanaceousrootstock-table/ 





The best way to manage pathogens before they become an issue. 

TriClor is chloropicrin based and can be used as a standalone or as a compliment 

to Telone® depending on your orchard redevelopment needs. 

When targeting soil borne disease and nematodes, TriClor and Telone® 

can be applied in a single pass. This reduces application costs, promotes 

early root development, and improves soil health. For more information 

about TriClor or to schedule an application contact TriCal, Inc. 

TRICAL, INC. 

669-327-5076 

www.TriCal.com 

23

FORTIFIED 

THAT’S HOW ALMONDS FEEL WITH MOVENTO. ® 

Movento ® insecticide is the only foliar application with downward movement 

within the tree to protect roots by suppressing nematodes. With Movento, 

trees will show improved vigor and produce high yields year after year. 

For more information, contact your retailer or Bayer representative or visit www.Movento.us. 

© 2019 Bayer Group. Always read and follow label instructions. Bayer, the Bayer Cross, and Movento are registered trademarks of the Bayer Group. Not all products are registered for use in all states. For additional product 

information, call toll-free 1-866-99-BAYER (1-866-992-2937) or visit our website at www.CropScience.Bayer.us. Bayer CropScience LP, 800 North Lindbergh Boulevard, St. Louis, MO 63167. CR0319MOVENTB045S00R0 


ADVERTORIAL 

HOLD THE LINE 

AGAINST HUANGLONGBING. 

THE TIME HAS COME TO MEET ACP HEAD ON. 

HUANGLONGBING 

Huanglongbing (HLB) is the most devastating 

citrus disease worldwide and threatens all 

commercial citrus production. Since 2005, 

Florida has lost 72% of its citrus production. 1 

According to California Citrus Mutual, 

infected trees have been found in Southern 

California and quarantine areas are growing. 2 

The Asian citrus psyllid (ACP) feeds on new 

leaf growth and is a vector of the bacterium 

that causes HLB. Once a citrus tree is infected, 

the disease is fatal. At this time there is no 

known cure for the disease. Symptoms of the 

disease include yellowing leaves and bitter 

fruit followed by the death of the tree. 

Best management practices center around 

controlling ACP through use of insecticides 

and removing infected trees. 

ACP and Insect Management Options from Bayer 

Bayer has a proven portfolio of insecticides that provides 

the foundation for season-long ACP control and controls 

other important California citrus pests. The Bayer portfolio of 

insecticides encompasses multiple modes of action to limit 

insecticide resistance and is flexible relative to application timing 

and method to optimize crop quality and to help growers stay 

ahead of HLB. 

PEST 

ASIAN 

CITRUS 

PSYLLIDS 

 

CITRUS 

THRIPS 

RED 

SCALE 

BLOOM 

 

PETAL 

FALL 

 

POST- 

BLOOM 

 

FRUIT 

GROWTH 

 

WINTER 

MONTHS 

KATYDIDS 

 

CITRICOLA 

SCALE 

 

 

IRAC 

GROUP** 

GROUP 4 (D) 

GROUP 3 GROUP 4 (A) GROUP 23 GROUPS 

3 and 4 (A) 

*Suppression only. **Insecticide Resistance Action Committee's mode of action groups. 

How ACP Affects Citrus Plants 3 

The psyllid damages citrus 

directly by feeding on new 

leaf growth (fl ush). 

More importantly, the psyllid 

is a vector of the bacterium, 

Candidatus Liberibacter asiaticus 

(CLas), that causes HLB and 

transmits the bacteria into the 

phloem when it feeds on fl ush. 

HLB disease spreads from 

tree to tree when a bacteriacarrying 

psyllid fl ies to a 

healthy plant and transmits 

the bacteria as it feeds on 

the leaves and stems. 

The bacteria multiply in the 

tree’s phloem tissue, blocking 

the fl ow of nutrients through 

the plant. If not well managed, 

trees will eventually die within 

three to fi ve years. 

Effective control of Asian citrus 

psyllid reduces the chance 

that a citrus tree will become 

infected by the bacteria 

and helps ensure a healthy, 

productive tree. 

Visit www.CropScience.Bayer.us for more information. To stay informed on the latest Bayer 

products and solutions, visit www.CropScience.Bayer.us/email-alerts-and-updates. 

1 

USDA’s National Agricultural Statistics Service Florida Citrus Statistics (2015–2016 and 2017–2018 reports). 

2 

https://www.farmprogress.com/fruit/california-citrus-mutual-marks-four-decades-important-industry-watchdog-group 

3 

University of California Integrated Pest Management Program, http://ipm.ucanr.edu/PMG/PESTNOTES/pn74155.html 

© 2019 Bayer Group. Always read and follow label instructions. Bayer, the Bayer Cross, Admire, Baythroid, Leverage, Movento, and Sivanto are registered trademarks of the Bayer Group. 

Baythroid XL and Leverage 360 are Restricted Use Pesticides. Not all products are registered for use in all states. For additional product information, call toll-free 1-866-99-BAYER 

(1-866-992-2937) or visit our website at www.CropScience.Bayer.us. Bayer CropScience LP, 800 North Lindbergh Boulevard, St. Louis, MO 63167. CR0219MULTIPB597S00R0 



25

WALNUT HUSK FLY 

Management 

By EMILY J. SYMMES| Sacramento Valley Area IPM Advisor 

University of California Cooperative Extension and Statewide IPM Program 

Walnut husk fly poses particular 

challenges for developing 

a truly integrated pest 

management (IPM) program due to 

the nature of its life cycle (one generation 

per year with a long emergence 

period) and lack of natural 

enemies. As a result, best practices for 

management rely heavily on monitoring 

and insecticide treatments. Precise 

timing based on monitoring method 

and rotation of chemistries to minimize 

resistance risk are keys to successful 

long-term control of this pest. 

Susceptible Varieties 

Walnut husk fly (WHF) damage earlier 

in the season causes shriveled and 

darkened kernels, increased mold 

growth, and lower yields. Later season 

infestations result in little kernel 

damage, but may stain the shells 

and make husk removal difficult. All 

commercial English walnut cultivars 

are susceptible to WHF infestation, 

although they differ in their relative 

degrees of susceptibility and thus 

damage potential. In general, Hartley, 

Tulare, Franquette, Payne, and Serr 

are considered more susceptible, with 

Howard, Ashley, Chico, and Chandler 

exhibiting less susceptibility (in 

order as listed). However, even less 

susceptible varieties can be damaged 

by high populations of WHF. Black 

walnut is also a preferred host, 

therefore proximity to black walnut can 

significantly increase WHF pressure in 

commercial English walnut orchards. 

The varietal differences in susceptibility 

have been correlated to fruit 

characteristics including husk color, 

husk hardness, fruit size, trichome 

density, and plant volatile profiles, 

in addition to temporal factors (i.e., 

more severe earlier season damage 

may be more evident in earlier-leafing 

cultivars). Current research led by 

Dr. Steven Seybold (United States 

Department of Agriculture (USDA) 

Chemical Ecology Entomologist) 

is characterizing the plant volatile 

profiles associated with differences in 

varietal susceptibility, which may lead 

to improvements in monitoring and 

control products, as well as inform 

plant breeding approaches for genetic 

resistance or tolerance to WHF 

infestation. 

WHF Life Cycle 

The life cycle and basic biology of 

walnut husk fly is fairly well understood 

(Figure 1. See page 27) There is a 

single generation per year, with adult 

emergence historically beginning in 

early to mid-June and lasting through 

September in the Central Valley. In 

coastal areas, and recently some inland 

valley locations, emergence can be 

detected earlier, in mid- to late-May. 

Peak emergence is generally observed 

July through mid-August in most 

locations. Females must mate and 

develop eggs prior to the initiation of 

oviposition into the walnut husk, a 

period which averages approximately 

two weeks after emergence. Once 

eggs are laid, maggots emerge within 

approximately four to seven days, and 

feed on the husk for a typical period of 

three to five weeks. After this period, 

mature maggots drop to the ground and 

pupate in the soil. Most adults emerge 

the following year, but a portion of the 

population may remain in the soil as 

pupae for two or more years before 

emerging as adults. 

Extended Emergence Period 

The extended emergence period of 

the single generation of WHF, and 

significant differences in the timing of 

initial emergence, peak emergence, and 

end of the flight based on location, year, 

and other factors, have been the subject 

of much research. As opposed to some 

other key pests (e.g., codling moth), 

there is not yet a validated phenology 

or degree-day model available for 

growers and pest control advisors 

(PCA) to readily adopt to predict key 

WHF development and adult activity 

timings. Two recent publications out of 

University of California (UC) Berkeley 

(Emery and Mills 2019a, 2019b) 

investigated the effects of temperature 

and other environmental parameters 

on walnut husk fly development and 

timing. One study evaluated 18 years 

of historical trap catch data from 49 

walnut orchards spanning the Central 

Valley to determine which factors 

most influence emergence timing and 

thermal requirements for development 

(degree days to emergence), with 

the goal of developing a phenology 

model that can be used to predict 

initial and peak emergence. Some 

of the factors evaluated included 

latitude, walnut cultivar, orchard age, 

winter precipitation, winter chill, and 


Figure 1. Life cycle of walnut husk fly. 

Photo courtesy of University of California Statewide Integrated Pest Management Program 

degree-day accumulation. While 

this model requires refinement for 

adoption by orchard practitioners 

(growers and PCAs), it represents a 

great step forward in improving our 

understanding of WHF developmental 

requirements to aid in our IPM 

program development. 

Biological Control Agents 

Biological control agents for walnut 

husk fly in California walnuts are 

virtually non-existent. The pest in 

general appears to have few natural 

enemies. Some reports from the 

state of Washington indicate that a 

predatory mite and anthocorid bug 

species have been observed feeding 

on WHF eggs, and some spiders and 

ants may feed on larvae and adults. In 

addition, chickens and other birds are 

said to be among the natural enemies 

of WHF. However, any naturallyoccurring 

WHF biological control 

agents that may be found in walnut 

orchards are not known to provide 

any significant level of population 

reduction. Other mortality factors, 

particularly those that may impact 

the overwintering pupal stage in the 

soil (e.g., intentionally augmenting 

soil moisture, various cultivation 

practices, effects or augmentation 

of insect-parasitic nematodes or 

other microorganism populations, 

soil insecticide applications) have 

been explored to some degree with 

no specific recommendations or 

guidelines emerging as a result. 

WHF Management Guidelines 

In spite of some of these challenges 

for WHF management, guidelines 

regarding treatment timing and 

options are available, and when 

employed properly tend to provide 

adequate control of WHF in many 

situations (albeit with more insecticide 

intervention than may be desirable 

or sustainable in the long-term). 

Because WHF activity and population 

abundance can vary significantly 

from orchard to orchard (even those 

in very close proximity), site-specific 

monitoring is necessary to get the 

most effective results from insecticide 

applications. 

Monitoring 

Monitoring should begin earlier than 

the June 15 historical guideline (no 

later than June 1 in the Central Valley 

is the more recent recommendation). 

Some reports of late May catches in 

2016 further support the “earlier-isbetter” 

practice—there is little harm 

in counting zeroes for a few weeks. 

Yellow sticky card traps baited with 

ammonium carbonate lures should be 

hung high in the canopy (minimum 

2 per 10 acres) in dense foliage on the 

north side of trees and checked two 

to three times per week. Each orchard 

should be monitored individually for 

WHF activity to best determine if 

and when to treat. A summary article 

regarding the efficacy of available traps/ 

lures for WHF monitoring was published 

in 2014 (http://www.sacvalleyorchards. 

com/walnuts/insects-miteswalnuts/ 

walnut-husk-fly-trap-and-low-volumespray-study/). 

Treatment Timing 

Treatment timing can be based on one of 

three monitoring methods (the first two 

have typically been most effective). 

1. Detection of eggs in trapped females. 

This is a simple process that requires 

slightly more time than counting overall 

trap catches and can increase the efficacy 

of treatments by timing applications to 

specifically target female oviposition 

activity. Females can be distinguished 

from males by the shape of the abdomen 

(pointier in females) and color of the 

front leg (female leg is entirely yellow, 

male leg is black close to the body, 

(Photo 1. See page 28). After females are 

identified, gently squishing the female 

abdomen will squeeze out eggs if they 

are present (Photo 2. See page 28). 




27


Eggs resemble small grains of rice. 

Previous guidelines indicated that 

the treatment window is one week 

after egg detection. However, recent 

modifications suggest that treatments 

should be considered as soon as the 

first female with eggs are found because 

in practice there is often a lag time in 

getting the treatments out, and trap 

checks (even two to three checks per 

week) may not be frequent enough to 

represent initial egg development in the 

female population. Therefore, planning 

to treat as soon as possible after eggs 

are detected may be the best option to 

minimize infestation and damage. [Note 

that this is the preferred method for 

timing treatments unless using GF-120® 

alone; see below]. 

2. Overall trap catches. For low to 

moderate populations, consider 

treatment when a sharp increase 

occurs in trap counts. In high pressure 

orchards or if using GF-120® alone, 

treatment should be considered when 

any flies are detected rather than 

waiting for a sharp increase in catches. 

3. Stings on nuts. This is the least 

preferred method, as damage has 

already occurred. However, examining 

nuts for stings (Photo 3) can 

provide indication of efficacy of your 

management program when using one 

of the first two methods. If using this 

method to time treatments, consider 

treating when the first sting is observed 

using full cover neonicotinoid materials 

that have some ovicidal activity mixed 

with an adulticide. 

Continued monitoring throughout 

the season is crucial. Short-residual 

insecticides plus bait will generally 

kill WHF for seven to ten days. Target 

subsequent applications at two- to fourweek 

intervals based on the efficacy of 

the previous spray and trap catches. 

Clean traps the day after application 

and check three to four days later. If 

the number of flies drops to near zero, 

the spray was highly effective and a 

longer treatment interval may be used. 

If post-treatment catches increase or 

eggs are detected in trapped females, 

and the residual period of the previous 

treatment has elapsed, additional 

treatments may be required if harvest is 

more than three weeks away. 

There are several materials effective 

against WHF, both for conventional and 

organic orchards. All materials aside 

from GF-120® (which contains its own 

bait) should be applied with a bait (e.g., 

Nu-Lure®, molasses, etc.). However, 

very high population orchards with 

extensive previous damage may require 

full coverage sprays (no bait needed) to 

achieve adequate suppression. Keep in 

mind that rotation of chemistries (based 

on the Insecticide Resistance Action 

Committee (IRAC) mode of action 

classification) is critical to minimize 

resistance development for pests that 

are treated multiple times each season. 

Proper aphid management can also 

help limit movement of WHF within 

and between orchards by reducing 

honeydew accumulation (a food source 

for adult WHF). 

The UC IPM Pest Management 

Guidelines (ipm.ucanr.edu/PMG/ 

r881301211.html) lists insecticides, 

baits, and rates for WHF. A summary 

of efficacy data for selected materials 

(updated September 2016) are 

summarized at (www.sacvalleyorchards. 

com/walnuts/insects-mites-walnuts/ 

walnut-husk-fly-biology-monitoringand-spray-timing/). 

Referenced Articles 

Emery, S. A. and N. J. Mills. 2019a. 

Effects of temperature and other 

environmental factors on the postdiapause 

development of walnut husk 

fly, Rhagoletis completa (Diptera: 

Tephritidae). Physiological Entomology 

44: 33-42. 

Emery, S. A. and N. J. Mills. 2019b. 

Sources of variation in the adult flight of 

walnut husk fly (Diptera: Tephritidae): a 

phenology model for California walnut 

orchards. Environmental Entomology 

48: 234-244. 




Photo 1. Male (left) and female 

(right) walnut husk fly adults. 

Photo 2. Female walnut husk fly with 

eggs. 

Photo 3. Walnut husk fly sting. 

All photos courtesy of University of California 

Statewide Integrated Pest Management Program 


Enhanced Codling Moth Larval Control! 

Mating disruption product for conventional and organic California walnuts!! 

DECREASE DAMAGE 

40% Average Reduction Compared to Insecticide Alone * 

Available in 10, 20 and 

40 acre container sizes! 

MICRO-ENCAPSULATED 

SPRAYABLE! 

“ 

CIDETRAK DA MEC will provide a higher level 

of insecticide efficacy in killing hatched larval 

worms and protecting the walnut set that 

the grower currently sees and counts on by 

targeting the Codling Moth 1B, 2nd and 3rd 

flights, with the added benefit of decreasing 

damaged-nut sites for NOW to later infest. 

~ Dr. Douglas Light, USDA-ARS, Emeritus 

“ 

CIDETRAK ® DA MEC contains a novel, patented kairomone in a micro-encapsulated liquid formulation that influences the 

behavior of adult and larval Codling Moth, resulting in significant enhancement of the control of Codling Moth larvae when 

tank mixed with various insecticides. Additionally, Codling Moth adult control is significantly enhanced when mixed indirectly with 

airborne Codling Moth pheromone applied as a mating disruption treatment. 

• What it does: Disrupts oviposition. Changes larval behavior: 

Stops/delays locating walnut; stops/delays walnut entry and reduces damage. 

• How to use it: Simply tank mix with each insecticide application. 

• Longevity: More than 14 days following application. 

® 

ENHANCED CODLING MOTH CONTROL 

INCORPORATED 


Your Edge – And Ours – Is Knowledge. 



PLEASE: ALWAYS READ THE LABEL *Based on USDA analysis global data base. 

© 2019, Trécé Inc., Adair, OK USA • TRECE, PHEROCON and CIDETRAK are registered trademarks of Trece, Inc., Adair, OK USA • TRE-1489, 4/19 

29

ACP Control 

with Systemic Insecticides 

By CECILIA PARSONS | Associate Editor 

All photos courtesy of Citrus Disease and Pest Prevention Program. 

Last summer’s long hot spell may 

have contributed to the low 

trap counts of Asian Citrus Psyllid 

(ACP) in the Central Valley, but 

researchers remain adamant that 

keeping the numbers low is the best 

defense the state’s citrus belt has to 

keep out Huanglongbing (HLB). 

Meanwhile, detection of HLB infected 

trees in residential areas of the southern 

California counties of Orange, Los 

Angeles and San Bernardino, continues 

to expand. 

At the Kern County Spring Citrus 

meeting, Dr. Beth Grafton-Cardwell, 

director of the University of California 

(UC) Lindcove Research and Extension, 

said the threat to commercial citrus is 

real. 

Best Techniques for Reducing 

Spread of ACP 

Newly hatched ACP nymphs feeding 

on an infected tree quickly pick up the 

bacterium that causes the disease, and 

move on to infect other citrus trees. 

Removal of infected trees can help slow 

the spread, but detecting an HLBinfected 

tree can take time. Grafton- 

Cardwell said trees may initially only 

be infected on one quadrant and can be 

missed in a survey. It may take a year 

or two before the entire tree is infected, 

diagnosed and removed. 

Coordinated spray treatments by 

growers when warranted by trap 

finds, treating with insecticides that 

have an extended residual and being 

vigilant about cultural practices are the 

important steps in keeping the state’s 

citrus industry viable in the face of 

HLB. 

Movement of stem and leaf material, 

whether by harvest crews, hedging and 

topping equipment or on spray rigs can 

help prevent ACP from hitchhiking to 

new territory. 

Although ACP finds in the San 

Joaquin Valley have been spotty, 

Grafton-Cardwell said the coordinated 

treatments are a tremendous tool. 

“We are still in the eradicative mode 

here,” she stressed. 

Besides the San Joaquin Valley, 

growers in the desert and Coachella 

areas have also been keeping the lid 

on ACP populations with coordinated 

treatments. The Ventura coastal growing 

region and Riverside-San Bernardino 

citrus have more ACP pressure. A 

summary of 224 scouted sites in 

California from June 2017 to September 

2018 showed that at Ventura’s 47 sites, 

87 percent had ACP nymphs present. 

In the Riverside San Bernardino region 

of the 47 sites, 88 percent were infested. 

The 50 sites in the San Joaquin Valley 

had zero percent while Coachella’s 45 

sites had 8 percent. 

Samples 

The hot, dry weather in the desert and 

San Joaquin Valley growing areas help 

harden new flush depriving ACP as 

they need soft flush to lay eggs and as 

food for the nymphs. Growers or farm 

managers are asked to sample for ACP 

whenever young flush is present. The 

Tamarixia radiate male cisr. 

protocol is to sample one flush on ten 

trees on each border of a block. If ACP 

is found, the grower liaison should be 

notified to confirm a find and make 

plans for a coordinated treatment. 

Grafton-Cardwell said not to rely on 

empty yellow sticky traps to determine 

if ACP has invaded an orchard, as they 

prefer the new flush. 

Workshops on sampling for ACP will be 

held again this year, Grafton-Cardwell 

said. 

When growers are asked to participate 

in a coordinated treatment they 

should respond quickly and use the 

most effective product possible. These 

treatments are another reason why 

ACP levels have been lower in the San 

Joaquin Valley, plus growers are also 

using pyrethroids to control glassy 

winged sharpshooter. 

It is important to note that ACP tend 

to be found on the border trees of the 

blocks. For all insecticide applications, 

the borders should be treated before 

treating the interior. Research has 

shown, Grafton-Cardwell said, that 80 

percent of the ACP in a block are on the 

border trees. This does not hold true for 

young citrus. 

Residual Toxicity 

In addition to the coordinated 

treatments, the residual toxicity of 



Because protection 

requires great 

precision. 

Protect against harmful pests while helping safeguard beneficials. 

Sivanto ® Prime insecticide precisely targets key damaging pests like Asian citrus psyllid, 

citricola scale and aphids while helping safeguard beneficial insects. In doing so, Sivanto 

Prime preserves the overall health of your plants and, most importantly, protects your 

investment. Sivanto Prime: precision that preserves and protects. 

Learn more at SivantoInsecticide.com. 

© 2019 Bayer CropScience LP, 800 North Lindbergh Boulevard, St. Louis, MO 63167. Always read and follow label instructions. Bayer, the Bayer Cross, and 

Sivanto are registered trademarks of Bayer. Sivanto is not registered for use in all states. For additional product information, call toll-free 1-866-99-BAYER 

(1-866-992-2937) or visit our website at www.CropScience.Bayer.us. 



31

“ 

In southern California a total 

of 1,127 HLB positive trees 

have been removed. Last 

year at this time the number 

was 501 trees. This shows the 

disease is spreading... 

“ 

ACP tamarixia emergence holes. 


the pesticide used is important. Broad 

spectrum products that have a four plus 

week residual include Baythroid, Danitol, 

Actara, Admire, Leverage and Agri-flex. 

These products come with a warning 

that use may cause flare ups of scale or 

mites. Insecticides that are selective with 

a two to four week residual are Delegate, 

Exirel, Fujimite, Movento and Surround. 

Materials allowed in organic production 

have a residual of less than two weeks. 

They include Pyganic, Entrust, oils and 

Celite. These need to make direct contact 

to be effective and Grafton-Cardwell 

recommends two spray applications to 

increase chances of control. 

The longer the residual, the more effective 

the product will be in controlling ACP 

as eggs and nymphs are difficult to reach 

with a spray and adult ACP can fly in from 

untreated areas and not be affected. The 

goal is to keep ACP nymphs below 0.5 per 

flush. Admire and Platinum gave the best 

results. 

Biological Control 

Biological control, release of the parasite 

Tamarixia by California Department of 

Food and Agriculture (CDFA) throughout 

ACP infested residential sites in southern 

California, will continue, Grafton-Cardwell 

said. Releases in commercial citrus are not 

feasible due to use of spray applications for 

other insect pests and timing. 

Tamarixia populations build and move 

into citrus October-November, after fall 

flush. 

Control measures buy time for research 

and horticultural advances including 

early detection, using genetic engineering 

Navel Orangeworm Control! 

Mating disruption product for conventional and organic California tree nuts!! 

LESS DAMAGE – MORE PROFIT 

SEASON-LONG CONTROL THROUGH POST-HARVEST 

MATING DISRUPTION PRODUCT 

FOR NAVEL ORANGEWORM IN 

ALMONDS, PISTACHIOS & WALNUTS 

© 2019, Trécé Inc., Adair, OK USA • TRECE, PHEROCON and CIDETRAK are registered trademarks of Trece, Inc., Adair, OK USA • TRE-1491, 4/19 

Navel Orangeworm, 

Amyelois transitella 

• Up to 80% or more potential reduction in 

damage vs. current insecticide program 

• Season-long control through post-harvest 

• Easy application with ready-to-use 

carrier pack 

• No moving parts, no batteries, no 

gummy deposits 

• Removal not required 

INCORPORAT ED 


Your Edge – And Ours – Is Knowledge. 



® 


Bio control Foliar application Inspecting leaves 

to create a protected tree, and HLB 

resistance. Other strategies include 

higher density orchards planned for 

shorter tree life span, using interference 

RNAs to prevent ACP from picking up 

the disease and growing citrus under 

protective cover. 

Pest Control Districts 

Judy Zaninovich, Kern County ACP/ 

HLB grower liaison said residential 

finds of ACP were very high 2015-16. 

The county pest control district’s pilot 

program for residential citrus has 

taken out 2,000 trees near sites where 

ACP was detected. There are similar 

pilot programs in southern California 

counties. 

In southern California a total of 1,127 

HLB positive trees have been removed. 

Last year at this time the number 

was 501 trees. This shows the disease 

is spreading, but also that CDFA is 

improving their detection. 

Last year, Zaninovich said, the 

potential for a late summer spike in 

ACP populations was recognized and 

coordinated treatments were done. 

Knowing there is the potential for an 

upswing in ACP at that time, she said 

the plan would be repeated this year. 

She said there is also evidence that 

nighttime applications may be more 

effective. 

Irrigation Injection 

Best practices for application of 

systemic pesticide imidacloprid 

delivered via irrigation was discussed 

by both Sarge Green, director of 

Center for Irrigation Technology at 

Fresno State and Rick Leonard of 

Bayer. 


Control Pocket Gophers in Tree Fruit & Nuts 

- Effective Control 

- Preventative perimeter 

treatments intercept 

gophers before they 

enter the grove 

Photo by Wayne Lynch 

LEARN 

MORE 

25 lb. Pail — 60 / Pallet 

888-331-7900 • www.liphatech.com 

Reduce Tree Fruit Damage 



33

Lab Research Foliar application Tamarixia 


Distribution optimization is the key. 

The goal there is to make sure the 

water is in the right place at the right 

time. Green said the soil type controls 

movement of the material and pore size 

dictates movement. Matching water 

delivery to the soil type will improve 

efficacy of the material applied. Green 

noted that regular maintenance and 

auditing of the water delivery system is 

important in micro and drip systems. 

® 

The Grower’s Advantage 

Since 1982 

Leonard supplied some of the basics for 

efficient use of imidacloprid delivered 

via irrigation. Admire systemic can be 

tank mixed with fertilizer, but needs 

agitation. In a 12 hour set, the product 

should be injected in a one to two 

hours period after the first three to 

four hours of the set to achieve the best 

distribution. 

It will take two to three weeks for the 

material to move up from the roots into 

the trees. The cooler the weather during 

that time, the longer it will take to move 

throughout the tree. The best strategy of 

use is to target the fall flush. 

Ventura coastal area growers have a 

more difficult time achieving success 

with this systemic application, Leonard 

said, due to the high clay and organic 

matter soils. If the material only reaches 

the sub lethal levels for ACP, it invites 

resistance. 




ORGANIC 

Contains Auxiliary Soil & Plant Substances 

Herbicide EC 

Blossom Protect 

Bactericide 

DART® 

Fungicide 

Effective Plant Nutrients 

and Biopesticides 

® 

® 

Now EPA Approved! 

California Registration Pending 

ORGANIC 

Plant Nutrients & Adjuvants 

Botector ® 

Biofungicide 

Call or visit us today at (800) 876-2767 or www.westbridge.com 

® 


MAY/JUNE 2019 

VINEYARD REVIEW 

In This Issue 

36 

Grapevine Heat Stress and Sunburn 

Management 

42 

Grapevine Trunk Diseases: Current 

Management Strategies 

48 Pierce’s Disease and Glassy-winged 

Sharpshooter: Still a Threat to California 

Viticulture 



35

Grapevine 

Heat Stress 

and Sunburn 

Management 

By GEORGE ZHUANG | UCCE Fresno County 

Heat waves with extreme daily 

temperatures are becoming 

more and more common in the 

San Joaquin Valley (SJV) during the 

middle of growing season, e.g., July 

and August. In 2017, grape growers in 

the SJV experienced two to three weeks 

with maximum daily temperature ≥ 

110 °F. Sunburn with the associated 

severe water stress have resulted in 

significant yield loss and poor berry 

quality at harvest. Berry sugar, organic 

acids, anthocyanins, and phenolics 


all can be impacted by extreme daily 

temperatures. Sugar accumulation can 

be significantly affected since the leaf 

photosynthetic rate starts to decrease 

when the canopy temperature passes 30 

°C. Under high berry temperature (≥ 

30 °C), the degradation of organic acids 

start to accelerate as well as anthocyanins 

and phenolics. 

Water Stress 

When the heat wave occurs, it usually 

also causes grapevine water stress due to 

the need of evaporative cooling in order 

to lower the canopy temperature. High 

daily temperature coupled with severe 

water stress will eventually reduce the 

berry size and ultimately make the 

berry shrivel and raisin (Figure 1. See 

page 38). Several vineyard practices can 

be adopted by growers to alleviate the 

potential damage from the heat wave 

and reduce the yield loss as well as the 

degradation of berry composition: 




37


1 

1) Row orientation 

2) Trellis selection 

3) Variety selection 

4) Canopy management 

5) Irrigation scheduling 

6) Canopy shading 

7) Canopy cooling 

Row Orientation 

The optimum row orientation in the 

SJV is southwest to northeast with 

approximately 45° angle to have the 

equal sunlight exposure on both sides 

of the canopy. The traditional row 

orientation of raisin vineyard in the SJV 

of east to west is still good to minimize 

the direct light exposure on fruit-zone. 

North to south row orientation should 

be avoided for sunburn susceptible 

varieties, e.g., Muscat of Alexandria and 

Chardonnay. 

2 

Trellis Selection 

Trellis selection is as important as row 

orientation. Vertical shoot positioning 

trellis is usually not suitable in the SJV 

due to the excessive light exposure on 

fruit-zone. Two-wire vertical trellis, 

or “California Sprawl”, is the most 

common and yet suitable for the SJV. 

Any trellis with a sprawling system is 

preferred under the hot climate. 

3 

Figure 1. Berry shrivel, raisining, and sunburn of Syrah during the heat wave. 

All photos courtesy of George Zhuang. 

Varieties 

Variety evaluation has been on-going in 

University of California (UC) Kearney 

REC for a couple of years and the initial 

data has confirmed that certain varieties 

from southern Mediterranean regions 

can tolerate the heat and produce 

the decent yield and berry composition. 

Some varieties, e.g., Fiano, are under 

commercial test to further prove their 

suitability under the SJV’s hot climate. 

However, the adoption of alternative 

varieties might largely depend on marketing 

and consumers’ acceptance. 



SIGNS OF A POWDERY 

MILDEW PROBLEM? 

YOU’VE ALREADY 

WAITED TOO LONG. 

Stop Powdery Mildew before it starts with the 

advanced science of PROLIVO® 300SC fungicide. 

Early control is critical to prevent a Powdery Mildew epidemic. Used as 

a preventative treatment, PROLIVO® 300SC inhibits the disease before it 

can become a problem. Its effective chemistry can even protect untreated 

plant surfaces through redistribution on the leaf surface and vapor activity. 

In a disease management program, add FERVENT® 475SC fungicide as a 

partner for rotation with PROLIVO for Powdery Mildew control and Botrytis 

suppression to yield healthy fruit and a healthy harvest. 

KENJA® 

® 

PROLIVO AND FERVENT FUNGICIDES 

ARE SOLD EXCLUSIVELY THROUGH 

HELENA AGRI-ENTERPRISES AND 

TENKOZ MEMBER COMPANIES. 

Always read and follow label directions. Check with your retailer to confirm PROLIVO and FERVENT are registered for 

use in your state. PROLIVO and FERVENT are inventions and registered trademarks of Ishihara Sangyo Kaisha, Ltd., 

and manufactured and developed by ISK Biosciences Corporation. © 2019 Summit Agro USA, LLC. All rights reserved 



39


4 

Canopy Management 

Canopy management, e.g., shoot 

thinning and leafing, is applied to 

provide enough light exposure and 

air circulation on fruit-zone without 

exposing the clusters to too much direct 

sunlight. Hand or mechanical leafing 

(Figure 2) can be applied only on the 

“morning” side of the canopy to avoid 

the afternoon sunlight exposure on 

fruit-zone. 

5 

Irrigation Management 

Irrigation management might be the 

most critical and powerful tool for 

growers and the appropriate irrigation 

scheduling can be applied to avoid 

excessive heat damage/water stress as 

well as berry sunburn. Severe deficit 

irrigation should be avoided before the 

heat wave occurs to make sure vines 

have no or minimal water stress under 

the extreme daily temperature. Soil 

moisture sensor, pressure chamber, or 

basically by feel and appearance can 

help growers to assess soil moisture and 

vine water status, or growers can simply 

follow the grape evapotranspiration 

(ET) report (https://ucanr.edu/ 

sites/viticulture-fresno/Irrigation_ 

Scheduling/) to decide the amount 

of irrigation per week to avoid severe 

grapevine water stress during the heat 

wave. 

6 

Canopy Shading 

Canopy shading including shade cloth 

(Figure 3) and sun protectant, e.g., 

Kaolin and CaCO3 (Figure 4), can 

be used to shade the canopy and fruit 

to avoid excessive light exposure and 

sunburn. Cost and timing might be the 

most important factors when growers 

decide to use shade cloth and sun 

protectant. Generally, the optimum 

timing to apply canopy shading is after 

berry set or several days before the heat 

wave. 

7 

Canopy Cooling 

Canopy cooling can also be applied by 

in-canopy misting. Studies in Australia 

have found by in-canopy misting it 

can cool canopy and clusters by several 

degrees, and ultimately improve yield 

and berry composition during the heat 

wave (https://www.wineaustralia.com/ 

research/search/completed-projects/ 

ua-1502). 

Integrated Approach 

Finally, it might require an integrated 

approach by using more than one of the 

mentioned strategies to maximize the 

production and berry quality during 

the heat wave. Growers should consult 

local farm advisors and conduct the 

small trials to evaluate the effectiveness 

of different approaches under the local 

condition. 

Figure 2. Mechanical leafing at 

“morning” side of the canopy during 

bloom. 




Figure 3. Shade cloth on fruit-zone at “afternoon” side 

of the canopy. 

Figure 4. Sun protectant of CaCO3 foliar spray during 

veraison. 


Helping Farmers Grow 

Naturally 

Since 1974 

Helping Farmers Grow NATURALLY Since 1974 

www.newerafarmservice.com 

Organic Products & Services 

• Compost 

• Custom Blends 

• Vitazyme TM 

• Gypsum 

• Limestone 

• Root Stimulants 

• Liquid Fish Fertilizers 

• Mycorrhizae Fungi 

• Leaf Test 

• Acadiam TM Seaweed Extract 

• Liquid Compost 

• Liquid R/S 

• Foliar Nutrients 

• Liquid Potassium 

• Humic Acid 

• Yucca Saponin Extract 

• Soil Test 

Certified Crop Advisors on Staff 

Contact Us Today! 

Doug Graham Certified Crop Advisor License #329563 

Tel 559-686-3833 

doug@newerafarmservice.com 

2904 East Oakdale Ave. Tulare, CA 93274 



41

Grapevine 

Trunk Diseases: 

Current Management Strategies 

By AKIF ESKALEN | Department of Plant Pathology-UC Davis 

and JOSÉ RAMÓN ÚRBEZ-TORRES | Agriculture and Agri-Food Canada 

Background 

Grapevine trunk diseases (GTD) are currently 

considered one of the most important 

challenges for viticulture worldwide. These 

destructive diseases are caused by a broad range of 

wood-colonizing fungal pathogens, which primarily 

infect grapevines through pruning wounds. In 

most occasions, a single vine can be infected by 

more than one of these pathogens. The economic 

impact of GTD can be significant in both 

young and mature vineyards. Characteristic 

symptoms include poor vigor, distorted 

leaves and shoots, shoot and tendril dieback 

and berry specks caused by fungal 

toxins produced by some of these pathogens. 

Perennial cankers produced by 

canker-causing fungi on grapevine cause 

spur, cordon and trunk dieback and the 

eventual death of the entire vine. 


Epidemiology 

Most of the fungal pathogens responsible 

for GTD produce overwintering fruiting 

structures containing the spores of the 

fungus. When environmental conditions 

are favorable, these fruiting bodies release 

the spores into the environment. Spores 

will land on susceptible pruning wounds and 

will initiate infection completing their life cycle. In 

California, research suggests that the majority of GTD 

spores are released during winter (December to February) 

following primarily though not always precipitation events. 

GTD fungal pathogens have a broad host range and in 

California are known to cause dieback in many different 

native or introduced tree species and also in other woody 

perennial crops, including tree fruits and nut trees. Therefore, the 

source of GTD inoculum (spores) can come into a vineyard from 

multiple sources. 


REGISTERED MATERIAL 

For Use In 

Organic Agriculture 

Washington State Dept. of Agriculture 



43


Figure 1 

A B C D 

Figure 1. Leaf (tiger stripes) (A), fruit (black measles) (B) and vascular (C) symptoms caused by esca disease 

complex. Esca (black measles) and petri disease are primarily caused by the vascular pathogens Phaeomoniella 

chlamydospora and Phaeoacremonium minimum, which are also involved in Petri disease in young plants (D). 

Figure 2. 

In mature 

plants, several 

basidiomycetes 

fungi (primarily 

in the genera 

Fomitiporia, 

Fomitiporella, 

Inocutis, 

Inonotus, and 

Phellinus) play 

also a role in 

disease and 

symptoms 

development. 

Characteristic 

symptoms are 

a white rot in 

the vascular 

system in many 

occasions 

observed as 

a yellowishspongy 

wood. 

Figure 2 

Treat pruning wounds on mother plants to prevent new infections 

Management 

in Nursery: 

Sanitation in mother fields and during the entire nursery process 

Disinfect grafting machines regularly 

Reduction of the cutting hydration period 

Apply control products (chemicals or biologicals) as a dip after 

grafting, before storage and/or before dispatch 

Hot water treatment of dormant nursery plants prior to dispatch 



WE WILL PUMP YoU UP 

with our mycorrhizal products 

POWER UP YOUR PLANTS 

Ask us about our other soil care products. 

• BACTERIAL Inoculants • Soil Products • Biological Food Products 

• Micro Nutrients • Foliar Nutrients 

Contact Us Today at 1-800-279-9567 

callnrg.com 

May/June 2019 www.progressivecrop.com 

45


Management 

Figure 3 

A 

B 

C 

in VINEYARDS: 

Use the cleanest plant material available 

when establishing new vineyards. 

Minimize stress conditions on young 

vines after planting. 

In California, delayed pruning has 

been shown to minimize infection of 

pruning wounds as wounds are past the 

high disease pressure period of winter 

months 

Figure 3. Botryosphaeria dieback, commonly known in California as ‘Bot 

canker’ is caused by multiple species in the Botryosphaeriaceae family. 

Characteristic symptoms are the lack of spring growth of infected areas, 

including cordons (A) or spurs (B). Cross sections of infected parts 

reveal a wedge-shape canker (C). The GTD disease known as Phomopsis 

dieback and primarily caused by the fungus Phomopsis viticola shows 

very similar symptoms as Botryosphaeria dieback. 

In vertical shoot position (VSP) 

systems, double pruning has shown to 

facilitate late pruning of large acreage 

vineyards and thus, reduce infection. 

Prune dead shoots, spurs and cordons 

below the symptomatic tissue (at least 

a few inches past the last symptomatic 

wood). 

Make a clean and smooth pruning cut 

to speed up the callusing process at the 

pruning wound. 

Sanitation is very important in 

the vineyard. Remove pruned and 

infected plant materials to prevent the 

development and increase of GTD 

fungi overwintering structures in the 

vineyard. 

A 

Figure 4 

Figure 4. 

Symptoms of 

Eutypa dieback, 

caused by the 

fungal pathogen 

Eutypa lata and 

several other 

Diatrypaceae 

species, are 

characterized 

by distorted and 

chlorotic leaves and 

short internodes 

(A) and by wedgeshape 

cankers (B). 

B 

Protection of pruning wounds with 

effective registered chemicals and/or 

biological control agents is the most 

effective way to prevent new infections 

from airborne spores of GTD fungal 

pathogens. More than one application 

may be necessary to protect the pruning 

wound during its susceptible time 

period. 

Remedial surgery, where visible infected 

parts of the vine (spurs, cordons and/or 

trunk) are removed, can be an effective 

strategy to eradicate the pathogen from 

the vine (primarily when cuts are done 

lower down on the trunk about 20 to 30 

cm above ground) and thus, prolong the 

lifespan of vineyards. 

Free Access Literature: 

Gramaje, D., Úrbez-Torres, J. R., and Sosnowski, M. R. 2018. 

Managing grapevine trunk diseases with respect to etiology 

and epidemiology: current strategies and future prospects. 

Plant Disease 102:12-39. 

https://doi.org/10.1094/PDIS-04-17-0512-FE 

https://ucanr.edu/sites/eskalenlab/ 





Science-Driven Nutrition SM 

Do you know if your 

foliar nutrients are getting in? 

the form of foliar nutrients do matter! 

The 5 R’s of foliar nutrition are - apply the Right nutrients, 

in Right form, at the Right time, in the Right mix and in the 

Right place. Applying effective nutrients based on a “Science 

Driven” approach that DO penetrate leaf tissue ensures 

your crop is getting the nutrients it needs at the right time. 

The form of foliar nutrients DO matter. Many foliar nutrient 

formulations are built on large chain molecules or unreacted 

oxides or carbonates that are not in-solution. These types of foliar 

nutrients and others have limited uptake on most leaf surfaces. 

Agro-K has three main foliar lines – one based on phosphite 

(Sysstem ® ) another based on dextrose/lactose (Dextro-Lac ® ) 

and a third for organic growers (CLEAN ). They are true 100% 

nutrient solutions based on low pH small molecular formulations 

that penetrate leaf tissue rapidly and completely. 

Rapid and complete uptake of foliar applied nutrients 

gives growers the ability to effectively meet “peak nutrient 

demand” timing. Whether you’re applying zinc for rapid leafout 

to maximize leaf size, or magnesium and iron to ensure 

maximum chlorophyll development or potassium for fruit 

bulking, if nutrients do not go in quickly and fully then your 

foliar dollars are less effective and yield and quality suffers. 

Make sure you know how well your foliar nutrients penetrate. 

Ask for SAP analysis comparisons. 

The chart shows three Agro-K zinc formulations, Sysstem-ZN, 

Zinc Dextro-Lac and CLEAN Zinc were applied to Viognier 

grapes on August 8th, along with a commonly available 

competing zinc amino acid product. Leaves were pulled prior to 

application and eight days after treatment. SAP analysis, which 

measures only the free-nutrients available within the leave sap, 

100 

75 

50 

25 

0 

Viognier Wine Grapes 

Zinc levels (ppm) via SAP Analysis 

4 5 4 3 

5 5 

Pre-treatment 

n UTC n Sysstem ZN n Zinc DL n Clean Zinc n Competing Zinc Amino Acid 

showed that zinc levels prior to zinc applications were the same 

for all treatments in this fully replicated trial. SAP analysis eight 

days later shows all three Agro-K foliar products were far more 

effective than the competing amino acid product in delivering 

zinc into the leaf tissue where it matters. 

This year make sure you know the efficacy of your foliar 

fertilizers before you spray! Talk to an Agro-K representative 

or your authorized Agro-K distributor and/or PCA for more 

information on foliar nutrients that truly WORK!. Call 800-328- 

2418, visit www.agro-k.com, or email info@agro-k.com. 

AGRO-K CORpORAtiOn 

8030 Main Street, NE • Minneapolis, MN 55432 

800-328-2418 • www.agro-k.com 


96 

83 

68 

8 Days After Treatment 


© 2019 Agro-K Corporation. 

49 

47

Pierce’s Disease and 

Glassy-winged Sharpshooter: 

Still a Threat to California Viticulture 

By STEPHEN VASQUEZ | Technical Viticulturist, Sun-Maid Growers 

First known as Anaheim grapevine 

disease or California vine 

disease, Pierce’s disease (PD) has 

impacted California’s grape production 

since the late 1880’s. Grape 

growers had been losing vineyards 

to an unidentifiable disease, which 

prompted the US Government to hire 

Newton B. Pierce, the first United States 

Department of Agriculture (USDA) 

plant pathologist and namesake of the 

disease. Pierce had spent considerable 

time walking vineyards in Los Angeles, 

San Bernardino and Orange Counties 

where Muscat of Alexandria used for 

raisins and Mission and other wine 

grape varieties were dying at alarming 

rates (2). At the time, approximately 

25,000 acres had been infected and or 

lost to an unknown “malady”. Pierce 

also spent time traveling to France, Italy 

and other Mediterranean grape growing 

regions studying plant disease symptom 

expression and declining grapevines 

to compare with those found in California. 

After researching all aspects 

of California viticulture production, 

including pests, diseases and associated 

symptoms, Pierce could never correctly 

identify the cause of California vine disease. 

For many years, a plant virus was 

thought to be the culprit of PD. It wasn’t 

until the mid-1970’s when University 

of California (UC) researchers isolated 

a bacterium from diseased vines. Once 

isolated, the bacteria were reintroduced 

to healthy grapevine plants that developed 

Pierce’s disease symptoms within 

two to four months (1). The bacterium 

is known to move from vine to vine 

with the help of insect vectors representing 

the sharpshooter (Cicadellidae) 

and spittlebug (Cercopidae) families. 

Infected insects ease of movement into 

a vineyard can be devastating in a few 

seasons when a PD susceptible grape 

variety is planted. 

Although Pierce’s disease outbreaks 

occurred in California vineyards from 

time to time since being ID’d it was not 

a primary issue for the grape industry. 

Major raisin, table and wine grape 

growing regions had moved north 

into the San Joaquin and Sacramento 

Valleys and the central and north 

coast. The mild, southern California 

weather was the perfect environment 

for the pathogen, vectors and disease 

development. In contrast, the 

seasonality of the interior valleys and 

coastal grape growing regions seemed 

to result in a lower PD incidence year 

to year. However, there were PD “hot 

spots” located near riparian areas 

(i.e. Napa and Kings Rivers) or alfalfa 

planting that experienced significant 

vine deaths. Those hot spots were costly 

to individual farming operations but 

was not a concern for the industry. 

That changed when the disease/vector 

dynamics shifted. 

In 1999, the nonnative PD vector, 

glassy-winged sharpshooter (GWSS), 

arrived in Temecula Valley. At that time 

a once thriving southern California 

wine industry was experiencing rapid 

vine death. GWSS turned out to be an 

effective vector and superior flyer when 

compared to native sharpshooters. 

Additionally, vineyards planted 

next to citrus proved to be a deadly 

combination. GWSS used citrus groves 

to feed, breed and for protection from 

potential predators from late fall to early 

spring. California grape growers were 

concerned about their future as they 

watched Temecula Valley vineyards 

die. As GWSS spread to other parts of 

California, PD became a much greater 

concern and problem. According to K.P. 

Tumber et. al (3) California growers are 


paying $56+ million in lost production 

and vine replacement annually. 

Pierce’s Disease: Cause, 

Symptoms and Management 

Cause of Pierce’s Disease 

A gram-negative bacterium was found 

to be the causal organism of Pierce’s 

Disease in 1975 (1). Prior to Xylella 

fastidiosa being identified, it was 

thought that a virus was responsible 

for the demise of southern California 

vineyards. Newton B. Pierce, the 

diseases namesake, began researching 

the cause in the late 1880’s but never 

properly identified it as a bacterium. 

Living in the xylem of grapevines, 

X. fastidiosa blocks the movement of 

water and nutrients throughout the 

plant. Once infected, the bacterium 

moves systemically from the point 

of infection to other parts of the 

plant. Early season symptoms can be 

confused with nutrient deficiencies 

(i.e. Zinc), displaying interveinal leaf 

chlorosis and stunted growth. Late 

season symptoms have a scorched 

foliage appearance resulting from 

the plants inability to move water 

through the xylem vessels. Young 

vines are more susceptible than older 

vines to infection and may die by the 

end of the season, while older plants 

may display symptoms over several 

seasons. However, when bacteria 

populations increase to a level that 

restricts significant sap movement, 

foliage and fruit will dehydrate and die. 

Geographical location, time of year 

and variety (Table 1. See page 50.) will 

determine how severe the symptoms 

Photo courtesy of University of CA. 

become. As temperatures increase, 

fruit will shrivel, and green shoots 

mature poorly and never cure prior to 

winter. At this point, financial losses are 

expected to impact vineyard viability. 

Pierce’s Disease Symptoms 

• Springtime symptoms consist of 

grapevine leaves displaying interveinal 

chlorosis 

• Late-summer or fall symptoms 

consist of grapevine leaves displaying 

concentric rings of drying from the 

leaf margin towards the center. Leaf 

margins of red or black grape varieties 

turn red and then brown 

• Leaves that have turned brown 

will detach, leaving only the petioles 

attached to canes 

• A unique disease symptom is the 

irregular, patchy bark maturity, leaving 

half the shoot brown and half green, 

displayed as islands of green and 

mature brown coloration 

• Berries on clusters will shrivel and/ 

or raisin 

Pierce’s disease symptoms can often be 


DON’T 

FALL FOR 

THEIR 

BULL. 

Buck the rest. Get Acadian ® . 

Talk is cheap. Other products claim to be as 

effective as Acadian ® but lack the research or 

in-field trials to prove it. Ask for the ingredients. 

Ask for the research. Better yet – Ask for Acadian ® … 

100% Ascophyllum nodosom. Get growing. Potency matters. Get growing. 

Acadian Plant Health is a division of Acadian Seaplants Limited, 

Acadian ® is a registered trademark of Acadian Seaplants Limited. 

acadian-usa.com 

Do Not Print 

May/June 2019 www.progressivecrop.com 

McDaniels Marketing • Client: Acadian• “2019 Acadian Bloom Ads” Print Ad • Ad Size: Half 

49

Table 1. Variety Susceptibility to X. fastidiosa** 

Highly susceptible Moderately susceptible PD resistant* 

• Chardonnay 

• Redglobe 

• Fiesta 

• Riesling 

• Chenin blanc 

• Cabernet Sauvignon 

• Ruby Cabernet 

• Muscat of Alexandria 

• Thompson Seedless 

• 07355-075 (50% Petite Sirah, 25 % Cabernet Sauvignon) 

• 09331-047 (50 % Zinfandel, 25 % Petite Sirah, 12.5 % 

Cabernet Sauvignon) 

• 09356-235 (50 % Sylvaner, 12.5 % Cabernet Sauvignon, 

12.5 % Carignane, 12.5 % Chardonnay) 

• 09314-102 (62.5 % Cabernet Sauvignon, 12.5 % 

Carignane, 12.5 % Chardonnay) 

• 09338-016 (62.5 % Cabernet Sauvignon, 12.5 % 

Chardonnay, 12.5 % Carignane) 

*UC Davis PD resistant wine grape varieties released in 2017 from Dr. A. Walker. 

** This is a partial list of susceptible PD varieties. Contact your local UC farm advisor for a complete list. 


confused with nutritional deficiencies, 

water related issues or other diseases. 

Multiple tissue samples should be 

shared with your pest control advisor 

(PCA), certified crop advisor (CCA), 

local farm advisor or university 

plant pathologist to correctly ID the 

symptoms. Once properly identified, 

a treatment plan can be devised to 

improve the vineyard’s health. 

Management 

Management strategies will depend 

on several factors. Insect vector, 

grape variety and location will have 

a significant impact on the success 

of managing PD. The four main 

insects that transmit PD are the bluegreen 

sharpshooter (Graphocephala 

atropunctata), native to coastal 

regions near riparian areas; the green 

sharpshooter (Draeculacephala 

minerva) and red-headed sharpshooter 

(Xyphon fulgida), native to interior 

valleys; and the glassy-winged 

sharpshooter (Homalodisca vitripennis), 

a non-native species to California 

and the most dominate vector of X. 

fastidiosa. It is important to monitor 

for sharpshooter insects if PD is to be 

managed. Sticky cards, sweep nets and 

visual observations of the vineyard 

and nearby properties will help in 

determining the population size and 

what control measures will be needed. 

Once identified, properly timed 

insecticide applications will help reduce 

the population. Vineyards located 

in areas where the PD bacterium is 

common, and temperatures are mild 

will be a challenge at keeping PD 

under control. In this case, identifying 

and managing the insect vector will 

be most important. If GWSS is the 

primary vector, insecticide applications 

will need to be timely to keep insects 

from moving into the vineyard. Citrus 

planted next to a vineyard will have to 

be sprayed as well to keep populations 

in check. Citrus should be visually 

checked for adults, nymphs and 

eggs. Visit the UC Pest Management 

Guidelines online for the most current 

insecticide management strategies (4,5). 

Locations that have a history of 

PD should not be planted to highly 

susceptible varieties like Chardonnay 

if possible. Finding a more tolerant PD 

variety will improve the health of the 

vineyard. Newly developed PD resistant 

varieties have been released from UC 

Davis. These numbered wine grape 

selections (Table 1.) can be planted 

in areas with a high incidence of PD 

and used for blending with traditional 

varieties. Unfortunately, there are not 

any PD resistant varieties for raisin or 

table grape production, but research is 

ongoing. 

Grapevines showing unusual foliar 

symptoms should be taken to your 

local UC Cooperative Extension 

office for identification. Plant tissue 

suspected of having Pierce’s disease 

can be sent to a diagnostics lab for 

positive identification using molecular 

tools. Leaf blades and petioles sampled 

from green portions of the cane in the 

late summer to early fall will give the 

best results. Vineyard insects should 

be caught and identified, too. A sweep 

net or sticky cards strategically placed 

in the vineyard can be used to survey 

insect populations in areas displaying 

foliar symptoms. Unique insects can 

be taken to your local Agriculture 

Commissioners office or the California 

Department of Food and Agriculture— 

Plant Health and Pest Prevention 

Services Division for identification. 

These first steps are paramount for 

developing a management plan. 

References 

1. Davis, MJ, Purcell, AH, Thomson, SH, 1977. 

Pierce’s Disease of Grapevines: Isolation of the 

Causal Bacterium. 

2. Pierce, NB. 1892. The California vine disease: 

a preliminary report of investigations. U.S Dep. 

Agric. Div. Veg. Pathol. Bull. 2, 222. 

3. Tumber K, Alston J, Fuller K. 2014. Pierce’s 

disease costs California $104 million per year. 

Calif Agr 68(1):20-29. https://doi.org/10.3733/ 

ca.v068n01p20 

4. UC Pest Management Guidelines – Pierce’s 

Disease: Xylella fastidiosa http://ipm.ucanr.edu/ 

PMG/r302101211.html 

5. UC Pest Management guidelines – 

Sharpshooters http://ipm.ucanr.edu/PMG/ 

r302301711.html 





Donʼt leave out this critical part of your nutrition program! 

THINK ZINC 

Zinc-Shotgun 

Zinc-Shotgun is a fertilizer that focuses on micronutrients to satisfy needs of customers seeking high zinc with manganese, 

iron and copper. The micronutrients are completely chelated with natural organic acids, amino acids, and carbohydrates 

that are readily bio-degradable and supply energy to the plant and soil microflora. 

For more information visit us online at wrtag.com/zinc-shotgun. 

Call (209) 720-8040 today to create a plan that’s best for you. 

We’re always here to help. 

Call: 1-844-WRT-LIFE 

Visit wrtag.com 



51

Worms, Thrips, Leafminers 

IN ONE PASS 

Only Radiant ® insecticide controls worms, thrips and leafminers. And 

university trials in Arizona and California show that Radiant outperforms other 

commonly-used vegetable insecticides on all three of these pests. As a member 

of the spinosyn class of chemistry (IRAC Group 5), Radiant controls pests like no 

other class of chemistry used in vegetables. The Re-Entry Interval is only 4 hours, 

and the Pre-Harvest Interval is 1 day for most crops. 

Visit us at corteva.us 


® 

Trademark of Dow AgroSciences, DuPont or Pioneer and their affiliated companies or 

respective owners. Always read and follow label directions.

PCC_MayJun_2019_e

Create successful ePaper yourself

Delete template?

Save as template?