OCTOBER–DECEMBER 2008 • VOLUME 62 NUMBER 4 California Agriculture

Wine grapes go green The Sustainable Viticulture Issue

University of California | Peer-reviewed Research and News in Agricultural, Natural and Human Resources SUSTAINABLE VITICULTURE Wine grapes go green

Research and review articles

Cover: The grape-growing indus- try, in partnership with UC scien- tists, has aggressively promoted [ Encouraging best practices] sustainable viticulture practices that are environmentally friendly, 133 Agro-environmental partnerships facilitate sustainable economically viable and socially wine-grape production and assessment responsible. In the Carmel Valley, Broome and Warner a wine-grape vineyard shows its fall colors. Photo: David Gubernick/ Innovative collaborative approaches have extended sustainable AGStockUSA practices across California vineyards, including reduced pesticide use. 138 Interest in organic viticulture is increasing McGourty 142 Innovative outreach increases adoption of News departments sustainable winegrowing practices in Lodi region Ohmart Growers representing two-thirds of Lodi wine-grape acreage Editorial overview participated in a unique self-assessment program to improve 125 Wine grapes go green: their sustainable wine-growing. The sustainable viticulture story 148 Decision support tool seeks to aid stream-fl ow recovery and enhance water security Research news Merenlender, Deitch, Feirer 127 Research fuels sustainable Watershed mapping of modeled stream-fl ow data can help viticulture revolution growers and regulators decide where to place small storage reservoirs for irrigation, offseting impacts to salmon habitat.

131 Nest boxes can attract wildlife 152 Collaborative conservation helps achieve to vineyards regional water-quantity goals Merenlender [ Dealing with disease] 156 Leafroll disease is spreading rapidly in a Napa Valley vineyard Golino et al. Possible causes include ecological changes in vectors, use of less-virus-tolerant rootstocks and new virus strains that are more effi ciently transmitted by pests. 161 Botryosphaeria-related dieback and control investigated in noncoastal grapevines Epstein, Kaur, VanderGheynst Pycnidia on deadwood apparently are a major source of inoculum for new B. obtusa infections; latex paint may protect wounds from the fungus.

164 Vine surgery tested as management strategy for Botryosphaeria Huffsmith et al.

122 CALIFORNIA AGRICULTURE • VOLUme 62, NUmber 4 156 167 191 195

[ Controlling pests] 167 Vineyard managers and researchers seek sustainable solutions for mealybugs, a changing pest complex Daane et al. Editor’s note Parasitoids, natural predators, ant control and pheromones can help control a persistent vineyard pest. California Agriculture gratefully acknowledges the faculty co-chairs 172 Pomace management reduces spread of vine mealybugs for this special issue: Deborah Golino, Smith and Varela director of Foundation Plant Services 174 Studies needed of vectors spreading leafroll disease in California vineyards (FPS), and James Wolpert, viticulture Golino and Almeida specialist, both at UC Davis. We also thank FPS and Viticulture Consortium 177 Liquid baits control Argentine ants sustainably West for providing funds to defray the in coastal vineyards costs of its expanded length. Cooper et al. Foraging ants bring toxicants to their nests, an approach that targets the ant colony and spares benefi cial insects killed by broadcast insecticides. UC prohibits discrimination or harassment of any person on the basis of race, color, Managing vineyard fl oors national origin, religion, sex, gender [ ] identity, pregnancy (including childbirth, 184 Vineyard fl oor management affects soil, and medical conditions related to pregnancy plant nutrition, and grape yield and quality or childbirth), physical or mental disability, medical condition (cancer-related or genetic Smith et al. characteristics), ancestry, marital status, age, A 5-year study of cover crops and weed control strategies sexual orientation, citizenship, or service in a Monterey County vineyard found differences in water use, in the uniformed services (as defi ned by microbial activity and other important soil parameters. the Uniformed Services Employment and 191 Self-reseeding annual legumes evaluated Reemployment Rights Act of 1994: service in as cover crops for untilled vineyards the uniformed services includes membership, application for membership, performance of McGourty et al. service, application for service, or obligation All 22 cover crops assessed in a high-elevation Lake County for service in the uniformed services) in any vineyard were low-statured and fi t well in row middles. of its programs or activities. University policy also prohibits reprisal or retaliation against any person in any of its programs or activities for [ Studying soils and plant nutrition ] making a complaint of discrimination or sexual harassment or for using or participating in the 195 Soil-landscape model helps predict potassium supply in vineyards investigation or resolution process of any such O’Geen et al. complaint. University policy is intended to be Based on soil properties that affect potassium supply, consistent with the provisions of applicable the Lodi Winegrape District has fi ve nutrient management regions. State and Federal laws. Inquiries regarding the University’s nondiscrimination policies may 202 Vineyard nutrient needs vary with rootstocks and soils be directed to the Affi rmative Action/Equal Lambert, Anderson, Wolpert Opportunity Director, University of California, Tailoring fertilization to vineyards will cut both costs and Agriculture and Natural Resources, 1111 nutrient-polluted runoff, making the grape industry more sustainable. Franklin Street, 6th Floor, Oakland, CA 94607, (510) 987-0096.

http://CaliforniaAgriculture.ucop.edu • OctOber–December 2008 123 About California Agriculture

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124 CALIFORNIA AGRICULTURE • VOLUme 62, NUmber 4 Editorial overview

Karen Ross Deborah Golino President Director California Association Foundation Plant Services, of Winegrape Growers UC Davis Wine grapes go green: The sustainable viticulture story ine grapes and wine are among California’s signature products, and they fuel a powerful economic engine inW the state. Each year, 20 million tourists roam the state’s wine regions, tasting, purchasing and taking in the beauty of the landscape. California, which produces 90% of the na- tion’s wine supply, generates revenues of $19 billion a year for wine and wine grapes alone. The full economic impact of California wine is $51.8 billion a year. However, the story of California viticulture — and par- ticularly the story of sustainable wine-grape growing — is about more than productivity, wine country tours, or dollars and cents. Beginning in the early 1990s, winegrowers worked to- gether to make groundbreaking commitments to agricultural- environmental partnerships. They invested time, money and energy in adopting sustainable practices — sustainable not only in terms of the bottom line, but in terms of California water, soil, wildlife, conditions for workers and community- farmer relationships. Wine grapes are cultivated on some of the most sensitive acres in the state, in areas of high population growth, high land values and environmental activism. Vineyards are part of scenic landscapes prized by Californians; they border urban and suburban development, and they are adjacent to abundant and diverse wildlife. Growers and winemakers realized early that they could have a positive impact on this environment and their em- ployees, and that their credibility in the wider commu- nity, outreach to neighbors, and market reputation would be strengthened through efforts to establish sustainable practices. Through early adoption by groups such as the Lodi Winegrape Commission (page 142), the Central Coast Vineyard Team, the Napa Sustainable Winegrowing Group, Fish Friendly Farming, and later through the statewide Sustainable Winegrowing Program created by the California Association of Winegrape Growers and the Wine Institute, they have promoted sustainability both in the vineyard and the winery. Their innovative efforts are now prototypes for other commodities. Research promotes sustainable practices. Decades of UC research and extension have helped to facilitate sustainable viticulture. Growers applied years of research results to the

http://CaliforniaAgriculture.ucop.eduhttp://CaliforniaAgriculture.ucop.edu • • Oct Octoober–Decemberber–December 20082008 125 Editorial overview specifics of their local production regions (see page 127). on sustainable viticulture and enhancing the flavor of They implemented leaf removal and canopy management grapes and wine. to control several key pests such as Botrytis bunch rot, The Pierce’s Disease/Glassy-Winged Sharpshooter sour rot complex, powdery mildew and leafhoppers; they Program, funded by industry, federal and state dollars, used cover crops to improve year-round vineyard access, has fostered dramatic findings that could someday lead reduce soil erosion and encourage populations of natural to prevention of this fatal bacterial illness of grapevines enemies of pests. They adopted integrated pest manage- (page 127). In the last 10 years, about $36 million has been ment methods, using economic injury thresholds and awarded in competitive grants reaching across the UC weather data, as well as models of disease risk forecast- system, the United States and the world. Resulting UC re- ing, to reduce pesticide use. For instance, growers were search has made strong advances toward disease-resistant able to sharply cut their use of sulfur and other pesticides vines, and in another case has elucidated a signal mol- to control powdery mildew, the disease that spurs the ecule that could be used to suppress the virulence of the bulk of pesticide use on grapes. pathogen and offer substantial disease control. By 2006, statewide reports showed that total pesticides A broad public-private coalition brought about suc- applied to wine grapes had declined 50% per acre planted cess of another kind in the 2008 Farm Bill. Thanks to a since 1994 (see page 133). Also, according to their self- unified effort across commodity groups and the research assessments, growers reduced sedimentation and pesti- community, millions of dollars are now being invested in cide pollution of water, managed dust and improved air specialty crop initiatives at USDA and through state-run quality, and reduced herbicide and fungicide use. block grant programs. But the drive for sustainability is not over. The competi- The Farm Bill contains other big wins that directly tive global marketplace, continued population growth, benefit the grape industry and move it closer to sustain- global climate change, scarce natural resources, the need ability, including the National Clean Plant Network (the for new technology and human resource skills — all make grape portion of which will be headquartered at UC UC research, from basic to applied, even more important Davis) and pest and disease programs to step up detec- if industry is to continue innovating and adopting best tion and surveillance activities, and identify and mitigate practices. Evidence of this ongoing work fills this special new threats from invasive species. Without a united mes- collection: work on stream-flow models to ease irriga- sage from industry and the land-grant universities, none tion impacts (page 148), biological and chemical control of this would have been possible. of mealybugs and ants (pages 167, 177), improved tech- Funding needs. Despite these successes, the funding niques for the detection and elimination of grapevine currently available for grape and wine research is no viruses (pages 156, 161), vineyard floor management and longer sufficient to support needed projects in an in- use of cover crops (page 184, 191), and tailoring fertiliza- creasingly expensive research environment, or to meet tion to cut costs and reduce nutrient pollution in runoff matching-fund requirements for new Farm Bill research (pages 195, 202). programs. Many key types of research cannot be ac- These examples — all involving long-term funding, complished without large, multidisciplinary research commitments by distinguished scientists, collaboration teams, advanced instrumentation and updated labo- across disciplines, use of UC facilities and infrastructure, ratories, in addition to technicians and field trials. All and partnerships with industry — are at the heart of wine- require long-term funding commitments. Furthermore, grape sustainability. This work has taken place at a time competition for researchers has also become global; the when public funding for agricultural research has been United States is losing valuable individuals in the wine steadily declining for years. In most cases, it was made research community to positions in institutions around possible by a combination of public and private funds. the world where their research will be better supported Public-private partnerships. Other recent milestones (often with government investment). Real and substantial in public-private partnerships include the UC Davis increases in funding are needed to improve our position Robert Mondavi Institute for Wine and Food Science, in California. That research must involve collaboration first established in 2001 with a $25 million gift from between disciplines and integrated investigations from winemaker Robert Mondavi. In 2004, California voters the basic to the applied. funded $33.6 million for construction of the institute’s Sustainability is about meeting the needs of the academic building, and more private gifts followed. present without compromising the livelihood and In summer 2008, the departments of Viticulture and needs of future generations. Today’s robust viticulture Enology, and Food Science and Technology moved in. industry is the result of visionary leaders willing to In June 2009, construction will begin on a teaching and make investments for the future and create partnerships research winery and the August A. Busch III Brewing between UC research and extension, and growers and and Food Science Laboratory, entirely funded with pri- vintners. Building on this past success, diverse stake- vate donations. holders are exploring ways to ensure a vital research Another $12.5 million donated to UC Davis by the infrastructure is adequately funded to meet our current Rossi family will endow faculty positions focused on challenges and the needs of upcoming generations. The grape-growing and winemaking, and will fund work future depends on it!

126 CALIFORNIA AGRICULTURE • VOLUME 62, NUMBER 4 Research news

Research fuels sustainable Beverly Ferguson viticulture revolution

purred by decades of University of California research, sustainable viticulture has become increasinglyS mainstream in California. Sustain- ability helps both the environment and wine-grape growers, with benefits that range from reducing ag- richemicals that pollute water and harm wildlife to cutting costs, enhancing wines and boosting public perception of the industry. “Sustainability is a big tent,” says Deborah Golino, director of the UC Davis-based Foundation Plant Services, which certifies disease-free grape Foundation Plant stock and which celebrated its 50th anniversary in ties statewide, and about 2,000 wineries produce Services staff members July 2008. “Some sustainable practices are driven more than 90% of wine nationwide. Altogether the Sue Sim (sitting, left) by environmental regulations, and more are driven wine industry pumps close to $52 billion yearly and Waclawa Pudo shared information with by green marketing and stakeholders wanting to into the California economy. grape nurseryman Craig be good stewards of the land.” To help keep wine-grape growers in the sustain- Stoller and his wife For the wine industry, economic benefits are key. ability loop, Golino maintains several comprehensive Nancy about technology “The bottom line is that sustainability has to work used to create viticulture Web sites. “People in industry don’t al- collections of disease- in a business model,” says Karen Ross, president of ways know where to look,” she says. “We want to let screened strawberries, the California Association of Winegrape Growers. everybody know how much UC is doing” (see box). grapes, fruit and nut “The fundamental reasons to change practices are The implementation of sustainable viticulture trees and other plants, during the FPS 50th increasing quality and marketability, and decreasing has been spurred by important research-based ad- anniversary celebration costs.” This industry group represents more than vances that have been extended to grape growers. on July 1, 2008. half of the state’s grape crush and actively promotes sustainability, defining it as economically viable, en- Leaf removal for bunch rot vironmentally sound and socially responsible. One of the most widely adopted sustainable What’s good for the wine industry is also good practices, leaf removal to control bunch rot and im- for California, Ross says. About 4,600 wine-grape prove grape quality, was developed in the 1980s by growers farm more than 520,000 acres in 46 coun- Douglas Gubler, UC Cooperative Extension (UCCE)

Web sites organize sustainable grape-growing info, research grants Deborah Golino, director of Foundation Plant Services at UC Integrated Viticulture Online (http://iv.ucdavis.edu) UC Davis, has set up and runs several comprehensive, Web sites makes UC research more accessible, listing grape research- to organize critical information for wine-grape growers and ers, a calendar of upcoming events and information about viticulture researchers. “Wine-grape growing is complicated grape-growing topics in 30 categories, including diseases, by the sheer number of clones and varieties available and rootstock and vineyard economics. the fact that each variety can have multiple names, plus the Viticulture Consortium West (http://vcw.ucdavis. abundance of information on pest, weed and disease manage- edu) and Unified Grant Management for Viticulture and ment,” Golino says. “These sites can help.” Enology (http://uvegrants.ucanr.org) coordinate grape- The National Grape Registry (http://ngr.ucdavis.edu) en- growing research programs and grant-making for experi- ables growers to access information for all grape varieties avail- ment stations and universities in the Western states, as well able in the United States. Growers can find out which nurseries as in Oklahoma and Texas. carry a particular variety or clone — the first time there has Also of interest: California Association of Winegrape been a central site to answer this question. There is also a spe- Growers (www.cawg.org) and California Sustainable cial search feature that allows users to sort through multiple Winegrowing Alliance (www.sustainablewinegrowing. names (or synonyms) for grape varieties. org).

http://CaliforniaAgriculture.ucop.edu • October–December 2008 127 Research news

plant pathologist at UC Davis; Larry Bettiga, UCCE berry quality and therefore wine quality. viticulture advisor in Monterey County; and Jim In the late 1980s, Gubler and colleagues showed Marois, UC Davis plant pathologist. “We stumbled that machine leaf removal could control bunch rot onto it — we were originally looking at how canopy as effectively as hand-removal, making the tech- management affected spray coverage,” Gubler says. nique feasible for large acreages of wine grapes. By “We found that leaf removal controlled bunch rot 1990, leaf removal was practiced on about one-fifth better than three fungicide applications.” of the state’s bunch rot–susceptible wine grapes, Caused by the fungus Botrytis cinerea, bunch rot decreasing fungicide use by at least half. Today infects grape berries through wounds or even di- leaf removal is widespread in most of California’s rectly though the skin. Once a grape is infected, if production regions and also around the world. conditions are favorable the fungus spreads rapidly “It’s working really well in disease control and in- to infect the rest of the cluster. This type of bunch creases quality,” Gubler says. rot afflicts vineyards in cool moist areas, notably those along the coast, in the marine-influenced Powdery mildew control without sprays northern San Joaquin Valley and in the southern Another successful tool for controlling grape- San Joaquin Valley (table grapes). vine diseases sustainably is the UC Davis Powdery The technique entails removing leaves around Mildew Index. Also called the Gubler-Thomas grape clusters when the berries are just formed or Index, this approach was developed in the 1990s the blossoms have just dried. This allows increased by Gubler and then–lab member Carla Thomas. light penetration, decreased relative humidity Caused by the fungus Erysiphe necator, powdery and increased wind speed through the canopy. mildew is among the worst grapevine diseases in Berries dry more rapidly after rainfall, warding off California. The fungus occurs in all grape-growing or stopping infection. In addition, this technique regions of the state and accounts for most vine- can decrease leafhoppers and mites, because these yard pesticide use. Infected leaves are covered by pests are concentrated on the basal leaves that are a web of white strands that bear dustlike spores, removed. Leaf removal also exposes clusters to sun- giving the disease its name. Powdery mildew can light, which further increases bunch rot resistance also cause grape berries to crack, allowing Botrytis by thickening the berry’s epicuticular wax layer. cinerea to infect through the injured tissue. In addi- Another benefit of sun exposure is that it increases tion, as little as 3% infection of berries can produce off-flavors in wine. Powdery mildew is a fact of life for grape grow- ers. “We can’t eradicate the pathogen,” Gubler says. “They just have to expect it.” While the infection varies over the course of a growing season and from year to year, its inevitability and huge po- tential for crop destruction led many growers to spray fungicides on a fixed schedule, whether they needed to or not. This was because they could not tell when powdery mildew would strike initially and when it would spike over the course of the growing season. “The disease is driven by moderate temperatures and rainfall,” Gubler says. The team developed a model to predict the onset and severity of powdery mildew in vineyards. The onset of infection is pre- dicted based on temperature and leaf wetness, and

and bunch rot) William J. Moller; (Bot canker) iv.ucdavis.edu; (mildew) Jack Kelly Clark Kelly (mildew) Jack iv.ucdavis.edu; (Bot canker) Moller; William J. and bunch rot) its subsequent severity is predicted based solely on

Eutypa temperature. In 1995 the researchers validated their ( model in Kern, Napa and Sonoma county vine- yards, using networks of weather stations that were established with a grant from the UC Statewide Integrated Pest Management (IPM) Program as well UC researchers have developed environmentally friendly treatments for several as grower contributions. important grape diseases. Top left, basic research has shown that many wood Today the UC Statewide IPM Program offers an infections diagnosed as Eutypa dieback were actually Botryosphaeria canker online Powdery Mildew Index (PMI) for Fresno, disease; bottom left, the spread of Bot canker can be slowed down by double- pruning in winter and early spring; top right, to ward off bunch rot, leaves around Madera and San Joaquin counties. In other parts of clusters can be removed as berries form; bottom right, the Powdery Mildew Index the state, grape growers can either subscribe to pri- uses weather data to help growers spray fungicide only when necessary. vate online PMI services or buy their own weather

128 CALIFORNIA AGRICULTURE • VOLUME 62, NUMBER 4 stations. Following the PMI lets growers spray

only when necessary, which can add up to sub- Altieri Miguel stantial cost savings. “At $40 per acre, eliminating three sprays a year on 5,000 acres is a big savings,” Gubler says. “Spraying less also reduces environ- mental concerns about pesticide use.” To assess implementation of the PMI, Gubler and Travis Lybbert, an agricultural economist at UC Davis, surveyed growers in early 2008. For the In Napa Valley, first few years after the PMI was introduced, less researchers are than one-third of growers used it. Today more than studying the use half do. Participating growers generally are more of summer cover crops such as experienced, manage larger vineyards they are less alyssum planted likely to own, and produce higher-value grapes. under the vines Reasons for not using the PMI included not trust- with a buckwheat- ing it. “It’s hard to change,” Gubler says. “They’re phacelia seed mix in the middles. Early nervous about stretching the interval between monitoring has shown sprays.” To build trust, he encourages growers to that beneficial insects start small, setting aside 5 acres for following the are attracted to the PMI while spraying the rest as usual. “Once they vineyard. start, they really get hooked,” he says. “People who use it love it.” also “bleed” and wash away the fungal spores. But Grape growers will soon have more reason to this is not feasible in large vineyards because prun- use the PMI than ever. “We’re refining it,” Gubler ing is so labor-intensive. Gubler’s team got around says. “Right now it errs on the side of caution this by doing the bulk of the pruning in winter and and we’re making it less conservative, which then snipping off a bit more in early spring. The means growers will be able to reduce spraying second cut doesn’t take much time and removes quite a bit more.” any wood that may have gotten infected after the first cut. Gubler estimates that a high percentage Double-pruning for canker disease of vineyards in the Napa Valley are now double- Gubler and his colleagues also recently devel- pruned. “It’s gaining every year,” he says. oped yet another widely adopted sustainable prac- Double-pruning on its own is not enough to tice: double-pruning to control canker diseases. prevent canker diseases, however, because wounds These fungi infect pruning wounds, and ultimately from spring pruning can still be susceptible to infec- so much wood that grape production declines, tion. Gubler found that painting these wounds with necessitating early vineyard reworking or replace- a boron paste could keep them virtually infection- ment. The infection is insidious, often escaping free for up to 6 weeks. “It’s a great treatment,” detection for 8 to 10 years until wedge-shaped he says, noting that boron is a natural, nontoxic cankers are evident in the trunk or arms. The most compound. This work has resulted in a commer- common canker diseases in California vineyards are Bot canker (see page 161), and Eutypa dieback. Following the Powdery Mildew Index A decade ago losses to the latter were estimated to lets growers spray only when necessary. exceed $260 million statewide. To clarify the causes of canker diseases in cially available wound treatment called B-LOCK. California, Gubler’s team identified the fungi Another promising treatment is painting vines in infected wood samples from 180 vineyards with latex paint (see page 161). around the state between 2004 and 2007. They Biocontrol for vineyard pests found that contrary to the conventional wisdom, Bot canker is more common than Eutypa die- Other sustainable practices target the weak back, which afflicted 90% and 55% of the study points of pest insects. A likely approach to control- vineyards, respectively. They also identified nine ling vineyard pests is planting summer cover crops, species of Botryosphaeria causing Bot canker and according to a UC study currently under way in found that four of these grow much faster than Napa and Sonoma counties. Cover crops provide the others. “They grow up to 10 or 12 inches a year food and shelter for beneficial insects such as minute compared to about an inch with Eutypa,” Gubler pirate bugs, which eat thrips, and Anagrus wasps, says. “They can kill wood fast.” which are tiny parasites that lay their eggs inside The best way to limit canker diseases is pruning leafhopper eggs. However, most wine-grape grow- in early spring, when the wounds heal faster and ers plant cover crops during the winter (see pages

http://CaliforniaAgriculture.ucop.edu • October–December 2008 129 Research news

184 and 190), which means that insect pests have Jack Kelly Clark Kelly Jack fewer natural enemies during the summer. “Some growers are spraying insecticides several times a season,” says study leader Miguel Altieri, an agro- ecologist at UC Berkeley. “This increases the expense and the environmental impact.” Altieri is testing two summer cover crops on 1- to 2-acre test plots in seven vineyards. The first summer cover crop is sweet alyssum, which is planted along drip-irrigated rows. Sweet alyssum is small with shallow roots and so does not compete with grapevines for water, nutrients and sunlight. The second is a seed mix planted between the rows, where there is no irrigation. The seed mix ensures continual blooming with no extra water: buck- Cultural practices such as strategic pruning to prevent wheat and phacelia bloom from late March to June, grapevine diseases are increasingly being adopted by grape and wild carrot (or Queen Anne’s lace) blooms for growers throughout California. the rest of the season due to its taproots. To see how well summer cover-cropping works, the researchers monitor both the pest and benefi- cial insects. The study began last year and so far is promising. “The results are pretty dramatic,” Altieri says. For example, last summer the plots with the buckwheat seed mix exhibited substan- tially fewer leafhopper nymphs than plots under organic insecticide sprays. Sustainable Ag Expo to feature research, best practices Altieri works closely with growers, sharing the data with them monthly. Pest control has been so The Fourth Annual Sustainable Ag Expo will feature trade effective that a participating grower plans to ex- exhibits and programs to help growers and ranchers maintain pand the cover-cropped area to 10 acres next year. economic viability while also protecting the environment and Ultimately, Altieri envisions scaling up the study to promoting healthy communities. “Farmers of all crops and com- include 10- to 20-acre test plots in 50 vineyards by modities can learn about sustainable farming methods,” says the end of 2010. Kris O’Connor, executive director of the Central Coast Vineyard Altieri also involves the participating vineyards Team, sponsor of the Expo.* by training farmworkers in Spanish to identify Expo seminars will focus on best management practices to the various insects. This lets the farmworkers protect water quality, alternative energy sources, erosion control help monitor the insects, which benefits both the and integrated farm management practices, including reduced- researchers and the workers themselves. “They’re risk pest control and whole-farm practices. Among speakers very excited,” Altieri says. “They enjoy doing some- from government, agriculture and academia, featured UC re- thing more intellectual plus they know this could searchers include: reduce their pesticide exposure.” • Michael Cahn, UC Cooperative Extension farm advisor. Pest-resistant rootstocks • Trevor Suslow, UC Davis extension research specialist. Another way of decreasing pesticide use in vine- • Jay Gan, UC Riverside professor. yards is to breed pest-resistant rootstocks. Many of • Gail Feenstra, UC Sustainable Agriculture Research and the currently available rootstocks are susceptible Extension Program. to nematodes, tiny soil worms that eat plant roots. • Andy Walker, UC Davis professor. Nematodes plague grapevines in the Central Coast • Jean-Jacques Lambert, UC Davis soil science scientist. and San Joaquin Valley, where vineyards were of- ten planted following vegetable crops that had high What: Sustainable Ag Expo levels of these pests. State regulations limit chemi- When: Nov. 13 and 14, 2008 cal treatments, and UC has provided growers with Where: Monterey County Fairgrounds the environmentally friendly option of planting More info: www.sustainableagexpo.org five new nematode-resistant rootstocks. “Resistant rootstocks are the best solution now *California Agriculture journal is a media partner with the Sustainable Ag Expo. that fumigants are almost gone and nematicides are on their way out, as they should be,” says

130 CALIFORNIA AGRICULTURE • VOLUME 62, NUMBER 4 Andrew Walker, UC Davis geneticist who devel- sistance,” Walker says. “After Cover crops provide food oped these rootstocks over 15 years. “It’s either use one more backcross, we’ll be and shelter for beneficial these or other resistant rootstocks or don’t grow at 96% Vitis vinifera and we’ll grapes in areas with nematode buildup.” test those by evaluating for insects such as ladybugs, Released in April 2008, these rootstocks were de- wine quality.” which eat aphids, and rived from multiple parents that each resist different In other research, UC pyrethroid wasps, which are kinds of nematodes, including dagger, lesion and Berkeley plant pathologist root-knot. “We bred them to be as resistant as pos- Steven Lindow has discov- tiny parasites that lay their sible,” Walker says. Even so, he expects that these ered a signaling system eggs inside leafhopper eggs. pests may eventually adapt. By rotating among the involving the secretion of a five types, however, growers should be guaranteed a small molecule produced by long period free of nematode problems. Xylella fastidiosa, the cause of Pierce’s disease. This Walker is also developing wine grapes that resist molecule is involved in the suppression of Xylella powdery mildew and Pierce’s disease, a fatal bacterial virulence when cells become abundant in the plant. illness spread by sharpshooters. These projects entail Artificially increasing the abundance of this sig- breeding commercially grown wine grapes (Vitis nal molecule in various ways, including the use vinifera), which are native to the Mediterranean, with of plants that have been genetically engineered to disease-resistant wild North American grapes. To get produce it, has led to the suppression of virulence of as close to wine grapes as possible, disease-resistant the pathogen and Pierce’s disease control. Extensive hybrids are selected and then repeatedly crossed back greenhouse tests are under way, but field studies to pure wine grapes. This backcrossing increases the will not commence before next year at the earliest. ratio of wine grape-to-wild grape in the successive As scientific advances occur and are made hybrids while retaining their disease resistance. The available, even more growers will be encouraged powdery mildew project is still in early stages, while to adopt sustainable practices. “The work by UC the Pierce’s disease project has made strong advances. has been critical to our success,” Ross says. “We have good fruit quality and Pierce’s disease re- — Robin Meadows

Nest boxes can attract wildlife to vineyards

lacing nest boxes for songbirds, owls and bats research on songbird boxes in and around vineyards can contribute to the in vineyards. “Plus the birds sustainableP management of pests and help mitigate are in there eating insects, oak-woodland habitat losses, according to a new and that may have some ben- booklet published by the UC Division of Agricul- eficial effect in terms of pest ture and Natural Resources, “Songbird, Bat and control.” Owl Boxes: Vineyard Management with an Eye Many species native to toward Wildlife.” woodlands — such as some “Nest boxes are readily accepted by a number songbirds, owls and bats — of bird and bat species and provide places for use cavities in oak trees for these animals to roost and nest. Used properly, roosting or nesting, and they they can help maintain biodiversity in vineyard lose habitat when trees are landscapes,” says Emily Heaton, co-author of the cleared for new agricultural 51-page booklet with Rachael Long, Chuck Ingels plantings. Vineyard devel- and Tom Hoffman. opment expanded rapidly The booklet is illustrated with color images and during the 1990s, especially provides information on the rationale for placing on the Central Coast and North Coast, says Bill ANR Pub 21636 nest boxes and bat houses in vineyards; which spe- Tietje, technical editor of the booklet. “Unlike can be ordered at anrcatalog.ucdavis. cies may be attracted to them, as well as feeding most row crops, soil characteristics and topogra- edu. and nesting behavior; detailed plans for building, phy did not completely restrict some new vine- placing and monitoring bird boxes and bat houses; yard development from areas formerly classified and references and resources. as oak woodland.” “The growers that I worked with really enjoyed “There was a lot of public concern about impacts seeing birds in the vineyards,” says Heaton, a on views and biodiversity,” Tietje continues, “and UC Berkeley doctoral student who has conducted growers would like to demonstrate that they are

http://CaliforniaAgriculture.ucop.edu • October–December 2008 131 Research news

Laura Barrow Many unanswered questions remain that, if an- swered, would assist both growers and biodiversity conservation. “Although some cavity-nesting birds, especially western bluebirds, readily use and fledge young from nest boxes in vineyards, what happens to the fledged young?” Tietje says. “Are the vine- yards functioning as an ‘ecological trap,’ and is the trap sprung after young fledge from the boxes, per- haps due to increased predation or altered food re- sources in the vineyard?” A few studies are under way in California that will help to develop manage- ment guidelines for nest and bat boxes.

Research on vineyard wildlife Julie Jedlicka, a Ph.D. candidate in environmen- tal studies at UC Santa Cruz, is studying the use of At Dooley Creek in Hopland, UC Santa Cruz Ph.D. candidate Julie Jedlicka (right) and field assistant Matthew Poonamallee monitor nest boxes placed in a vineyard. nest boxes as a biocontrol agent and conservation tool. She points out that this type of research is not new: Between 1885 and 1940, the U.S. Department practicing good conservation.” For example, grow- of Agriculture’s “Department of Economic ers who participate in sustainability assessments Ornithology” extensively studied the use of insect- such as the Lodi Winegrower’s Workbook receive eating birds to control pests in agriculture. But when credit for placing nest boxes for birds of prey (see chemical pest-control methods began to take prece- pages 133 and 142). dence, Jedlicka says, the department was disbanded. Jedlicka’s research in Sonoma and Mendocino Pros and cons counties is examining the breeding success and di- Heaton monitored 288 songbird boxes placed in ets of songbirds that use vineyard and riparian nest and arou