Leaf Fan and Leaf Roll Virus Information

Leaf fan and leaf roll virus's infect vines and rootstocks during propagation and can cross infect vines in a vineyard. They can only be avoided by scrupulous attention to their prevention with good nursery practice, and by frequent virus testing.

Leaf-roll virus can be detected visually by downward-curving leaf edges; the leaves of the red-grape varieties turn a brilliant red. It impedes the grape's sugar accumulation, which means that, by the time the grapes reach a sugar level at which they can be harvested, their acid levels and overall quality is greatly diminished. Such grapes naturally produce wines in which flavour, colour and body are attenuated. Leaf-roll virus doesn't kill grapevines but markedly reduces yields. The only treatment currently known for this disease is removal of the vines. Growers can protect against leaf-roll virus by purchasing only vines that have been Elisa tested and are negative for leaf roll virus's types 1 & 3.