Growing Grapes in WV - West Virginia Department of Agriculture

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are wormy at harvest time. It is adark-colored caterpillar. It passesthe winter in the pupal stage onfallen leaves. It emerges about thetime the grapes are blossoming.There are two broods. The first eatsthe stems and external portions ofthe young berries. The caterpillarsof the second brood live entirely inthe berries. They attack all cultivars.They are most injurious to thosecultivars that have compact clusterssince they tend to be protected insuch clusters and can feed readilyon more than one berry. Someof the injured grapes fall from theclusters; the rest must be discardedat harvest time. Spraying is the bestcontrol, but deep cultivation of theleaves in late fall or early springalso aids in control. For a few vines,it often pays to pick and destroy theberries infested by the spring broodand to rake and burn the leaves inthe fall to reduce the overwinteringpopulation. Populations may bemonitored with a commercially availablepheromone trap. Trichogramaminutum Riley is an egg parasitethat will provide some biologicalcontrol.The rose chafer (Macrodactylussubspinosus (Fabricius)) may bevery bad in some seasons, especiallywhere there is light, sandysoil nearby. It is a long-legged,yellowish-brown beetle about onethirdinch long. It may appear in vastswarms about the middle of June orearlier. It stays about a month andeats foliage of all kinds in gardens,vineyards and orchards. The larvaefeed on the roots of grasses in sandysoil. Consequently, if most of thesurrounding land is under cultivation,the number of chafers may bekept down. Cultivation also destroys-20-some of the pupae. Petal-fallsprays for grape berry moth willalso control rose chafers.The Japanese beetle(Popillia japonica (Newman))is a shiny metallic-green beetleless than half an inch long withcoppery-brown front wings. It isof considerable importance inparts of West Virginia. It usuallyappears between June 1 and 15,and may be present until mid-August or later. Grape leavesare among its favorite foods, andunless protected many of theleaves may be reduced to a lacelikeskeleton. The eggs are laid inthe soil in grassy areas and thegrubs develop there. The larvaemay be controlled by a bacterium,Bacillus popillae (milkyspore). This biological controlagent is applied to grassy areasto control large larval populations,but is not effective againstadults. Commercially availableattractant traps are generally notadequate to protect vineyards,but can be useful in monitoringpopulations. Insecticide applicationswill usually be necessary forcontrol of the adults.The Grape root borer(Vitacea polistiformis (Harris))can cause extensive damage toa vineyard before its presence iseven detected. Although inconspicuous,the larval feeding canresult in yield losses and deathof the vines. The borers, whichare white with brown heads andrange in size from less than aninch to two inches, feed beneaththe outer bark of the roots. Theadults, unlike most moths, flyonly during the day, and often escapeidentification because they
esemble wasps. Control of this pestis difficult because contact insecticidesare ineffective against subterraneanlarvae. An effective culturalcontrol method involves moundingsoil beneath vines after borers havepupated, and then leveling theridges in the fall or spring. Whenadults leave the cocoons they areunable to dig to the surface. Timingis important because if moundingis done too early the larvae merelytunnel up into the ridge beforepupating. Proper weed controlappears to be important in borermanagement because of increasedlarval mortality at the exposed soilsurface. Nitrogen fertilizer may helpthe vines overcome some of the effectsof damage.Other DisordersNutrient deficiencies canstunt, yellow, blacken, scorch orkill grape leaves. Symptoms canbe used to identify the deficientelement; however, petiole analysisis best used to confirm a suspectedsymptom. The extent of thedeficiency is gauged by the time atwhich the symptoms appear andby their severity. Growers shouldbe familiar with the leaf symptomsof deficiencies of nitrogen, potassium,magnesium, and manganeseand should closely inspect theirvineyards in late August or earlySeptember to determine whethersymptoms are present. Consultyour extension agent or specialistfor assistance in identification.Nitrogen deficiency is seenin reduced vine size and small,pale leaves. Potassium deficiencyis seen in interveinal or marginalchlorosis or both. With increasingseverity, marginal necrosis(scorch) develops. Magnesiumdeficiency appears first and ismost severe on basal leaves ofthe shoots. Magnesium deficiencyis usually indicated by chlorosisbetween the large veins; howeverthe veins remain green and thereis usually a thin line of greentissue at the margin of the leaf.When severe, the tissue betweenthe veins can become necrotic andeasily confused with potassiumdeficiency. Manganese deficiencyis indicated by intermittent interveinalchlorosis which is usuallymore severe on shaded leavesthan those in full sun.-21-
Page 1: Growing GrapesIN WEST VIRGINIAW e s
Page 4 and 5: Locating the VineyardProper site an
Page 6 and 7: Table 2. The expected ten-year freq
Page 8 and 9: for filling in vacancies in anestab
Page 10 and 11: or medium vineyard is to use awire
Page 12 and 13: weeds controlled with herbicides.Th
Page 14 and 15: 1. The fruit is borne onshoots prod
Page 16 and 17: Geneva Double Curtain:This system u
Page 18 and 19: -16-
Page 20 and 21: HarvestingGrapes should be picked w
Page 24 and 25: Table 3. Summary of grape cultivar
Page 26 and 27: Table3C. Wine CultivarsProductivity
Page 28 and 29: Appendicesw Weather stations are of
Page 30 and 31: Appendix 1a. continuedw x yStation
Page 32 and 33: Appendix 1b. continuedw x y zStatio
Page 34 and 35: Appendix 1c. continuedStations w x

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