Issue link: http://read.dmtmag.com/i/117824
G rowers are encouraged to contact Naidu Rayapati for advice and visit the WSU grape virology web site for additional information: naidu.rayapati@wsu.edu, wine.wsu.edu/virology/ A Merlot grapevine shows redleaf symptoms on mature leaves in the lower portions of the canopy. Symptoms are easily confused with grapevine leafroll disease. wide host and geographic distribution, and the fact that it is transmitted through grafting, the disease is thought to spread through propagative material. Redleaf disease has been detected in young and old vineyards. Research conducted at WSU has implicated the Virginia creeper leafhopper (Erythroneura ziczac Walsh) as a carrier or possible vector based on tests under greenhouse conditions. Both nymphal and adult leafhoppers have piercing and sap sucking mouth parts. Economic impact Cabernet Franc clusters from a single vine show infection on the left, nonsymptomatic cluster on the right. The economic prosperity of Washington���s wine industry is at risk of irreparable damage due to the new disease and its negative impact on fruit and wine quality. Initial reports from University of California and USDA scientists at Davis have found the new disease can result in significant reduction of sugar accumulation in fruit���up to 5�� Brix. Dr. Naidu Rayapati���s research team, among the first to conduct extensive yield and fruit quality evaluations of diseased vines, found reduced yields of 22 percent and 37 percent in own-rooted Merlot and Cabernet Franc, respectively, when compared to nonsymptomatic vines. Pruning weights and shoot lengths of infected vines of Merlot and Cab Franc were also reduced���pruning weights by 25 percent and shoot lengths by up to 20 percent. An analysis of fruit quality attributes showed that berries from redleaf disease-affected grapevines of both ets OVS Apart? CONVENIENT ONE-STOP SHOPPING NE Prou ly offering oudl ffering udl the full-line o isit ovs.com to download your copy of rellis Supplies Catalog today! lies We stock only the highest quality vineyard, apple, and berry trell systems ney yard, pp y y trellis y lis OVS MED MEDFORD tion Warehouse n Warehouse Mas Way son Way Medford, OR 97501 d, O (541) 613-7330 13- www.goodfruit.com OVS MCMINNVILLE MINNV 2700 St. Joseph RD. oseph McMinnville, OR (503) 435-2700 OVS UMATILLA A ATILLA Distribution Warehouse n Warehouse COLO Logistics 30900 Launch Lane unch Lan Umatilla, OR 97882 9788 (800) 653-2216 ext.1 -2216 e ML910-01-108190-2 OVS AURORA UR 19658 HWY. 99 E. HW Hubbard, OR d, O (971) 216-0111 1616 GOOD FRUIT GROWER April 1, 2013 45