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JANUARY NEWS Update on Red Blotch Disease Cornell professor details the virus for Napa wine grape growers N apa, Calif.—There was standing The symptoms of red blotch disease— room only as growers and wine- more formally, grapevine red blotch associmakers skipped the wine reception ated virus (GRBaV)—were first described at the Nov. 13 Napa Wine + Grape in 2008, and transmission by grafts was Expo to hear the latest intelligence on red confirmed in 2012. The virus was also recblotch virus from Dr. Marc Fuchs of the ognized that year, and an assay was develDepartment of Plant Pathology at Cornell oped to detect and confirm it. University in Geneva, N.Y. The symptoms of the virus are winesandvines.com Fuchs asked for a show of hands red blotches and spots on leaves, Learn more: of growers and vintners who see though a small percent (2.5%) of Search keywords "Red blotch update." signs of red blotch in their vineinfected vines don't show any yards, and most in the room raised symptoms, likely because of the their hands, a sign of the malady's spread in latency of disease onset. The red ranges from Napa Valley and elsewhere. Fuchs said he'd pink to crimson. (Editor's note: further get the same response among New York description of GRBaV, numerous photos by grapegrowers. Dr. Fuchs and others, and a short list of labs that can test for the virus can be found in a special report by Practical Winery & Vineyard in the April 2013 edition of Wines & Vines.) Red blotch virus delays ripening. It can lead to 5° or 6° lower Brix in mature grape berries. It also affects the anthocyanins and can lead to reduced color in red grapes and their wines. Fuchs mentioned the challenge of confirming that the phenomenon met the criteria for a disease, a problem partly because viruses won't grow in petri dishes, but only in their hosts. Nevertheless, researchers have found that GRBaV causes red blotch. Polymerase chain reaction (PCR) assays are available to identify the virus. —Paul Franson Winery Experiments with Trellis System Crew Wine Co. uses hanging curtain to improve grape quality, lower costs D unnigan Hills, Calif.—Crew Wine Co. in Yolo County, Calif., is experimenting with a newer, non-traditional trellis system on 110 acres of vineyards that were planted in 2012 and designed to produce a larger number of smaller, looser clusters for red grape varieties to reduce vineyard production costs and enhance wine quality. Called the "hanging curtain," the trellis is a high-wire system with installation costs similar to a more conventional vertically shootpositioned (VSP) trellis. The vine trunk grows up a 6.5-foot-tall stake and is trained into a unilateral cordon from the trunk along a cordon wire at the top of the trellis. Instead of being trained straight up (as with winesandvines.com VSP), the canes are trained downward and Learn more: Search keywords draped across two wires below the cordon "Hanging curtain." wire—then to an even lower wire, located about 1 foot above the irrigation drip line. The goal is to create a long, loose curtain of leaves to shade the fruit but allow better air movement to prevent powdery mildew and Botrytis bunch rot. This design should produce a wall of fruit spread throughout the curtain, enabling more even ripening of each cluster. Smaller clusters are expected to produce more concentrated flavor. Vineyard spacing is 8 feet between rows with vines 6 feet apart. Crew Wine co-owner and vineyard manager Karl Giguiere said there is additional cost and labor to train the vines during the first three years, but once in production, the goal is to save money on mildew and mold control. 24 W in es & V i ne s January 20 14 Karl Giguiere, co-owner of Crew Wine Co. and JK Vineyards in Yolo County, Calif., walks among an experimental planting of 2-year-old Cabernet Sauvignon vines that use the hanging curtain trellis system. The vines can be mechanically hedged for the initial pruning pass to save on overall pruning costs. Giguiere said the trellis also offers good potential for managing high vigor. The trellis trial involves 40 acres of Petite Sirah, 30 acres of Petit Verdot, 27 acres of Cabernet Sauvignon and smaller plantings of Tempranillo and Tannat. The grapes are intended for Crew Wine's Matchbook and Sawbuck brands. "Cabernet Sauvignon is all about quality, and we still want to get good tonnage at a reasonable cost to match our $10-$15 per bottle price point, with yields of about 8 tons per acre," Giguiere said. "With the labor shortage and increasing costs, we're looking for more affordable ways to increase or maintain quality and still give the consumer a great wine at a reasonable price. That's the challenge," he added. —Jon Tourney See us at Unified booth #4104