Variety and Clonal Database Needed

Wolpert airs ambitious proposal at Lodi Grape Day

by Jon Tourney
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Keynote speaker Christian Miller of Full Glass Research (left) with Lodi-Woodbridge Winegrape Commission executive director Mark Chandler.
Lodi, Calif. -- The University of California, Davis' Foundation Plant Services (FPS) has been collecting and certifying new clean grapevine materials at an increased pace in recent years. This is due to more efficient methods of virus elimination, efforts to collect and certify historically important selections from within California, and relationships with European organizations with large collections of grapevine materials that have enabled importation of new materials. As a result, FPS has released from 50 to 100 new selections per year during the past decade. Although some specific clonal comparison trials have been conducted by researchers since the 1990s, evaluations have not kept pace with the flood of materials being released.

Dr. Jim Wolpert, UC Davis extension viticulturist, presented his vision for a long-term statewide research project to systematically evaluate winegrape varieties and clones at the 57th annual Lodi Grape Day on Feb. 3. Wolpert compared the situation to a book collection at a public library, where a list of book titles is available, but with little organization by subject and no description of an individual book's content.

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Dr. Jim Wolpert discusses his research proposal to systematically evaluate grape varieties and clones.
Wolpert said, "We're proposing a book review for each of these varieties and clones." Wolpert compiled the following list of major winegrape cultivars and the corresponding number of available untested clones: Cabernet Sauvignon, 13; Chardonnay, 28; Merlot,13; Pinot Noir,40; Sauvignon Blanc,15 and Syrah/Shiraz, 14. He listed the following minor cultivars (with untested clones) that are of increasing interest to growers and winemakers: Barbera, 5; Cabernet Franc, 12; Cinsaut, 2; Counoise, 2; Grenache, 4; Malbec, 6; Marsanne, 3; Mourvèdre, 4; Petite Verdot, 3; Pinot Gris, 10; Rousanne, 3; Tannat, 3; Tempranillo, 8 and Viognier, 5. In addition, many obscure cultivars have been imported about which little is known. They include Iberian and Italian varieties such as Arinto, Biancolella, Bonarda, and Coda di Volpe, to name a few

Wolpert discussed three main objectives of the proposed project:

  • Evaluate winegrape cultivars and clones for characteristics suitable for winegrape production;
  • Develop an informational outreach program for nurseries, growers, and vintners;
  • Establish a database of information from all previously published trials done in California, and add new information as it becomes available. This will preferably be a searchable database that can target all data available on a specific varietal or a specific clone.

"The overall goal is to give the industry information to make more educated planting decisions, and to have better vineyards in the future," Wolpert said.

Wolpert submitted a funding proposal this year for $40,000 to the California Fruit Tree, Nut Tree and Grapevine Improvement Advisory Board (IAB) to begin a trial and get the program started. The IAB, under the California Department of Food and Agriculture (CDFA), collects assessments through certified commercial nurseries for funding projects and research. In the past, it has funded a Pinot Noir clonal trial, and provided funds to FPS to hire experts to help determine and verify the varietal identity of grapevine materials in FPS blocks.

Wolpert noted that traditional research funding sources, such as the American Vineyard Foundation, have been spread thin with other research priorities recently. However, targeted funding has also come from special interest groups such as Zinfandel Advocates and Producers (ZAP) for research on Zinfandel heritage clones, and more recently from the Petite Sirah advocacy group, P.S. I Love You, to fund a Petite Sirah (Durif) heritage clonal trial that will be planted at UC Davis.

UC currently has experimental stations to perform vineyard trials at sites in Oakville (Napa Valley), Hopland (Mendocino County), the UC Davis campus, and Kearney Ag Center in Parlier (Fresno County). Wolpert said he would like to have additional field trial sites in the Lodi appellation, and in Region I and II climate zones in the Central Coast.

Trial data collected would include traditional viticultural measurements such as yields, vine pruning weights, clusters/vine, berry weights, and observational data on seasonal development from budbreak to harvest. In addition, grape composition data such as soluble solids (Brix), titratable acidity, pH, anthocyanins, tannins, organic acids and pyrazines would be collected that are important to winemakers. On the latter list, Wolpert commented, "This list is going to grow as we identify more flavor and aroma chemicals, and doing these analyses will get us a long way toward better wine quality."

Wolpert indicated that new trials would appropriately be a "nursery-driven" effort, as the nurseries have a direct interest in knowing about and carrying the best and most viable materials for sale. He encouraged growers to talk with their nursery suppliers to obtain support for these research trials.

Lodi's annual Grape Day, sponsored by the Lodi Chamber of Commerce and UC Cooperative Extension of San Joaquin County, featured a series of vineyard management sessions organized by San Joaquin County extension farm advisor Paul Verdegaal.

Larry Williams, UC Davis professor of viticulture and enology based at the Kearney Ag Center, discussed nutrient management and the importance of analyzing vine nutrient status for efficient fertilization with nitrogen (N) and potassium (K). "More efficient use and applications of nitrogen in the vineyard are very important now due to concerns about its global warming potential," Williams noted.

Based on his research, he advocated vine tissue analysis (petiole analysis) as the most accurate way to determine nutritional needs, as soil analysis for N is not an accurate measure of vine status. He concluded, "Being able to assess your vineyard and the vines' needs for K and N is the most important thing in a fertilization program. If your goal is nutrient maintenance, you should put back in only the same amounts you lose each year."

Luncheon keynote speaker Christian Miller of Full Glass Research discussed the outlook for the wine industry in the current economic recession, and the outlook for Lodi producers. He echoed the general consensus of industry market watchers, saying that sales data show "the higher-end market is running out of steam," and talked about the "melt-down" in on-premise sales for restaurants.

Based on research on past wine sales data and recessions, Miller said there is little correlation between wine consumption and per capita income. "It's probably a good thing to be in this industry rather than in others in times of economic slowdowns," he observed.

Speaking regionally, Miller said, "Lodi is in a sweet spot right now." With sales and growth favoring affordable wines, he said, "Larger producers in the off-premise retail market are well-positioned, as more people will be trading down in price." He said Lodi producers also have an opportunity to compete with higher-end coastal wines in the $15-$20/bottle category with good quality Old Vine Zinfandels and Syrah, and could compete with imports with less mainstream varietals such as Malbec and Iberian varietals. He also cited Lodi's sustainable certification and labeling program, "Lodi Rules," as a "green" benefit that is of interest to more consumers, and said, "It could be icing on the cake to tip sales in your favor."
Posted on 02.10.2009 - 17:11:27 PST
The proposed systematic approach to variety and clone evaluation will be a boon to the wine grape industry. A companion project to evaluate the dozens of rootstocks available from FPS is just as important, especially given the soil challenges present at many vineyard sites, the increasing costs of soil management inputs, and the trend towards sustainable vineyard management.
Turlock, CA USA