Grapevine leafroll virus, able to spread through vineyards from infected propagation material, vectors, human activity, and root grafting, is a growing problem in Washington State. Several years ago, based on a statewide survey, industry experts estimated that 10 percent of the state’s wine grape acreage was infected. Today, anecdotal evidence suggests the disease is more widespread than previously estimated, says a Washington State University virologist. Dr. Naidu Rayapati, WSU grape virologist, believes that leafroll virus is a threat to the sustainability of Washington’s wine grape industry. Left unchecked, the virus reduces the lifespan of a vineyard by delaying ripening, lowering […]