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18 WINES&VINES April 2016 WINE INDUSTRY NEWS N apa, Calif.—Grapegrowers have a new virus to worry about. The grapevine Pinot Gris virus (GPGV) recently was identified in a number of Napa Valley vineyards after being found in vineyards from Korea to Canada. The virus was the topic of a session organized by the Napa Valley Grapegrow- ers, University of California Cooperative Extension and the Napa Valley Vineyard Technical Group. Napa County viticulture advisor Dr. Monica Cooper presented for Dr. Maher Al Rwahnih, associate plant scientist for Foundation Plant Services, who couldn't attend. Symptoms of the grapevine Pinot Gris virus—chlorotic mottling, leaf deforma- tion and stunting—were first noticed in north- eastern Italy in 2003. In 2012 it was identified as a new member of the Trichovirus genus. The new virus was subsequently found on Traminer (also known as Gewurztraminer), Pinot Noir, Chardonnay and other varieties. The eriophyid mite Colomerus vitis (Pagen- stecher) is believed to spread GPGV. In most cases, GPGV has been reported in plants with multiple viral infections. Other viruses found in vines with GPGV include: grapevine rupestris stem pitting-associated virus and grapevine rupestris vein feathering virus. GPGV diagnosis can be challenging, be- cause in some cases it appears asymptomatic, and in others it occurs with other viruses. Early research showed that GPGV could be eliminated by in vitro meristem tip culture and/or thermotherapy. At the FPS vineyard Russell Ranch, 254 vines were tested with real-time quantita- tive qRT-PCR assay; none had GPGV. At the Classic Foundation Vineyard in Davis, FPS tested 1,760 vines and found one infected vine that didn't exhibit symp- toms, a Touriga Nacional vine imported from Portugal in 1981 and planted in the FPS collection in 2001. FPS tested 20 vines surrounding the infected vine, and all tested negative. GPGV also has been detected in a grapevine rootstock breeding selection originally propagated from seedlings. Also very recently, a private virus-testing laboratory re- ported GPGV from three separate vineyards in Napa Valley. Seven vines from four commercial vineyards tested positive for GPGV, including selections of Cabernet Sauvignon, Cabernet Franc and Chardonnay. —Paul Franson Grapevine Pinot Gris Virus Found in Napa Valley © Photo : Christophe Deschanel Stave Grade Oak Alternatives for Enology Caroline Hoogenboom Napa - Sonoma - East Coast Cell. (707) 364-6334 caroline@oenosylva.com Amy Lee Oregon - Washington - California Central Coast Cell. (509) 995-2771 amy@oenosylva.com To discover the Œnosylva ® range: Contact your Ermitage / Berthomieu representative Offce: 1285 S. Foothill Blvd - Cloverdale, CA 95425 - Ph: (707) 224-2377 - Fax: (707) 224-2390 www.oenosylva.com | contact@oenosylva.com NEW RANGE Chauffe Convection Leaves from a Pinot Grigio grapevine show chlorotic mottling and deformation, symptoms of grapevine Pinot Gris virus. DR. PASQUALE SALDARELLI / UNIVERSITY OF BARI