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ARS_Nov05.qxt 9/23/05 2:12 PM Page 1 GRAPEGROWING WINEMAK Geneva, N.Y., who recently shared the latest intelligence regarding red blotch virus. The virus also was recognized in 2012, and an assay was developed to detect and confirm its presence. The first potential vector was identified in 2013. The symptoms of the virus are red blotches and spots on leaves, though a small percentage (2.5%) of infected vines don't show any symptoms, likely because of the latency of disease onset. The red ranges from pink to crimson. (Editor's note: Find further description of GRBaV, numerous photos by Dr. Fuchs and others, as well as a short list of labs that can test for the virus in Wines & Vines' April 2013 issue.) Other viruses like leafroll also color leaves, but GRBaV displays a different pattern of red than leafroll does. "Red blotch can dramatically affect quality," Fuchs said. 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—only in their hosts. Nevertheless, researchers have found that GRBaV causes red blotch. Unfortunately, he noted, your eyes aren't enough to identify the virus. Polymerase chain reaction (PCR) assays are available to identify GRBaV. Tests can identify presence of the virus in any tissue of the vine—leaf, petiole, dormant canes or clusters—at any time of year. Because of the difficulty confusing symptoms of the virus with other viruses, he said: "Test, don't guess." Fuchs said research suggests there may be two variants of the virus. Red blotch virus can be found in both red and white wine grapes, in table grapes, raisin grapes and rootstocks. As of November 2013 it had been detected in winegrowing regions in California, Oregon, Washington, British Columbia, Virginia, Pennsylvania, Maryland, New Jersey, New York and Ontario, Canada. Red blotch virus is spread by propagation and grafting, and anecdotal evidence suggests it may spread by other means. The Virginia creeper leafhopper (Erythroneura ziczac) seems to be able to transmit red blotch virus from vine to vine in the greenhouse, but it's not yet proven that the leafhopper is a vector in the field. Fuchs says that at this point, the best way to manage the disease is to select planting material carefully. Clean • Sterilize • Humidify "We can do it all" ... Steam Generators • Bottling Lines • Barrels Pressure Washers • Tanks • Floors and Walls • Winery Equipment Barrel Washers and Rinsers • Vineyard Equipment Humidifiers Trust_Dir11.qxp We work well under pressure. Stemware Washers ARS/Pressure Washer Company 10/28/10 3:09 PM Page 1 We work well under pressure. 800-735-9277 or www.cleanwinery.com "People, Product, Profit Without top people, you cannot do much with the others." - Malcolm Forbes WWW.RECRUITINGASSOCIATESNETWORK.COM Tel: 707-931-4707 822 College Avenue, Ste. B, Santa Rosa, CA 95404 Discover the Difference of Our Specialized Services: Duarte Nursery owner John Duarte noted that growers are more educated about diseases and viruses than in the past, and they request clean plant stock. It's Our Niche It's Our Network It's Our Approach It's Our Guarantee! Win es & Vin es F EB Rua ry 20 14 57