MS-29 June 2003 Growing Grapes in Missouri · grapes, vinifera and muscadine, lack suffi-cient...

Growing Grapes in MissouriGrowing Grapes in MissouriGrowing Grapes in MissouriGrowing Grapes in MissouriGrowing Grapes in Missouri

State Fruit Experiment Station Missouri State University-Mountain Grove

MS-29 June 2003

Growing Grapes in MissouriGrowing Grapes in MissouriGrowing Grapes in MissouriGrowing Grapes in MissouriGrowing Grapes in Missouri

Editors: Patrick Byers, et al.

State Fruit Experiment StationMissouri State University

Department of Fruit Science9740 Red Spring Road

Mountain Grove, Missouri 65711-2999http://mtngrv.missouristate.edu/

The AuthorsThe AuthorsThe AuthorsThe AuthorsThe Authors

John D. AveryPatrick L. ByersSusanne F. HowardMartin L. KapsLaszlo G. KovacsJames F. Moore, Jr.Marilyn B. OdnealWenping QiuJosé L. SaenzSuzanne R. TeghtmeyerHoward G. TownsendDaniel E. Waldstein

Manuscript Preparation and LayoutPamela A. Mayer

The authors thank Sonny McMurtrey and Katie Gill, Missouri grape growers, for their criticalreading of the manuscript.

Cover photograph cv. Norton by Patrick Byers.

The viticulture advisory program at the Missouri State University, Mid-America Viticulture andEnology Center offers a wide range of services to Missouri grape growers. For further informa-tion or to arrange a consultation, contact the Viticulture Advisor at the Mid-AmericaViticulture and Enology Center, 9740 Red Spring Road, Mountain Grove, Missouri 65711-2999; telephone 417.547.7508; or email the Mid-America Viticulture and Enology Center [email protected]. Information is also available at the websitehttp://www.mvec-usa.org

Table of ContentsTable of ContentsTable of ContentsTable of ContentsTable of Contents

Chapter 1 Introduction.................................................................................................. 1Chapter 2 Considerations in Planning a Vineyard ......................................................... 3Chapter 3 Cost of Establishing a Vineyard ..................................................................... 5Chapter 4 Site Selection ................................................................................................ 9Chapter 5 Cultivar Selection ....................................................................................... 13Chapter 6 Selecting and Constructing a Trellis System ................................................. 19Chapter 7 Planting the Vineyard and Care of Young Vines .......................................... 27Chapter 8 Training and Pruning .................................................................................. 29Chapter 9 Irrigation Systems ........................................................................................ 37Chapter 10 Fertility Management in Vineyards .............................................................. 41Chapter 11 Disease Management ................................................................................. 45Chapter 12 Insect Pest Management ............................................................................. 57Chapter 13 Weed Control ............................................................................................. 61Chapter 14 Bird and Deer Management ........................................................................ 67Chapter 15 Harvest Management .................................................................................. 69

Appendix A Literature Cited and Resources.................................................................... 71

The GrapeThe GrapeThe GrapeThe GrapeThe Grape

The grape is a woody perennial vine of thegenus Vitis. Missouri has at least eight nativeVitis species. The important cultivated variet-ies, or cultivars, of grape grown in Missouri aredivided into three general groups, the Ameri-Ameri-Ameri-Ameri-Ameri-can cultivarscan cultivarscan cultivarscan cultivarscan cultivars, the French hybrid cultivarsFrench hybrid cultivarsFrench hybrid cultivarsFrench hybrid cultivarsFrench hybrid cultivars, andthe American hybrid cultivarsAmerican hybrid cultivarsAmerican hybrid cultivarsAmerican hybrid cultivarsAmerican hybrid cultivars. The Americancultivars are derived from native North Ameri-can grape species and include cultivarsderived from Vitis labrusca (Concord, Niagara,Catawba, Delaware), V. aestivalis (Norton/Cynthiana), and other grape species. TheFrench hybrid grapes were derived from nativeAmerican species and Vitis vinifera, the classicgrape of Europe. French hybrid grapes includecultivars such as Seyval Blanc, Vidal Blanc,Vignoles, Chambourcin, and many others.The American hybrid cultivars have a com-plex parentage that includes North American,French hybrid, and V. vinifera cultivars.Examples include Cayuga White, Reliance,Chardonel, and many others. Two groups ofgrapes, vinifera and muscadine, lack suffi-cient hardiness for consistent production inMissouri.

Missouri’s Grape IndustryMissouri’s Grape IndustryMissouri’s Grape IndustryMissouri’s Grape IndustryMissouri’s Grape Industry

Missouri has a long and interesting historyof grape production. The earliest viticulturalefforts were by French settlers in the St. Louisand St. Genevieve areas of eastern Missouri,and date to the late eighteenth and early

nineteenth centuries. Grape production in-creased tremendously in the early 1800sthrough the efforts of German settlers in the“Little Rhine” region of central Missouri nearthe Missouri River. By 1900 Missouri was aleading producer of grapes and award-winningwines. Production continued to increasestatewide until the advent of Prohibition in1920 outlawed the production of wine andother alcoholic beverages. Smaller scale grapeproduction, primarily of the cultivar Concordfor unfermented juice, continued throughProhibition and in the years following repealin 1933. Missouri’s wine industry experi-enced a rebirth in the 1960s, and growth ofboth grape and wine production continuestoday. At present (2002) Missouri has 41bonded wineries and approximately 1200acres of vineyard (Anderson, 2001; Saenz,2002). Wine production (2002) approaches500,000 gallons. Production of grapes isprimarily for wine, although a small part ofthe crop is used for unfermented juice orsold for fresh table use.

Missouri’s grape and wine industry is basedon production of a number of grape cultivarsof the American, French Hybrid, and Ameri-can Hybrid groups. While small plantings ofvinifera cultivars are found in Missouri, ex-treme winter cold limits the potential of thisgroup. In addition, Missouri’s range of geogra-phies, soil types, precipitation patterns, andclimates can limit production at specific sitesand for specific cultivars.

Chapter 1Chapter 1Chapter 1Chapter 1Chapter 1

IntroductionIntroductionIntroductionIntroductionIntroduction

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Growing Grapes in Missouri

Missouri was a leader in developing theconcept of viticultural areas. Designatedviticultural areas, which are regulated by theU.S. Bureau of Alcohol, Tobacco, and Fire-arms (BATF), have helped Missouri winesdevelop a regional identity. Portions of Missouriare currently included in four viticultural areas:

Augusta (the first viticultural area established inthe U.S.), Hermann, Ozark Mountain, andOzark Highlands. Figure 1-1 illustrates theseareas. For a detailed description of eachviticultural area, consult the appropriatesections of the US Code of Federal Regulations(CFR, 2001).

Fig.Fig.Fig.Fig.Fig. 1-1.1-1.1-1.1-1.1-1. Viticultural regions of Missouri

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Many factors must be considered beforeestablishing a vineyard. First of all you must besure the grape cultivars you choose to plantwill be marketable when they bear fruit. Plant-ing cultivars that are marketable and adaptedto your site is key. You must consider thenature of the site you have to work with, thevineyard operations you need to perform, andthe best architecture for the vines.

Select cultivars. Contact wineries and othervineyards to see what cultivars are in shortsupply or popular at the moment. What culti-vars will be popular or in short supply in thenext 5 years? 10 years?

Site considerations include water availabil-ity, slope, depth and fertility of the soil, andprevailing winds.

Vineyard operations include irrigation,mowing, spraying, harvesting, and pruning.The vineyard should be designed so thatoperations can proceed efficiently and effec-tively.

The architecture of the vineyard is thetraining system, the between-row spacing, andthe in-row vine spacing. You want to build avineyard that will best expose the canopy tosunlight. The grower needs to have an idea ofhow much vigor a given cultivar will exhibiton a particular site before row and plantspacing and training system decisions aremade. If you spread the buds too far apart, you

will lose productivity. If you place them tooclose together, you will lose quality.

The row orientation depends on severalfactors. It is better to orient rows across hillsidesor slope than to orient rows up and down toprevent erosion and for more efficient irriga-tion design. Many areas of Missouri are windyand it is best to orient the rows so the prevail-ing winds blow down the row and not againstit (Patterson, 1996a). Often it is mentioned thatrows should be oriented north and south tobetter intercept the sunlight, but this is not asimportant a consideration in Missouri as slopeand prevailing winds.

The design of the vineyard should also takeinto consideration the economics of establish-ment. If two designs will take into account theslope and prevailing wind, choose the onewith fewer end post assemblies. Of course themost economical may be one with very longrows but these may be depressing to workerswho are hand harvesting or pruning. Remem-ber that you have to efficiently harvest andtransport the grape to the winery when you aredesigning the vineyard. Rows longer than 600feet long may be interrupted by alleys (Wolfand Poling, 1995).

Between the row spacing most often isdetermined by the width of the vineyardmachinery and the training system. Narrowvineyard equipment is available, but the rowsshould never be closer together than the trellis

Chapter 2Chapter 2Chapter 2Chapter 2Chapter 2 Considerations inConsiderations inConsiderations inConsiderations inConsiderations inPlanning a VineyardPlanning a VineyardPlanning a VineyardPlanning a VineyardPlanning a Vineyard

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is high (Smart and Robinson, 1991). In Missouri,the most common between row spacing is 10feet. Wider spacing may be used if planting ona steeper slope or where vigorous cultivars areplanted to a horizontally divided trainingsystem like the Geneva Double Curtain.

Within the row spacing depends on the vigorand hardiness of the cultivar selected, howvigorous the cultivar will grow on the site with orwithout irrigation, and the training system se-lected. In Missouri, spacing between vines in therow commonly varies from 6 to 8 feet. Vigorous

cultivars such as Norton/Cynthiana may beplanted more than 8 feet apart, particularly if adivided canopy training system is not used,vines are planted on a deep and fertile soil,and/or irrigation is used.

Decisions made at vineyard establishmentwill have long-term effects on the profitabilityof your vineyard operation. You can avoidmany problems down the road such as ero-sion, irrigation design problems, vines that areout of balance, and wasting fuel and time ifyou consider your vineyard establishmentcarefully.

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The cost of establishing a vineyard canvary greatly in Missouri because of differencesin the cost of real estate, labor, machinery,materials, site characteristics, grape cultivars,vineyard and trellis design, training system,pest management strategies, and other culturalpractices. The following budget for vineyardsite preparation and first year management isbased on standard viticultural practices inMissouri. All costs were current at the time ofpublication. Alternative materials and practicesare available that may reduce costs in specificsituations. Several references detail the cost ofestablishing a vineyard (Bordelon, 1997; Crossand Casteel, 1992; Vaden and Wolf, 1994;Wolf et al., 1995).

Initial planning of all aspects of a vineyardis critical. Substantial capital is required toestablish a vineyard, and the recovery time onthis capital will be spread over several years.As is the case with any agricultural enterprise,risk is present and the potential for loss is real.A grape grower must recognize that establish-ment and production costs can vary greatly.Refer to Wolf et al. (1995) for grape productioncosts.

The economic viability of a specific vine-yard depends on many factors. Several ofthese factors should be addressed during theplanning phase of establishing a vineyard.These factors include a careful evaluation ofthe strong and weak points of a prospectivesite, selection of cultivars that are both

profitable and in demand, selection of thetrellis design and the training system, pestmanagement and cultural practices, andharvest requirements.

Vineyard establishment costs are both fixedand variable. Fixed costs are usually specific toa given site, and include equipment costs andoverhead, irrigation water sources, interest onland and money investments, and taxes.Because these costs are site specific, thisbudget will not consider fixed costs.

Variable costs include land, site prepara-tion, vine and planting costs, trellis materialsand installation, pest and weed managementcosts, fertilization costs, canopy managementcosts, irrigation system costs, labor for vineyardmanagement, and debt on the loan of capital.This budget will not include land costs andfixed costs associated with land ownership,cost of a water supply, major site preparationcosts, fixed ownership costs for machinery andequipment, and management fees.

The figures in this budget are based on sitepreparation and first year management for a10-acre vineyard of own-rooted French hybridor American winegrapes. Budget amounts arebased on costs associated with one acre ofvineyard. This one-acre vineyard has 11 rows,each 400 feet long. Rows are spaced 10 feetapart, and vines are spaced 8 feet apart in therow. The trellis is a two-wire trellis, and thevines are trained to a high wire bilateral cordon


Cost of Establishing a VineyardCost of Establishing a VineyardCost of Establishing a VineyardCost of Establishing a VineyardCost of Establishing a Vineyard

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Table 3-1. Soil Preparation for One Acre Vineyard

Budget Item Estimated Cost Your Estimate

Soil test $8 ______Lime ($6/ton, 3 ton) $18 ______Cover crop (0.68/lb, 50 lb.) $34 ______Labor (14 hours) $105 ______Total $165 ______

system. Labor costs are figured at $7.50 per hour, and the finance rate for capital is 8%. Onlyoperating costs are included for machinery.

This vineyard site is assumed to be clear of vegetation. A soil test will help guide applications oflime and nutrients. For this example, 3 tons of lime are applied to modify soil pH. A between-row cover crop of grass is seeded. Labor for site preparation is also included.

Table 3-2. Planting for One Acre Vineyard


Vines (545/acre, $2/vine) $1090 ______Sleeves (545 @ 0.30) $163 ______Labor (72.7 hours) $545 ______Total $1798 ______

Table 3-3. Trellis for One Acre Vineyard


3.5” x 8’ CCA posts (187) $808 ______6” x 8’ CCA posts (22) $219 ______12.5 ga HT wire (10,000 ft) $180 ______Anchors (22) $88 ______Strainers, sleeves, staples $70 ______Labor (50 hours) $375 ______Total $1740 ______

The trellis is a two-wire system using CCA pressure treated wooden posts and galvanized hightensile wire. Posts are spaced 24 feet apart in the row. End post assemblies are secured usinghelical screw-in anchors. This category also includes hardware and labor.

Planting costs include 1 year rooted cuttings, sleeves or grow tubes, and labor for planting.

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Cost of Establishing a Vineyard

Table 3-6. Nitrogen for One Acre Vineyard


Ammonium nitrate (0.25 lb./vine) $19 ______Labor (2 hours) $15 ______Total $34 ______

A single application of ammonium nitrate will supply the vine’s nitrogen needs during theestablishment year.

Table 3-5. Canopy Management for One Acre Vineyard


Training stakes (545 @ 0.25) $136 ______Tie materials $5 ______Labor (22 hours) $165 ______Total $306 ______

Canopy management during the establishment year includes trunk training and removal ofexcess side shoots. The trunk is trained to a 6’ bamboo stake.

Table 3-4. Irrigation for One Acre Vineyard


Backhoe operations (2 hr @ $50/hour) $100 ______Drip tube (3’ inline, 4400 feet) $506 ______Irrigation wire $66 ______Tube attachers $14 ______Labor (11.5 hours) $86 ______Total $662 ______

This vineyard is irrigated with a trickle system, with 6mm drip tube laterals with 3’ inline emitters.The tubes are attached to a trellis wire that is 18” high. A backhoe is used to bury the irrigationmanifold line. This budget does not include the cost of a water source, pump, filters, distributionlines, manifold lines, and controls.

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Annual cash expenses for vineyard site preparation and first year establishment are summarizedbelow.

Table 3-9. Summary Budget for One Acre Vineyard


Site preparation $165 ______Planting $1798 ______Trellis construction $1740 ______Pest management, fertilizer $464 ______Canopy management $306 ______Irrigation $772 ______Machinery operating cost $578 ______Operating interest $232 ______

Total $6046 ______

Table 3-8. Operating Interest for One Acre Vineyard


Machinery operating costs $578 ______Operating interest $232 ______

Additional expenses associated with vineyard establishment include machinery operating costsand operating interest. Machinery operating costs are based on standard hourly operation costs,and include the use of a tractor, pickup, herbicide and pesticide sprayers, post driver, mower,fertilizer spreader, PTO driven auger, and a flatbed trailer. Operating interest is estimated as 8%of the total capital outlay for the vineyard for 6 months.

Table 3-7. Pest Management for One Acre Vineyard


Herbicides $28 ______Fungicides/insecticides $109 ______Labor (39 hours) $293 ______Total $430 ______

Pest management during the establishment year includes the use of herbicides for weed man-agement and application of insecticides and fungicides.

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The first consideration for successful invest-ment in a new vineyard is the selection of anoutstanding site. This strategic and critical stepwill condition all the future performance of thevineyard, not only in the years of establish-ment, but also for the rest of the more thanthirty years of expected vineyard life. Theselection of the site is of such paramountimportance that it is a major factor controllingthe success or failure of vineyards in Missouri.For all these reasons and given the abundanceof land for expansion of the viticulture industryin Missouri, emphasis has to be placed onchoosing only superior sites. Superior sitesoptimize yield, grape quality for winemaking,and costs of production.

Site selection is not a new topic inviticulture. Since ancient times experience hasshown that selecting the right site was a key forsuccess. For example, Romans developed theproverb, “Bacchus loves the hills”, probably toemphasize that hills provide a better environ-ment for grape ripening, avoidance ofdiseases, and reduced risk of frost injury.

Poor site selection could present an in-crease in future maintenance cost because ofan increased need for fungicide sprays, in-creased cost for replacing missing plants, aneed for construction of drainage systems, anda need to use frost protection systems.

The important factors to be considered forsite selection under Missouri conditions include:

• Topography: elevation, slope, aspect andrelative position

• Climate: rain and temperature• Soil: depth of top soil, internal drainage,

texture, pH, etc.• Neighboring land: wildlife, cereal crops

(herbicides), densely forested (tall, thick trees)

Other factors that are not horticultural butalso could be of relevance are the reputationof the region, and the proximity to markets,labor force availability, and services.

Topographic factorsTopographic factorsTopographic factorsTopographic factorsTopographic factors

Elevation is a factor known to dramaticallyinfluence the climate of a site, primarily be-cause with every 150 feet gain in elevation theaverage temperature decreases 1 oF. Giventhat Missouri viticulture areas range from 300feet (100 meters) to 1300 feet (400 meters) inelevation, it is expected that elevation couldbe an influential factor on temperature.

Aspect is another prominent factor influ-encing the mesoclimate. For Missouriconditions with the high risk of frost andfreeze, a southern exposure could be a nega-tive factor because of an early induction tobudbreak. During ripening, a southern expo-sure could be a negative factor because ofincreased temperatures that decrease fruitquality. Practically speaking, however, aspectis generally not the primary factor in selectinga vineyard site.


Site SelectionSite SelectionSite SelectionSite SelectionSite Selection

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Slope has a big influence on cold airdrainage. Given that cold air is heavier thanwarm air, cold air tends to move downhill andpool in valleys, analogous to the flow of water.When the temperature of the grape tissues isbelow the dew point, free water starts formingon it and the dew provides the optimumcondition for disease infection. Planting avineyard in a “cold spot” not only will make itmore susceptible to frost and freeze, but alsowill create conditions for increased fungalinfections. In addition, steep slopes alwaysincrease the risk of erosion, especially slopesabove 10%, but the use of contour rows andother practices can help to reduce this risk.

Climatic FactorsClimatic FactorsClimatic FactorsClimatic FactorsClimatic Factors

Low temperature is thesingle most important limit-ing factor for grape growingin the state of Missouri. Thetotal number of days withtemperatures below thefreezing point fluctuatesfrom approximately 40 daysin the Northwest to 10 daysin the Southeast. In a paral-lel fashion, the length of thegrowing season is shorter inthe Northwest (approxi-mately 150 days) comparedto the Southeast (approxi-mately 210 days) (Fig. 4-1).In general, the majorviticulture areas located incentral and south Missourihave enough season toadequately ripen the fruit ofthe common varieties beforethe first killing frost. On rareoccasions fall cold tempera-tures can reduce quality oflate ripening cultivars suchas Norton.

Average minimum temperatures for Januaryrange from -12 oF in the Northwest to +20 oF inthe extreme Southeast. This provides an ideaof the big differences in cold hardiness limitson varieties growth in the NW compare to theSE. Also, it indicates that winter minimumtemperature is one of the most importantlimiting factors for selecting a superior site.

Rain provides needed water for grapegrowth. On average, annual rainfall increasesfrom the NW corner of the state with approxi-mately 34 inches (800 mm) to the SE part ofthe state, with an average of 50 inches (1200mm) (Fig. 4-2). Erratic rainfall distribution,often coupled with soils of low water infiltra-tion rates and/or shallow soils with low waterholding capacity, can lead to water stress for

Fig. 4-1.Fig. 4-1.Fig. 4-1.Fig. 4-1.Fig. 4-1. Length of growing season in Missouri

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grapes. Supplemental irriga-tion is a useful tool foroptimizing yields and quality.

SoilSoilSoilSoilSoil

Adequate internal soildrainage that prevents water-logging is an importantelement. Deep soils, capableof providing adequate waterstorage and fertility, are a bigadvantage. Nevertheless,shallow soils like the ones inthe Ozarks provide a suitableenvironment but these soilsrequire supplemental irriga-tion and careful andcontinuous fertility manage-ment. Soil pH tends to beacidic and generally de-mands correction by limingto reach desirable valuesabove 6.

Corrective measures, like soil ripping ordrainage installation, are efficient and costeffective if adopted before planting.

WildlifeWildlifeWildlifeWildlifeWildlife

Missouri vineyards are often surrounded bywoodlands or open areas devoted to livestockgrazing. Wildlife is particularly abundant.Isolated vineyards can be devastated by wildlifedamage, commonly the case in Missouri, if careis not taken. Deer and birds are the mostconspicuous examples of vertebrates preyingon grapes and/or grapevines. Deer are a hugeproblem almost everywhere in the state.Establishment is the most critical period fordeer damage, but deer can also be a limitingfactor later. Bird (including wild turkey) dam-age is another serious problem particularly insmall vineyards.

Phenoxy HerbicidesPhenoxy HerbicidesPhenoxy HerbicidesPhenoxy HerbicidesPhenoxy Herbicides

The use of broadleaf weed herbicides iswidespread in field crops like corn. The herbi-cides of the phenoxy group, such as 2,4-D,will cause dramatic injury on grapes. Thepoisoning effects of these herbicides can occurmiles away from the area where the herbicideshave been sprayed. Grape production can beseverely impacted in regions where phenoxytype herbicides are widely applied.

How to Get InformationHow to Get InformationHow to Get InformationHow to Get InformationHow to Get Information

Many Missouri counties have an office ofthe Natural Resources Conservation Service ofthe U.S.D.A. This office can provide you withreliable, detailed soil studies and soil surveymaps, and also with topographic maps andaerial photography. There is also a University

Site Selection

Fig. 4-2.Fig. 4-2.Fig. 4-2.Fig. 4-2.Fig. 4-2. Annual average precipitation in Missouri

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of Missouri Extension and Outreach office inmany counties where you can send soilsamples for analysis.

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The selection of grape cultivars is a veryimportant decision. Select cultivars based ontheir intended use as fresh fruit (table), jam,juice, or wine. Color, taste, aroma, sugar andacidity content, seedless condition, and vinegrowth will vary widely depending on cultivar.Grape species and cultivar adaptation towinter cold temperature is as important toMidwestern viticulturists as fruit and vinecharacteristics.

Over 90 percent of world viticulture isrepresented by the grape species Vitis vinifera.It is grown in geographic locations in the U.S.where weather patterns and large bodies ofwater moderate winter temperatures, such asthe eastern seaboard, west coast states, andeastern and southern shores along the GreatLakes. This species is not hardy in the Mid-western U.S. temperate climate. A fewviticulturists successfully grow Vitis viniferavines in cold climates by mounding soil overvines trained low or bent-over to ground level.For most viticulturists this is not practical oreconomical for any more than a few vines.Because of this cultivars of Vitis vinifera are notrecommended.

Grape cultivars recommended for theMidwestern U.S. are selected native Americanspecies, some French-American hybrids, and afew more recent American hybrids. The nativeAmerican species used for fruiting are prima-rily Vitis labrusca and Vitis aestivalis. Mostolder cultivars of Vitis labrusca and V. aestivalis

were selections from the wild and are notconsidered to be pure species but naturalhybrids. A number of these cultivars havebeen grown for well over a hundred years. TheFrench-American hybrids are an importantgroup of cultivars for wine. These were a resultof late nineteenth and early twentieth centuryFrench breeders’ efforts to obtain direct pro-ducing (ungrafted) grapes that combined goodfruit quality with adequate disease and insectresistance. Both native American species andVitis vinifera were used in breeding. Thegeneology of these cultivars is often complexand sometimes unknown. The French-Ameri-can hybrids are usually grown on their ownroots without grafting, and they retain much ofthe fruit quality of their Vitis vinifera parents.More recently, state or Canadian provincialbreeding programs have developed cultivarsfor regional climates, some of which areadapted to the midwestern U.S. These hybridcrosses often include native American grapespecies, Vitis vinifera, and French-Americanhybrids in their geneology, and are calledAmerican hybrids. Tradition plays an impor-tant role in grape cultivar selection and culturein world viticulture. Tradition plays much lessa role in Midwestern U.S. viticulture. Newcultivars of grapes continue to be evaluated.

Grape cultivar recommendations are basedon their productivity in southern Missouri atMountain Grove. A cultivar trial was initiatedin 1985 and continued through 1994. Twenty-seven wine grape and ten table grape cultivars


Cultivar SelectionCultivar SelectionCultivar SelectionCultivar SelectionCultivar Selection

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were evaluated. The more productive cultivarsfrom this trial have gained acceptance by theMissouri grape and wine industry and arelisted below. Exceptions to this are Chardonel,Marquis and Traminette; their recommenda-tions are based on later trials at MountainGrove and grower experience. All the recom-mended cultivars require a spray program forcontrol of insect and disease problems. Referto Table 11-1 for relative disease susceptibilityratings.

American SpeciesAmerican SpeciesAmerican SpeciesAmerican SpeciesAmerican Species

Vitis labruscaVitis labruscaVitis labruscaVitis labruscaVitis labruscaCatawbaCatawbaCatawbaCatawbaCatawba is a red grape for table fruit, juice

and wine with large berry size and small, looseclusters. It has high vigor and a high degree ofwinter hardiness. The fruit matures late season.Dormant pruning adequately controls crop-ping. Yield is moderate to high. The vine trainswell to a cordon system with spur pruning.High vigor sites will allow for divided canopytraining. Shoot positioning is recommendedseveral times during the growing season. Agood spray program is necessary to controldisease with Black Rot and Downy Mildewbeing the major problems. Table fruit quality isvery good but berries are seeded. Juice qualityis very good. Labrusca ‘foxy’ character isstrong. It is typically made into a sweet, blushwine or used in blending.

ConcordConcordConcordConcordConcord is a blue-black grape for tablefruit, juice and wine with large berry size andsmall, loose clusters. It has high vigor and ahigh degree of winter hardiness. The fruitmatures late season. Dormant pruning adequatelycontrols cropping. Yield is high. The vinetrains well to a cordon system with spur prun-ing. High vigor sites will allow for dividedcanopy training. Shoot positioning is recom-mended several times during the growingseason. A good spray program is necessary to

control disease with Black Rot being a majorproblem. Table fruit quality is very good butberries are seeded. Juice quality is very good.Labrusca ‘foxy’ character is strong. It is typi-cally made into a sweet, red wine or used inblending. SunbeltSunbeltSunbeltSunbeltSunbelt is a 1993 Arkansas releasethat has vine and fruit characteristics that arevery similar to Concord. Fruit of Concord canripen unevenly during warm maturing seasons;Sunbelt is less prone to this.

DelawareDelawareDelawareDelawareDelaware is a red grape for wine with smallberry size and small, compact clusters. It hasmoderate vigor and moderate winter hardi-ness. The fruit matures midseason. Dormantpruning adequately controls cropping. Yield ismoderate to high. The vine trains well to acordon system with spur pruning. Shootpositioning is recommended several timesduring the growing season. A good sprayprogram is necessary to control disease withBlack Rot and Downy Mildew being themajor problems. Juice quality is very good.Labrusca ‘foxy’ character is mild. It is typi-cally made into a sweet, blush wine or usedin blending. It is also used in sparkling wineproduction.

NiagaraNiagaraNiagaraNiagaraNiagara is a white grape for table use, juiceand wine with large berry size and medium,loose clusters. It has high vigor and a highdegree of winter hardiness. The fruit maturesmidseason. Dormant pruning adequatelycontrols cropping. Yield is high. The vinetrains well to a cordon system with spur prun-ing. High vigor sites will allow for dividedcanopy training. Shoot positioning is recom-mended several times during the growingseason. A good spray program is necessary tocontrol disease with Black Rot being a majorproblem. Table fruit quality is very good butberries are seeded. Juice quality is very good.Labrusca ‘foxy’ character is strong. It is typi-cally made into a sweet, white wine, or used inblending.

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Vitis aestivalisVitis aestivalisVitis aestivalisVitis aestivalisVitis aestivalisCynthiana and NortonCynthiana and NortonCynthiana and NortonCynthiana and NortonCynthiana and Norton cultivars are geneti-

cally the same. It is a blue-black grape for redwine with small berry size and small, looseclusters. It has high vigor and a high degree ofwinter hardiness. The fruit matures late season.Dormant pruning adequately controls crop-ping. Yield is low. On any site other than verylow vigor, the vine should be trained to adivided canopy system with spur pruning toimprove yield. Shoot positioning is recom-mended several times during the growingseason. Foliage and fruit are much less suscep-tible to the major grape diseases but somespray program will be needed. Wine quality isexcellent. It is typically made into a dry, redvarietal wine.

American HybridsAmerican HybridsAmerican HybridsAmerican HybridsAmerican Hybrids

Cayuga WhiteCayuga WhiteCayuga WhiteCayuga WhiteCayuga White is a 1972 New York release.It is a white grape for wine with large berry sizeand large, compact clusters. It has high vigorand moderate winter hardiness. The fruitmatures midseason. Dormant pruning usuallycontrols cropping but cluster thinning may beneeded to prevent overbearing. Yield is high.The vine trains well to a cordon system withspur pruning. High vigor sites will allow fordivided canopy training. Shoot positioning isrecommended several times during the grow-ing season. A good spray program is necessaryto control disease with Black Rot and Anthrac-nose being the major problems. Wine qualityis excellent. Labrusca ‘foxy’ character is mild. Itis typically made into a semi-dry to dry, white,varietal wine.

ChardonelChardonelChardonelChardonelChardonel is a 1990 New York release. It isa white grape for wine with medium berry sizeand medium to large, compact clusters. It hasmoderate vigor and low to moderate winterhardiness. The fruit matures late season. Dor-mant pruning usually controls cropping butcluster thinning may be required in some

years. Yield is moderate. The vine trains well toa cordon system with spur pruning. It shouldbe planted on a vineyard site with good waterdrainage because of its susceptibility to wintertrunk injury. A good spray program is neces-sary to control disease. Clusters are lesssusceptible to bunch rot. Wine quality isexcellent, having characteristics of itsChardonnay and Seyval blanc parents. It istypically made into a dry, white, varietal wine.This cultivar is only adapted to better sites inMissouri. In areas where its hardiness has notbeen determined, it should be planted on atrial basis.

MarsMarsMarsMarsMars is a 1985 Arkansas release. It is ablue-black, seedless table grape with mediumberry size and small, loose clusters. It has highvigor and a high degree of winter hardiness.The fruit matures early season. Cluster thinningmay be needed in years of high production toprevent overbearing. Yield is moderate to high.The vine trains well to a cordon system withspur pruning. High vigor sites will allow fordivided canopy training. Shoot positioning isrecommended several times during the grow-ing season. Foliage and fruit are lesssusceptible to the major grape diseases butsome spray program will be needed. Tablefruit quality is very good. Berries may haveoccasional soft seeds. Skin is somewhat tough.Labrusca ‘foxy’ character is strong and similarto Concord.

Marquis Marquis Marquis Marquis Marquis is a 1996 New York release. It is agreenish-white, seedless table grape with largeberry size and medium, loose clusters. It hasmoderate vigor and moderate hardiness. Thefruit matures midseason. Cluster thinning maybe needed in years of high production toprevent overbearing. Yield is high. The vinetrains well to a cordon system with spurpruning. Shoot positioning is recommendedseveral times during the growing season. Agood spray program is necessary to control

Cultivar Selection

16


disease. Table fruit quality is excellent.Labrusca ‘foxy’ character is mild.

RelianceRelianceRelianceRelianceReliance is a 1982 Arkansas release. It isa red, seedless table grape with mediumberry size and medium to large, loose clus-ters. It has high vigor and a high degree ofwinter hardiness. The fruit matures earlyseason. Cluster thinning may be needed inyears of high production to prevent over-bearing. Yield is moderate to high. The vinetrains well to a cordon system with spurpruning. High vigor sites will allow for di-vided canopy training. Shoot positioning isrecommended several times during thegrowing season. A good spray program isnecessary to control disease with Black Rotand Anthracnose being the major problems.Table fruit quality is excellent. Berry skin isthin which leads to fruit ‘cracking’ and rot insome years. A large crop maturing in warmweather leads to poor red color develop-ment. Labrusca ‘foxy’ character is mild.

TraminetteTraminetteTraminetteTraminetteTraminette is a 1996 New York release. Itis a white grape for wine with medium berrysize and small, loose clusters. It has low tomoderate vigor and low winter hardiness. Thefruit matures late season. Cluster thinning is notrequired. Yield is low to moderate. The vinetrains well to a cordon system with spur prun-ing. It should be planted on a vineyard sitewith good water drainage because of its sus-ceptibility to winter trunk injury. A good sprayprogram is necessary to control disease withBlack Rot, and Downy and Powdery Mildewsbeing the major problems. Clusters are lesssusceptible to bunch rot. Wine quality isexcellent, having characteristics of itsGerwurztraminer parent. It is typically madeinto a semi-dry to dry, white, varietal wine.This cultivar is only adapted to better sites inMissouri. In areas where its hardiness has notbeen determined, it should be planted on atrial basis.

VanessaVanessaVanessaVanessaVanessa is a 1983 Ontario, Canada re-lease. It is a red, seedless table grape withmedium berry size and medium, loose clus-ters. It has moderate vigor and moderate winterhardiness. The fruit matures midseason. Clusterthinning is usually not required. Yield is mod-erate. The vine trains well to a cordon systemwith spur pruning. Shoot positioning is recom-mended several times during the growingseason. A good spray program is necessary tocontrol disease. Table fruit quality is excellent.Berries are non- slipskin, similar to viniferatable grapes. Berries may have occasional softseeds. Labrusca ‘foxy’ character is mild.

VivantVivantVivantVivantVivant is a 1983 Ontario, Canada release.It is a white grape for wine with small berrysize and medium, compact clusters. It has lowto moderate vigor and moderate winter hardi-ness. The fruit matures late season. Yield is lowto moderate. The vine trains well to a cordonsystem with spur pruning. A good spray pro-gram is needed to control diseases with BlackRot, Downy and Powdery Mildews and An-thracnose being the major problems. Clustersare less susceptible to bunch rot. Wine qualityis excellent. It is typically made into a dry,white, varietal wine.

French-American HybridsFrench-American HybridsFrench-American HybridsFrench-American HybridsFrench-American Hybrids

ChambourcinChambourcinChambourcinChambourcinChambourcin is a red grape for wine withmedium to large berry size and large, looseclusters. It has low to moderate vigor. It haslow to moderate winter hardiness. The fruitmatures late season. It does not require clusterthinning. Yield is moderate. The vine trainswell to a cordon system with spur pruning.Spacing should be closer than eight feetbetween vines on lower fertility sites. It growsbetter when planted on a vineyard site withgood water drainage and higher soil fertility.A good spray program is needed to controldiseases with Powdery Mildew being amajor problem. Loose clusters make it not

17

Cultivar Selection

susceptible to bunch rot. Wine quality isexcellent. It is typically made into a dry, redwine.

Seyval blancSeyval blancSeyval blancSeyval blancSeyval blanc is a white grape for wine withmedium berry size and large, compact clus-ters. It has moderate vigor and moderate winterhardiness when managed to a moderatecropping level. The fruit matures midseason.Cluster thinning is required in most years.Yield is high. The vine trains well to a cordonsystem with spur pruning. A good spray pro-gram is needed to control diseases with BlackRot and Powdery Mildew being the majorproblems. Bunch rot can be a problem insome years. Wine quality is good. It is typicallymade into a dry, white, varietal wine.

St. Vincent St. Vincent St. Vincent St. Vincent St. Vincent is considered to be a chancehybrid of a French-American hybrid cultivarwith an unknown parent. It is a red grape forwine with large berry size and small, looseclusters. It has high vigor and moderate to highdegree of winter hardiness. The fruit matureslate season. It does not require cluster thinning.Yield is high. The vine trains well to a cordonsystem with spur pruning. A good spray pro-gram is needed to control diseases. Looseclusters make it not susceptible to bunch rot.Wine quality is good. It is typically made into adry, red wine, or used in blending.

Vidal blancVidal blancVidal blancVidal blancVidal blanc is a white grape for wine withmedium berry size and large, elongated,compact clusters. It has high vigor and moder-ate winter hardiness when managed to a

moderate cropping level. The fruit matures lateseason. Cluster thinning is required in mostyears to prevent over cropping. Yield is moder-ate to high. The vine trains well to a cordonsystem with spur pruning. It should be plantedon well drained vineyard sites because of itssusceptibility to winter trunk injury. A goodspray program is needed to control diseaseswith Powdery Mildew and Anthracnose beingthe major problems. Berries have thicker skinsand clusters are less compact than Seyvalwhich makes it more resistant to bunch rot.Wine quality is excellent. It is typically madeinto a dry, white, varietal wine.

VignolesVignolesVignolesVignolesVignoles is a white wine grape with smallberry size and small, compact clusters. It haslow to moderate vigor depending on plantingsite fertility. It has moderate to a high degree ofwinter hardiness. The fruit matures earlyseason. It does not require cluster thinningbecause of low bud fruitfulness. Yield is low tomoderate. The vine trains well to a cordonsystem with spur pruning. Spacing should becloser than eight feet between vines on lowerfertility sites. It should not be cropped the firstthree years to promote good vine establish-ment. A good spray program is needed tocontrol diseases with Black Rot and Anthrac-nose being the major problems. Compactclusters make it very susceptible to bunch rot.Frequently, this can not be adequately con-trolled by protective sprays. Wine quality isexcellent. It is typically made into a semi-dry tosemi-sweet, white, varietal wine.

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19

Key Planning Points ChecklistKey Planning Points ChecklistKey Planning Points ChecklistKey Planning Points ChecklistKey Planning Points Checklist

• Get professional assistance. Considercontacting advisers from the Missouri StateUniversity Department of Fruit Science, UMCExtension Service, Missouri Department ofAgriculture Grape and Wine Program, estab-lished vineyard growers, an irrigationspecialist, and sales reps for the products youwill need for trellis construction, i.e., post,wire, and hardware. This should be the firstitem on your list of things to do!

• Check your soils. Sands, loam, clay ormixture. Deep soils or shallow. Clay, chert, orrock subsoil layer. Get a soil test for pH andnutrients and get advice on interpreting theresults, if needed. Make needed adjustmentsbefore the vines go in the ground.

• Locate water, electrical, gas, telephonelines.

• Check topography. Level land or rollingterrain. Are there rises or dips?

• Consider your needs. Will you handharvest? Or will you machine harvest? Do youneed access aisles?

• Plan ahead. Is there expansion in thefuture?

• Focus on vineyard location. How far is it topublic gravel road or paved road?

• Sketch the vineyard. Draw a simple map oftopography; locate hazards, roads, waterresources, note prevailing winds, generallocation and orientation of vineyard.

• Choose a trellis system. These are allquestions that need to be answered when

deciding on the trellis system to utilize with anew vineyard: What cultivars will be grown?What is the vigor of the cultivars? How deep isthe soil? Will the vineyard be irrigated? Whatare the yield goals for the vineyard? Willgrapes be machine harvested or hand har-vested?

• Bracing assemblies (end post). Decide whatkinds of end post assembly you want to use forthe vineyard. What is the trellis system beingconstructed? What are your soil types, theterrain of your land, and the length of therows?

Training SystemsTraining SystemsTraining SystemsTraining SystemsTraining Systems

High wire cordonHigh wire cordonHigh wire cordonHigh wire cordonHigh wire cordonThe high wire cordon (Fig. 6-1) is used with

cultivars that tend to have a drooping growthhabit. Most wine grapes in the state are grownon this system. It is easy to train and maintainvines on this system. The trellis itself is easy tomaintain. Generally only two wires are neededfor the trellis. The top wire is the cordon wireand the bottom wire serves as a training wireand a hanging wire for the irrigation system. Itis the least expensive system to construct andreadily lends itself to machine harvesting.

Low wire cordonLow wire cordonLow wire cordonLow wire cordonLow wire cordonThe low wire cordon (Fig. 6-2) was devel-

oped for low to moderate vigor cultivars,which have an extremely upright growthhabit, such as Vignoles. It also keeps the

Chapter 6Chapter 6Chapter 6Chapter 6Chapter 6 Selecting andSelecting andSelecting andSelecting andSelecting andConstructing a Trellis SystemConstructing a Trellis SystemConstructing a Trellis SystemConstructing a Trellis SystemConstructing a Trellis System

20


fruiting zone exposed thus allowing foruniform spray coverage of the fruit. Withdisease prone cultivars it can be used tohelp control disease by leaf removal in thefruiting zone. The system is a little morecomplicated than the high wire cordon. Thecordon wire is placed about 36 inchesabove the ground with pairs of catch wireabove. Some systems utilize one pair ofmovable catch wires while others use twopairs of non-movable catch wires. With thelow wire cordon, the grower must sendworkers through the vineyard two or threetime during the growing season to push newshoot up and behind the catch wire. Oftenshoots are trimmed in the summer when they

grow over the top wire of the system.In some years this may need to be donetwice before growth ceases. Approximatelyfour feet of canopy is maintained. The sys-tem does lend itself to some mechanization.

Geneva Double Curtain (GDC)Geneva Double Curtain (GDC)Geneva Double Curtain (GDC)Geneva Double Curtain (GDC)Geneva Double Curtain (GDC)The Geneva Double Curtain (Fig. 6-3)

was developed for vigorous cultivars thatcan fill in the trellis in a year or two. Culti-vars like Concord or Cynthiana/Norton aregenerally too vigorous to put on a singlecurtain type system of training. The numberof new buds needed each year would crowda short length of cordon. With the doublecordon wires, adjacent plants can be trained

Fig. 6-1.Fig. 6-1.Fig. 6-1.Fig. 6-1.Fig. 6-1. High Wire Cordon training system

Fig. 6-2.Fig. 6-2.Fig. 6-2.Fig. 6-2.Fig. 6-2. Low Wire Cordon training system

21

to opposite wires thus giving 16 feet ofcordon for the bud spurs to be spread oninstead of just 8 feet with the single wiretrellis. Long spurs (4 to 6 buds) can bespaced 10 to 12 inches apart on the cordonthus allowing better light and airflow to thenew developing shoots. This is importantwith vigorous cultivars that can grow canesof 15 or more feet each year. The GDCallows for the use of mechanical hedging,pruning and harvesting. It also allows forhigher yields of better quality grapes thancould be accomplished with a single wiresystem.

A number of other training systems areused to a limited extent in Missouri. Thesesystems include various cane pruned Kniffensystems and divided canopy systems such asthe Lyre, the Scott Henry, and variations ofthe Smart-Dyson system.

Bracing SystemsBracing SystemsBracing SystemsBracing SystemsBracing Systems

Tie back brace assemblyTie back brace assemblyTie back brace assemblyTie back brace assemblyTie back brace assemblyThe tie back system (Fig. 6-4) of bracing

the end of a trellis utilizes an end post thatleans away from row centers at a sixty-

degree angle from the perpendicular.With this system the end post is the anchorand must be in the ground a minimum offour feet. The second post should be set at a20 to 30 degree angle from perpendicularfrom the row center and at least three feet inthe ground. Subsequent line posts should beplumb with the ground and set two feet inthe ground. This system is suited to soils thathave a deep sandy or loamy structure withclay subsoil where it is relatively easy toauger holes to the proper depth. This systemis not the best for shallow rocky soils with a

Selecting and Constructing a Trellis System

Fig. 6-3.Fig. 6-3.Fig. 6-3.Fig. 6-3.Fig. 6-3. Geneva Double Curtain training system

Fig. 6-4.Fig. 6-4.Fig. 6-4.Fig. 6-4.Fig. 6-4. Tie back brace assembly

22


hardpan in the subsoil layer. These soils canbe difficult to auger to the required depthfor setting the post.

Single Span brace assembly (H system)Single Span brace assembly (H system)Single Span brace assembly (H system)Single Span brace assembly (H system)Single Span brace assembly (H system)The H system (Fig. 6-5) uses a brace be-

tween the first two posts in the row. The endpost should be set four feet in the ground whilethe second post should be set three feet in theground. Both posts should be set with a 1”lean away from vertical from each other. Thepost should be notched to hold the brace in

place and a brace wire should also be utilizedto pull the post tight against the brace. Thissystem can be used with any trellis system butis particularly good with the GDC system andthe low wire cordon.

Deadman brace assemblyDeadman brace assemblyDeadman brace assemblyDeadman brace assemblyDeadman brace assemblyDeadman assembly (Fig. 6-6) uses an

anchor to hold the end post. The end post isput two to three feet deep and leaning at asixty degree angle away from vertical from thedirection of pull. The anchor can be any ofseveral types. One of the easiest to install is ascrew anchor. A tractor-mounted auger can bemodified to screw the anchors in. Other typesof anchors are made with rebar and concrete.

Old railroad ties and large rocks have beenused. These anchor types will require anaugered or trenched hole so the anchor can beburied. This system is good where the soil isunderlain with a rocky or chert subsoil whichwould make it hard to set posts a full four feetdeep.

Site PreparationSite PreparationSite PreparationSite PreparationSite Preparation

SoilsSoilsSoilsSoilsSoilsThe soils must be tested for the needs of the

new planting and nutrients added as deter-mined by the soil test. The site is prepared toreduce weed and/or grass competition for thenew plants. The soil structure should also beanalyzed. The type of equipment needed forconstruction of the trellis system as well as thebrace system to utilize will be determined bysoil structure. Deep sandy or loamy soils willbe easier to work in than a shallow chert soil.Shallow soil underlain with a hard rocky chertlayer can be difficult to dig postholes or todrive post. Deeper soils with a lot of sand orloam are easier to drill. The brace system touse will be determined by the type of soil.

Alleys and roadsAlleys and roadsAlleys and roadsAlleys and roadsAlleys and roads

Fig. 6-5.Fig. 6-5.Fig. 6-5.Fig. 6-5.Fig. 6-5. Single span brace assembly

Fig. 6-6.Fig. 6-6.Fig. 6-6.Fig. 6-6.Fig. 6-6. Deadman brace assembly

23

The placement of roads and alleys in thevineyard needs to be carefully considered.Trellis rows should not exceed about 800 feetin length for hand harvest. An alley each 800feet in the vineyard can be beneficial in mov-ing the grapes, especially when vines are handharvested. Where machine harvest is used,rows can be longer. Terrain of the field shouldbe studied so that road and alleys are notplaced in low areas that may become impass-able during rainy periods.

Row spacingRow spacingRow spacingRow spacingRow spacingRow spacing will be determined by three

factors: the trellis system, vigor of the cultivarexpected on the site, and the equipment to beused. Most vineyards are set up with 10 feetrow spacing. This works well with single wiretrellis systems (high wire, low wire, and canesystems). When a Geneva Double Curtain is tobe used then 12 feet row spacing may beneeded. If specialized vineyard equipment isto be used, when tractors are narrower thannormal farm equipment, then 10 feet rowspacing may be kept with the GDC. Wherenarrow vineyard equipment is going to beused and low vigor cultivars are being plantedthen the row spacing may be reduced to nine


or even eight feet for single wire trellis sys-tems.

LayoutLayoutLayoutLayoutLayoutFlag and layout the corners of the vine-

yard, squaring the corners of the vineyardbefore proceeding. Use the Pythagoreantheorem (A2+B2=C2) to square the vineyard(Fig. 6-7). Run rows with the terrain of theland. It is preferable to run rows across theslope of a hill than to run them up and downthe hill. Any rises or dips need to be flagged soline posts can be set in the areas ahead of otherline posts.

Set the four corner end posts first and thenfill in with the rest of the end posts. String aguide wire down the row to aid with line postalignment. Be sure to set line posts on any risesor in any dips in the landscape. The wireshould be set about 4 inches above the ground.

Last set the line posts and when finishedpull the guide wires up to make the bottomtraining wire of the trellis.

MaterialMaterialMaterialMaterialMaterial

Wire, fasteners, and other hardwareWire, fasteners, and other hardwareWire, fasteners, and other hardwareWire, fasteners, and other hardwareWire, fasteners, and other hardware

WiresWiresWiresWiresWiresLoad bearing wiresLoad bearing wiresLoad bearing wiresLoad bearing wiresLoad bearing wires. There are many types

of wire which can be used in trellis construc-tion. High tensile (HT) galvanized wire hasproven to be the most cost effective andlongest lived of the available options. For themain load bearing (top) wire, 12.5 gauge hightensile wire with No. 3 galvanizing is preferred.It can be tightened to its load capacity and leftduring the winter without stretching andsagging, as soft wires will do. It is a little moreexpensive in the short run but will outlast softwire by 10 to 15 years. Most high tensile wirewith No. 3 galvanizing will last 40 years beforeFig. 6-7.Fig. 6-7.Fig. 6-7.Fig. 6-7.Fig. 6-7. Squaring the vineyard layout

24


rust weakens it.

Non-load bearing wiresNon-load bearing wiresNon-load bearing wiresNon-load bearing wiresNon-load bearing wires. Soft or HT wire issuitable for nonload bearing wires. The wiregenerally does not need to be as tight as theload bearing wires. For training and catchwires 14 gauge wire in HT or soft is sufficient.

FastenersFastenersFastenersFastenersFastenersWire vises (Fig. 6-8) can be used for rows of

200 feet or less. In line strainers (Fig. 6-9) need

to be used for rows of 200 feet or more. If therow length is less than 400 feet, the strainercan be placed at one end of the row. If the rowis over 400 feet long, the strainer needs to beplaced in the middle of the row so that bothends can be tightened at the same time.

HardwareHardwareHardwareHardwareHardwareCrimp holders are needed for splicing wire

at the ends of rows or at the end of a role ofwire. They are readily available at local farmsupply stores. Staples need to be 1¼ inchgalvanized at a minimum.

PostsPostsPostsPostsPosts

Wood preservative treatmentsWood preservative treatmentsWood preservative treatmentsWood preservative treatmentsWood preservative treatmentsUse pressure treated pressure treated pressure treated pressure treated pressure treated for maximum

penetration. CCA-chromated copper arsen-ate will outlast penta by several years. DoDoDoDoDonotnotnotnotnot use dipped or sprayed posts, but buyonly pressure treatedonly pressure treatedonly pressure treatedonly pressure treatedonly pressure treated. Pressure treated postswill last 15 to 20 years longer than dipped orsprayed posts of the same wood. Use AWPAStandard C16- 0.40 to 0.60 pcf treatment.The most common treatment for posts is the0.40 pcf treatment but if sufficient posts areordered the higher treatment can be re-quested. This may be beneficial in humidclimates.

SizingSizingSizingSizingSizingEnd post: 4” to 8” X 8’ to 10’ wood. Line

post: 3”X 8’ wooden or 8’ metal T post. Woodposts can be spaced 20 to 30 feet apart.Metal T posts should be spaced 16 feet orless with some recommendations for onepost at every plant. Metal T posts may beused where mechanical harvest of the vine-yard is anticipated.

ConstructionConstructionConstructionConstructionConstruction

If the vineyard is mechanically planted therows will need to be flagged for the planters to

Fig. 6-8.Fig. 6-8.Fig. 6-8.Fig. 6-8.Fig. 6-8. Wire vises

Fig. 6-9.Fig. 6-9.Fig. 6-9.Fig. 6-9.Fig. 6-9. In line strainers

25


follow. Trellis construction can start after thevines have been planted. When planting byhand, the trellis can be constructed beforeplanting. Trellis should be in place as soonafter planting as practical to aid in training ofthe young vines.

Brace assemblies must be constructed first.A guide wire is run between the end posts atabout 4” from ground.

Set line posts by driving or auguring themin the ground. They should be placed ½ inchfrom the guide wire and with the wire on thewindward side of the post. This allows theprevailing wind to blow the foliage and wireagainst the post instead of away from the post.Wood line posts are spaced at 24 to 40 feetapart or between every 3 or 4 vines. Steel Tposts are commonly spaced 8 to 16 feet apart.

The guide wire can then be positioned asthe bottom training wire or irrigation supportwire. Other wires can then be installed as perthe system being built.

After all wires have been installed thecordon wires should be tensioned to 100 psifor the first year. This will give the end braceassemblies’ time to settle into their location.During this first year the vines can be trained tothe cordon wires. There will not be sufficientload to cause problems with sagging wireduring the first year. After one year the cordonwires can be tensioned to 250 psi. Other wiresin the system can be tightened sequentiallyfrom the bottom to the top to match the cor-don wire.

The wires are then fastened at the properheight to the line post. With wood line posts,double staples can be used or the postnotched to hold the wire. Staples should be1¼ inch in length at a minimum. Staplesshould be spread so they splay outward as

they are nailed in. Generally it is best to usetwo staples at each site on the post. The first isnailed in parallel to the wire so the wire canrest on the staple. The next staple is nailed inover the wire and first staple so that it will holdthe wire to the post. The staples should beloose enough that the wire can slide as it istightened. Notch the post at the properlocations at about a 75-degree angle and ½to ¾ inch into the post. The wire is then laidinto the notch and a nail driven in above thewire to keep it from pulling out of the notch astension is placed on the wire. Wires areattached to steel T posts with wire connectors.

MaintenanceMaintenanceMaintenanceMaintenanceMaintenance

Maintenance of the vineyard trellis shouldbe done each year, before new growth hasstarted in the spring. Posts should be checkedto see they are still solid. Wire should bechecked for breaks and tightened as needed.End brace assemblies should be checked tomake sure they are not loosened due to frostheaving. It is much easier to replace post or fixwires in the early spring than to have to try andfix a problem in the summer with full foliageand a heavy fruit load on the vines.

Additional information on trellis planningand construction is found in How to BuildOrchard and Vineyard Trellises (United StatesSteel Corporation, 1982), the OregonWinegrape Growers Guide (Casteel, 1997),and Vineyard Establishment II from MichiganState University (Zabadal, 1997).

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27

Planting stock should be ordered from thenursery well in advance of the planned plant-ing date. One year number one rooted cuttingsare recommended. Popular or difficult topropagate vines like Norton/Cynthiana mayhave to be ordered at least two years in ad-vance.

Planting stock should be inspected onarrival. Planting stock should be 3/8 inch indiameter or about pencil thickness. Rootsshould be moist, not dried out and not too wet.If there is a problem contact the nursery imme-diately.

New plants are trimmed to one cane with3 to 4 buds, and side shoots are removed atplanting.

If plants cannot be placed in the groundimmediately, store in a cool place and keepmoist until planting. Cold storage should bemaintained just above freezing. Plants can alsobe placed in a shallow trench with soil ormulch covering the roots in a shady locationfor planting later.

Mark the plant spacing accurately beforeplanting.

Most planting is done by hand. An 8 to 10inch auger works well, trenches may be dugdown the row before trellis is constructed, orhand shovels can be used. It is important thatthe planting hole is not glazed on the sides.

In clay soils you can weld a bit of metal on theedges of the auger to break up the sides. Ifplanting with a shovel, make sure to disturbany glazed sides.

Mechanical planting is used in Missouri.Mechanical planting is done before the trellisis constructed. In general, grower experienceshave been that there are more spacing discrep-ancies and lower percentage survival withmechanized planting, but the results will varywith planting area and type of machine used.

Plants must not dry out during the plantingoperation. Keep roots moist by placing them inwater in buckets or by wetting them andprotecting them with a tarp.

No matter what planting method you use,dig the trench or hole large enough to accom-modate all of the roots so you don’t have toprune any off (Zabadal, 1997b). Spread theroots out evenly, firm soil around the roots,and water the plants.

Spring planting is recommended. Aftervines are planted, they should be watered in.If planting by hand, it is best if the irrigationand trellis systems are installed before planting.If mechanically digging a trench or mechani-cally planting, water plants in by hand andinstall irrigation and trellising as soon as pos-sible after planting. Make sure that adepression is not left around the vine whereherbicide can pool and damage vines.

Chapter 7Chapter 7Chapter 7Chapter 7Chapter 7 Planting the VineyardPlanting the VineyardPlanting the VineyardPlanting the VineyardPlanting the Vineyardand Care of Young Vinesand Care of Young Vinesand Care of Young Vinesand Care of Young Vinesand Care of Young Vines

28


Fall planting is possible but only with verycold hardy varieties and is best handled by anexperienced grower. Most nurseries do not digin the early fall so stock may have to be spec-ially arranged. Stock must be dormant. Plantsshould be mulched to help prevent frostheaving. It is not as critical to water plants inafter planting in the fall as it is in the spring.

Care the first two years focuses on training(Chapter 7), fertility management (Chapter 10),providing adequate moisture (Chapter 9),weed control (Chapter 13), and protecting thevines from pests (Chapters 11-14). Read thesesections for details on the care of young vines.Pest management in particular is important

during the first two years. Weed control gener-ally consists of a combination of hand hoeing,shallow cultivation, mulching, and herbicideapplications.

Disease and insect control is also impor-tant. Black rot, downy mildew, anthracnose,phomopsis, and other foliar diseases canreduce vine vigor and result in winter injury tovines. Foliar feeding insects can likewisedamage young vines. Monitor vines frequentlyduring the first two years, and address anyproblems promptly. Deer, rabbits, and otherchewing animals are also threats to youngvines. Develop a management strategy beforeplanting the vineyard (Chapter 2).

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IntroductionIntroductionIntroductionIntroductionIntroduction

Grapes are vining plants that need sup-port to spread out their leaves and interceptas much sunlight as possible. In a vineyard,the shape of a vine’s canopy will be deter-mined by the training system selected. In thisguide, only training systems and pruningmethods recommended for grape growing inMissouri are described. Specifically these arespur pruning systems for own rooted Frenchhybrids, American hybrids, and Americangrapes.

In a modern vineyard, the perennialportions of the grape vine include the rootsystem, the trunk, and cordons. Fruit is borneon current season’s growth, which arisesfrom compound buds that were formedduring the previous growing season. Thecompound bud usually contains 3 buds. Thelargest bud, the primary bud, has the poten-tial for greatest fruitfulness. If coldtemperature or some other factor kills theprimary bud, a secondary bud may producea smaller crop. Grape cultivars vary in thelevel of fruitfulness from secondary buds. Ifboth primary and secondary buds are killed,vegetative growth may result from a smallerbud, but these tertiary buds usually are notfruitful.

Fruit clusters are formed directly oppositea leaf on current season’s growth. Environ-mental and genetic factors control

fruitfulness in a vine. Location of clusters onthe vine is also specific to cultivars. Ameri-can cultivars, for instance, usually have 2 to4 fruit clusters located at nodes 2, 3, 4, and5 from the base of the shoot. French hybridcultivars, on the other hand, may have fouror more clusters per shoot, distributed out-ward from the base of the shoot. Locationand number of clusters are important consid-erations when choosing a vine training andpruning system.

New compound buds form in the leafaxils of current season’s shoots. These shootseventually become woody and are thesource of next year’s fruiting wood.

DefinitionsDefinitionsDefinitionsDefinitionsDefinitions

• Trunk - vertical part of the vine, trained upto the trellis wires

• Cordon - horizontal extension of the trunk,supported by trellis wires; spurs arelocated here

• Shoot - current season’s extension growth,green in color

• Cane - shoot that has matured(hardened off), brown in color

• Spur - canes that have been pruned backto a few nodes

• Buds - swelling at nodes; after bud break,these will grow into the shoots, bearingboth flower clusters and leaves

• Canopy - all shoots and their leaves makeup the canopy


Training and PruningTraining and PruningTraining and PruningTraining and PruningTraining and Pruning

30


Training SystemsTraining SystemsTraining SystemsTraining SystemsTraining Systems

The goal in training vines is to maximizethe amount of foliage exposed to sunlight bycreating the concept of balance, having a largesurface area without shading adjacent vines.The surface area is much larger for thin cano-pies than for thicker, more spherically shapedcanopies. Training systems exist where thefruiting wire with the cordons is high above theground and new growth is directed down-ward. Others direct shoot growth upward andthe fruiting zone is closer to the ground. Bothhigh and low training systems have variationsin which two separate foliage curtains areproduced, called divided canopies in contrastto the non-divided canopies.

Divided canopies are used for varietieswith high vigor; since they have twice as muchcordon length per plant, they make it possibleto keep more buds on each vine withoutcrowding the spurs, therefore increasing theyield from each vine, generally without reduc-ing the fruit quality. Dividing the canopy candecrease shading of fruit and allow better airmovement in the fruiting zone.

Systems with high or low cordons shouldbe selected according to the growth habit ofthe variety. Most American grape varietieshave trailing growth habits. Their shootsnaturally hang down, and a system with a highfruiting zone is more appropriate. Frenchhybrids can vary in their growth habits. Lowcordon systems with the shoots trained upwardmay be selected for those with an uprightgrowth habit.

The following systems represent possiblecombinations of single and double curtainsystems; horizontally and vertically divided;and shoots trained upward or downward.Variations exist for several of these systems, butthe pruning principles remain the same.

High Cordon (HC)High Cordon (HC)High Cordon (HC)High Cordon (HC)High Cordon (HC)The cordon wire is about 6 to 6½ feet

above ground level and cordons are trainedbilaterally from the trunk. Often two trunks aregrown, producing one cordon from eachtrunk. The shoots grow downward, so duringpruning spurs that are oriented downwardshould be selected (Figs. 8-1a and 8-1b).

Low Cordon (LC) or Vertical ShootLow Cordon (LC) or Vertical ShootLow Cordon (LC) or Vertical ShootLow Cordon (LC) or Vertical ShootLow Cordon (LC) or Vertical ShootPositioning (VSP)Positioning (VSP)Positioning (VSP)Positioning (VSP)Positioning (VSP)

Contrasted with the high cordon, the fruitingwire of the LC is 36 to 44 inches above theground, and growth is held above the cordonwith sets of movable catch wires at 17 to 21 and34 to 42 inches above the fruiting wire. Shootsare often topped after they reach the highest setof catch wires, maintaining about 4 feet ofcanopy. During pruning select spurs that areoriented upward. Both HC and LC systems havenon-divided canopies (Fig. 8-2).

Fig. 8-1a.Fig. 8-1a.Fig. 8-1a.Fig. 8-1a.Fig. 8-1a. High cordon system. Shoots above thecordon should be removed duringpruning.

Fig. 8-1b.Fig. 8-1b.Fig. 8-1b.Fig. 8-1b.Fig. 8-1b. High cordon system after pruning.

31

Geneva Double Curtain (GDC)Geneva Double Curtain (GDC)Geneva Double Curtain (GDC)Geneva Double Curtain (GDC)Geneva Double Curtain (GDC)This and the following training systems

have divided canopies. In the GDC system thecurtains are divided vertically. When prunedand shoot positioned correctly, two canopies,side by side, should be visible. To achieve this,the curtains must be separated occasionally.The area between the two fruiting wires mustbe kept clear of shoots. To achieve this, shootsare postitioned or removed away from thisarea. Shoots and spurs grow downward; oftenone trunk each is trained to one set of fruitingwires, spaced 48 inches apart (Fig. 8-3).

Open Lyre or UOpen Lyre or UOpen Lyre or UOpen Lyre or UOpen Lyre or UContrasted with the GDC system, the Lyre

system has two sets of low bilateral cordons,multiple trunks and shoots trained upwardsusing catch wires and topping. The canopiesare vertically separated, about 30 inches apart(Fig. 8-4).

Scott Henry (SH)Scott Henry (SH)Scott Henry (SH)Scott Henry (SH)Scott Henry (SH)In an SH system, the canopies are vertically

divided and stacked on top of each other.Shoots growing from the lower set of bilateralcordons are trained downward, shoots fromthe upper bilateral cordon are trained upwardswith catch wires and are topped (Fig. 8-5).

Training and Pruning

Fig. 8-2.Fig. 8-2.Fig. 8-2.Fig. 8-2.Fig. 8-2. Low cordon system. Left, shoots growing downward should be removed during pruning.Right, Low cordon system after pruning. The two sets of two wires close together are the catch wires.

Fig. 8-3.Fig. 8-3.Fig. 8-3.Fig. 8-3.Fig. 8-3. Left, GDC system before pruning. The middle wire helps to train the vine.Right, GDC system after pruning. The next vine would be trained to the opposite side of the trellis.

32


TrainingTrainingTrainingTrainingTraining

Training the vine takes place in the first 2 to3 years after planting. The goals are to estab-lish a strong root system, and a framework forthe desired training system, including a straighttrunk that will be able to support much of thevine’s weight once the vine has matured.

Year OneYear OneYear OneYear OneYear OneAt planting, a support system for the vine

should be installed. This can be a string tiedfrom a spur on the plant to the top trellis wireor a stake placed next to the vine and attached

Fig. 8-4.Fig. 8-4.Fig. 8-4.Fig. 8-4.Fig. 8-4. Left, Lyre or U system before pruning. All downward growing shoots should be removed.Right, Lyre system after pruning.

Fig. 8-5.Fig. 8-5.Fig. 8-5.Fig. 8-5.Fig. 8-5. Left, Scott Henry system before pruning.Right, Scott Henry system after pruning. The broken lines are the catch wires.

to the top wire with a clip. As growth occurs,the shoots are loosely fastened to their supportby tying (Fig. 8-6). A tape fastener can speedthis up considerably. A medium to lightweight tape (4 to 6 gauge) will break as thetrunks of the vines expand, eliminating theneed for removal of the ties. Other ties and clipsystems are available.

Vines in their first growing season shouldnot be pruned, as all top growth is needed toestablish a root system as large as possible.

33

Grow tubes can be used to protect thevines from herbicide sprays and to promoteshoot growth. The narrowness of the tubes alsomakes it easier for the tendrils of the newgrowth to attach to the support, eliminating theneed for tying until the shoots emerge from thetop of the tubes. The tubes provide a ‘green-house’ environment, increasing temperaturesand moisture levels and providing shelter fromwinds that could cause breakage and dry outnew growth. Tubes also protect vines frommechanical injuries and damage by rabbitsand deer, at least until the shoots emerge at thetop. Various types of tubes have been used,and no differences in effectiveness betweentypes have been reported. All tubes need to beremoved about 4 to 6 weeks before the date onwhich the first freeze is expected. This gives thevines time to harden off (to be able to withstandlow winter temperatures).

Year TwoYear TwoYear TwoYear TwoYear TwoAfter the danger of severe freezes is over,

the young vines should be evaluated. Vineswith very little, thin growth should be cut back

to leave only 2 to 3 buds. They can then betreated as described for the first year.

If several healthy canes have grown, 2 or 3should be selected as future trunks. If possible,the selected canes should be about pencilthickness and the nodes should not be muchmore than 4 to 5 inches apart. Usually nomore than two trunks per vine are developed.This makes it easier and faster to replace partsof a vine that have been injured by coldtemperatures or disease.

Remove any competing shoots that de-velop on the lower portion of the canesselected at trunks. The canes should befastened to the support system. Any canes thatreach a fruiting wire can be either bent overgently and fastened to the wire, or they can betopped just about at the height of the wire. Ifthe latter method is used, side shoots develop-ing from the buds at wire height will befastened to the fruiting wire. If the shootshaven’t reached the fruiting wire, continuetraining them up the support.

All fruit should be removed, so that thevine can put all its energy into growth ofshoots and roots. An exception to this rulewould be extremely vigorous vines that havealready filled their space on the fruiting wire.On vines like this you can leave 3 to 4 clustersper cordon.

Year ThreeYear ThreeYear ThreeYear ThreeYear ThreeTraining should be completed for most

vines during the third year. Canes for trunkshave been selected and trained to reach thefruiting wire. The canes trained horizontally onthe fruiting wires will start forming the cordons.On plants where this is not the case, treat theplants as in year two.

To form the cordons, tie and wrap canesloosely around the wires. Any side shoots on


Fig. 8-6.Fig. 8-6.Fig. 8-6.Fig. 8-6.Fig. 8-6. Young vine at planting (left) and newgrowth tied to a stake (right).

34


these canes should be cut back to 4 to 5 buds,spacing these spurs out on the entire length ofthe cordon. To encourage side shoot forma-tion on a cane, leave the cane 3 to 4 footlonger than needed to fill the space on thefruiting wire and let this ‘extra’ portion droopdownward. This removes inhibition of budbreak due to apical dominance on the middlepart of the cane (Fig. 8-7).

As in year two, vines should be defruited,with the exception of very vigorous vines thathave already filled their space. In the case ofVignoles vines, the crop should be thinned toabout one cluster per shoot or less.

PruningPruningPruningPruningPruning

Year Four and OlderYear Four and OlderYear Four and OlderYear Four and OlderYear Four and OlderAt this point, the framework for the training

system should be present. The emphasis nowshifts from encouraging purely vegetativegrowth to maintaining a balance betweencropping and vegetative growth. This is ex-pressed in the concept of balanced pruning(Howell et al., 1987; Partridge, 1926). Thegoal is to produce a profitable crop everyyear, while maintaining enough vegetativevigor to support this crop. If the crop load istoo large, vegetative growth slows down orstops and the vine will be weakened. If thecrop load is too light, the vines will producemuch more vegetative growth, shading thefruit, lesseningquality, andshading newbuds, resulting inloss of fruitful-ness thefollowing year.

When usingbalanced prun-ing, the number

of buds left on the spurs of a vine is deter-mined by pruning weight of the vine. TheTheTheTheThepruning weight includes only the weight ofpruning weight includes only the weight ofpruning weight includes only the weight ofpruning weight includes only the weight ofpruning weight includes only the weight ofprevious season’s shoots that are removedprevious season’s shoots that are removedprevious season’s shoots that are removedprevious season’s shoots that are removedprevious season’s shoots that are removedfrom the vine; do not include the weight offrom the vine; do not include the weight offrom the vine; do not include the weight offrom the vine; do not include the weight offrom the vine; do not include the weight oftwo year old or older woodtwo year old or older woodtwo year old or older woodtwo year old or older woodtwo year old or older wood. The vine is‘rough pruned’, leaving more spurs on thecordons than needed in the end. The removedshoots are then weighed and the number ofbuds is calculated as follows: A fixed numberof buds is left for the first pound of pruningweight, and another fixed number of buds isadded to the previous number for eachadditional pound of prunings. The numbershave been determined by long-term observa-tions, confirmed by research at severallocations, and vary among species andcultivars.

Fig. 8-7.Fig. 8-7.Fig. 8-7.Fig. 8-7.Fig. 8-7. Three year old vine, tied to a stake, bentand wrapped loosely around the fruitingwire. Trunk length will depend on trainingsystem selected.

Pruning weight Buds left for Buds left for Total budsin pounds the first pound additional pounds left on the vine

1 20 0 201 1/2 20 0.5 x 10 = 5 252 20 1 x 10 = 10 302 1/2 20 1.5 x 10 = 15 353 20 2 x 10 = 20 40

Table 8-1. 20 + 10 balanced pruning formulas

35


For most French-American hybrids theformula is 20+10. Table 8-1 contains ex-amples on how to use this formula.

For American grape varieties, such asNorton/Cynthiana, Concord, Niagara andothers, the formula changes to 30+10. Thesecultivars are generally very vigorous. Thevarieties Seyval Blanc (5 +10) and Vidal Blanc(15+10) tend to overcrop, and the slightlylower bud numbers will help to reduce croploads.

Low vigor vines, usually defined as vineswith less than 1 pound of prunings, are oftendefruited to encourage vine development.Mark these vines at pruning time, and removeflowers or developing clusters in late spring.

The maximum number of buds left on avine is usually 65-75 buds on vines spaced 8feet apart in the row, with rows spaced 10 feetapart.

Once the number of buds has been deter-mined, spurs of 4 to 5 buds each are selected.They should come from canes that are live(green inside when cut), healthy looking andabout pencil sized. Canes with a much largerdiameter and nodes that are widely spaced arecalled ‘bull canes’; they will not be fruitful.Canes from the outside of the canopy are alsomore fruitful than those grown on the inside ofthe canopy where the light levels were lower.

Spurs should be evenly spaced across theentire cordon length and not clustered to-gether; this will help to avoid shading duringthe growing season. The position of the spursshould also be selected according to thetraining system (upward or downward facing).Close to each of the fruiting spurs, one or twospurs with only 1 to 2 nodes should be left onthe cordon. These are ‘renewal’ spurs, andshoots growing from these will replace, or

renew, the fruiting spurs of the current year.Renewal spurs especially should be kept asclose to the cordon as possible. While this alsoapplies to fruiting spurs, it is not as crucialhere, as these spurs will be removed thefollowing year. Keeping the renewal zone closeto the cordons prevents the fruiting zone fromshifting slowly ever more outward (Fig. 8-8).

This pruning is often referred to as dormantpruning because is it carried out during thedormant, or winter, season. Often ‘roughpruning’ is done earlier in the winter, andadjusting the bud numbers is carried out onlyafter the danger of severe and potentiallydamaging freezes is over, in late winter/earlyspring, up to bud break. Pruning cuts madeclose to bud break will ‘bleed’. This does notappear to harm the vines.

Shoots forming on trunks and from thebase of the vine are called “suckers” but areactually basal shoots and not suckers fromroots. Unless a shoot is needed to replace atrunk or a cordon, they should be removedperiodically, especially during spring and earlysummer. Also, any areas on the cordons wheremany shoots grow from buds directly on the

Fig. 8-8.Fig. 8-8.Fig. 8-8.Fig. 8-8.Fig. 8-8. Close-up showing part of the cordon, afruiting spur with 4 buds, and a renewalspur with 1 bud. The two remaining budsdirectly on the cordon are non-count buds.

36


cordon should be thinned during any time ofthe growing season. This thinning, as well asany hedging or topping of plants during thegrowing season, is often referred to as summerpruning.

Cluster ThinningCluster ThinningCluster ThinningCluster ThinningCluster ThinningDormant pruning is the most important

means of adjusting crop levels. In some variet-ies, especially those where shoots arisingdirectly on the cordons are fruitful, the cropload might need further adjusting to maintainfruit quality. This is generally done by remov-ing some flower or berry clusters as earlyduring the growing season as possible.

Cluster thinning is particularly importantfor table grapes and large clustered FrenchAmerican hybrids. Cluster thinning removessmall and sparse clusters, increases berry sizeand cluster weight of remaining clusters, andbrings weak vines into balance betweenfoliage and fruit. Begin thinning clusters 2 to 3weeks before bloom, and finish no later thanone week postbloom. One or two clusters areleft per shoot; the cluster thinning procedureleaves the basal cluster and sometimes thesecondary cluster. The following cultivars arethinned to two clusters per shoot: Mars andVanessa. The following cultivars are thinned toone basal cluster per shoot: Seyval, Vidal,Chambourcin, and Reliance. Remove allclusters from low vigor vines, such as thosewith less than one pound of prunings.

Shoot PositioningShoot PositioningShoot PositioningShoot PositioningShoot PositioningShoot positioning reduces shading in the

upper part of the canopy, where next year’sfruiting wood is developing. Developing woodthat is exposed to the sun will have improvedfruitfulness the following year. Shoot positioning

also increases fruit exposure to sun, air move-ment, and pesticides, which will improve fruitquality and reduce disease problems.

Shoot positioning improves canopy micro-climate, and involves separating the shootsand positioning them in a way to maximizelight and air penetration into the fruiting zone.With high cordon systems, such as the bilateralcordon and the Geneva Double Curtain, theshoots are positioned in an outward anddownward position. With low cordon systems,such as the VSP or the Lyre, the shoots arepositioned in an upward position, usually withthe aid of pairs of catch wires. With dividedcanopy systems (GDC or Lyre), shoots are notallowed to grow into the zone between thecanopies. Positioning is done manually ormechanically with specialized equipment. Thebest time to position shoots is one to twoweeks post-bloom, when the tendrils are stillsoft enough to easily separate and the shootsare strong enough to resist excessive breakage.

MechanizationMechanizationMechanizationMechanizationMechanizationPruning, canopy manipulations such as

shoot positioning, and harvesting are laborintensive. Besides making these processesexpensive, labor is often insufficient or notavailable when needed. To address theseproblems, systems have been, and are still,being developed to mechanize pruning,canopy management and harvesting.Single curtain, spur pruned cordon systems arethe easiest to mechanically prune and positionbecause the shoots are evenly distributed.Some hand labor is still needed to ‘clean up’after the machines have gone through, but thetime involved is significantly reduced. Simi-larly, cordon systems are easier tomechanically harvest.

37

The Midwest is fortunate to have a reason-ably consistent rainfall pattern throughout theyear. However, there is enough inconsistencyin the pattern, especially in the summermonths, to make it economical to irrigate avineyard. Young vines are susceptible todrought conditions. During the first two yearsafter planting irrigation can pay for itself in vinesurvival and in vine growth. Even in years withadequate rainfall for mature vines, there canbe extended periods without rain, which canhurt newly planted vines. Thus systems shouldbe sized to take care of new vineyards, that is,the first 3 or 4 years, and then to help with oldervineyards in those years when extended dryperiods occur. Always look into the future atplans for expansion and design the system withexpansion in mind.

Irrigation design is a broad topic that cannotbe covered in a few pages. Use the services of anirrigation specialist from the beginning. It’s easierand less expensive to correct a problem onpaper than one in the field.

This chapter will help you develop ques-tions that need to be answered by a specialist,thoughts to help in your discussion with thespecialist, and information on irrigation basics.

Water sourceWater sourceWater sourceWater sourceWater source

There are several questions that must beanswered first before planning your irrigationsystem. What is the source of irrigation water?

Do you have a well? Will you dig a well? Whatis the expected output of your well? Generally,the deeper the well, the higher the output thatwill be obtained. But, the deeper the well thehigher the cost to drill and the more expensivethe pumping equipment needed.

Will you use a pond, a creek, or a river foryour irrigation water? Ponds are expensive tobuild but can provide a source of water. Theremust be a suitable site for pond constructionnear the vineyard. The pond must be sized toprovide the needed water for the proposedvineyard and any future expansion. If a streamor river is to be used, is there sufficient flow forirrigation, particularly during extendeddroughts? In some cases government permitsmust be obtained to withdraw water from thesource. Will the government allow sufficientwater removal to meet expected needs? Whenusing open water sources the water must befiltered to remove contaminants, which wouldplug emitters. Filter systems can be expensiveand require constant upkeep.

Sizing the SystemSizing the SystemSizing the SystemSizing the SystemSizing the System

The size of the system will depend on theanswers to a few questions. What is the size ofthe vineyard or proposed vineyard? Is thevineyard an older established planting or anew vineyard? What is the expected output ofthe water supply? What funds are available toobtain a water source? All of these questionsare interrelated. If a well is available, what is


Irrigation SystemsIrrigation SystemsIrrigation SystemsIrrigation SystemsIrrigation Systems

38


the output? If an open water source is avail-able, such as a pond, how much water can bewithdrawn from the pond? How fast will thepond refill?

ComponentsComponentsComponentsComponentsComponents

The basic component of an irrigationsystem is the emitter, where the water meetsthe plant. There are many styles with varyingoutputs to consider. There are the drip emittersand then there are the micro-sprinkle emittersthat spray a relative large area under the plant.Generally the drip emitters are used in grapes.Drip emitters include plug-in types and in-linetypes. With in-line emitters there are differ-ences in spacing in addition to different wateroutputs. Output is given in gallons per hour orliters per hour. Spacing can vary from 1 foot to10 feet between emitters.

Generally, for grapes use one or twogallons per hour output and a spacing whichallows two emitters per plant. For example, ifvines were spaced at 8 feet then emitterswould be spaced at three to four feet to givetwo emitters per vine. The output of the emitterwould be selected based on the total output ofthe water supply and the size of vineyard to beirrigated. Another consideration would be thenumber of zones the vineyard can or might bedivided into. Zones are areas that can or must beirrigated separately.

The next component is the black polyethyl-ene tubing that carries water down the row.These lines are referred to as laterals. Theemitters are either inserted into the tubing orbuilt into the tubing when manufactured. Thesize of tubing is dependent upon the emitteroutput and the number of emitters the linemust support. Generally, 16-mm tubing isstandard for row lengths of 400 to 800 feet.An irrigation specialist can help with sizingthe lateral lines.

DefinitionsDefinitionsDefinitionsDefinitionsDefinitions

The following definitions will aid in yourunderstanding of irrigation systems and whentalking with irrigation designers or sales repre-sentatives. The design of an irrigation systemcan be complicated and a design engineer orspecialist should be used for your needs.

Air vents Air vents Air vents Air vents Air vents - Devices that release air from theirrigation system. The two basic types arecontinuous and non-continuous. The non-continuous type releases large volumes of airas the system is being pressurized and is sealedwhen the system is fully pressurized. Thecontinuous vents release air while the system ispressurized and functioning.

Check valves Check valves Check valves Check valves Check valves - Devices that prevent water fromflowing back in the direction from which itcame. Check valves are needed where fertil-izer/chemical injectors may be used. Also,they are needed at the wellhead to keep waterfrom flowing back down the well and allowingair back in the system.

EmittersEmittersEmittersEmittersEmitters - the point where water is releasedfrom the lateral to the soil. Emitters releasewater at low pressures and low flow rates.Emitters may be molded into lateral lines, orcan be mechanically inserted into the lateralline.

Lateral lines Lateral lines Lateral lines Lateral lines Lateral lines - Water lines that move waterdown individual rows of the planting andgenerally contain the emitters.

Mainline Mainline Mainline Mainline Mainline - The main water line that carries waterfrom pump to the field and distribution lines.

ManifoldManifoldManifoldManifoldManifold - The manifold water line connectsthe lateral lines to the mainline.

Output Output Output Output Output - The amount of water released in unitsper time at the reference point. Example: an

39

emitter has an output of 1 gallon per hour or awell has an output of 100 gallons per minuteat the head.

Pressure relief valve Pressure relief valve Pressure relief valve Pressure relief valve Pressure relief valve - Device that drains offexcess pressure at any place the pressuremight exceed the system design capability.

Pumps Pumps Pumps Pumps Pumps - Device that provides a prescribedamount of water at a given pressure. There aremany types of pumps. The right one for youwill depend on the water source, the irrigationsystem needs, and the amount available tospend on the pump.

Irrigation Systems

Sub-mainline Sub-mainline Sub-mainline Sub-mainline Sub-mainline - Water lines that break thesystem down at various points and distributeswater to individual plantings.

Valves Valves Valves Valves Valves - Devices that control the flow of waterfrom one line to another at various points inthe system. Generally there is a main valve atthe source or pump. Then there are valves atfilters, sub-main lines, chemical injector loca-tions and finally at drainage points. There aretwo main types of valves: butterfly or gatevalves. They can be either manual or auto-matic types.

40


41

Fertility management in a vineyard beginsduring the site selection and preparationperiod. A soil test of the proposed vineyard sitewill yield valuable information on soil pH andnutrient status. Information on collection andsubmission of soil samples is available fromUniversity of Missouri Outreach and Extensionoffices. The suggested soil pH range for hybridand American grape cultivars is 5.5 to 6.5. Thesuggested ranges for soil potassium (K) and soilphosphorus (P) are 150 to 250 and 80 to 100pounds per acre, respectively. Base saturationnumbers of 65% to 75% for calcium, 10% to15% for magnesium, 3% to 5% for potassium,and less than 2% for sodium should be ad-equate (Wolf et al., 1995).

Agricultural lime is commonly used to raisesoil pH. The amount needed depends oninitial and target pH, and the ENM rating of thelime. Dolomitic limestone will add magnesiumas well as raise pH. Add sufficient amounts ofK and P fertilizers to bring soil levels to sug-gested ranges. All of these materials are bestadded during the site preparation period,when incorporation into the soil is possible.

Newly planted grape plants usually do notrequire additional nutrients during the firstseason, as long as soil pH and nutrient levelsare adequate. Fertilization during the secondand third years is usually limited to nitrogen.Apply 0.66 to 1.66 ounces of actual N perplant in the second year, and double this ratein the third year. Apply the fertilizer in a ring

around each plant, but do not let fertilizercontact the plant. Apply dry fertilizers as budsbreak in the spring.

As vines mature and crops are harvested,vineyards may require periodic applications ofone or more nutrients, and adjustment of soilpH with lime. A combination of soil analysis,plant observation, and plant tissue analysis areused to determine grape nutrient needs.

A soil test is recommended every two orthree years in bearing vineyards to monitor soilpH. Agricultural lime is applied to raise the pH;do not apply more than 4 tons per acre perapplication. If additional lime is needed, splitthe application into 2 to 3 tons per acre appli-cations, spread over several years.

The grape grower should develop a profileof each cultivar in the vineyard with regards tovisual observations of growth. Among theinformation to collect for each cultivar ispruning weights of 6 to 10 vines, dates whenshoot growth ceases and trellis is filled withfoliage, size and color of leaves, yield of vines,average cluster weight, and fruit quality. Threeto four years of data collection are needed toestablish the profile.

Tissue analysis reveals the concentration ofessential nutrients within vine tissues. Ingrapes, the only tissue sampled is the leafpetiole, which is the slender stem that con-nects the leaf blade to the shoot. Basically,


Fertility Management in VineyardsFertility Management in VineyardsFertility Management in VineyardsFertility Management in VineyardsFertility Management in Vineyards

42


there are two reasons to collect petiolesamples. The first is the routine evaluation ofnutrient status. The second reason is to diag-nose a particular visible disorder in which anutrient problem is suspected (Gu, 1998).

Nutrient levels fluctuate in the vine, and noone sampling time is best for all nutrients.Petiole sampling at full bloom will provide agood measure of vine nitrogen, boron, andseveral other nutrients. Other nutrients, such aspotassium, are better sampled for at veraison.In practice, growers generally collect samplesat full bloom for routine evaluation of vinenutrient status. If a problem related to a specificnutrient such as potassium is suspected basedon the bloom sample, collect a second sampleat veraison. Petiole samples may be collectedat any time to help diagnose an unknownvisible disorder. In this case collect a sample ofthe tissue in question, and a second sample ofhealthy petioles from another vine for compari-son.

A petiole sample should represent a rela-tively homogenous management unit not morethan 10 acres in size. Sample each cultivarseparately, and make sure that the sampleuniformly represents the entire unit. Sampleseparately areas of different soil type or weakor strong vine areas. Avoid atypical leaves,diseased or damaged leaves, and dead orseverely stressed tissue. Don’t sample immedi-ately after a nutrient spray. Sample early in theday, before leaves are water stressed.

Each tissue sample should consist of 75 to100 petioles. For the bloom time sample,collect petioles from leaves opposite the first orsecond flower cluster from the bottom of theshoot, at full bloom. For the veraison sample,collect petioles from the youngest fully ex-panded leaves on the shoot, usually locatedfrom 5 to 7 leaves back from the shoot tip.Collect no more than 2 petioles per vine, and

choose leaves from shoots exposed to sunlight.Remove the leaf blade first, then remove thepetiole from the shoot. Place petioles in cleanpaper bags and keep cool. In most cases, drythe petioles as soon as possible in a dust freearea at room temperature. Label the driedsamples for your records, and submit thesamples to the University of Missouri Soil andPlant Testing Lab (local University Outreachand Extension offices can provide assistance).Private labs are also available to analyzepetiole samples. For consistent results, use thesame lab for each petiole sample.

Nitrogen is the nutrient used in greatestamounts by bearing vines, and is commonlyapplied annually to Missouri vineyards. Nosingle index serves well as a guide in assessingthe vine’s need for nitrogen fertilizer. Instead, anumber of observations made over severalyears is the best way to determine nitrogenstatus. Visual observation of vine growth is theprimary criteria, coupled with plant tissueanalysis for verification or as a backup injudging response to nitrogen fertilization.Table 10-1 summarizes the key characteristicsfor diagnosing nitrogen status. In general, anannual application of 40 to 80 pounds ofactual N per acre, applied at bud break, isrecommended. This amount is modified basedon the criteria mentioned earlier (Gu, 1997).

Of the other nutrients, potassium, magne-sium, and boron are most commonly related tonutrient problems. Petiole analysis, coupledwith visual observation of the vines, is used todetermine the status of these nutrients. Table10-2 includes sufficiency tissue levels forseveral nutrients (Wolf et al., 1995).

43

Fertility Management in Vineyards

Table 10-2. Sufficiency ranges of essential elementsbased on bloom-time sampling of leaf petioles(Wolf et al., 1995)

Nutrient Sufficiency Range

Nitrogen 1.20-2.20 %Phosphorus 0.15-? %Potassium 1.50-2.50 %Magnesium 0.30-0.50 %Iron 40-? ppmManganese 25-1000 ppmCopper 7-15 ppmZinc 35-50 ppmBoron 30-100 ppm

Table 10-1. Diagnosis of grapevine N status based on visual observation, vine growth,fruit quality, and petiole N contents (Vineyard and Vintage View 12(2):12)

Trellis filling by foliage

Yield

Pruning weight

Mature leaves

Shoot growth

Internodes

Fruit maturation

Fruit quality

Bloomtime petioletotal N

Bloomtime petiolenitrate-N

Fail to fill by Aug 1

Chronically low

< 1/4 lb per foot ofcordon or arm

Uniformly small andlight green or yellow

Slow and ceases inmidsummer

Short

Advanced

Poor, including poorcolor in red varieties

Less than 1%

<350 ppm

Fill by Aug 1

Acceptable

0.3 to 0.4 lb per foot ofcordon or arm

Normal size and uni-formly green

Rapid and ceases inearly fall

4 to 6 inches

Normal

Normal

1.2 to 2.2%

5000 to 1200 ppm

Fill with excessive foliage(more than 2 layers of leaves)Low due to fewer clusters and/or poor fruit set

> 0.4 lb per foot of cordonor arm

Exceptionally large and verydeep green

Rapid and ceases in late fall.8 to 10 feet by mid-July

> 6 inches and possiblyflattened

Delayed

Poor

Greater than 2.5%

> 2000 ppm

Deficient Adequate Excessive

44


Fig. 10-1.Fig. 10-1.Fig. 10-1.Fig. 10-1.Fig. 10-1. Bloomtime petiole sampling (Vineyard and Vintage View 13(2):4)

C.C.C.C.C. Fresh petioles ready to be sent for testingor drying

D.D.D.D.D. Dried petioles ready to be sent to the laboratory

A.A.A.A.A. Select petiole opposite the basal clusters duringfull bloom

B.B.B.B.B. Save the petiole and discard the blade

45

Disease management is an important andintegral part of grape production. The warmand humid growing season that characterizesthe grape growing areas of Missouri favors thedevelopment of many diseases, especiallythose caused by fungi. Disease managementrepresents a major annual expense in theproduction of grapes in this state as well asother areas of the middle and eastern UnitedStates.

Although grape growers rely upon fungi-cides as a major disease control strategy, otherstrategies remain important and can reducechemical useage. Among these are culturalmethods, sanitation, resistant cultivars, andpathogen-free planting stock.

Cultivar Susceptibility and FungicideCultivar Susceptibility and FungicideCultivar Susceptibility and FungicideCultivar Susceptibility and FungicideCultivar Susceptibility and FungicideEffectivenessEffectivenessEffectivenessEffectivenessEffectiveness

Cultivars differ in their susceptibility todiseases. For example, Catawba is extremelysusceptible to black rot and downy mildewand only slightly susceptible to powderymildew, whereas Chancellor is moderatelysusceptible to black rot and highly susceptibleto downy mildew and powdery mildew (Table11-1). Because of these differences the fungi-cides that should be used in a spray programwill depend upon the cultivar. Only fungicidesthat will effectively control the diseases specificto a cultivar should be used on that cultivar.Note that some cultivars are sensitive to sulfuror copper sprays (Table 11-1).

Specific fungicide recommendations arenot given in this publication, as these arefrequently revised. Refer to the Missouri Com-mercial Grape Pest Control Guide (MS-19revised annually) for current pesticide recom-mendations.

Disease ForecastingDisease ForecastingDisease ForecastingDisease ForecastingDisease Forecasting

Disease forecasting can be used to deter-mine when to apply fungicides for control ofcertain grape diseases. Forecasting plantdisease depends upon knowing the exactenvironmental conditions needed for initiationof infection by the pathogens causing thosediseases. Each different fungus causing a grapedisease requires a specific set of temperatureand moisture conditions to occur simulta-neously over a given period of time to cause aparticular disease. These conditions are neces-sary for spore formation, dispersal,germination, and penetration of susceptiblehost tissue by the pathogen.

The conditions required for black rotinfection are the easiest to illustrate as amodel for infection. After overwintering inold infected grape berries, and when thetemperature rises in the spring, the black rotfungus produces spores, which are ejectedinto the air under moist conditions. If thespores are carried by air currents to susceptibletissue such as leaves, shoots, flowers, anddeveloping fruit, infection will take place if aset of conditions occurs simultaneously.


Disease ManagementDisease ManagementDisease ManagementDisease ManagementDisease Management

46


Table 11-2 shows the temperature and leafwetness conditions that are favorable for blackrot infection. For example, at 55 oF grapeleaves must be wet for 12 hours for infection totake place, whereas at 70 oF only seven hoursof leaf wetness are required for infection.

A number of instruments are availablewhich can be used to forecast grape diseases.Black rot, which has a simple disease model,can be forecasted using no more than a ther-mometer and the observation of length of timethat vines are wet. However, the diseasemodels for predicting downy mildew, powderymildew and Botrytis bunch rot are much morecomplex and use additional environmentalparameters. Plant disease forecasting instru-ments are available which contain predictionmodels for several grape diseases on computerchips. These computerized instruments collectenvironmental data and make the determina-tion of when the infection period for aparticular disease has occurred.

In order to use infection period informationto control diseases, fungicides must be appliedwhich will kill or inhibit the growth of the

fungal pathogen after the infection process isinitiated. These fungicides are referred to asbeing curative or eradicative in their action.

Major Fungal Diseases in MissouriMajor Fungal Diseases in MissouriMajor Fungal Diseases in MissouriMajor Fungal Diseases in MissouriMajor Fungal Diseases in Missouri

Black RotBlack RotBlack RotBlack RotBlack Rot

Pathogen: Pathogen: Pathogen: Pathogen: Pathogen: Guignardia bidwelii (Ellis) Viala& Ravaz

Impact: Impact: Impact: Impact: Impact: Black rot is the most importantlimiting factor of grape production in Missouri. Itdevelops in every growing season and, if leftuncontrolled, it will destroy fruit on mostcultivars. The development of the pathogenis favored by the weather conditions duringmost of the spring and early summer, andtherefore the application of a preventivespray schedule during the susceptiblegrowth stages is essential. In fact, the chemi-cal control of black rot should form thebackbone of the spray schedule from mid-bloom until veraison. Because diseasebuildup can be explosive, the appearance ofsymptoms in the vineyard calls for an imme-diate application of a curative fungicide. Theonly cultivar that possesses good geneticresistance to this disease is Norton/Cynthiana.

Symptoms: Symptoms: Symptoms: Symptoms: Symptoms: Berries: sunken brown spotsdevelop and rapidly spread through the entireberry. Small black pustules develop in thecenter of the spots, the berry desiccates andthen becomes mummified in a matter of days,Leaves: tan spots develop with small blackpustules, concentric with the lesion margin;the leaf blade remains flat.

Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: From mid-bloom until veraison for flowers and fruit. Alsosusceptible from bud break to July for leaflesions.

Table 11-2. Black rot infection periodprediction table

Minimum Leaf WetnessTemperature oF duration in hours

for light infection

50 2455 1260 965 870 775 780 685 990 12

(Data from R.A. Spots, Ohio State University)

47

Favorable conditions: Favorable conditions: Favorable conditions: Favorable conditions: Favorable conditions: Warm, humid, andwet weather. Black rot develops only if warmtemperatures and free water (from rain or dew)on the plant surfaces coincide.

Control measures:Control measures:Control measures:Control measures:Control measures:Preventative spraysPreventative spraysPreventative spraysPreventative spraysPreventative sprays. Good control of

black rot is essential for the production ofgrapes in Missouri. To achieve adequatecontrol in most cultivars, preventative fungi-cide sprays must be applied on a regularschedule from the beginning of shoot develop-ment through veraison. Sprays should bereapplied after periods of rain that wash off theprotective coating of fungicide. An exception tothis is when systemic fungicides are used aspreventative sprays. Most systemic fungicides areeffective for up to seven days early in theseason during rapid growth and up to 14 daysafter growth has slowed later in the season.

If applied after the black rot fungus hasinfected the fruit or leaves, preventative spraysof non-systemic fungicides will not preventdisease development. Black rot control withpreventative non-systemic fungicide sprays isdependent upon keeping all susceptible plantparts coated with an effective fungicide. This isespecially important when rain and heavydews occur, since the black rot fungus initiatesnew infections only when the fruit and leavesare wet. Preventative sprays are applied atshorter intervals during the early part of theseason in order to keep the young tissue ofrapidly developing leaves and fruit coated.

Curative sprays.Curative sprays.Curative sprays.Curative sprays.Curative sprays. Curative fungicides,having “kick-back” action against black rot,can be applied up to 72 hours after the begin-ning of an infection period for control of blackrot. The sooner that a spray is applied after theinfection period, the greater the black rot controlachieved. However, preventative fungicidesprays should still be the basis for good black rotcontrol.

Cultural practicesCultural practicesCultural practicesCultural practicesCultural practices. Removal of mummifiedclusters from vines, and covering those mum-mified clusters that have fallen to the groundwith soil helps prevent the overwintering of thefungus. Maintenance of an open canopy topromote rapid drying of rain and dew willreduce black rot infections.

Downy MildewDowny MildewDowny MildewDowny MildewDowny Mildew

Pathogen: Pathogen: Pathogen: Pathogen: Pathogen: Plasmopara viticola (Berk &Curt.) Berl. & de Toni

Impact: Impact: Impact: Impact: Impact: The conditions of the Missourisummer are highly favorable for downy mil-dew. Fortunately, many hybrid and nativeAmerican grape varieties grown in the stateoffer some genetic resistance to this disease.Vinifera varieties, however, are extremelysusceptible to downy mildew, and need to bepainstakingly protected. If the weather stayswet and warm during September and earlyOctober, the leaves can get severely infected,and the plants can be prematurely defoliated.This may be a problem because the fallendiseased leaves will help overwinter a largeamount of inoculum for the following season,and because the defoliated plants will not beable to accumulate an adequate amount ofcarbohydrate for the winter. For these reasons,it is advisable to control the disease even afterharvest.

Symptom: Symptom: Symptom: Symptom: Symptom: Translucent, oil spot-like areasdevelop on the upper surface of the leaves.The spots rapidly turn yellow, and a whitevelvety growth (mildew) appears on the lowerside of the leaf, precisely opposite to the spots.Note that downy mildew always appears onthe lower side of the leaf, never on the top!Subsequently, the leaf spots turn necroticbrown and the mildew withers away.

Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: Flowers andfruit are susceptible until veraison; leaves and

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48


new shoot growth remain susceptible allthrough the season.

Favorable conditions: Favorable conditions: Favorable conditions: Favorable conditions: Favorable conditions: Warm, humid, andwet weather, especially when humid nights arefollowed by rainy days; disease develops onlyif warm temperatures and free water (from rainor dew) on the plant’s surface coincide.

Control measures: Control measures: Control measures: Control measures: Control measures: Any cultural practicethat promotes rapid drying of the foliage, suchas good weed control and high trellises, willhelp reduce downy mildew. Keeping canes onhigh trellises and removing suckers at the baseof the vine also lowers the chance of thefungus being splashed up on new growth inthe spring. Tilling fallen leaves into the soil willreduce overwintering inoculum of the fungusavailable for new infections in the spring.

Fungicide sprays are important in thecontrol of downy mildew. The frequency ofsprays should be increased in wet weather foradequate control on susceptible cultivars suchas Catawba.

Powdery MildewPowdery MildewPowdery MildewPowdery MildewPowdery Mildew

Pathogen: Pathogen: Pathogen: Pathogen: Pathogen: Uncinula necator (Schw.) Burr.

Impact: Impact: Impact: Impact: Impact: This disease rarely causes seriousdamage in Missouri because the weather tendsto be too hot and wet for the development ofthe pathogen. Nevertheless, mild and humidweather may facilitate the development of thedisease in susceptible cultivars. Care should betaken when the disease is controlled withsulfur sprays, because many of the hybrid andAmerican grape varieties grown in the state aresensitive to sulfur. In vineyards where powderymildew has become difficult to control inprevious years, a dormant lime sulfur sprayapplied shortly before budbreak providesexcellent control for the following growingseason. Lime sulfur applied during dormancy

does not present a danger to sulfur-sensitivevarieties.

Powdery mildew infection frequently devel-ops on the leaves of most varieties inSeptember and October in Missouri. If thevariety is susceptible to the disease, it is advis-able to control the pathogen at this stage toprevent a heavy inoculum pressure in thefollowing season.

Symptoms: Symptoms: Symptoms: Symptoms: Symptoms: White powdery growth (mildew)appears on the upper side of the leaves. Notethat this disease never develops on the lower sideof leaves! Fruit may crack open if heavily in-fected. Powdery mildew is usually accompaniedby a characteristic moldy odor in the vineyard.

Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: From immedi-ate pre-bloom to fruit set; heavy infection onolder leaves in September and October.

Favorable weather conditions: Favorable weather conditions: Favorable weather conditions: Favorable weather conditions: Favorable weather conditions: Humid andwarm (but not hot) weather; free water hindersdisease development.

Control measures: Control measures: Control measures: Control measures: Control measures: Powdery mildew hasbecome more important with the increasedplanting of some of the susceptible French-American hybrid and Vitis vinifera cultivars.During the growing season, preventativesprays of fungicides may be used on highlysusceptible cultivars to prevent an outbreak ofpowdery mildew. Maintenance of an opencanopy to lower humidity will help reducepowdery mildew infections.

Phomopsis Cane and Leaf SpotPhomopsis Cane and Leaf SpotPhomopsis Cane and Leaf SpotPhomopsis Cane and Leaf SpotPhomopsis Cane and Leaf Spot

Pathogen: Pathogen: Pathogen: Pathogen: Pathogen: Phomopsis viticola (Sacc.) Sacc.

Impact: Impact: Impact: Impact: Impact: Phomopsis is a cool climate dis-ease that develops in Missouri only when theweather is cool and wet during the early partof the growing season. The fungus causes

49

lesions at the base of the stem. It makes thestem brittle and may kill perennial wood. In adry or warm spring, the disease will not ap-pear. In Missouri, the economic impact of thisstage of the disease is questionable. As theweather warms up later in the spring, thepathogen stops growing but will survive in thetissues during the summer. If August turnscooler and rainy, the pathogen will resume itsgrowth, will sporulate, and may cause seriousfruit rot. The primary reason why the cane andleaf spot stage of disease needs to be con-trolled is to reduce the possibility of fruit rot byreducing inoculum levels.

Symptoms:Symptoms:Symptoms:Symptoms:Symptoms: On most hybrid grape varieties,small black spots develop on leaves andcanes; on Vitis vinifera varieties, cane lesionscan be larger and deeper. Leaf spots oftencoalesce along veins and are surrounded by ayellowish halo.

Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: From beginningof growing season until fruit set.

Favorable conditions: Favorable conditions: Favorable conditions: Favorable conditions: Favorable conditions: Cool, rainy weatherin April and May.

Control measures: Control measures: Control measures: Control measures: Control measures: Phomopsis cane andleaf spot is most likely to become a problemwhen inoculum is allowed to build up on thedead canes in the vineyard and if the weatheris wet during the first few weeks of shootgrowth. The disease can be controlled by acombination of sanitation and fungicideapplication. Pathogen-free propagation materi-als should be used for planting and replanting.Diseased and dead wood should be removedand destroyed by shredding, disking or plow-ing into the soil, or burning. Under heavydisease pressure, a preventative spray programshould begin as early as 1/2-inch shoot growthand continue through fruit set. The period frombloom through fruit set is a critical time toprevent fruit infection.

Phomopsis Fruit Rot and Rachis BlightPhomopsis Fruit Rot and Rachis BlightPhomopsis Fruit Rot and Rachis BlightPhomopsis Fruit Rot and Rachis BlightPhomopsis Fruit Rot and Rachis Blight

Pathogen: Pathogen: Pathogen: Pathogen: Pathogen: Phomopsis viticola (Sacc.) Sacc

Impact: Impact: Impact: Impact: Impact: The fruit rot/rachis blight stage ofthe disease occurs in Missouri only when theweather turns cool and rainy at the end ofJuly or early August. While such summerconditions are relatively rare, they do occuroccasionally and allow the disease to causeserious damage to the fruit. The problem canbe particularly severe if the leaves and thecanes had a heavy phomopsis infection inthe spring. Phomopsis fruit rot is quite diffi-cult to diagnose in its early phases, as thecharacteristic fruiting bodies (pustules) of thefungus will appear on the decayed berriesonly in the later phase of the disease. Ifsudden fruit decay is associated with shriv-eled-up rachis, it is likely to be caused byPhomopsis viticola.

Symptoms:Symptoms:Symptoms:Symptoms:Symptoms: Berries turn brown first anddevelop small black pustules only when theentire berry has been spoiled. Affected berriesremain round, but occasionally fall off therachis. When infected, the rachis shrivels upand dries out.

Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: Rachis infectioncan take place from cluster emergence untilripening; fruit infection can happen frombloom to pea-size berry stage, but symptomsdevelop only after veraison.

Favorable conditions: Favorable conditions: Favorable conditions: Favorable conditions: Favorable conditions: Cool, rainy weatherduring ripening; heavy rains appear important.

Control measures: Control measures: Control measures: Control measures: Control measures: The control measuresrecommended for the cane and leaf spotstage described above are essential forcontrol of the fruit rot stage. No fungicide isknown to provide eradicative control ofPhomopsis fruit rot once rot symptoms havedeveloped.

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50


Macrophoma RotMacrophoma RotMacrophoma RotMacrophoma RotMacrophoma Rot

Pathogen:Pathogen:Pathogen:Pathogen:Pathogen: Botryosphaeria dothidea(Moug. ex Fr.) Ces. & de Not

Impact:Impact:Impact:Impact:Impact: The pathogen that causesmacrophoma rot is a common microorganismin Missouri. The disease used to be knownonly as a fruit rot of muscadine grapes, butmore and more recent observations suggestthat it also is an important problem in grapevarieties grown in Missouri. In its early stages,the rot is difficult to identify and to differenti-ate from phomopsis fruit rot. The pathogen isable to grow in numerous woody plantspecies, causing such diverse diseases aswhite rot of apples and stem blight of blue-berries. Because many other plants canserve as inoculum source, it is important toeliminate abandoned fruit trees from thevicinity of the vineyard. The pathogenappears to be difficult to control in otherplant species, and nothing is known aboutits control in grapes in Missouri.

If fruit rots present a perennial problem inthe vineyard, the most promising solution maynot come from the application of a novelfungicide, but from canopy management. Themaintenance of an open canopy that driesrapidly and that maintains low air humidity isthe best way to prevent fungal growth.Chardonel is susceptible.

Symptoms: Symptoms: Symptoms: Symptoms: Symptoms: This fungus blights rachis andflowers and spoils berries. In the early stages,the rachis becomes soft and off-colored, andlater develops elongated black lesions; parts ofthe cluster may become blighted. Rot of ripeberries occurs suddenly and may be associ-ated with rachis blight.

Susceptible growth stages:Susceptible growth stages:Susceptible growth stages:Susceptible growth stages:Susceptible growth stages: Rachis is sus-ceptible from fruit set to bunch closing, berriesbecome susceptible after veraison.

Favorable conditions:Favorable conditions:Favorable conditions:Favorable conditions:Favorable conditions: Not well known, butrain and wet weather appear to favor thedevelopment of the disease.

Control measures:Control measures:Control measures:Control measures:Control measures: Sprays applied immedi-ately after bloom and continuing to harvesthave been recommended for control of thisdisease in other areas. No fungicide is knownto provide eradicative control once the diseasehas established itself. Maintenance of an opencanopy, removal of old diseased trees fromaround the vineyard, and sanitation (pruningout of old wood, removal of diseased plantmaterial) will aid in control of Macrophoma.

Botrytis Bunch RotBotrytis Bunch RotBotrytis Bunch RotBotrytis Bunch RotBotrytis Bunch Rot

Pathogen: Pathogen: Pathogen: Pathogen: Pathogen: Botrytis cinereaBotrytis cinereaBotrytis cinereaBotrytis cinereaBotrytis cinerea Pers. Pers. Pers. Pers. Pers.Impact:Impact:Impact:Impact:Impact: Recent evidence indicates Botrytisbunch rot probably does not occur in Missourias often as had been assumed. Other late-season berry rots are often mistakenlyidentified as caused by B. cinerea. However,Botrytis can cause economic losses, particu-larly on some tight clustered hybrid andvinifera cultivars in cool weather. Once estab-lished, infection can move rapidly throughoutberries on a cluster.

SymptomsSymptomsSymptomsSymptomsSymptoms: Early infections of new growthcause tissue to turn brown and dry out. Infec-tions can spread from infected flower parts andaborted fruit to the rachis and pedicels causingbrown spots that later turn black. Ripeningwhite grapes turn brown and dark-colored fruitturn red. Infection spreads rapidly within tightclustered cultivars. In wet weather, infectedberries become covered with a brownish-graymold.

Susceptible growth stagesSusceptible growth stagesSusceptible growth stagesSusceptible growth stagesSusceptible growth stages: Any new growth,especially flowers. Fruit from veraison to harvest.

Favorable conditionsFavorable conditionsFavorable conditionsFavorable conditionsFavorable conditions: Cool, damp weatherwith 56 to 66 oF optimal for infection. High

51

temperatures during the latter part of theseason inhibit the bunch rot phase.

Control measuresControl measuresControl measuresControl measuresControl measures: Cultivars differ in sus-ceptibility to Botrytis bunch rot based on thecompactness of their clusters, the thicknessand anatomy of the berry skin, and theirchemical composition. Susceptible cultivarsmay need to be protected against Botrytis bunchrot by a combination of cultural practices andchemical control. Disease development can bereduced by avoiding excessive vegetativegrowth. This can be accomplished with culturalpractices such as controlled nitrogen fertiliza-tion, increased aeration and exposure ofclusters to the sun with appropriate trellisingsystems, shoot positioning, and leaf removal.Controlling diseases and insect pests capableof injuring the berries, particularly the grapeberry moth, will also reduce Botrytis bunch rotdevelopment. Botrytis bunch rot can bechemically controlled only with preventivetreatments. Leaf removal in the fruiting zoneimproves spray coverage and drying of clustersafter periods of dew and rain, thus reducingthe incidence of Botrytis.

Bitter RotBitter RotBitter RotBitter RotBitter Rot

Pathogen: Pathogen: Pathogen: Pathogen: Pathogen: Greeneria unicola (Berk & Curt.)Punithalingam

Impact:Impact:Impact:Impact:Impact: Bitter rot occurs on grapes in warmhumid areas. The causal fungus attacks musca-dine as well as bunch grape species. Infectedfruit have a bitter flavor that is carried throughthe winemaking process, imparting a burnt,bitter taste to wine. Catawba seems to beespecially susceptible with entire clustersrotting at harvest. Lack of control can result ina total crop loss.

Symptoms:Symptoms:Symptoms:Symptoms:Symptoms: Bitter rot is often mistaken forblack rot because the symptoms are similar.However, bitter rot infections of the fruit occur

in late season, whereas black rot infections donot occur after veraison. Although the patho-gen can invade undamaged ripening fruit, itsoccurrence is usually associated with crackingat the point where the fruit is attached to thepedicel. The first visible sign is the develop-ment of black pimple-like structures of thefungus on the skin around the pedicel andspreading in a matter of a few days to coverthe entire surface. At the same time, white- tolight red-colored cultivars turn brown whiledark red- to black-fruited cultivars remain dark.The fruit begin to shrivel and regardless ofcolor eventually turn black. Under certainweather conditions the fungus can spreadthroughout an entire cluster of fruit.

Favorable conditions:Favorable conditions:Favorable conditions:Favorable conditions:Favorable conditions: Warm wet weatherat ripening favors the development of bitter rot.It usually occurs more frequently on berries ofcultivars that have a tendency to split at thepedicel due to rain at ripening. However, otherdamage, such as that caused by insects orbirds, during ripening can also provide a pointof entry for the pathogen.

Control measures:Control measures:Control measures:Control measures:Control measures: Since bitter rot candevelop so rapidly, late season fungicidesprays are important for control on cultivarsthat have a tendency to crack in wet weather.However, these fungicides must be applied asprotective sprays. Prevention of insect and birddamage is also an important control measure.

AnthracnoseAnthracnoseAnthracnoseAnthracnoseAnthracnose

Pathogen: Pathogen: Pathogen: Pathogen: Pathogen: Elsinoe ampelina (de Bary) Shear

Impact: Impact: Impact: Impact: Impact: Anthracnose causes damage mostfrequently by weakening the canes, andthereby predisposing them to breakage inwindy weather. The disease proves to bedifficult to control once established during thegrowing season. Damage to fruit is usually notsignificant.

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Symptoms: Symptoms: Symptoms: Symptoms: Symptoms: The canes develop necroticlesions on the basal internodes. The lesionspenetrate deep into the stem, making it brittle.Young leaves develop gray, necrotic spots thatare often irregular in shape and may coalesce.Spots are surrounded by a yellowish or redhalo. The center of the lesions may fall out,giving a shot-hole appearance. As leavesexpand, tissue around the lesions becomespuckered and may tear in windy conditions.The fruit develops circular lesions that aresunken with a dark margin and gray center.

Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: Susceptible growth stages: Starting fromflowering, the plants are susceptible as long assucculent green tissues are formed.

Favorable conditions: Favorable conditions: Favorable conditions: Favorable conditions: Favorable conditions: Heavy rains andwarm weather.

Control measures: Control measures: Control measures: Control measures: Control measures: Research in Missourihas shown that certain grape cultivars, includ-ing Cayuga White, Reliance, and Vidal blanc,are highly susceptible to anthracnose. Invineyards where anthracnose has become aproblem, a dormant spray of liquid lime-sulfuris essential for effective control. Lime sulfurapplied during dormancy does not present adanger to sulfur-sensitive varieties. Protectionof the rapidly growing, succulent, green shootsof susceptible cultivars with fungicides is alsoimportant. Pruning out infected wood duringdormancy and removal from the vineyardprior to budbreak should reduce primaryinoculum of the anthracnose fungus in thecoming growing season.

Eutypa DiebackEutypa DiebackEutypa DiebackEutypa DiebackEutypa Dieback

Pathogen:Pathogen:Pathogen:Pathogen:Pathogen: Eutypa armeniacae Hansf. &Carter

Impact: Impact: Impact: Impact: Impact: Although eutypa dieback ispresent in Missouri, the disease is not con-sidered economically important. As more

and more vineyards are coming of age,however, it is important to scout for thesymptoms in the spring. Eutypa slowly killsinternal tissues in perennial wood, causingpartial or complete dieback of cordon armsor entire vines.

Symptoms:Symptoms:Symptoms:Symptoms:Symptoms: Young shoots are stunted withshort internodes and small, cupped and occa-sionally tattered leaves. The leaf symptoms arebest visible in May and early June when normalhealthy shoots are less than 10 inches long.

Susceptible growth stages:Susceptible growth stages:Susceptible growth stages:Susceptible growth stages:Susceptible growth stages: Infection occursduring the winter and spring when freshpruning wounds provide access to the internaltissues for germinating spores.

Favorable conditions: Favorable conditions: Favorable conditions: Favorable conditions: Favorable conditions: Warm periodsduring dormant pruning, especially whenplants are in deep dormancy and woundhealing is slow.

Control measures:Control measures:Control measures:Control measures:Control measures: Sanitation is essential.Dead grape wood should be removed fromthe vineyard and destroyed. In regions whereeutypa dieback is a serious problem, the use ofa double trunk system is recommended. InMissouri, no fungicide is labeled for the protec-tion of pruning wounds.

Oxidant StippleOxidant StippleOxidant StippleOxidant StippleOxidant Stipple

Ozone-induced injury, known as oxidantstipple, is a foliar disorder that sometimesoccurs in Missouri vineyards. Initial symptomsare small brown flecks on the upper surfaces ofmature leaves. These flecks can increase insize later in the growing season, resulting inlarge necrotic areas. Severe cases have beenassociated with reduced yield and solublesolids. In general, American grapes are moresusceptible to oxidant stipple than hybrids, butlarge cultivar differences are seen within eachgroup. The most severely affected cultivars

53

(many of which are not recommended forMissouri) listed in descending order of suscepti-bility are Ives, Elvira, Concord, Chambourcin,Baco noir, Leon Millot, Marechal Foch,Rougeon, Catawba, DeChaunac, Villard noir,and Villard blanc.

While the grower has no control over airquality within the vineyard, certain vineyardpractices can influence the severity of oxidantstipple damage. Maintaining optimal nitrogenlevels, controlling crop size, and avoidingexcessive irrigation lessen the degree of damage.

Bacterial and Viral Disease ManagementBacterial and Viral Disease ManagementBacterial and Viral Disease ManagementBacterial and Viral Disease ManagementBacterial and Viral Disease Management

Crown GallCrown GallCrown GallCrown GallCrown Gall

In Missouri, the only major bacterial dis-ease of grapes is crown gall. The causal agentof the disease is Agrobacterium vitis, a Gram-negative bacterium that is a common memberof the microflora that inhabits the grape rootrhizosphere and the internal tissues of thevines. This bacterium can cause disease only ifit comes in contact with a wounded grapevinecell. When this happens, the bacterial celltransfers a fragment of its own DNA into theplant cell. The DNA integrates into one of thegrape chromosomes. This DNA fragmentcontains genes, so-called oncogenes, thatdirect the synthesis of plant hormones. Thecells that receive the bacterial DNA are re-ferred to as transformed cells. The synthesis ofhormones by the transformed grapevine cellswill lead to a rapid cell division and to arampant proliferation of the diseased tissuewhich leads to the formation of a dysfunctionalmass of cells, the gall.

Most frequently affected by the disease arethe cambium and the transport system of thetrunk. The diseased portion of the vasculartissue is unable to carry out its nutrient transport

function, and if the gall girdles the trunk, thevine will starve to death. In addition, thecambium in the diseased tissue is killed andthe affected area will not be able to form newvascular elements. As a result, even thoseplants that survive the disease can becomeseverely weakened. Researchers in Californiaregistered a 20% to 40% reduction in yield,and a 10% to 40% reduction in vigor in plantsthat had 50% or more of their crown circum-ference covered with galls. The cultivation ofthe resulting incomplete, low-producingvineyard is unprofitable, and the replacementor retraining of the dead or injured plantsrequires additional expenses. Crown gall isparticularly severe in Missouri and othermidwestern states where changeable winterweather inflicts freeze damage to the grape-vine tissues and favors the development of thedisease.

Once the bacterium has invaded the vine,the vine will remain infected over its entire life.Therefore, the only control strategy availableto growers is prevention. Recent researchresults suggest that planting Agrobacterium-free propagating wood into non-vineyard soilwill result in vines that will stay free of thedisease unless the disease is introduced fromoutside. The major factors that limit the practi-cality of this approach is thatAgrobacterium-free propagating material iscommercially unavailable. Growers andnurseries often propagate plants from symp-tomless vines, assuming that the progeny willbe free of the disease. The lack of crown gallsymptoms on a vine, however, does not meanthat it is free of the bacterium.

Several techniques have been developedto test propagating wood for the presence orabsence of the pathogen, but unfortunatelynone of them has proven completely reliable.Hot water treatment of dormant propagatingwood also falls short of fully eradicating the

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bacterium from the canes. The only certainway to produce Agrobacterium-free plants isby passing them through shoot tip culture.This, however, is a long-term process and canbe organized and carried out only by well-equipped nurseries or academic institutions.It is our prediction that Agrobacterium-freepropagating wood will be commerciallyavailable in the future, just as certified virus-free propagating wood of Vitis viniferacultivars is commonly available now.

In the absence of pathogen-free propagat-ing material, growers can still reduce crowngall damage in their vineyards with carefulcultivar and site selection. In general, oneshould avoid the cultivation of cold-tendercultivars in Missouri, not only because of theinjury directly inflicted by the cold, but by thegreater susceptibility of these plants to crowngall. Growers should also be very cautiousabout planting cultivars that are known to behighly susceptible to crown gall. Chancellor, aonce popular hybrid cultivar in Missouri, forexample, all but disappeared from the statebecause it was devastated by the disease. As arule of thumb, Vitis vinifera cultivars tend to bemore susceptible than hybrids and AmericanVitis cultivars. Whenever grafted vines areplanted, the crown gall susceptibility of therootstock cultivar should also be taken intocareful consideration. On grafted vines thecold- and crown gall-sensitive graft union canbe protected from freezing temperatures bycovering it up with soil (hilling).

A common practice to moderate theeconomic impact of crown gall in Missouri isto train vines to have multiple trunks. Shouldone of the trunks be killed by crown gall, thereplacement trunk is already in place to pro-vide production. Mechanical injuries to thetrunk should also be avoided as much aspossible, as any injured tissue may becomethe site of gall formation.

Vineyard site selection is also important.One should avoid poorly drained, low-lyingareas, because the disease tends to be muchmore severe in such locations. In general, themore conducive a location is to cold injury,the more likely it is that the vines will bedamaged by crown gall there. When an oldvineyard site is re-planted with grapes, thelarger roots of the old vines should also beremoved, and the soil should be left fallow fortwo to three years. This will reduce, but notcompletely eliminate, the agrobacterial popu-lation. If the grower cannot afford to fallow thefield, the soil should be fumigated beforeplanting the new vines.

In summary, the extent to which grapescan be protected from crown gall is currentlyrather limited. The future availability of patho-gen-free propagating material is expected to bea major improvement in crown gall control. Inaddition, current efforts in research are likely tobring additional control strategies with theapplication of crown gall-antagonistic bacteriaand genetic engineering.

Viral DiseasesViral DiseasesViral DiseasesViral DiseasesViral Diseases

Until recently, little was known about theoccurrence of grape viruses in the eastern andmidwestern United States. Recently, however,several reports have pointed out that at leastone virus, the 3rd serotype of grapevineleafroll-associated virus (GLRaV-3) is wide-spread in this region. Canadian researchershave reported that GLRaV-3 is the most com-mon virus in eastern Canadian vineyards, andthat it is predominantly associated with Frenchhybrid grapes. The common occurrence ofGLRaV-3 in American Vitis grapevines hasbeen documented from New York, whereinfected Concord, Catawba, Elvira, andNiagara vines have been identified. Thewidespread occurrence of GLRaV-3 in Frenchhybrids has also been reported from Missouri.

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Of six commercial vineyards sampled on theOzark Plateau and the Missouri River valley inMissouri, four had GLRaV-3-infected plants.Disease incidence was also high for theAmerican Vitis cultivars Norton and Catawba.In addition to GLRaV-3, a high disease inci-dence of the grapevine fleck virus (GFkV) hasalso been found in a Vidal Blanc vineyard inMissouri. These results leave little doubt thatmany of the French hybrid vineyards in east-ern and midwestern North America are heavilyinfected by at least one leafroll virus, and withperhaps other viruses.

Since French hybrid, American hybrid andAmerican grape cultivars do not develop anyvisible symptoms when infected by theseviruses, this could mislead our perception ofgrape viral diseases. The potential for damageby these viruses on grape production can

Disease Management

never be precisely predicted. The risk, how-ever, exists as long as viruses are present in thevineyard. The potential risk is compoundedparticularly with the current situation in whichdissemination channels of viruses are notchecked robustly, and the problem of mixedinfections of different viruses within individualvines.

For the future of the grape industry, weinitiated a virus elimination program at theMissouri State University State Fruit Experi-ment Station based on a rationale that it isalways safe to propagate vines from cleanstocks in the beginning. The goal of thisprogram is to cure the most important hybridcultivars of their viral pathogens and makethese cultivars available to nurseries andgrowers. Contact the Missouri State Univer-sity State Fruit Experiment Station for moreinformation.

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Table 11-1. Relative Disease Susceptibility and Sensitivity to Sulfur and Copper of GrapeCultivars Under Missouri and New York Conditions

Black Downy Powdery Copper SulfurCultivar Rot Mildew Mildew Anthracnose Sensitivity1NY Sensitivity2NY

Aurore +++ + ++ + ++ noBaco Noir + + ++ + ? noCabernet Franc2 yr +++ +++ ++ ++ + noCanadice +++ +++ ++ ++ ? ?Catawba +++ +++ + + ++ noCayuga White +++ ++ ++ +++ + noChallenger +++ +++ ++ +++ ? noChambourcin + + +++ + ? ?Chancellor ++ +++ +++ ++ +++ yesChardonel ++ ++ ++ + ? noChardonnay3 yr +++ +++ +++ +++ + noChelois + + ++ + + noConcord +++ ++ + + + yesCouderc Noir2 yr ++ +++ ++ ++ ? ?DeChaunac ++ + ++ ++ + noDelaware +++ +++ ++ ++ + noGlenora +++ +++ +++ +++ ? ?Himrod +++ +++ +++ +++ ? noLeon Millot +++ ++ +++ + ? ?Marechal Foch ++ + ++ ++ ? yesMelodyNY +++ ++ + ? ? noMissouri Riesling2 yr ++ +++ ++ ++ ? noNiagara +++ ++ ++ ? + noNorton/Cynthiana3 + ++ + + - yesRayon d’Or +++ + ++ + ? ?Reliance +++ ++ + +++ ? ?RieslingNY +++ +++ +++ ? + noRougeon +++ + +++ ++ +++ yesSeyval blanc +++ + +++ + + noSteuben +++ +++ ++ + ? noTraminette +++ +++ +++ + ? ?Venus +++ +++ + ++ ? ?Vidal blanc ++ + +++ +++ ? noVignoles +++ ++ ++ +++4 ? noVillard blanc +++ + +++ +++ + ?Villard Noir2 yr +++ +++ +++ ++ ? ?Vincent +++ +++ +++ + ? ?Vinered +++ +++ ++ +++ ? ?Vivant2 yr +++ +++ +++ +++ ? ?

Key to ratings: +++ = highly susceptible/sensitive, ++ = moderately susceptible/sensitive,+ = slightly susceptible /sensitive, ? = unknown susceptibility/sensitivity.

Ratings based upon 4 or 5 years data collected at the State Fruit Experiment Station unless otherwise noted. 1Ratings from the Cornell University Pest Management Recommendations for Grapes. Copper applied under

slow, cool drying conditions may cause injury. Sulfur injury may occur on tolerant cultivars if the temperature is 85°For higher during or shortly after application.

2Observations in Missouri indicate that Cynthiana/Norton is very sensitive to Endosulfan and is likely sensitive to someother commonly applied pesticides.

3Fruit of Vignoles is highly susceptible to anthracnose while foliage and shoots are only slightly susceptible. NY Ratings under New York conditions. 2 yr or 3yrDisease susceptibility based on only 2 or 3 years data collected at the State Fruit Experiment Station.

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Grapes have many insect pests that attackall parts of the plant. Fortunately only a few ofthese pests pose a serious economic threat inMissouri. The following discusses the insectpests most commonly encountered in thevineyard. Specific insecticide recommenda-tions for control are not given, as these maychange. Current recommendations can befound in the Missouri Commercial Grape PestControl Guide (MS-19 revised) that is updatedeach year. Another useful reference is Insectand Mite Pests of Grapes in Ohio (Williams etal., 1986)

Climbing Cutworm and Grape Flea BeetleClimbing Cutworm and Grape Flea BeetleClimbing Cutworm and Grape Flea BeetleClimbing Cutworm and Grape Flea BeetleClimbing Cutworm and Grape Flea Beetle

Both climbing cutworm and grape fleabeetle attack the buds of the grapevine whenthey first start swelling early in spring. Buds willbe found which have the interior eaten out,usually through a hole in the side of the bud.There is no reliable way to tell the damage ofthese two insects apart. The grape flea beetle isabout 3/16 inch long and steel blue in color.They can be seen on the canes and attackingbuds on warm, sunny days. Cutworms arebrown in color, and feed only at night. Theyhide under loose bark or in trash on theground during the day, and then crawl up thetrunk to feed at night. If damage is observedand flea beetles cannot be seen, one canexamine the canes after dark with a flashlight.Flea beetle damage often occurs in the edge ofvineyards near wooded or brushy areas.Cutworms are usually more prevalent in

vineyards planted in sandy soils or those withweeds and grass under the vine.

Growers should scout their vineyards everyother day during bud swell to determine ifeither of these pests are doing economicdamage. Damage can be quite significantbecause buds that are attacked fail to develop.Cutworms often move along the canes andcan kill every bud. Insecticides are not neededunless these pests are damaging buds. Invineyards with a history of cutworm damage,the grower might opt to apply an insecticide atearly bud swell each year. In an average ornormal year, the buds grow quickly, and oncethe buds have grown out to ½ inch theseinsects are no longer a threat. In years withcool spring weather, the buds may grow outvery slowly, so they are prone to damage for 2weeks or more. Under such conditions, thegrower should scout the vineyard every fewdays until the danger stage is past.

Grape Berry MothGrape Berry MothGrape Berry MothGrape Berry MothGrape Berry Moth

The grape berry moth is the most importantpest of the fruit. This insect overwinters aspupae within a flap of grape leaf. The fallengrape leaves frequently are blown out of thevineyard during winter winds, and may con-centrate in fence rows and weedy areas, brushand woods near the vineyard. For this reason,berry moth is often most severe on the edge ofvineyards near these areas. The overwinteringadults usually appear in the vineyard at the


Insect Pest ManagementInsect Pest ManagementInsect Pest ManagementInsect Pest ManagementInsect Pest Management

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end of bloom, where they deposit eggs on thenewly set berries. When the eggs hatch, thelarvae web together several very small berriesand consume them. This damage can be seenas a light webbing in which the berries aremissing. The mature larvae make cocoons bycutting a flap out of a leaf, usually near theedge. The flap is folded over and secured bysilk, and the larvae pupate inside. Whenmature, adults emerge and deposit eggs on thedeveloping berries. When the larvae hatch,they burrow into the grape berry, usuallywhere two berries touch. This tunneling resultsin the affected berries turning red or purple inthe area of the entrance. A single larva maytunnel into several berries before it is mature.The mature larvae again pupate and usuallyemerge about the end of August in Missouri.This generation can be especially damagingbecause infested berries frequently are at-tacked by rots that destroy more berries thanjust the ones infested by the berry moth.Heavily infested grapes can have so much rotthat they are unacceptable to processors.

Grape berry moth can be controlled byapplying insecticides. The first applicationshould be made right after bloom. This appli-cation will also give control of a large numberof minor pests that sometimes infest grapes.Applications should be continued throughoutthe season with a maximum of two weekintervals. A sex pheromone that attracts malegrape berry moths to a trap is available com-mercially. These traps can be placed in thevineyard and will enable the grower to deter-mine when adult berry moth emergence isstarting, and when peak emergence is occurring.

Grape Root BorerGrape Root BorerGrape Root BorerGrape Root BorerGrape Root Borer

The damage caused by the grape rootborer is insidious in that the grower normallywill not see it. However, this pest is probablypresent in all vineyards in Missouri. The borer

is the larva of a clear winged moth that greatlyresembles a common wasp. This larva feedsinside the grape root for almost two years.When it is mature, it leaves the root and tun-nels to just beneath the soil surface where itmakes a cocoon. Adults begin to emerge fromthe soil during the first week of July in Missouri,and emergence may continue until earlyOctober. After mating, females deposit eggs ongrape leaves and weeds under the vine. Theseeggs are loosely attached and most of themprobably fall to the ground. When the eggshatch, the larvae immediately burrow into thesoil in search of grape roots, which they enterand where they feed for about 22 months. Theeffects of this root feeding are not usuallyevident in vigorous vineyards. However, invineyards that are under stress from lack ofwater, poor nutrition, or lack of weed control,a general decline may result. Vine growth maydecline, along with yield, and winterkill mayoccur. Over a period of a few years, the vine-yard may decline to a state where it is nolonger sustainable.

Control of the root borer is difficult becausethe larva is inside the root where it cannot bereached with insecticides. One insecticide hasbeen approved for treating the soil under thevine, but it is fairly expensive. Growers canminimize damage by keeping the vines ingood health through proper nutrition andwatering. Pheromone traps are also availablefor monitoring adult male root borer emer-gence and numbers.

Potato LeafhopperPotato LeafhopperPotato LeafhopperPotato LeafhopperPotato Leafhopper

The potato leafhopper is a very small greenor white wedge shaped insect about 1/8 inchlong. This leafhopper feeds on at least 200different plants. It does not overwinter inMissouri, but is carried north each year fromthe gulf coast states by spring winds. Thisleafhopper feeding causes the leaves to take

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on a characteristic cupping and yellowing.This leafhopper is probably present in smallnumbers in all vineyards, but occasionally isfound in damaging numbers in a few vine-yards. Insecticides will give control if needed.

Grape Cane GallmakerGrape Cane GallmakerGrape Cane GallmakerGrape Cane GallmakerGrape Cane Gallmaker

This insect is a very small snout beetle,about 1/8 inch long and brown or black incolor. Adults overwinter in brushy or woodedareas and in May move to the vineyard. Thefemale chews holes just above a node in thenew canes when they are 10 to 20 incheslong, and deposits an egg in the hole closest tothe node. A red gall about ¾ to 1 inch longthen develops at the site of the egg deposition.New adults emerge from the gall in August,and there is only one generation each year.This damage is usually first noticed when thevines are pruned. The galls at this time arehard and have a longitudinal crack in them.Since the galls usually occur beyond the site ofclusters, the damage is mostly cosmetic andthere is no loss of crop. If chemical control isdeemed necessary, it should be applied whenthe shoots are 3 to 6 inches long and againwhen they are 10 to 12 inches long.

Grape PhylloxeraGrape PhylloxeraGrape PhylloxeraGrape PhylloxeraGrape Phylloxera

There are two forms of grape phylloxera, aleaf form and a root form. The leaf form over-winters as an egg under the bark of the vine.Upon hatching, the nymphs crawl to the newleaves where they settle and feed. This feedingcauses a gall to form around the insect on theunderside of the leaves. These galls have anopening on the upper surface of the leaf.Mature phylloxera deposit eggs in the galls,and when they hatch, the crawlers exit thegalls through the openings and crawl to newleaves to repeat the cycle. The leaf galls onmost American grape cultivars rarely becomenumerous enough to cause damage, but can

cause severe damage on Delaware and severalof the French hybrid cultivars. The leaves onsusceptible cultivars may curl up, dry out, andfall from the vine. The leaf form of phylloxeracan be controlled using insecticide applica-tions.

The root form of phylloxera can be verydamaging. The insect overwinters asimmatures on the roots. Feeding on the rootscauses gall-like growths to appear, whicheventually die and rot, thus depriving the vineof its root system, which can cause death. TheAmerican cultivars are resistant to the rootform, and are thus not damaged by it. How-ever, the Vitis vinifera cultivars are verysusceptible to the root form, and these cultivarsare usually grafted on resistant rootstocks.Recent evidence suggests that certain Frenchhybrids are also susceptible to the root form;contact the Missouri State Fruit ExperimentStation for more information. There is nochemical control for the root form of the grapephylloxera.

HornwormsHornwormsHornwormsHornwormsHornworms

Hornworms are the larvae of variousspecies of hawkmoths. These worms arefrequently found feeding on grapes, but are oflittle economic concern because normal berrymoth control measures also give good controlof sphinx moth larvae. However, the pandorussphinx moth larvae can do damage to newlyplanted vineyard which are not under a regu-lar insecticide program. These larvae can getas large as a thumb, and can be a rich brown,green, or yellow color. They have a very goodappetite and can eat all the leaves off a newlyplanted vine in a very short period of time. Thegrower should scout newly planted vineyardsfor this pest. Infested vines will have areaswhere the leaves are missing, with only the leafstems left. The ground under such areas maybe covered with droppings which look similar

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60


to rabbit droppings. The larvae feed mostly atnight, but they can commonly be found hidingof the shaded north side of the main trunk ofthe vine near the ground. Larvae can bedestroyed by hand if they can be found,individual infested vines can be treated withan insecticide, or the whole vineyard can betreated.

Other Foliage FeedersOther Foliage FeedersOther Foliage FeedersOther Foliage FeedersOther Foliage Feeders

There are several insects that feed on theleaves, but are normally controlled by thegrape berry moth sprays. Rarely are insecticideapplications needed to control these pests, asthey normally do little real damage. They arebriefly described here so that the grower can

recognize them. The larvae of grape fleagrape fleagrape fleagrape fleagrape fleabeetlebeetlebeetlebeetlebeetle larvae feed on the upper surface ofleaves, resulting in skeltonized areas. Theselarvae are a dirty brown or green color. Thegrape leaffoldergrape leaffoldergrape leaffoldergrape leaffoldergrape leaffolder folds the leaf and feeds insidethe fold. These are frequently found on wildgrape. Eight-spotted foresterEight-spotted foresterEight-spotted foresterEight-spotted foresterEight-spotted forester larvae are yellow,white and black and consume all of the leafexcept for the leaf petiole and the heavy veins.Grapevine EpimenisGrapevine EpimenisGrapevine EpimenisGrapevine EpimenisGrapevine Epimenis larvae are very similar tothe eight-spotted forester, but they feed withina shelter made by drawing the edges of a leaftogether forming a somewhat ball shape. Thegrape plume mothgrape plume mothgrape plume mothgrape plume mothgrape plume moth feeds in the terminal leavesthat it webs together. The larvae are small,green or yellow in color, and covered withwhite hairs.

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Weed control is very important in grapegrowing. Weeds compete with vines for soilmoisture and nutrients. Strong weed competi-tion during the first and second years ofestablishing a new vineyard will greatly reducevine growth and delay full bearing. This is thenumber one mistake that new grape growersmake. For mature bearing vines, early throughmid-season weed control is most importantbecause vines must grow vigorously to de-velop a canopy with maximum photosynthesisto support flowering and fruit set. From ripen-ing (veraison) through the remainder of theseason, additional vegetative shoot growth isusually not beneficial. Mature bearing vinescan tolerate some weed competition at thistime. These could be short, annual grass andbroadleaf weeds. Perennial weeds should becontrolled. Climbing or tall growing weedsshould also be controlled because they com-pete with vines for sunlight and restrict airmovement in the vineyard. In the latter case,leaves and fruit dry-off slowly following rain-fall. This increases the potential for fungaldisease outbreak. Mid- to late season weedsthat grow to maturity will become a source ofweed seed the following season. Mowing orpost-emergence, contact herbicides should beused to prevent them from maturing.

Permanent sod cover is usually establishedbetween trellis rows in Missouri vineyards.Perennial, cool-season grasses such as com-mon bluegrass or tall fescue are seeded as thecover. These must be kept mowed during the

growing season or they will also compete withvines. This is better than allowing native weedspecies to establish in row middles every year.Native weed cover must have timely mowingsor post-emergence, contact herbicide treat-ments to prevent uncontrolled weed growth.It is also unsuitable for sloping vineyard siteswhere soil erosion can occur. Cultivation ofrow middles is not recommended because ofshallow, rocky soil and sloping ground inmany vineyards. Damaged vine roots, soilerosion, and loss of soil structure are detrimen-tal effects of cultivation.

Mulching is a very effective way of control-ling weeds in both row middles and beneaththe trellis. This is a labor intensive practiceunless it is mechanized. Mulch can be expen-sive unless a large source close to the vineyardis available. A consideration might be to growstraw or hay for mulch. Most growers wouldconsider mulching impractical for all but avery small vineyard. However, growers that donot want to use herbicides in their vineyardshould consider mulching. Combining a widegrass alley between trellis rows along with anarrow mulched strip beneath the trellis caneffectively control weeds. The mulch will haveto be replenished because of decomposition.Even for those growers that will use herbicides,mulching is a good practice around first yearvines with shallow root system that cannottolerate pre-emergence herbicides. Straw, hay,sawdust or bark mulch can be applied in a twoto three foot diameter circular area around the


Weed ControlWeed ControlWeed ControlWeed ControlWeed Control

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vine in a thick layer to obtain season longweed control. Weeds must still be controlledin other areas of the vineyard. Growers thatuse mulch around young vines or along thetrellis row need to check vines periodically forany sign of rodent feeding and take correctiveaction if needed. This may be the use of rodentbait and/or moving mulch away from the vinetrunk.

Weed control should start one or twogrowing seasons before planting a vineyard.The goal is to eliminate aggressive, woody andherbaceous perennial weeds, and to reducethe amount of annual weed seed in the soil.This is usually accomplished by applying abroad spectrum, non-selective, post-emer-gence herbicide to the entire planting area.Weeds with extensive root systems are oftendifficult to control and may require additionalspot-treatment applications of herbicide to geta good kill.

After weeds have died, brush-hog the areato reduce the ground cover height. Follow thisby cultivation to work the ground cover intothe soil and prepare a seed bed for establishinga cover crop or a permanent sod cover. If thevineyard will not be planted for a year ormore, cover crops are useful because theydisplace weeds and add organic matter to thesoil when cultivated in.

Depending on the site and the amount ofground cover to be incorporated, cultivationmay need to be a combination of both plow-ing and multiple discings or the discings aloneto prepare the soil. In some pasture groundthat is being converted to vineyard it may bepossible to eliminate full-field cultivation andonly apply herbicide and cultivate the areawhere vines will be planted. This requireshaving a suitable pasture grass that is in goodcondition as an established cover, and carefullayout of planting rows.

Remember that problem weeds are mucheasier to eliminate through a combination ofbroad spectrum, non-selective, post-emer-gence herbicide applications and cultivation.This is most effectively done before the vine-yard is planted. Afterwards it becomes muchmore difficult because herbicides that can beused in vineyards are more limited, and vinesand trellis interfere with cultivation.

Perennial, cool-season grasses are thepreferred cover between trellis rows. Thealternative which are perennial, warm-seasongrasses are either too competitive or expensiveto establish. Cool-season grasses should beseeded from early September through earlyOctober. Spring seeding is less desirablebecause of competing, early season, weedgrowth. Enough time should be allowed forany cover crops to be cultivated into the soil.Additional time for residue breakdown andseedbed preparation will be required. Thismeans starting your final cultivations fromearly through mid-August.

Drilling seed to a shallow depth in pre-pared soil is the preferred method ofseeding. The strips where the trellis will beerected and vines planted can be leftunseeded. Broadcasting seed followed byvery shallow incorporation or rolling is analternative method. This usually places seedin the area where vines will be planted.Germinating grass can be allowed to growand killed out along the planting row thefollowing spring using cultivation or post-emergence herbicide. In the latter casewhere the dead cover is left undisturbed,vines can be planted into the residue whichacts as a mulch. Trellis construction is bestdone during late winter or early springbefore vines are planted.

The use of herbicides beneath the trellis isthe most common way to control weeds in

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Missouri vineyards. Herbicides are applied tothe soil pre-emergence (before weeds germi-nate) or post-emergence (after weedsgerminate.) Some herbicides have both postand pre-emergence activity. The followingtable lists the common chemical names ofherbicides that can be used in vineyards.

Growers should consult the MissouriCommercial Grape Pest Control Guide forcurrent recommendations on the use of theseherbicides as well as any new herbicides thatbecome labeled. Common names, tradenames, formulations, toxicity signal words,

application rates, surfactant requirement, pre-harvest intervals, restricted entry intervals, andimportant comments are listed in the guide.

The application rate for the treated striparea beneath the trellis is equal to the rate peracre for broadcast treatment times the strip width

in feet divided by row spacing in feet. Pre-emergence herbicides often need rainfall orirrigation to move them into the soil wherethey are active. Prolonged exposure on the soilsurface can lead to decomposition or volatileloss. Labels attached to herbicide containers

Weed Control

Table 13-1. Herbicides for Vineyard Use

Common Name Time of Application Weeds Controlled

Dazomet Preplant Soil FumigantDichlobenil Pre-emergence Annual Grass and BroadleafDiuron Pre-emergence Annual Grass and BroadleafIsoxaben Pre-emergence Annual BroadleafNapropamide Pre-emergence Annual Grass and BroadleafNorflurazon Pre-emergence Annual Grass and BroadleafOryzalin Pre-emergence Annual Grass and BroadleafSimazine Pre-emergence Annual Grass and BroadleafPendimethalin Pre-emergence Annual Grass and BroadleafTrifluralin Pre-emergence Annual Grass and BroadleafOxyfluorfen Pre and Post-emergence Annual BroadleafPronamide Pre and Post-emergence Annual Grass and BroadleafClethodim Post-emergence Systemic Annual and Perennial GrassDiquat Post-emergence Contact Annual Grass and BroadleafDSMA Post-emergence Contact Annual GrassFluazifop Post-emergence Systemic Annual and Perennial GrassGlufosinate Post-emergence Contact Annual Grass and BroadleafGlyphosate Post-emergence Systemic Annual and Perennial Grass and BroadleafMSMA Post-emergence Contact Annual GrassParaquat Post-emergence Contact Annual Grass and BroadleafPelargonic Acid Post-emergence Contact Annual Grass and BroadleafSethoxydim Post-emergence Systemic Annual and Perennial GrassSulfosate Post-emergence Systemic Annual and Perennial Grass and Broadleaf

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should always be read for this and othercurrent information on the use of the product.

Newly planted vines are a special problemfor growers because they cannot compete withweeds and their shallow root systems can beinjured by pre-emergence herbicides.Napropamide and Oryzalin are the only pre-emergents that can be used around newlyplanted vines. Applying less than the full rate isadvised, usually around three-fourths rate. Thesoil should be settled or packed around thevine with no depression where spray cancollect near the trunk. Mulch around the vine,particularly sawdust, will absorb much of theherbicide. Remember that extra nitrogenfertilizer may be required around mulchedvines because of nitrogen tie-up by the decom-posing mulch.

The use of a grow tube over each vine is apractice that should be considered. These areusually polyethylene plastic tubes 4 to 5inches in diameter and about three feet tall.They are placed over the newly planted vineand staked or tied to the trellis. Tubes act as atraining aid by directing growing shoots up-wards. They also shield the vine fromherbicide spray. Growers using these tubeshave effectively eliminated pre-emergenceherbicide use the first year and have gone topost-emergence sprays to control weeds.Tubes must be removed later in the growingseason before cordons are established on thetrellis.

Several of the listed herbicides can only beused in non-bearing vineyards, prior to plant-ing through the second growing season. Thiswill be written in the comments section of theMissouri Commercial Grape Pest ControlGuide. Bearing usually occurs in the third yearfor a well grown vine. A number of additionalherbicides can be used around bearing vines.Two to three year old vines still have shallow

roots that can be injured by pre-emergenceherbicides. The use of half rates of Diuron,Norflurazon and Simazine is advised.Napropamide and Oryzalin can be applied ata full rate. Four to five year old vines areusually well established and can have full ratesof pre-emergence herbicide applied aroundthem.

Using the same pre-emergence herbicideevery year allows weeds that are not con-trolled to spread in the vineyard. Because ofthis it is advisable to use alternative herbicidesfrom one year to the next. Tank mixing twopre-emergence herbicides for application inone year is another way to reduce the numberof uncontrolled weeds. For example, combin-ing a good grass herbicide such asNapropamide or Oryzalin with a good broad-leaf herbicide such as Diuron, Oxyfluorfen orSimazine will increase the number of weedspecies controlled. The product labels of bothherbicides should be consulted to determineallowable tank mixes and application rates.Pre and post-emergence herbicides can beeffectively tank-mixed to increase weedscontrolled. Because post-emergents can injurevines, they generally are used from late Marchthrough early June before grape shoots reachclose to the ground. Spraying on calm days isadvised, to reduce the risk of herbicide drift tonon-target areas! Again consult product labelsfor allowable pre- and post-emergence tank-mixes and application rates.

Post-emergence herbicides are eithercontact or systemic in action. Diquat, DSMA,Glufosinate, MSMA, Paraquat and PelargonicAcid are contact herbicides, meaning they killthe above ground part of the weed that thespray contacts. The root system can remainalive and regenerate the weed, particularly if itis a perennial. Clethodim, Fluazifop,Glyphosate, Sethoxydim, and Sulfosate aresystemic herbicides, meaning they translocate

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Weed Control

in the weed and kill both the above and belowground parts of the weed. Three post-emer-gence herbicides only control annual andperennial grasses. These are Clethodim,Fluazifop and Sethoxydim. Although it is agood idea to minimize spray on the vine, thesegrass herbicides can contact vine foliagewithout injury.

Post emergence herbicides that controlboth broadleaf and grass weeds should notcontact vine foliage. They are usually applied

through early June before foliage has devel-oped close to the ground where sprayapplications are made. Glufosinate andPelargonic Acid are unique in that they can beused for grape sucker control on mature vines.Consult labels for this use.

Missouri grape growers are advised toobtain a copy of the Missouri CommercialGrape Pest Control Guide, which includescurrent information on weed control.

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Bird ManagementBird ManagementBird ManagementBird ManagementBird Management

Bird depredation is a serious problem forMissouri grape growers. Birds of several spe-cies, including robins, starlings, andblackbirds, can quickly consume entire crops.Bird damage typically begins at veraison,weeks before harvest. Birds consume fruit andalso damage remaining fruit, leading to loss ofquality and increased incidence of bunch rots.Regardless of the control strategy, measuresmust be in place by veraison.

Many strategies are used for bird manage-ment, and they very widely in cost andeffectiveness. The most effective and mostcostly method is netting. Plastic or nylon netsare placed over the vines, either directly on theplants or supported overhead on posts and wire.Netting is costly, but with proper care nets willlast 3 to 5 years. Also available are disposablenets, intended for a single season of use.

Other strategies involve auditory scaredevices (propane cannons, amplified distresscalls, cracker shells) and visual scare devices(kites, balloons, reflective tape, mirrors). Birdsbecome accustomed to scare devices quickly,and these strategies are most effective whentheir location in the vineyard is changed everyfew days. Bird control is enhanced when visualand auditory devices are combined.

Chemical bird repellants may hold promisefor Missouri. Compounds such as methyl

anthranilate and sucrose may repel birds fromgrapes. Visit with specialists at the MissouriState University State Fruit Experiment Stationfor the latest information on bird manage-ment.

Deer ManagementDeer ManagementDeer ManagementDeer ManagementDeer Management

Deer are a problem for Missouri grapegrowers. Browsing injury is particularly damag-ing to young vines. The size of Missouri’s herdhas increased greatly in recent years, as hasthe level of damage.

In general, thinning of the deer herd throughhunting is not effective in reducing deer damagein areas with high deer populations. Damagecontrol permits are available from state agenciesto supplement hunting, but exclusion is themost effective way of reducing deer damage.

Several fence designs are used to excludedeer from vineyards. A 6-12 foot fence madeof woven wire, netting, or multiple strands ofhigh tensile wire is perhaps the ultimate bar-rier. Other deer fence configurations include aslanted fence that has 7' posts slanted to be 4'high on the deer side, making a barrier that isabout 6' wide. Using two fences 3 to 5 feetapart also gives the deer a wider barrier andmay confuse the deer’s sense of depth percep-tion. High tensile electric fence has alsoprovided good results. Using peanut butter onthe wires attracts deer to touch the wires. Usingconducting tape or rope is more visible and


Bird and Deer ManagementBird and Deer ManagementBird and Deer ManagementBird and Deer ManagementBird and Deer Management

68


deer are more attracted to touch it.Several chemicals are labeled as deer

repellants. Check product labels for informa-tion on application rates and timing.

A thorough discussion of deer managementis available in the publication Deer DamageControl Options (Lee, 1998), available fromthe Kansas State University Agriculture Experi-ment Station or online at http://www.oznet.ksu.edu/library/wldlf2/c728.pdf.

69

The optimum time to harvest grapes de-pends on the cultivar, the nature of thegrowing season, and the intended use of thefruit. Harvest date can vary from year to year,depending on environmental conditions.

The process of ripening involves severalstages. The first obvious sign of approachingripeness is veraison, or change in the berrycolor. Unripe green fruit develop color pig-ments (red or purple cultivars) or becomelighter in color and translucent (green oryellow cultivars). Soon after veraison the fruitwill develop aromas characteristic of thecultivar. Sugar content of the fruit begins torise, while acid content decreases. Acidstrength, measured as pH, weakens. Otherflavor and aroma compounds in the fruitundergo changes.

Wineries have very specific requirementsfor fruit quality, and will pay varying amountsof money for the crop based on quality param-eters. Those parameters include sugar content(measured as degrees Brix), pH, and titratableacidity. For a given cultivar, a range of accept-able values is usually given. In some cases, allthe parameters will be in acceptable ranges atharvest. In other cases, harvest date is deter-mined by one parameter, even though otherindices may be outside the ideal range. Mostwineries consider pH to be the single mostcritical parameter, as it is difficult to correct outof range pH values during the winemakingprocess. Sugar content and acidity are easier to

adjust. The generally accepted values for winegrapes at harvest are soluble solids, 18 to 24oBrix (white cultivars) and 21 to 25 oBrix (redcultivars); total acid content, 0.6-1.0 g/100 ml;and pH, 3.0-3.5.

A good way to accurately time harvest for agiven cultivar is by measuring the aboveparameters for a representative fruit sample.The most common sampling procedure inMissouri is to collect a random sample of atleast 200 berries. The sample must representthe entire crop. Sample an equal number ofberries from both sides of the row, and samplefrom throughout the entire vineyard. Avoidend plants or atypical plants. Sample cultivarsand different locations separately. Collect theinitial sample 3 weeks before the expecteddate of harvest. Sample weekly until the weekbefore harvest, and then every 3 to 4 days.Collect samples at the same time of day foreach sampling date. Crush the fruit, extract thejuice, and perform the chemical analysis toarrive at the quality parameters. Further infor-mation on berry sampling, including theprocedure for measuring quality parameters, isavailable in several references (Editor, 1995;Watson, 1992). In addition to using sugar,acid, and pH levels, the grape grower mustbecome familiar with qualitative measures ofripeness, such as the development of charac-teristic flavor and aroma components. Sensoryevaluation of flavor and aroma components ofthe juice sample should accompany thechemical analyses mentioned above


Harvest ManagementHarvest ManagementHarvest ManagementHarvest ManagementHarvest Management

70


(Zoecklein, 2001). With certain cultivars, forexample, undesirable compounds developduring the ripening process and harvest time isbased in part on the levels of these com-pounds.

Harvest parameters for table grapes includecolor, flavor, aroma, and a sugar/acid ratio of15:1 or higher.

Other factors enter into the harvest deci-sion. Adverse weather, presence of bunch rot,level of bird damage, and scheduling deci-sions at the winery can all influence the timingof harvest. Damaged fruit must be harvestedwithout delay to minimize loss of fruit qualityand to reduce crop loss.

Grapes for fresh market sale are harvestedby hand. Clusters may be packed directly intosales containers, such as 5 or 10 pound boxes,

or into baskets that hold from 8 to 12 quarts.Processing fruit may be harvested by hand,commonly into lugs or boxes that hold 15 to20 pounds. Processing grapes are also har-vested by machine, often into bins that hold2000 pounds. Grapes may be harvested in aonce-over single picking, or harvested in twopickings one to two weeks apart. Avoid har-vesting during the heat of the day; grapes areusually picked from dawn to 11:00 am.Grapes that are mechanically harvested can bepicked during the night.

Once harvested, transport grapes asquickly as possible to the consumer or theprocessor. This is particularly the case withmechanically harvested fruit. If fruit must beheld for a period of time, ideal storage condi-tions are under refrigeration at 30 to 32 oF and85% to 90% relative humidity.

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Literature Cited and ResourcesLiterature Cited and ResourcesLiterature Cited and ResourcesLiterature Cited and ResourcesLiterature Cited and Resources

Literature cited – Chapter 1Literature cited – Chapter 1Literature cited – Chapter 1Literature cited – Chapter 1Literature cited – Chapter 1

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Patterson, W. K. 1996a. Vineyard establishmentin the Ozarks. Vineyard and Vintage View 11(5):1-5.

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Kaps, M. L. and M. B. Odneal. 2001. Grape cul-tivar performance in the Missouri Ozark region.J. American Pomological Society 55(1):34-44.

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Appendix AAppendix AAppendix AAppendix AAppendix A

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Casteel, T. (ed.). Oregon wine grape grower’sguide. Oregon Winegrowers Association, Port-land, Ore. 258 p.

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Howell, G. S., T. K. Mansfield, and J. A. Wolpert.1987. Influence of training system, pruning se-verity, and thinning on yield, vine size, and fruitquality of Vidal blanc grapevines. Am. J. Enol.Vitic. 32:105-112.

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73

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Howell, G. S., D. P. Miller and T. J. Zabadal.1997. Table grape varieties for Michigan. Michi-gan State University Extension Bulletin E-2642.

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Literature Cited and Resources

For a copy of this publication please write to State Fruit Experiment Station,9740 Red Spring Road, Mountain Grove, MO 65711-2999

or visit our website http://mtngrv.missouristate.edu

Southwest Missouri State University is a community of people with respect for diversity. The University em-phasizes the dignity and equality common to all persons and adheres to a strict nondiscrimination policyregarding the treatment of individual faculty, staff, and students. In accord with federal law and applicableMissouri statutes, the University does not discriminate on the basis of race, color, religion, sex, nationalorigin, ancestry, age, disability, or veteran status in employment or in any program or activity offered orsponsored by the University. In addition, the University does not discriminate on any basis not related to theapplicable educational requirements for students or the applicable job requirements for employees. The Uni-versity maintains a grievance procedure incorporating due process available to any person who believes he orshe has been discriminated against. Southwest Missouri State University is an Equal Opportunity/AffirmativeAction employer. Inquiries concerning the grievance procedure, Affirmative Action Plan, or compliance withfederal and state laws and guidelines should be addressed to Jana Estergard, Equal Opportunity Officer,Siceluff Hall 296, 901 South National Avenue, Springfield, Missouri 65804, 417-836-4252.

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