Grapevine fanleaf virus
Fanleaf degeneration affects vinifera cultivars. It is characterized by fan-shaped leaves with toothed margins, proliferation of shoots, short internodes and zigzag growth. Foliar symptoms appear early in spring and persist through the growing season. Sometimes leaves show a bright yellow mosaic or yellow vein banding with little or no malformation. Fruit clusters are small with poor fruit set, irregular ripening and shot berries. The causal virus is spread by dagger nematodes and planting material. The virus is not transmitted through seeds and has no natural weed hosts. Roots from infected vines can be a source of infection even after the mother plant has been removed.
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