Issue link: https://read.dmtmag.com/i/117824
Grapes New grape disease reduces yields, quality new disease that threatens the health of grapevines nationwide highlights the need for stronger clean plant campaigns. The disease, first reported in a Napa Valley vineyard in 2008, has been identified in infected vines in the top three U.S. grape growing regions of California, Washington, and New York, as well as a few other East Coast and southern states, and Canada. Washington State University researchers are tentatively calling the new disease grapevine redleaf disease due to the red to purple color on leaves of red varieties. Symptoms range from red veins and blotches to total reddening of the leaves in some red grape cultivars. Veins on the leaf undersides can be pink or red, or the major veins can still be green. California and New York scientists have dubbed it ���grapevine red blotch disease,��� but WSU scientists preferred to use the broader term ���redleaf��� to cover the full spectrum of symptoms, so that growers pay attention to by Naidu Rayapati all suspicious red leaves. and Melissa Hansen The difference in symptoms could be due to ownrooted vines being used in Washington and grafted vines in California, New York, and other places. New disease has symptoms similar to grapevine leafroll disease. Misidentified in vineyards? The symptoms of redleaf disease in red-fruited cultivars may look similar to those produced by grapevine leafroll disease, but the new disease is distinct in several respects. Like leafroll, redleaf symptoms show up just after veraison and look very similar to leafroll, which could be why growers and university researchers never paid much attention to it in the vineyard. Many just thought it was leafroll virus. But the epidemiological aspects are quite distinct. It���s like a person having the flu or West Nile virus. Symptoms can be similar, but the nature of the virus and mode of its spread are very different, and the same treatment doesn���t work for both. With leafroll disease, growers have focused on controlling grape mealybug and scale infestations to slow the spread of the disease. But with redleaf, a new vector is suspected, and a different set of management tactics is required. How does it spread? WSU bench graft tests showed that redleaf disease is graft-transmissible. Symptoms on the scion (virus-free Cabernet Franc) were similar to those observed in the source vines used as the rootstock. Based on the PACKING LINE EQUIPMENT FOR SALE NOW Increase your packing speed and ef���ciency! 8��� Sizer Roller and 16 Lane Sizer Central Weigh Clam & Bag Fillers (indexing conveyer serves 1, 2, and 3# clamshells plus adaptable bag ���llers) (6 Lane Tank) 2 Drive Motors (8 Lanes each) Belting is available. For more information Phone: (209) 931-4392 E-mail: mail@ogpacking.com Website: www.ogpacking.com 44 April 1, 2013 GOOD FRUIT GROWER www.goodfruit.com