BY Erica Lundquist, consultant,Glenn McGourty, University ofCalifornia Cooperative Extension

There are many noteworthyefforts to improve sustainabil-ity and environmental steward-ship among different California

winegrowing regions. Located in themountains north of Napa County,Lake County winegrowers use fewerpesticides and more low-risk crop pro-tectants than other winegrowing

regions in the North Coast andCalifornia.The climate of Lake County is very

favorable for wine grape productionbut not for diseases and pests. Theregion has many new vineyards thatare designed and managed by experi-enced growers. There are also well-educated crop consultants knowledge-able in environmentally-friendlyintegrated pest management (IPM)practices to assist growers in pestmanagement decisions. There are

many activities in the region to edu-cate growers on sustainable practices:1. Under the leadership of the Lake

County Winegrape Commission

LAKE COUNTY

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G R A P E G R O W I N G

Environmentally-friendly practices,high elevation, and favorable climate

reduce pest pressures

Environmentally-friendly practices,high elevation, and favorable climate

reduce pest pressuresZinfandel vines in the Madder LakeVineyard above the east end of Clear Lake(1300 foot elevation), spaced 7 x 5. Tractorrows are mowed once a year in the NO-tillvineyard. A Landini or Yanmar crawlertractor with minimal compaction is used inthe hillside vineyard and a weed whackeris used to knock down weeds in vine rows.

MARCH/APRIL 2009

(LCWC), over 75% of Lake Countygrowers have completed the Code ofSustainable Winegrowing PracticesSelf-Assessment Workbook.2. During the rapid expansion of

the vineyard business in the 1990s, anErosion Prevention Education Com-mittee was formed as part of a permit-ting process that required all newvineyard developments to submitplans for a no-fee county permit thatincluded consultation with the com-mittee composed of: two LCWC grow-ers with large acreage, two LCWCgrowers with small vineyards, an at-large community member interestedin environmental conservation, the UCWinegrowing Farm Advisor, and theNRCS Soil Conservationist. The pur-pose of the consultation was toencourage the use of BestManagement Practices (BMP’s) to pre-vent soil erosion, and conserve nativevegetation and habitat.3. Improving water quality by

funding cover crop research with UCCooperative Extension (see “Perfor-mance of 18 Cover Crop Species inNew High Elevation North CoastVineyard,” PWV Sept/Oct 2006); hold-ing well-attended tailgate meetings onBest Management Practices to preventsoil erosion; and conducting aVineyard Water Quality PlanningShort Course (a joint effort betweenUC Cooperative Extension, Mendo-

cino College-Lakeport Center, and theLake County Farm Bureau) on waterquality issues and help growers pre-pare water quality plans for their vine-yards. Forty producers participated inthe effort.4. From 2002 to 2007, the LCWC

organized and funded a sustainablewinegrowing education program withfive to ten meetings each year that cov-ered irrigation, soil fertility, canopymanagement, and many aspects ofpest management.5. Funding of ongoing research

with UC Cooperative Extension todevelop “Soft, Safe, and Sound” inte-grated pest management practices thatreduce pesticide use by creating in-vineyard habitat while protecting soilfrom erosion, reducing dust, choosing“least toxic” materials if spraying isneeded, and augmenting predatorymite populations.6. Working with the Lake County

Air Quality Management District tohelp the region maintain its position ashaving the cleanest air in California byreducing dust (cover cropping andminimizing sulfur dust applications)and minimizing agricultural burning(chipping and shredding vineyardwaste).7. Lake County growers have a

commitment to alternative farmingpractices. There is more than 500 acresof certified organic and biodynamic

vineyards in the region. The LCWChas also conducted tailgate meetingand seminars on organic winegrow-ing, partnering with the CaliforniaCertified Organic Farming “GoingOrganic” program and UC Coopera-tive Extension.More than 100 growers in the Lake

County region are taking a very proac-tive approach to sustainable and envi-ronmentally-friendly farming prac-tices. A recent review of pesticide usereports and testimonies from individ-ual Lake County wine grape growershelp explain how Lake County grow-ers keep pesticide use low.ClimateDuring the growing season, Lake

County’s elevation (mostly above1,300 feet) and crystal clear and dry airlead to diurnal temperature swings inmost locations (between 40 to 50oFmost days). This temperature patternis less favorable to development ofpowdery mildew as measured by theUC Davis Gubler-Thomas powderymildew risk assessment index.Winters are cold and relatively wet

(averaging 35 inches of rain aroundClear Lake and up to 70 inches inhigher elevation areas). Problem pestsand diseases that plague adjoiningwinegrowing regions have not beendetected in Lake County, includingPierce’s disease, glassy winged sharpshooter, light brown apple moth, andvine mealy bug (males have beendetected in traps but no females haveever been found).There are other Lake County factors

that reduce pest incidence and pestmanagement costs. “Cold wintersknock out some pests, and budbreak islater, leading to a shorter growing sea-son,” explains Peter Molnar (ObsidianRidge Vineyard).Integrated ProductionLake County growers have the

goal of farming balanced vines thatare not excessively vigorous (whichpredisposes the fruit to vegetative fla-vors, the canopy to leaf hopper dam-age and fungal diseases) or stressed(causing unbalanced ripening, shriv-eled fruit, and mite attacks on vines)as the foundation of their pest man-agement program.Cultural practices to dissuade dis-

ease include trunk- and cordon-suck-ering, shoot-positioning, and leaf-

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Common annual grasses and forbes in the Beckstoffer Amber Knolls Vineyard of CabernetSauvignon include Soft chess (Bromus hordeaceus), Common vetch (Vicia sativa), Crimsonclover (Trifolium incarnatum), and Rose clover (Trifolium hirtum).

pulling. Self-reseeding annual covercrops are widely planted to preventsoil erosion and reduce dust in thesummer, and provide habitat and bio-diversity for predators and para-sitoids.Growers work closely with crop

consultants to avoid spraying insecti-cides or any other materials that willactively disrupt predator/prey rela-tionships. Many growers are trying toremove sulfur products from their dis-ease control program to encouragepredatory mites and reduce any off-aromas during fermentation.

Fungal disease controlThe annual average applications of

sulfur in Lake County is 35 to 40 lbsper acre (Figure I). Lake County grow-ers take an IPM approach to diseasemanagement. Many growers use theUC Davis Gubler-Thomas powderymildew risk assessment index toschedule powdery mildew control. Dr.Doug Gubler, UC Extension PlantPathologist, has worked closely withLake County growers to educate themon how to use the powdery mildewrisk index, and suggest the use of newmaterials to reduce sulfur use.Lake County growers have access

to local powdery mildew indices andweather information through a pub-licly-available Lake County Pear andGrape Network of weather stations.(This network is a cooperative effortbetween UC IPM, UC CooperativeExtension, Lake County Air QualityManagement District, the LakeCounty Department of Agriculture,and three growers who own fiveweather stations.)Information is available to growers

for disease forecasting, air dispersion,fire hazard, fruit frost hazard, and gen-eral weather data. Any grower canaccess the web-based network at nocost. The LCWC pays for year-roundweather forecasts and growing seasonET (evapotranspiration) forecastsavailable on the website.Several growers emphasize the

importance of vine balance and main-taining an open canopy for diseasemanagement. Walt Lyon (longtimewinegrape grower in Big Valley) has45 acres of Syrah and Sauvignon Blancon a lyre trellis that allows the shootsto grow out at an angle rather thanpositioning them vertically. This pro-

motes air circulation and requires littleor no leaf removal. If grape clusters arepiled on top of each other, the fruit isthinned so that no clusters touch eachother to prevent botrytis.Peter Molnar has experience with a

high elevation Lake County vineyardand a cool, coastal vineyard. His 105-acre Obsidian Ridge Vineyard is at anelevation of 2,350 to 2,640 feet in RedHills, and his family also has a vine-yard in Carneros along the NapaRiver. The varieties grown are suitedto the two locations: CabernetSauvignon, Syrah, Cabernet Franc,and Petite Verdot in Red Hills;Chardonnay and Pinot Noir inCarneros.For powdery mildew control in Red

Hills, Lake County, Molnar avoids sul-fur dust to prevent spider mite out-breaks and applys JMS Stylet-Oil earlyin the season and wettable sulfur forpowdery mildew control pre-bloom.“We make two to three fewer pow-

dery mildew applications per seasonin Red Hills compared to Carneros,”reports Molnar. With a hillside vine-yard location, canopy growth is lim-ited by gravelly soil conditions, per-mitting better air circulation andreducing costs for leaf removal com-pared to Carneros.The Carneros vineyard has substan-

tial Pierce’s disease pressure. Molnarhas made efforts, at great cost, to limitPierce’s disease damage. Lake County,

on the other hand, has never demon-strated a conclusive Pierce’s diseasefind. With a few vineyards at 900 feetelevation and most winegrape grow-ing above Clear Lake at 1,300 feet,winter in Lake County is colder thanin many grape growing regions, possi-bly preventing the Pierce’s diseasecausal agent Xylella fastidiosa fromestablishing a foothold.Balanced nutrition for healthy vinesDavid Weiss (owner of Bella Vista

Farming Company), emphasizesbalanced vine nutrition to avoid pestand disease pressure. His own vine-yards and those he manages total 300acres of Sauvignon Blanc,Gewurtztraminer, Reisling, Zinfandel,Petite Sirah, Cabernet Sauvignon,Cabernet Franc, Syrah, Merlot, PetiteVerdot, and Tempranillo.Mike Boer, of Ag Unlimited, helped

Weiss develop a vine nutrition pro-gram. Boer’s approach is to ensureplenty of plant-available potassium,calcium, and phosphorus that willminimize leafhopper and mite pres-sure. At the same time, this programmaintains better vine health in thepresence of phytophagous nematodesand oak root fungus, according toBoer. Weiss credits the fertility pro-gram and canopy management witheliminating the need for Botrytissprays since 1999.

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LakeMendocinoSonomaNapaSan JoaquinMonterey

01020304050607080

Sulfur

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/ac)

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2.5

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0Non-sulfur fungicides Herbicides Insecticides

Figure I. Average winegrape pesticide use for 2002–2004 in several pesticide categories forLake, Mendocino, Napa, Sonoma, San Joaquin and Monterey Counties.

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Soil tests help Boer to adjust the fer-tility program for each block. His rec-ommendations depend on the soil.Lake County soils range from highmagnesium/low potassium soils inlocations influenced by serpentineminerals to high potassium soils involcanic areas.Soil amendments are an important

part of a sustainable farming approachto improve soil physical qualities andsoil fertility.A typical amendment program will

include fall application of four tons peracre of compost (50% winegrape andpear pomace and 50% animal manure),and one ton per acre of lime or gypsumby broadcast-application to the vine-yard floor. When needed, micro-nutri-ents, including zinc, boron, iron, man-ganese, and copper are applied in earlyseason fungicide sprays.While compost application might

seem expensive, “Where multiplenutrients are needed, it becomes cost-competitive,” explains Boer. The com-post builds long-term soil nutrientavailability, eventually eliminating theneed for most drip-applied nutrients.Boer emphasizes the need to track

changes using soil tests: “Eventuallycompost and amendment rates will bereduced, eliminated, or applied infre-quently as needed.” Compost alsobenefits cover crops which can make

small contributions of nitrogen to thevineyard soil.Weed controlWhen looking at total herbicide use,

Lake, Mendocino, and Napa Countiesapply very low annual rates (Figure I).This may be due to organic growersand an increasing number of conven-tional growers who use mechanicalweed control. Lake County growersconfirm that many herbicide programsare based primarily on Roundup. Pre-emergent herbicides with high-leach-ing potential are avoided.With 115 acres of vineyard in Big

Valley, 58 of which are in transition orcertified organic, Steve Devoto reliesprimarily on cultivation for weedcontrol. Devoto uses a PellencSunflower in-row cultivator, and ifthe soil has dried and become toohard, he uses a Bianco cultivator. Hehas found that the cultivators arehard on vines under two-years-old. Innewly planted blocks, sturdy stakesare used to allow cultivation withoutdamaging vines. In some conven-tional blocks, glyphosate is sprayedfor weed control.Weiss farms both conventional and

organic vineyards. For organic weedmanagement, a combination of hoe-plowing under the vine row and disk-ing in the tractor-row is done. In thespring, a hoe plow moves soil out ofthe vine row. After several weeks, the

tractor rows are disked, and, at thesame time, soil is thrown back into thevine row to cover weeds that haveemerged since the hoe plow pass.After harvest, soil amendments are

applied, and disking throws more soilinto the vine row.Conventional blocks are managed

the same way, or vine rows aresprayed with glyphosate supple-mented with a low rate of Goalor Chateau for improved control.Weiss has been able to reduce weedsprays to one per year in some con-ventional blocks.Insect / Mite controlThe experience of Lake County

winegrowers confirms relatively littleneed for pesticides to control leafhop-pers and mites (Figure I). Only thegrape leaf hopper Erythroneura elegan-tula is found. The parasitic wasp of theleafhopper Anagrus epos is widely dis-tributed. Since growers try to keep thecanopies in balance, this helps in theirintegrated approach to managingleafhoppers and often there is no needto spray to control this pest.Many growers, in valley locations

where vines are more vigorous, treatfor leafhoppers or mites only everysecond or third year, and even then,only on 5% to 20% of their vineyardacreage. In upland vineyards, manygrowers have never sprayed forleafhoppers. Machine-harvesting hasenabled many growers to avoid spray-ing for leafhoppers that would be anuisance to pickers.In hillside locations, spider mite

infestations are more common than invalleys. Taking an IPM-approach,growers focus on reducing dust byplanting self re-seeding cover crops ina no-till management system, andapplying dust suppressants to road-ways. Some growers have had goodsuccess releasing Galendromus occiden-talis predatory mites.North Coast counties are fortunate

to suffer little damage fromLepidopteran (moth) pests such asomnivorous leafroller and orange tor-trix, which are more serious problemsin warmer regions.Promoting biological controlThe IPM program at Beckstoffer

Vineyards (500 planted acres of redwine grapes, primarily CabernetSauvignon, planted on rolling, volcanic

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2002

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Lake Mendocino Napa Sonoma San Joaquin Monterey

Figure II. Application of horticutural oil for the years 2002, 2003 and 2004 in Lake,Mendocino, Napa, Sonoma, San Joaquin, and Monterey Counties.

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terrain of the Red Hills Lake CountyAVA) is to avoid chemicals that disruptnatural pest control or practices thatpromote a flare up of pests, includingcontrol of powdery mildew and spidermites.Randy Krag (Beckstoffer vineyard

operations manager), credits FrankAnderson (recently retired generalmanager), with a philosophy of mini-mizing pesticide application. Theslope of the hillside vineyards has dic-tated a no-till vineyard floor manage-ment approach to prevent soil erosionwhich also reduces dust. Mainavenues within the vineyard are grav-eled and/or treated with dust sup-pressants.To avoid a potential increase in spi-

der mite populations, Krag makes nomore than two sulfur dust applica-tions per season for powdery mildewcontrol in any block. Powdery mildewcontrol starts with one application ofJMS Stylet-Oil, which controls bothpowdery mildew and mites. Thisspray is combined with a sterolinhibitor or DMI-fungicide, and is fol-lowed by a rotation of fungicidechemistries throughout the season.Products include Flint, Elite, andQuintec.Since planting of Cabernet Sau-

vignon in 1999, Beckstoffer Vineyards(Red Hills) has applied no chemicalmiticide beyond one early seasonStylet-Oil application, instead aug-menting natural control with preda-tory mites, Galendromus occidentalis. InJune (post-bloom), mites are releasedat a rate of 2,000 per acre. Krag takesdelivery of bean plants in small lots, sothat the mites can be applied between6 and 9 AM, before the bean plants(containing the mites) dry out.Working with UC Cooperative

Extension on an experimental basis,Krag has eliminated sulfur completelyfrom the powdery mildew control pro-gram, released predatory mites, andapplied only 22 ounces of fungicidefor the entire growing season with nomite problems or detectable powderymildew. No insecticides or miticidesare used in the trial blocks.While field-monitoring has not con-

vinced Krag that innoculative preda-tory mite releases are necessary, itappears to confirm that avoiding dis-ruption of natural control is important.“I see some blocks with lots of preda-

tory mites and no spider mites, so per-haps there is an alternate food sourcefor the predatorymites. I have also seenpredation by six-spotted thrips.”Several years ago, the grape leaf-

folder arrived at Beckstoffer-Red Hills.Lucia Varela (UC North Coast IPMAdvisor), encouraged Krag to hold offon chemical control. She advised Kragto be on the lookout for a Brachonidwasp parasite. “2007 was the first yearthat we saw widespread parasitism bya Brachonid wasp” reports Krag.Horticultural Oil applicationStylet-Oil is another tool in Lake

County’s sustainable winegrape pestmanagement strategy that can beapplied for mildew and mite control.Stylet-Oil is typically applied early inthe season to control both powderymildew and spider mites, beginningshortly after the leaves are open (FigureII.).In hillside vineyards, both Beck-

stoffer Vineyards and Obsidian RidgeVineyard apply oil in early seasonsprays, however in valley locations,where mite outbreaks are less frequent,oil is seldom applied.Cover CropsAll surveyed growers have cover

crop strategies. Besides protecting soilfrom erosion and suppressing dust,cover crops increase habitat diversityand food sources for biological controlagents and their alternate prey.In Big Valley, Walt Lyon encourages

natural predators with a legume-grasscover crop in alternate tractor-rows.The cover crop is mowed in the latespring (May) to maintain habitat forbeneficial insects.In valley locations, David Weiss has

seeded a legume-grain mix to addnitrogen and build soil organic matterin developing vineyards. In establishedvineyards, a Brassica mix cover crop isseeded in alternate tractor-rows to repelphytophagous nematodes. All covercrops are disked early in the growingseason (April or May).Steve Devoto seeds a Brassica cover

crop mix in blocks where he suspectsnematodes could be a problem. In otherblocks, cover crops are mowed in trac-tor-rows, only tilling in the vine row.Almost all hillside Lake County

vineyards are managed no-till with acover crop in the tractor-rows to pre-vent soil erosion and strip sprayed in

vine rows to prevent erosion and con-trol weeds.At Beckstoffer-Red Hills, the no-till

annual cover crop is fertilized in the fallwith a balanced fertilizer to promotebiomass production and enhance ero-sion control. After it is mowed in April,the annuals dry out in the well-drainedsoil. Since seeding during vineyarddevelopment, the cover crop composi-tion has self-selected to include roseclover, crimson clover in wet years, andannual grasses such as soft chess,ripgut brome, and Italian ryegrass.ConclusionLake County’s sustainable pest

management can be credited to twofactors: the favorable mountain cli-mate, and grower commitment to sus-tainable pest management.The PUR data and interviews show

that Lake County winegrowers use avery low amount of pesticides amongCalifornia wine growing regions. Useof cultural practices including canopymanagement and cover crops toreduce pest incidence is nearly univer-sal. Increasingly, growers are adoptingapproaches such as tillage for weedcontrol and promotion of natural pestcontrol to eliminate or greatly reducechemical use. !

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Pesticide Use Report (PUR) Data Base

In 1990, California’s pesticide usereporting program was devel-oped to insure that pesticide usecan be easily tracked by commod-ity, product, and county. It is themost comprehensive in the world.Under the program, all agriculturalpesticide use must be reportedmonthly to the county agriculturalcommissioner, who in turn, reportsthe data to the CaliforniaDepartment of Pesticide Regulation(DPR). The data is then tabulated,summarized, and made public. Thedata base can be accessed by any-one with web access and fairly com-plex reports can be generated. Thedata base was used to generate theinformation used in the graphs inthis article. For more information,go to this web address: www.cdpr.ca.gov/docs/pur/purmain.htm.