Management of viruses and grape mealybug vectors in a commercial leafroll-diseased vineyard

Grape leafroll is one of the most important viral diseases of Vitis vinifera wine grapes around the world, including the USA. This disease is caused by several different viruses in the plant virus family Closteroviridae that are vectored by mealybugs and soft scale insects. There is no known genetic resistance against the leafroll viruses and their vectors in Vitis. We tested the efficacy of removing infected vines and the two adjacent vines (spatial roguing), insecticide control of the vector, and the combination of the two at reducing disease incidence and reducing grape mealybug populations in a leafroll diseased Cabernet franc vineyard in NY. Over six years, spatial roguing significantly reduced disease incidence. Insecticides significantly reduced vector populations, but had little impact on disease when used alone. We discuss our results in the context of an economic based model for making leafroll disease management decisions.