Symptoms of grape fanleaf disease (shown on the leaf on the left) include vein banding and yellowing, possibly resembling herbicide-damaged leaves. Washington State University Grapevine viruses are the silent killer of vineyards. They lurk in unclean propagative material, the mouths of tiny vectors, and old root material, and wait to take hold in a vineyard, reducing yield and quality. And worse, state programs designed to produce clean ­material are not ­fail-safe. The grapevine, a “treasure trove” for viruses, can be infected by more than 70 viruses worldwide, said Washington State University’s Dr. Naidu Rayapati. Fortunately for Washington State grape growers, […]