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Grapes: Organic Production

  1. 1. ATTRA Grapes: Organic Production A Publication of ATTRA - National Sustainable Agriculture Information Service • 1-800-346-9140 • www.attra.ncat.orgBy Rex Dufour Organic grape production provides a fairly predictable economic return in irrigated parts of the aridNCAT Agriculture West. In the East, organic grape production is complicated by a climate that fosters insect and diseaseSpecialist problems. Production is compounded by consumer preferences for grape cultivars (both dessert and© 2006 NCAT wine grapes) that are difficult to grow in the East. This guide presents organic management options for diseases, insects and weeds, discusses cultivar choices in terms of disease resistance, and briefly presents marketing ideas for eastern labrusca-type grapes and organic wines. References and an appendix on disease resistance rating follow the narrative.ContentsIntroduction ........................ 1 “Simply put: the principles of organic farm-Geographical Consider- ing and sustainable practices are the singleations and Disease most important tools you can employ toManagement ...................... 4 improve wine quality.” John Williams, owner,Diseases ................................ 5 Frog’s Leap Winery, Rutherford, California,Geographical Consider- speaking at the 54th Annual Meeting of theations and Insect and American Society for Enology and ViticultureMite Management .......... 12 (ASEV). June 20, 2003. Reno, Nevada.Plant ParasiticNematodes ........................ 18Vertebrate Pests .............. 18 diseases, and weeds. ForWeeds .................................. 21 general information onAlleyway Vegetation organic fertility manage-Management .................... 21 ment in tree and vineGrazing Options ..............25 crops, refer to ATTRA’sEconomics and Tree Fruits: Organic Pro-Marketing ...........................25 Photo by Rex Dufour, NCAT duction Overview.Wine Making andSustainable Energy......... 28 In some parts of the country, grapes areSummary ............................30 Introduction among the easiest fruit crops to grow organ- GReferences .........................30 rapes are grown in many parts of the ically. Diseases can be managed with aFurther Resources ........... 32 U.S., in a wide range of climates and combination of cultural strategies (includingAppendix I: Disease conditions. Certain considerations specific pruning and training techniques,Resistance Rating Chartfor Grape Cultivars..........38 and practices in grape production will be cultivar selection, and proper siting of the the same for both organic growers and con- vineyard) and organically acceptable oils ventional growers within a given region. For and soaps, and mineral- and biologically-ATTRA—National Sustainable instance, site selection, pruning and train- based fungicides. A similar range of prod-Agriculture Information Serviceis managed by the National Cen- ing, and planting techniques are similar for ucts, but including pheromonal controls,ter for Appropriate Technology both conventional and organic grape cul- can be relied upon to control most mite and(NCAT) and is funded under agrant from the United States ture. Information on these topics is available insect problems. Cover crops, mulching,Department of Agriculture’s through the Cooperative Extension Service, mowing, and mechanical cultivation can beRural Business-Cooperative Ser-vice. Visit the NCAT Web site grape growers associations, and common used to control weeds, and fertility needs( vineyard texts, bulletins, and trade maga- can be met with ecological soil managementhtml) for more informa-tion on our sustainable zines. Accordingly, this publication focuses practices and purchased organic fertilizers,agriculture projects. primarily on organic controls for pests, when necessary.
  2. 2. Table 1. Wine Grape SpeciesGrape Common Names Cultivars Native to Climatic/pest AdditionalSpecies and Hybrids considerations InformationVitis vinifera European Grape, Many Asia Minor Widely planted in western US, but on hybrid root- Vinifera grape stocks, as V. vinifera root- stocks are susceptible to phylloxera. Generally not as cold hardy as native V. labrusca grapes, so less widely planted in the Northeast. Vinifera grapes can be generally charac- terized as requiring a long growing season, relatively high summer temperatures, low humidity, a ripening season free of rainfall, and mild winter temperatures.Vitis rotundifolia, Arkansas Grape, Big White Black Beauty, Black Southern Delaware Adapted to humid south- Because of its resistance to(Please note that some Grape, Black Grape, Bull Fry, Bountiful, Car- to southern Illinois, east. Lacks frost hardi- many pests, V. rotundifoliaauthorities place this Grape, Bullace Grape, Bul- los, Chief, Cowart, south by southwest ness and can be injured by would be the ideal rootstockspecies in a separate let Grape, Bullit Grape, Bush Darlene, Dear- to northeastern minimum winter temps of candidate for Vinifera graftsgenus, Muscadinia.) Grape, Bushy Grape, Currant ing, Delight, Dixie, Texas, south to the 0 degrees F. Should avoid were it not for the fact that italso: Vitis acerifolia Grape, Flowers Grape, Green Doreen, Florida Gulf, and east to the growing in areas that often will rarely accept a graft from(Le Conte), Vitis angu- Muscadine, Hickman’s Grape, Fry, Fry, Higgins, Atlantic. have 10 degree F temps. It any but its own species. Somelata (Le Conte), Vitis Muscadine Grape, Musca- Hunt, Ison, Jane- is most abundant on sandy, authorities consider that thiscallosa, Vitis cordi- dinia Rotundifolia, Mustang bell, Janet, Jumbo, well-drained bottom lands species (along with the relatedfolia, Vitis hyemalis, Grape, Roanoke Grape, Scup- Loomis, Magno- and along river banks and V. munsoniana) should beVitis incisa (Rafin- pernong Grape, Southern lia, Nesbitt, Noble, in swamps, thick woodlands in a different genus, due toesque), Vitis musca- Fox Grape, Warty Grape, Pineapple, Regale, and thickets. They tolerate a number of morphologicaldina (Rafinesque), White Grape, White Musca- Scuppernong, hot summers but do not differences (not to mentionVitis mustangensis, dine, White Musky Grape, Sterling, Summit, withstand drought and do that V. rotundifolia has a differ-Vitis peltata (Rafin- and Yellow Muscadine Supreme, Sweet not adapt well to semi-arid ent number of chromosomesesque), Vitis rotun- Jenny, Tara, Tar- conditions. Satisfactory (n=20) than other Vitas spe-difolia Flowers, Vitis heel, and Triumph growth in warmer grape cies (n=19). California Rarerotundifolia Scup- growing areas of Washing- Fruit Growers website providespernong, Vitis taurina ton, California and Oregon. much information about plant-(Bartram), Vitis ver- Nearly immune to phyllox- ing and care of this species, asrucosa (Muhlenberg), era, Pierce’s disease well as a listing of the variousand Vitis vulpina and nematodes. cultivars and their characteris-(Linnaeus). tics: cadinegrape.html. Also, Jack Keller’s website has a wealth of information on this species: http://winemaking.jackkeller. net/rotundif.aspVitis labrusca, also: Alexander Grape, Alexan- Alexander, Northeast and Nearly immune to phyllox- Tougher skin than EuropeanVitis blandii (Prince), dria Grape, Beaconsfield Catawba, Cham- east of US. era. Vitis labrusca has long grapes. Deep purple in color.Vitis canina, Vitis Grape, Black Cape Grape, pion, Concord been used as rootstock Major use is for sweet grapecatawba (Hort.), Black Champion, Black Fox (80% of V. labrusca for V.vinifera grafts and juice (Welch’s) and associatedVitis ferruginga, Vitis Grape, Black Grape, Buck production), Dela- for development of hardy products–jelly, jam, preserves,labrusca alexandrer, Grape, Cape Grape, Cham- ware, Niagara, hybrids. some wine.Vitis labrusca cham- pignon Grape, Clifton’s Con- Lakemont, Reli-pion, Vitis labrusca stantia Grape, Clifton’s Lom- ance, and Himrodvar. subeden tata (Fer- bardia Grape, Columbiannald), Vitis labrusca Grape, Constantia Grape,var. typica (Regel), Early Champion Grape, Grapes grow all over North America, except in the most extreme desert and tun-Vitis latifolia, Vitis Farker’s Grape, Fox Grape, dra. North America is home to more than half of the world’s 50 or so species ofluteola, Vitis sylves- Frost Grape, Madeira of York grapes. Various authorities recognize between 19 and 29 species of native Northtris virginiana (Bauh), Grape, Northern MuscadineVitis taurina (Walter), Grape, Plum Grape, Rothrock American grape. Table 1 lists the four American grape species used in wine pro-Vitis vinifera sylvestris Grape, Rothrock of Prince duction: V. rotundifolia, V. labrusca, V. aestivalis, and V. riparia. Please note, how-americana (Pluk), and Grape, Schuykill Muscadel, ever, that except for Vitas rotundifolia and Vitas munsoniana, these “species”Vitis vulpina Schuykill Muscadine, Skunk readily hybridize, resulting in a situation where one specie’s traits and range(Marshall) Grape, Springmill Constantia overlap with another (or several others!). Some areas may have two or more Grape, Swamp Grape, Tal- species co-existing and with the various permutations of hybrid offspring pos- mam’s Seedling Grape, Task- sible, identification becomes difficult. This is why there are so many names listed er’s Grape, Tolman, Vevay under “Grape Species”—some authorities described “new” grape species that Grape, Winne Grape, and had already been described by others under a different name. (Table adapted from: York Lisbon Grape Winemaking Homepage, Jack Keller, 2005. 2 ATTRA Grapes: Organic Production
  3. 3. Table 1. Wine Grape Species (continued) Grape Species Common Cultivars and Native to Climatic/pest Additional Names Hybrids considerations Information Vitis aestivalis (Munson), also: Cynthiana Grape, Norton, Cynthiana, Tolerant of Pierce’s Dormant cuttings of this species do Vitis nortoni, Vitis lincecumii, Arkansas Grape, Nor- America Disease. (Rombough, not root well and this trait is com- Vitis bicolor. The later two ton Grape, Norton 2002) monly passed on to hybrids (an are considered varieties of Virginia Grape, Nor- exception is the hybrid America, a V. aestivalis ton’s Seedling Grape, cross with V. rupestris, which roots Norton’s Virginia readily from dormant cuttings). Seedling Grape, and Green cuttings will root on mist Red River Grape benches (Rombough, 2002). This grape can make an excellent red wine that can compete in quality with that made from vinifera grapes. Vitis riparia, also: Vitis amara, Bermuda Vine, Frost The better root- Riparia is the most It is known to with- Riparia grows readily from from Vitis boulderensis, Vitis cal- Grape, June Grape, stocks in France widely distributed stand temperatures to cuttings and makes a good stock losa (Le Conte), Vitis canaden- Maple Leaved Cana- have been given of any American -60 degrees F., is mod- for grafting, where the union with sis acceris folio (Tournefort), dian Grape, Mignon- varietal names such species of grape. erately drought resis- other species is usually permanent. Vitis colombina, Vitis con- ette Vine, River Grape, as Riparia Gloire, It is found in New tent when naturalized Native Riparias are early bloomers color, Vitis cordifolia (Darling- Riverside Grape, Riparia Grand Gla- Brunswick and to such conditions, but late ripeners, and their fruit is ton), Vitis cordifolia riparia Riverbank Grape, bre, Riparia Scribner, northern Quebec and is found along the best for wine when left on the (Torr. et Gray), Vitis cordifolia Scented Grape, Riparia Martin and to Manitoba and banks of streams, in vine until over-ripe and even var. Riparia (Gray), Vitis cor- Sweet-Scented Grape, others. There are no Montana, south to ravines, on the islands slightly shriveled. difolia var. culpina (Eaton), Uferrebe Grape, and American or Cana- Tennessee, north- of rivers, and in wet Vitis dimidiata (Le Conte), Vignes des Battures dian counterparts ern Texas, Colo- places. It is very resis- Vitis hyemalis (Le Conte), Vitis to these French rado, and Utah, tent to phylloxera. It illinoensis (Prince), Vitis incisa varietals. and from the Atlan- is less resistent to rot (Planchon), Vitis intermedia tic to the Rock- than Aestivalis, but (Nuttal), Vitis missouriensis ies in all areas in somewhat more resis- (Prince), Vitis montana, Vitis between. tent than Labrusca. odoratissima (Donn.), Vitis The foilage is rarely odoratissima (Pursh), Vitis attacked by mildew, palmata (Vahl), Vitis popu- but is susceptible to lifolia, Vitis riparia var. pal- the leaf-hopper. mata (Planchon), Vitis riparia var. praecox (Englemann), Vitis rubra (Desf.), Vitis sero- tina (Bartram), Vitis tenuifo- lia (le Conte), Vitis virginiana (Hort.), Vitis virginana (Poir), Vitis virginiana sylvestris (Parkins), Vitis virginiensis (de Juss), Vitis vulpina (Linnaeus), Vitis vulpina var. praecox (Bai- ley), Vitis vulpina var. riparia (Regel), and Vitis vulpina var. syrt. (Fernald and Weigand). Vitis rupestris, also: Vitis Beach Grape, Bush Cultivated French Southern Mis- Rupestris is remark- Rupestris bench-grafts well but is populi foliis (Lindh.), Vitis rup- Grape, Currant Grape, rootstocks are vari- souri to Kentucky, ably resistant to phyl- less successful in field grafts. It is estris var. dissecta (Eggert), Felsenrebe Grape, ously known as western Tennes- loxera. Its propensity not widely cultivated in the United and Vitis vinifera var. rupes- Ingar Grape, July Rupestris Mission, see, Arkansas, to put down deep States as rootstock and its own fruit tris (Kuntze). Grape, Mountain Rupestris do Lot, Oklahoma, eastern rather than lateral are unprofitable. It is considered Grape, Rock Grape, Rupestris Ganzin, and central Texas roots make it espe- drought-resistent, but not if the Sand Grape, and Rupestris Mar- to the Rio Grande, cially suited to dry, land dries out deeply. It was widely Sugar Grape tin, Rupestris St. westward into New rocky soils on south- and successfully used in France George, and other Mexico. Wild stands ern slopes. as grafting rootstock where deep names. These have in Pennsylvania, roots were desired. no American coun- Delaware and terparts other than Washington, D.C. simple Rupestris. are probably due to escaped cultivars. A note about French Hybrids: Seibel is the common name for a number of Vitis vinifera hybrids that have been introduced over the years in a quest to develop climate tolerant grape varieties that are resistent to rot, mildew and phylloxera. Some of these, notably the bunch rot resistant Chambourcin, were widely planted in France in the 1970s. How- ever, stringent European Union rules forbidding the blending of hybrids in traditional wine varieties have led to their disappearance from most European vineyards. Nonethe- less, several hybrids have found acceptance as wine grapes in the Eastern United States, Canada and England, including the dark-skinned Chambourcin (Noir), Chancellor (Seibel 7053), Chelois, and Vignoles (Ravat 51). Widespread light-skinned hybrids include Seyval Blanc, Vidal Blanc and Villard Blanc. Seyval Blanc is in fact so widely planted in parts of the Eastern United States that it is sometimes referred to as “Indiana Chardonnay.” It is also quite widespread in England. (from: Grapes, Wines, and Vines, Bella Vista Ranch webpage, 1999. ATTRA Page 3
  4. 4. Geographical Considerations Symposium. The report can be viewed online at and Disease Management organicvitwkshp/tabofcontents.html. As with other fruit crops, the generally drier conditions in the western half of the United Hard copies can be ordered as indicated in States are more conducive to organic grape the Publications and Resources section at production than in the humid East, particu- the end of this publication. larly with respect to cultivation of Vitis vinif- In the East, several diseases can be devas- era (European grape). The many large-scale tating, but black rot (Guignardia bidwellii) is organic wine and table grape vineyards in perhaps the most important of these to con- California are testimony to the relative ease of trol. It only takes a few black, rotted grapes organic grape culture in that part of the coun- to render a cluster unsaleable on the fresh try. As recently as 1997, California had 96 market. On the other hand, grapes produced percent of the country’s organic grape acreage. primarily for juice, wine, or other processed A table with a state-by-state listing of acreage products will have a slightly higher tolerance of organic fruit production may be found at for cluster damage. organic/table12.htm. Northern growers should choose cultivarsRelated ATTRA with proven cold hardiness for their par-Publications However, with careful attention to pest con- ticular climatic zone. The European wine trol (especially diseases) and cultivar selec- grape (Vitis vinifera) is not well-adapted out-Organic CropProduction Overview tion appropriate for each climate, grapes can side of USDA climate zone 8; zone 7 can be be grown organically almost anywhere in the marginal. In zones 5 to 7, American typesTree Fruits: Organic United States. Native American grape cul- (mostly V. labrusca) or some of the American-Production Overview tivars, or crosses between American grape European hybrids (French hybrids) are theKaolin Clay for cultivars and Vitis vinifera, known as French best choices. There are some American typesManagement of hybrids, may be easier to grow organically in that are cold hardy in zones 3 and 4.Glassy-winged Sharp- the East, because of their generally greatershooter in Grapes resistance to pests. (See Table 1, Wine Grape To view a USDA zone map, seeOrganic Orchard, Species on pg. 2.), and Berry ushzmap.htmlCrop Documentation In contrast to the West, organic viticultureForms in the eastern U.S. is still limited to a few innovative growers, and many questions As with other types of cultural informa- remain about organic management prac- tion, cultivar recommendations for a par- tices, especially those regarding disease con- ticular region are best obtained through the trol in a humid climate. An eastern grower county or state Cooperative Extension Ser- producing for the fresh market should have vice. A University of Illinois table indicat- a disease-control plan. From 1990 to 1995, ing susceptibility of cultivars to low-tempera- Cornell University researchers explored ture injury and disease is available online at organic vineyard management in the North- east in collaboration with grape growers. cfar/bbsusc.htm. (See also Appendix I: The results of this and other research are Disease Resistance Rating Chart for Grape found in Organic Grape and Wine Production Cultivars.) Cold Hardiness of Grape Cultivars: Very Hardy: Swenson hybrids: LaCrosse, St. Croix, St. Pepin , Edelweiss, Frontenac, Foch , Leon, Millot , Ventura Hardy: DeChaunac , Chancellor, Vignoles, Cynthiana, Steuben , Concord, Catawba , Niagara, Delaware Moderately Hardy: Seyval, Traminette , Melody Moderately Tender: Vidal, Chambourcin, Chardonel , Cayuga White Tender: Cabernet franc, Riesling, Chardonnay, Cabernet Sauvignon Very Tender: Merlot, Pinot Noir, Gewurztraminer From: Bordelon, 2002.Page 4 ATTRA Grapes: Organic Production
  5. 5. Extreme disease pressure makes organicculture of bunch grapes very difficult in the What Type of Grape to Plant? Grape Cultivar Information:deep South. However, many cultivars of theindigenous muscadine grape, V. rotundifo- Grape Cultivars for North-Central New Mexico, are readily grown without pesticides of This site provides names and descriptions of the various hybrids appropriateany sort. Muscadines have a special appeal for cultivation in New southern markets and are consumed Viticulture Site Suitability for North Carolinafresh as well as processed into jams, pre-, juices, and wine. This site provides maps with color-coded zones that outline regions rated as most reliable, good sites and risky sites for specific cultivars of grapes, as wellDiseases as maps showing growing season, precipitation at harvest, extent of Pierce’s Disease, and freezing temperatures.The simplest and most practical approach todisease problems on grapes is to plant dis- Grape varieties—crosses and genetic composition varieties (see Appendix I: Provides a chart of non-traditional (American and French hybrid) grape vari-Disease Resistance Rating Chart for Grape eties, including parentage, mostly for northern climes.Cultivars) and to use certified disease-free Wine and Juice Grape Varieties for Cool Climatesstock. Unfortunately, the market often pre- those varieties not native to a particular This site provides an excellent survey of grape cultivars suitable for plantingregion, and that are especially susceptible in cool climates, including American, French hybrid, and European diseases indigenous to the region. This Includes descriptions of the grapes, pictures, and strong and weak points ofis the case with the V. vinifera cultivars, each variety.the high-quality European wine grapes. In California Grapevine Nursurygeneral, they are highly susceptible to all grape diseases and pests, includ- This site has a table of information about 21 types of rootstocks, includinging downy mildew, black rot, Phomopsis parentage, maturity rates, nematode and drought resistance, best soil/climateleaf spot, powdery mildew, and phyllox- conditions, and other useful comments.era (a root-feeding, aphid-like insect). If a Resistance of Grapes Grown in Michigangrower in a humid climate decides to plant vinifera cultivars, the grower will likely be This site has a table of relative resistance of grape varieties (American, Frenchculturing a susceptible plant under environ- hybrid, and European) to winter freeze damage, disease (black rot, downy mildew, harvest season botrytis, and phomopsis), phylloxera, and sulfur-mental conditions that invite disease. There- induced damage.fore, profitable production of a marketableproduct without the use of fungicides willbe very difficult. However, as already indi-cated, states with dry, Mediterranean cli- As noted earlier, some breeders are exper-mates are quite amenable to the culture of imenting with French hybrids, and arethe European wine grape, and organically backcrossing French hybrids to developacceptable fungicides will be adequate for cultivars with cold hardiness, diseasecontrolling most disease problems. resistance, and good fruit/wine quality. The major breeding programs for French An excellent resource for those hybrids in the US are: interested in organic grape production in the Midwest may be found at: New York State Ag fruitpathology/organic/PDF/ Experiment Station, Geneva OSU-Organic-Grape-Diseases.pdf Bruce Reisch This document focuses on organic Geneva, NY 14456 management of grape diseases, 315-787-2239 including black rot, powdery mildew, 315-787-2216 FAX phomopsis cane and leaf spot disease, eutypa dieback, downy mildew, botrytis bunch rot, and crown ATTRA Page 5
  6. 6. University of Minnesota as spiders and mites that are present in the Peter Hemstad vineyard. Another problem associated with 952-443-14-92 the use of sulfur is tissue injury, or phyto- toxicity. This damage can occur when sul- Jim Luby fur is used while temperatures are above 612-624-3453 85°F. (about 30° C.). Some cultivars, espe- cially those of V. labrusca origin such as the Concord, are highly susceptible to sulfur Elmer Swenson, Private Breeder, injury even at lower temperatures. The Dis- Osceola, Wisconsin ease Resistance Rating Chart, Appendex I, lists sulfur-sensitive grape cultivars. In University of Arkansas regions where rainfall is plentiful during the Jim Moore growing season, wettable sulfur or flowable 479-575-2811 sulfur formulations are preferred for their retentive qualities. (Pearson and Goheen, John Clark 1988) Flowable formulations are less dam- 479-575-2810 aging to predatory mite populations and should be used whenever possible. Justin Morris Bordeaux mix (copper sulfate mixed with 479-575-4040 hydrated lime) is less likely to be phytotoxic than sulfur due to the “safening” influ- American grape varieties (V. labrusca and ence of the lime. However, damage can still others) differ in their susceptibility to vari- occur on sensitive cultivars, especially in ous diseases. Concord, for example is quite high temperatures. resistant to anthracnose but susceptible Organically acceptable alternatives to to black rot. Ives is relatively resistant to mineral-based fungicides exist. A new black rot but highly susceptible to downy generation of microbial fungicides, such mildew. Edelweiss (V. labrusca) and Cynthi- as AQ-10™ (for powdery mildew control) ana (V. aestivalis, also known as Norton) are and various commercial formulations of two American cultivars that appear to have Bacillus subtilis, (i.e., Serenade™, Epic™, significant resistance to most of the major Kodiak™), provide organic growers with grape diseases. Muscadine grapes (V. rotun- new tools to manage plant diseases. New difolia), suited only to the South, are very fungicides of this type, and new uses for resistant to most bunch grape diseases and previously registered microbials, appear pests. See Appendix I for more informa- regularly on the market. tion on varietal resistance. Compost teas have been successfully used Where varietal resistance, sanitation, and in other plant production operations as other cultural controls are not adequate, an a combined foliar feed and disease sup- organic grower will have to rely on organi- pressive technique. There is potential for cally acceptable mineral fungicides (various using aerobic compost tea in vineyards to sulfur and copper formulations), microbial- manage diseases, but the parent material based fungicides, compost teas, and veg- (i.e., manures vs. green waste) of the com- etable and mineral oils used as dormant post used to make the tea is an important applications, or on foliage, depending on consideration, as is the interval between the weather. last application of the tea and harvest. Organic growers are allowed to use some Additional information is provided in the mineral fungicides, since they are mined following pages under specific disease materials; however, sulfur and sulfur-con- headings. For more information, also see taining fungicides can be disruptive to ben- ATTRA’s Notes on Compost Teas and Use of eficial insects and other arthropods, such Baking Soda as a Fungicide.Page 6 ATTRA Grapes: Organic Production
  7. 7. The following discussion of grape diseases Some formulations of sodium and potassiumfocuses primarily on organic controls. For bicarbonate also have proven successfuldisease symptoms, life cycles, and epide- in controlling powdery mildew on grapes.miology, refer to the Publications and Research in Germany demonstrated thatResources section. sodium and potassium bicarbonate were highly effective against powdery mildewPowdery Mildew and can be used in organic viticulture toVitis species differ greatly in susceptibil- minimize sulfur or completely substituteity to powdery mildew. V. vinifera cultivars the use of sulfur. (Kauer, et. al., 2000). Seeare highly susceptible, whereas Ameri- ATTRA’s Use of Baking Soda as a Fungi-can species are much less so. The French cide for further details on this topic. Ore-hybrids developed by crossing V. vinifera gon State University’s 2002 Pest Manage-with American species have varying lev- ment Guide for Wine Grapes in Oregon ratedels of resistance. Cabernet Franc, Cabernet baking soda (bicarbonates) as “slightlySauvignon, Chancellor, Chardonnay, Chel- effective” for powdery mildew. Results withois, Gewurztraminer, Merlot, Pinot Blanc, these products will vary according to local PPinot Noir, Riesling, Rosette, Rougeon, factors, such as relative humidity, diseaseSauvignon blanc, Seyval, Vidal 256, and pressure, the grower’s experience with alter- owderyVignoles are considered highly susceptible. native controls, and context of use (i.e., use mildew can(Ellis, 1994) in a heavily sprayed, conventionally man- reduce vine aged vineyard vs. use in a lightly sprayed orPowdery mildew can reduce vine growth, growth, yield, fruit organically managed vineyard.) Kaligreenyield, fruit quality, and winter hardiness. quality, and winterThe fungus that causes powdery mildew, and MilStop are OMRI-listed formulations hardiness.Uncinula nector, overwinters inside dormant of potassium bicarbonate.buds on the grapevine or on the surface of Calcium has been shown to inhibit fungalthe vine. Its control in commercial vine- spore germination. Low calcium or excessyards generally is based on the use of fun- nitrogen levels in the grape leaf tissue cangicides. Sulfur is effective against powdery set up conditions for powdery mildew. (Jur-mildew, but, as mentioned above, care must gens, 2005) A 1:1 ratio of calcium to nitro-be taken to avoid damage to sulfur-sensitive gen in a tissue test is ideal. (Jurgens, 2005)cultivars. Cultural practices may reduce There is some evidence that foliar sprays ofthe severity of powdery mildew. Planting in milk, diluted 1:10 with water, can reducesites with good air circulation and sun expo- powdery mildew levels on grapes (Bettiol,sure, and orienting rows to take advantage 1999; Crisp and Bruer. 2001), althoughof these factors, are helpful. (Pearson and it is not clear if the fungal inhibition is aGoheen, 1988) The use of training systems function of calcium/milk toxicity to fungalthat promote good air circulation should be spores, competition from other organismsincorporated. Some vineyards manage the feeding on milk nutrients, increased cal-leaf canopy by leaf thinning so that both cium uptake by leaf cells resulting in stron-leaves and grape clusters are exposed to ger cell walls, or some combination of thesegood air circulation, allowing them to dry factors. Whey is also used by some practi-off quickly after heavy fogs or rainstorms, tioners due to its availability and is dilutedand thus helping reduce the possibility of at a ratio of 1:3 (whey:water). The milk/infection. Although moisture is not nec- whey formulations are most effective whenessary for powdery mildew infections to used on varietals that have some resistanceoccur, rains and heavy fogs can help spread to powdery mildew. David Bruer is a chem-the spores. ist and former professor of enology at theApplied materials for managing powdery University of Adelaide. He is the owner ofmildew include sulfur products, bicarbon- a 67 acre vineyard in Australia where someates, oils, and biologicals (including com- of the milk/whey trials were done. Dr. Bruerpost teas), described in more detail below. claims that under the influence of ATTRA Page 7
  8. 8. let light, a protein in whey (ferroglobulin) Black Rot produces an oxygen radical that is extraor- Black rot is the most important disease dinarily toxic to fungal spores. facing eastern growers, yet it is virtually Various formulations of oils, some of them unknown in the West. Black rot is caused botanically based, can be used to manage by the fungus Guignardia bidwellii. This powdery mildew. A commercial formula- fungus overwinters in mummified ber- tion of neem oil, Trilogy™, manufactured ries on the soil or in old clusters still on by Certis, is registered for use on grapes the vines. Fungal spores (ascospores) are against powdery mildew and several other spread by air currents and blowing rain, diseases and is also OMRI-listed. Research both in the early spring and throughout the in Germany demonstrated that rapeseed oil growing season. All cultivated varieties of reduced the incidence of Uncinula necator grapes are susceptible to infection by the by 66 to 99 percent and reduced the sever- black rot fungus. ity of the disease by 96 to 99.9 percent on ripening berries. However, some side Hours of leaf wetness required for effects on predatory mites were observed black rot infection period at various (Trimborn et al., 2000). JMS Stylet temperatures following a rain oil is effective against powdery mil- dew and is OMRI listed. Hours (of continual The use of compost Temp (ºF) wetness from rain) teas in organic pro- A new product from Agraquest is also duction has been 50 24 now available; Sonata is a formula- reviewed by the Com- 55 12 post Tea Task Force of tion of Bacillus pumilus and is reg- the National Organic istered for use against powdery mil- 60 9 Standards Board dew on grapes. In the late 1980s and 65 8 (NOSB). The Task Force ‘90s, field and greenhouse studies on 70 7 issued a report in April compost teas in Germany found that 75 7 2004 outlining the undiluted compost watery extracts issues associated with (derived from cattle manure-based 80 6 using compost teas compost, as well as supplemented 85 9 (such as feedstocks, extracts of composts derived from 90 12 additives, and pres- horse manure) were effective against Source: R.A. Spotts, The Ohio State University ence of human patho- the causative agent of powdery mil- gens) and also made dew, Uncinula necator. The effects some recommenda- do not appear to be systemic, but are Proper sanitation is important in controlling tions. This report can antagonistic in nature, correlating black rot. Removing overwintering mum- be downloaded at with high levels of active microbes mified berries from the vines and disking on the leaf surface. (Trankner and mummies into the soil are beneficial prac- nosb/meetings/ Brinton, 1994) More recent research tices that reduce the amount of primary CompostTeaTaskForce from Germany supports these fi nd- inoculum present in the spring. (Pearson FinalReport.pdf ings, but found that at high rates of and Goheen, 1988) Black rot control for infection pressure, compost extracts bunch grapes is very difficult in the East were not able to provide a sufficient due to high humidity and foliage density. level of protection against powdery mildew. For organic growers, liquid copper formu- (Trimborn et. al., 2000) More research lations, or copper-sulfur compounds such is needed to better understand how the as Bordeaux mix, can be used for preven- components of the extracts interact with tion of black rot, as well as suppression of powdery mildew spores and the time powdery mildew, downy mildew, and pho- duration between application and harvest mopsis leaf spot. Some of the new microbial needed to ensure no contamination of the fungicides may provide control, though they grapes by pathogens that may be in the may not yet be registered for use on grapes compost teas. against black rot.Page 8 ATTRA Grapes: Organic Production
  9. 9. Black Rot - Guignardia bidwellii (Ellis) Viala & Ravaz©Clemson University - USDA Cooperative ©M. Clerjeau, INRA, ©M. Clerjeau, INRA, ©M. Clerjeau, INRA,Extension Slide Series Centre de Recherches de Bordeaux Centre de Recherches de Bordeaux Centre de Recherches de BordeauxBecause copper and sulfur compounds can- However, because spores require free waternot remedy an established infection, they and a certain temperature range for ger-must be used as protectants. That is, these mination and infection, a rigorous spray Bcompounds need to be present on the plant schedule will probably not be necessary lack rot issurfaces before an infection period is antic- every year. Also, proper sanitation and good the mostipated. In the case of black rot, growers early-season control will help to reduce the importantwith a history of the disease should begin inoculum levels of the pathogen.spraying when the first vegetative shoots are disease facing east-3 to 6 inches long. This is roughly when With relatively resistant cultivars and good ern growers, yet it isthe pathogen begins releasing spores that early season coverage, some eastern viticul- virtually unknown inmay infect leaf or flower tissues. Protec- turists have been able to control black rot the West.tion should be maintained until the berries with as few as two to four sprays of Bor-begin their fi nal ripening stage (at about deaux mix (the fi rst when new shoots are5 percent sugar). (Pearson and Goheen, 2 to 4 inches long, and the remainder at1988) Depending on the cultivar, inoculum two-week intervals). There are few bunchlevel, and weather conditions, it is possible grape cultivars with high levels of resis-that this could entail sprays every 7 to 14 tance, but some relatively resistant cultivarsdays from bud break until mid-July or early include Chambourcin, Cynthiana (aka Nor-August. For example, in the wet growing ton), Edelweiss, Elvira, Esprit, Foch, Ives,season of 1991, organically grown Seyval Cascade, Missouri Reisling, and grapes (a rot-susceptible French The non-bunching muscadine grape ishybrid) required 17 fungicide applications very resistant to most races of G. bidwellii,for disease control. (Ellis, 1994) but there are races of this fungus that areSerenade, a formulation of Bacillus subti- pathogenic to muscadines in some areas oflis QST 713 strain, has been effective in the South. (Pearson and Goheen, 1988)reducing incidence of black rot in grapesby 50-70% over control treatments of water. PhomopsisIn other trials done by Agraquest, Sere-nade plus yucca, which is a natural deter- Phomopsis cane and leaf spot is caused bygent and acts as a sticker/spreader, also the fungus Phomopsis viticola. This fungusprovided good control of black rot. (Smith, overwinters in the bark of the canes and2005) Serenade is available through Agra- can be especially severe in the early spring,Quest in California (call 530-750-0150, when it rains for several consecutive days.or visit frames. Inoculum levels build over time, with dis-html). Yucca Ag-Aide manufactured by ease problems increasing in severity withDesert King International is a formulation each successive cool, wet spring. Few cul-of yucca that is OMRI certified and allowed tivars are resistant to Phomopsis, thoughin organic production. there are varying degrees of ATTRA Page 9
  10. 10. Control of Phomopsis for the organic grower of these measures is sufficient for cultivars consists of a combination of appropriate highly susceptible to downy mildew, fun- sanitation measures and the use of liquid gicidal control may be necessary. As men- copper fungicides. Mycostop™, a commer- tioned above, organic growers can use liq- cial formulation of Streptomyces griseoviri- uid copper, or Bordeaux mix, for control dis, is registered for use against Phomop- of this disease. Another option for downy sis. Growers should avoid introducing the mildew management is Trilogy, a commer- problem into the vineyard by using only cial formulation derived from neem seeds, pathogen-free propagation material when which is a broad spectrum fungicide and planting or re-planting. Once the disease miticide. has appeared, growers should remove as much infected wood as possible from the Vinifera (Vitis vinifera) varieties are much vines during pruning. Severely infected more susceptible than American types, and wood in the basal areas of the cane appears the French hybrids are somewhat suscep- bleached. Badly infected canes or spurs tible. Several resistant cultivars are listed will have brown/black patches irregularly in Appendix I.B mixed with bleached areas. Debris should otrytis is be shredded, disked, or plowed into the Botrytis more of a soil. (Pearson and Goheen, 1988) Botrytis bunch rot (causal organism: Botrytis problem on cinerea), also known as gray mold, can be In addition, measures such as avoidingvarieties with tight shaded planting sites, providing good soil a problem throughout the U.S., but is espe-clusters where mois- drainage and air circulation, and plant- cially troublesome in wet or humid regions.ture tends to collect. ing rows to take full advantage of sunlight Botrytis is more of a problem on varieties and wind movement also can help control with tight clusters where moisture tends to Phomopsis. collect. California research indicates that the incidence of botrytis bunch rot can be Downy Mildew greatly reduced by removing leaves around a ripening cluster, thereby improving sun- Another disease to which V. vinifera variet- light and air penetration into the cluster. ies are highly susceptible is downy mildew, caused by the fungus Plasmopara viticola. (Bettiga et al., 1989) Although this prac- Downy mildew is a major disease of grapes tice is labor intensive, and therefore rela- throughout the eastern United States. It usu- tively costly, it has positive side effects of ally overwinters as spores in fallen leaves, increased fruit quality, including higher but it may survive in buds as mycelium malic and total acids, decreased potassium, in regions with mild winters. Downy mil- increased brix, and better grape color and dew is favored by all factors that increase wine quality. (Gubler, no date) Reducing the moisture content of soil, air, and host fertilization, thereby reducing lush vine plants. Therefore, rain is the principal fac- growth, will also help control botrytis. tor promoting epidemics. The most serious Bordeaux mixture and sulfur-containing epidemics of downy mildew occur when a fungicides are generally regarded as inef- wet winter is followed by a wet spring and a fective control measures against botrytis. warm summer with intermittent rainstorms New biofungicides are available for man- every 8 to 15 days. (Pearson and Goheen, agement of botrytis. Trichodex, a formula- 1988) tion of the beneficial fungus Trichoderma Preventative management practices for harzianum, is now registered in the U.S. downy mildew consist of draining soils, (call 212-661-9800 for the closest distrib- reducing the sources of overwintering utor). Serenade, a formulation of Bacillus innoculum, pruning out the ends of infected subtilis, QST 713 strain, is a second biofun- shoots, and speeding the drying time of gicide registered for botrytis in grapes; it is leaves and fruit. However, because none available through AgraQuest in CaliforniaPage 10 ATTRA Grapes: Organic Production
  11. 11. (call 530-750-0150, or visit www.agraquest. disease to grapevines and probably manycom/prod_ frames.html). other plant species. The blue-green sharp- shooter (Graphocephala atropunctata) isPierce’s Disease the most important vector in coastal areas. The green sharpshooter (DraeculacephalaAlso known as PD, Pierce’s Disease is a minerva) and the red-headed sharpshooterxylem-clogging bacterial (Xylella fastidi- (Carneocephala fulgida) are also present inosa) infection generally fatal to European coastal areas but are more important as(vinifera) grape vines. The chief vector is vectors of this disease in the Central Val-the glassy-winged sharpshooter (GWSS). ley. Other sucking insects, such as grapeBoth the GWSS and PD are endemic to leafhopper (Erythroneura elegantula) arethe southern U.S., which would explain the not vectors. Management of this diseasenative American grape’s resistance to this mostly revolves around management of thepest, having co-evolved with the disease leafhopper vectors, and this informationand the GWSS over tens of thousands of can be found in the leafhopper section ofyears. Some American grape rootstocks are this to transfer resistance to vinivera vari-eties grafted onto it. A Texas researcherfound that vinifera grapes planted on Mus- Virusestang grape, V. mustangensis (synonym, V. Viruses in grapes are managed throughcandicans) rootstocks survived for eleven the use of clean planting stock. Virusesyears in an area where PD had killed all will spread from one plant to a neighbor-other susceptible grape varieties. (Rom- ing plant, but the spread is generally slow.bough, 2002) Each virus has a unique vector or set of vectors. The Virus Table on page 12 pro-The PD-GWSS complex is responsible for vides information on symptoms, cultivarthe difficulty of growing vinifera grapes in susceptibility, and modes of transmission.infested areas and has had heavy impacts (Rombough, 2002; Flaherty et al., 1992)on vinifera grape production in New Mex-ico, Arizona, and California. Chardon-nay and Pinot Noir are particularly sus- Root Rotsceptible. Researchers in California and Good soil management, particularly prac-Georgia have examined applications of tices that promote good soil drainage andterpene, a naturally occurring botanical avoid the creation of hard pans, will keepsubstance, via drip irrigation. Terpenes root rot problems caused by Phytophthorafound in plants are often associated with to a minimum. Standing water, or pro-plant defense mechanisms. Unfortunately, longed exposure of the trunk, crown orthe trials in California did not show any roots to water, will provide an environ-significant effect in treating PD. ment on these plant parts that is infection- friendly.PD and the GWSS are severe obstacles togrowing European-type (vinifera) grapes in Armillaria root rot is a disease that resultsthe southern U.S. The PD-GWSS complex from planting vines on ground on whichhas recently become a threat to Califor- host plants previously grew, either naturalnia grape growers. Although PD has been oaks or orchards of walnuts or plums. Thepresent in California since the 1880s, the armillaria exists in old roots of these cropsstrong-flying and voracious feeding glassy- that are still in the soil. When planting awinged sharpshooter was found in Ventura, new vineyard in such an area, it is impor-California, only in 1990 and has become tant that the new vines are not overwatered,the primary, though certainly not the only, and that they be planted into healthy, well-vector of the pathogen. The presence of drained soil that has good biological activ-the GWSS in California has resulted in ity, which will allow beneficial organismsthe rapid spread and transmission of the to compete with the armillaria ATTRA Page 11
  12. 12. Virus TableDisease Name Vector/mode of spread Cultivars Attacked Symptoms/CommentsGrape Leafroll Nursery stock Vinifera—American At harvest/leaf fall, infected red-grape vines will and possibly by mealy- rootstocks don’t show have red leaves with major veins still green. bugs. symptoms. White grape cultivars will turn yellow with major veins still green.Corky Bark Nursery stock, no known Can exist in many vinifera Grafted scions decline or die due to graft union vectors cultivars without symp- incompatibility, rootstocks may toms, which appear only survive, even be symptomless. Spread after infected bud grafted only by nursery materials in US. onto phylloxera-resistant rootstockRupestris Stem Pitting Nursery stock, no known High incidence of this Can cause a slow decline, or can be fatal if grafted vectors virus in Vinifera cultivars onto rootstock 3309, but Canada now allows mate- and French hybrids are rial with this virus as a “virus without consequence”. susceptible.Fanleaf Degeneration Nursery stock (infected Vinifera cultivars Seldom fatal, but symptoms can take rootstock, buds or cut- several forms: fanleaf deformation, vein banding, tings), and Dagger nema- and yellow mosaic. tode is vectorPeach Rosette Mosaic Nursery stock, and American cultivars Curly dock, Carolina horsenettle andVirus (PRMV) Dagger nematode Concord, Catawba and dandelion are virus hosts. Grape pommace should is vector Niagara are susceptible, be properly composted so seeds, which contain Delaware less so. virus, do not germinate and allow feeding by nema- tode vectors.Tomato Ringspot and Nursery stock, and Dag- French hybrid cultivars, Plantain, chickweed, dandelion, beans,Tobacco Ringspot ger nematode particularly blue-fruited and other plants are virus hosts. Grape pommace is vector cultivars, are susceptible. should be properly composted so seeds, which con- tain virus, do not germinate and allow feeding by nematode vectors. Geographical Considerations about providing beneficial habitat can be found in ATTRA’s Farmscaping to Enhance and Insect and Mite Biological Control. Management Wherever grapes are grown, there will be In the West, mites, leafhoppers, and lea- insect pests. Existing with each pest, how- frollers are likely to be the most trouble- ever, is a whole complex of natural controls, some arthropod pests, and all of these are including parasites (other insects), predators indirect pests; i.e., they do not directly (insects, birds, bats, mice, etc.), and dis- attack the fruit. In general, indirect pests eases (fungi, bacteria, viruses). One of the can be tolerated in higher numbers than grower’s jobs is to develop a viticulture eco- direct pests, allowing more time for system that takes advantage of and encour- naturally occurring or purchased biocontrol ages these natural controls, while also feed- agents to exert an acceptable level of control. ing the soil and supporting plant health. Although the glassy-winged sharpshooter Providing habitat for beneficial organisms is (GWSS, a leafhopper) is considered an indi- a sustainable approach to managing insect pests, but it must be tempered with aware- rect pest, it has recently emerged as a major ness of how the presence and management problem in California vineyards because it of habitat influences field operations, as well vectors Pierce’s disease. The GWSS/Pierce’s as other factors, such as incidence of harm- Disease complex has long been an obstacle to ful insects and diseases. More information production of vinifera grapes in the South.Page 12 ATTRA Grapes: Organic Production
  13. 13. The major insect pest for eastern organic vest. The row centers shouldgrape growers is the grape berry moth be almost level and seeded(Endopiza viteana). The berry moth is a to a winter cover crop. In thedirect pest of the fruit and flowers and, if spring, at least 15 days beforeleft unchecked, can render whole clusters grape bloom, the ridge soilunmarketable. A pheromone-based mat- containing the cocoons in its © Cornell University, New York State Integrated Pest Management Programing-disruption system for the berry moth surface is pulled from underprovides organic growers with an effective the trellis into the row centers Grape berry moth damage.non-pesticide option for berry moth control with a mechanical grape hoe.(see below). Any islands of soil left around the posts and grapevines may have to be raked by hand intoGrape Berry Moth the row centers. The row cen-The grape berry moth (GBM), Endopiza ters are then disked and cul-viteana, is native to eastern North America, tipacked to bury the cocoons.where it originally occurred on wild grapes. Rain or irrigation after thisIt does extensive damage directly to grape operation will help to seal in Grape berry moth larva.berries, flowers, and buds east of the Rocky the cocoons. This practice hasMountains, particularly in the Northeast. It reduced berry moth popula-feeds only on grapes. The number of genera- tions to a point where shortenedtions per year varies from 1.5 to 2 in New spray schedules can be used inYork, to 2 to 3 in Michigan, and 4 to 5 in commercial vineyards. (Pfief-Virginia. High populations and damage have fer and Schultz, 1986) Therebeen observed after consecutive mild win- is a higher risk of develop-ters. Substantial winter mortality occurs after ing GBM populations in vine- Grape berry moth adult.several days of very cold temperatures (-6 yards bordering +5°F). (Pfeiffer and Schultz, 1986) The (Martinson et al., 1991)Website, Pheromones can be used to monitor emerg-discusses in detail recent research about how ing populations. Pheromone traps can helptemperatures affect timing of GBM emergence time management activities, or pheromoneand diapause. dispensers can be used in a mating dis-The only biological control agent that has ruption system that disperses pheromonesbeen found to be of appreciable value is the throughout the orchard, making it difficultegg parasite Trichogramma minutum, which for males to locate females. The table belowcan be purchased from many insectaries. provides contact information for some sup-However, the grape berry moth does not pliers of these systems.appear to be an optimal host for the egg para-site, and resulting adults have poor vigor and To augment populations of natural enemies of pests, farmers canexhibit developmental abnormalities. (Nagar- apply beneficial insects purchased from commercial insectaries. Thiskatti et al., 2002) It’s possible that a differ- directory contains a comprehensive listing of companies raising biocontrolent T. minutum ecotype, one that is naturally organisms in North America.found parasitizing eggs of the GBM, would be Suppliers of Beneficial Organisms in North America. Hunter, Charles D. 1997.more effective. California Environmental Protection Agency, Sacramento, CA. 32 p. For a free copy, write to:Destruction of fallen grape leaves, which California Environmental Protection Agencyare overwintering sites for the cocoon-pro- Department of Pesticide Regulationtected pupa, can help reduce spring popula- Environmental Monitoring and Pest Management Branchtions. Covering leaves with at least an inch 1020 N Street, Room 161of firmed soil is another control option. One Sacramento, CA 95814-5624popular method is to throw the soil from the 916-324-4100row centers into a low ridge under the grape A Web-based version can be found at:trellis with a grape hoe, disk, or plow. This be done 30 to 45 days before ATTRA Page 13
  14. 14. Commercial Monitoring/ erythroneura, egg parasites) can be achieved if habitat for non-pest leafhopper species— Disruption Pheromone Systems especially blackberry bushes and French Timely use of Bacillus thuringiensis (Bt) can prune trees—is maintained near the vine- suppress populations of the grape berry yard. The bushes and trees attract related moth. Use of pheromone traps can aid the Erythroneura species of leafhoppers, provi- grower in timing Bt applications. The Bt ding an important food source for the para- should be applied as the fi rst instar larvae sitic wasp. However, maintaining diverse are hatching out of eggs. habitat in this manner may confl ict with management for the glassy-winged sharps-Pheromone Chart hooter (see below).Type of System Company Contact Information Clean cultivation in and around the vine- Pacific Biocontrol yard can help reduce leafhopper popula-Mating Disruption, 14615 NE 13 St, Suite A tions, because the adults overwinter in shel- Vancouver, WA 98685 ters provided by weeds in these areas. Ifrope dispenser leafhoppers are a problem, and the grower 800-999-8805 wants to use alley cover crops, then selec- 3M Canada ting those covercrops least attractive toMating Disruption, leafhoppers is an option. Organic growerssprayable industrial/ag/spray_canada/grape_ main.html can use insecticidal soaps and the botani- cal insecticide sabadilla to control leafhop- Gempler’s pers. Soap sprays are only effective if they 1210 Fourier Dr, Suite 150,Monitoring Traps Madison, WI 53717 cover the leafhopper; i.e., if there is no resi- dual effect from soap left on a plant surface. 800-382-8473 PyGanic, a formulation of pyrethrins, is an effective control of leafhoppers and also listed by OMRI. Leafhoppers Surround™, a kaolin clay-based insect Grape leafhoppers, Erythroneura species, repellent, is effective against leafhoppers, also can be a serious problem throughout leafrollers, and the glassy-winged sharpshoo- the United States, but these pests more con- ter. It is accepted by the Organic Materials sistently trouble West Coast vineyards. Review Institute for use in organic produc- Research in California indicates that biolo- tion. For leafhoppers and related insects, it gical control of grape leafhoppers by a tiny seems to act as a deterrent to locating host parasitoid wasp (Anagrus epos and Anagrus plants, as well as deterring feeding and egg- laying. For additional information, contact: John Mosko Marketing Manager Crop Protectants Engelhard Corporation 732-205-7140 More information about kaolin clay-based management options for the GWSS is avai- lable in the ATTRA publication Kaolin Clay for Management of Glassy-winged Sharpshooter in Grapes.Photo by Rex Dufour, NCAT According to Tom Piper, former managerSome vineyards are now using an innovative strategy of planting dwarf grasses in of Fetzer’s organic vineyards, leafhopperthe alleys in order to manage excessive vigor of some varieties. populations are proportional to the vigorPage 14 ATTRA Grapes: Organic Production
  15. 15. of the vine. He keeps close watch on both herbicides, and (2) cover crop biomass waswater and nitrogen inputs and tries to keep cut and left in row middles. If sulfur dustthe vines just vigorous enough to make a (used for disease control) was used sparin-good crop, but not so vigorous as to attract gly in late spring and early summer, the pre-leafhoppers. If leafhopper populations get sence of these cover crops increased earlyout of hand, Piper uses PyGanic. season activity of predatory mites, resulting in reduced spider mite infestations. Simi-The glassy winged sharp shooter, Homa- larly, where leafhopper numbers were notlodisca coagulata, emerged in the 1990s very low and cover crops were properly main-as a major pest of grapes in California. tained through early July, the presence ofThe GWSS feeds on stems and leaves of a cover crops resulted in reduced infestationswide range of plants and efficiently vectors of leafhoppers. These reductions were attri-Pierce’s Disease (PD), a xylem-clogging bac- buted to enhanced activity of certain groupsterial infection generally fatal to grape vines. of spiders that consistently attained higherAlthough PD has been present in California densities in the presence of cover crops,since the 1880s, the strong-flying and vora- compared to the clean-cultivated systems.cious feeding GWSS has become the primary Leafhoppers also used the cover crops asvector of the pathogen. PD and the GWSS non-host crops, which may have resulted inare important obstacles to growing Euro- less time spent on vines.pean-type (vinifera) grapes in the southernU.S. Riparian areas in the West have a wide For more information on this study, contact:variety of plants that are hosts to the GWSS Frank G. Zalomand can be leafhopper corridors. Monitoring Extension Entomologistshould be directed to areas of the vineyard Department of Entomologyclosest to riparian zones. University of California Davis, CA 95616Research in California has shown that, if 916-752-8350properly managed, winter annual legume- 916-752-6004 FAXgrass cover crops—such as a vetch and oats fgzalom@ucdavis.edumix—can reduce reliance on insecticidesand miticides to control leafhoppers and spi-der mites in vineyards. This is in addition Mitesto the soil-improving and weed-suppressive Various mite species cause problems onbenefits of cover crops. This research exami- grapes throughout the United States. Properned two cover crop systems: (1) cover crop irrigation, dust reduction along roadways,biomass was cut and placed on row berms as and other practices that conserve and aug-a dry mulch to suppress weeds and reduce ment natural enemies (including predatory Photos by Rex Dufour, NCATAlternate disking of alleyways decreases dust and conserves Every other row in this vineyard is planted to an oats-bell beanbeneficials. ATTRA Page 15
  16. 16. mites (Metaseiulus, Typhlodromus), sixspot- Trilogy™ are registered for use on spider ted thrips (Scolothrips sexmaculatus), and mites, but like soap sprays, can negatively other generalist predators) can help reduce affect wine quality if used too close to har- spider mite problems. vest. (Thrupp, 2003) Although sulfur dusts or pyrethrum can be used against mites, In the West, the three major spider mite they are not commonly used since they pests on wine grapes are Willamette mite, can be disruptive to beneficial mites and Eotetranychus willamettei (McGregor), other natural enemies of the pest mites, as twospotted mite, Tetranychus urticae well as natural enemies (such as the wasp (McGregor), and Pacific mite, Tetranychus Anagrus epos) of leafhoppers. pacificus. The most important mite preven- tion practice is dust control. Heat spikes in The beneficial predatory mite Metaseiulus the weather, combined with dust-stressed occidentalis is effective in controlling spi- plants, often result in a mite outbreak. Dust der mites in California. Another preda- can be managed several ways: improving tory mite, Typhlodromus pyri, is effective road surface from dirt to rock or gravel; against spider mites in locations as wide- using water, straw, or dust-suppressant spread as New Zealand and Oregon. TheseM compounds to prevent dust; reducing driv- beneficial mites can be purchased from aintaining ing speed; and disking only every other several insectaries in California and else- a ground alleyway—vehicle traffic is then routed where. Maintaining a ground cover on the cover on on non-disked rows to provide a dust-free vineyard floor is advantageous to predatorythe vineyard floor pathway for machinery performing agricul- mites and various beneficial insects such tural operations. as green lacewings, sixspotted thrips, andis advantageous to Growers in New Zealand use vegetable oil minute pirate bugs.predatory mites. or fi sh oil as dormant sprays in combina- tion with release of predatory mites. (Welte, Grape phylloxera 2000) Soap sprays also can be effective The grape phylloxera (Daktulosphaira against mites, but thorough spray cover- vitifoliae) is a very small, aphid-like insect age is essential, since the mites reside and that is very difficult to see with the unaided feed primarily on the underside of the leaf eye. It has two forms—an aerial, leaf- surface. Soap spray should only be used galling form and a subterranean root- early in the season because of the possi- feeding form. Historically, the root form bility of altering the taste of the grape or has been the more economically damaging the wine. Neem-based products such as of the two. Organic Management – Phlumoxes Phylloxera A two-year field study by UC Davis researchers found that in San Joaquin (own-rooted) were on AXR#1 rootstock. No soil management practices can significantly influence the significant differences between OMVs and CMVs were found amount of root damage resulting from phylloxera-induced for single year comparisons of percent organic matter, total fungal infections. The researchers found that per-unit root nitrogen, nitrate, and percent sand/silt/clay. The pooled data populations of phylloxera did not significantly differ between for the two years tell a slightly different story: OMVs’ soil had organically managed vineyards (OMV) and conventionally a significantly higher (by .5 percent) percentage of organic managed vineyards (CMV), when both were infested with matter (percent OM) than CMVs soil, and over all vineyards phylloxera. However, root samples from OMVs displayed and all years there was a weak but significant inverse corre- significantly less root necrosis (9 percent) caused by fungal lation between root necrosis and soil percentage OM. Cul- pathogens than did samples from CMVs (31 percent). Organic tures of the necrotic root tissue also revealed some interest- vineyard management is characterized by use of cover crops ing differences: significantly higher levels of the beneficial and composts and no synthetic fertilizers or pesticides. fungus Trichoderma were found in OMVs in 1997 (but not in This study sampled four OMVs in Sonoma, Napa, and Men- 1998), and significantly higher levels of pathogens Fusarium docino counties. Eight CMVs were initially sampled in these oxysporum and Cylindrocarpon species were found in CMVs counties and San Joaquin County. This was later reduced to in 1998 (but not in 1997). five CMVs for practical reasons. All vines except for those (Lotter et al., 1999)Page 16 ATTRA Grapes: Organic Production