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Research helps fuel revolution in sustainable viticulture

Winegrapes are one of California's signature agricultural products, bringing some $52 billion in revenue and 20 million tourists to the state each year. At the same time, grapes are grown on some of the most sensitive acres in the state, in areas of high population growth, high land values and environmental activism.
 
Since the early 1990s, the California winegrape industry has made an unprecedented effort to promote sustainable practices, those that prioritize environmental protection, economic viability and social equity. Winegrape growers have formed unique partnerships -- with UC researchers, government agencies, environmental groups, vineyard neighbors and others -- to define best practices and monitor progress along a "sustainability continuum."
 
The entire October-December 2008 issue of the University of California's California Agriculture journal is devoted to sustainable viticulture, with 11 research and review articles on how the winegrape industry is working to improve water management and combat grapevine diseases and insect pests in environmentally friendly ways, plant cover crops on vineyard floors to prevent erosion and runoff, and tailor plant nutritional needs to specific soils and rootstocks. The 88-page issue includes extensive news coverage and an editorial on the role of UC research in encouraging sustainability.
 
"By 2006, statewide reports show that total pesticides applied to winegrapes had declined 50 percent per acre planted since 1994," write Deborah Golino, director of Foundation Plant Services at UC Davis, and Karen Ross, president of the California Association of Winegrape Growers. "According to their self-assessments, growers reduced sedimentation and pesticide pollution of water, managed dust and improved air quality, and reduced herbicide and fungicide use."
 
California Agriculture's sustainable viticulture issue is available online: http://californiaagriculture.ucop.edu/0804OND/toc.html; for a free copy, e-mail janet.byron@ucop.edu.
 
Following is a sampling of the articles in the journal:
 
Lodi workbook helps winegrape farmers get sustainable
Just over two decades ago, federal authorities designated a half-million northern San Joaquin Valley acres as the Lodi winegrape appellation. Cool nighttime breezes off the Sacramento River Delta allow ripening fruit in the Lodi area to retain natural acidity. Unique in the San Joaquin Valley and isolated from California's coastal fine wine producing areas, Lodi became the ideal environment for farmers to collaborate on sustainable production. This journey toward sustainability is outlined in the current issue of California Agriculture journal in an article by Cliff Ohmart, the sustainable winegrowing director for the Lodi Winegrape Commission. Unlike organic farming, sustainable farming has not been defined by law. In fact, Ohmart says it is useful to think of sustainability not as a destination, but on a continuum. "A perfectly sustainable vineyard is not likely, in part because what is considered sustainable today may not be rigorous enough tomorrow," Ohmart wrote. Aiming for a moving target can prove frustrating for farmers, a feeling that led to the development of a groundbreaking winegrape production workbook by the commission, vineyard consultants, UC researchers and farm advisors, and others. The 105 worksheets in the "Lodi Winegrower's Workbook," which take three hours to complete, permit farmers to assess their progress on the sustainability continuum. A survey determined that a large portion of growers changed their insect monitoring practices and increased their usage of integrated pest management practices to manage insects, mites, diseases and weeds after using the workbook. For more information, contact Ohmart at (209) 367-4727, cliff@lodiwine.com.
 
Rapid spread of grapevine virus concerns researchers
UC viticulture researchers mapped the spread of a serious grapevine disease in a Napa County Cabernet Sauvignon vineyard from 2002 to 2006, documenting the spread of infection at a rate that had never before been seen in California. Graphs and maps showing the rapid spread of leafroll disease are in the current issue of California Agriculture journal along with a research report about the mysterious development. As recently as 20 years ago, viticulturists believed that leafroll disease, which can be caused by several related viruses, was only spread by propagating or grafting diseased vines. The swift disease spread observed in the Napa vineyard, however, suggests that something else is going on. The scientists now suspect that an insect common at low levels in Napa vineyards -- the grape mealybug -- may have been responsible for the rapid disease spread. However, such furious leafroll spread by grape mealybugs has never happened before, as far as the researchers know. "That they never did so suggests that something fundamental has changed in this vineyard to allow such spread to occur," wrote the report's authors, UC Davis plant pathologist Deborah Golino, the late Napa County viticulture farm advisor Ed Weber, Napa County UCCE staff research associate Susan Sim and UC Davis plant pathologist Adib Rowhani. "Additional research is urgently needed to help us better understand our observation of rapid spread of leafroll disease in the vineyard." For more information, contact Golino at (530) 754-8102, dagolino@ucdavis.edu.
 
Sustainable ant control made possible by UC research
Because of UC research on vineyard ant control, grape growers now have a new, sustainable option for controlling Argentine ants. Argentine ants were first introduced to California in 1905. The tiny, black insect is a common pest in California homes and causes severe problems in natural systems by displacing native ants, other insect species and even some plants and animals. In vineyards, the Argentine ant nourishes and protects a variety of harmful mealybugs, which produce the honeydew ants like to eat. Scientists found "incredibly large" ant populations in test vineyards -- in one trial, ants removed more than an ounce of sugar water a day from monitoring tubes, the equivalent of more than 100,000 ant visits. Because pesticide sprays often used to control ants can kill beneficial insects as well, UC researchers set out to develop a liquid bait ant-management system. A variety of liquid ant poisons and bait-station distribution densities were studied over two years; the research outcomes were shared with agricultural chemical manufacturers. As a result of this research, several liquid ant-bait products are now available for use in agricultural systems. The researchers detailed their work in the current issue of California Agriculture journal in a report written by staff research associate Monica Cooper, Cooperative Extension biocontrol specialist Kent Daane and their collaborators. For more information, contact Cooper at monicac@ufl.edu or (510) 643-4019.
 
Organic winegrape growers seek to maintain ecological harmony on their farms
Many organic farmers expect a premium price for their fruit, vegetables and grains. However, the complex equation that calculates the price of wine -- based on appellation, variety and subtle, individual merits of winegrapes -- effectively erases the organic premium. Still, environmentally conscious consumers, high-end wine shops and upscale restaurants have created an expanding market for farmers who wish to produce grapes following legally defined limitations set down by the USDA's National Organic Program. UC Cooperative Extension viticulture advisor Glenn McGourty wrote an essay for the current issue of California Agriculture journal about the state of organic winegrape production in California. In 2006, he wrote, almost 8,000 vineyard acres were certified organic. Most of California's organic wine is grown in Mendocino County, with 2,000 acres, and Napa County, with 1,600 acres. The lack of a specific price premium for organic wines means growers are answering to a higher call when they commit to organic production. "Most have a strong conservation ethic and want to minimize potential harm to the environment, workers, neighbors and their family," McGourty wrote. "They also embrace farming with nature and want to encourage biological diversity on their property." Grower experience has shown that, under most conditions, organic wine growing does not reduce yields or quality. For more information, contact McGourty at (707) 463-4495, gtmcgourty@ucdavis.edu.