Wine and table grape vine varieties are especially susceptible to more severe and damaging infestations of leafhoppers. Four main species of leafhoppers commonly attack grape vines: the potato leafhopper (Empoasca fabae), the grape leafhopper (Erythroneura comes), three-banded leafhopper (Er. tricincta) and Virginia creeper leafhopper (Er. ziczac). The adult leafhoppers are winged, 1/8-inch long and usually wedge-shaped or oblong. These insects are often found on the undersides of grape vine leaves and jump or fly away when disturbed.
Identify a leafhopper infestation by looking for tiny punctures or "stippling" in the grape leaves that may look like a white blotch. You may also see a sticky liquid called honeydew, which the leafhoppers naturally secrete, covering the leaves. About 10 days post-bloom, shake the grape vines to see the adult leafhoppers fly around, and then in late July, look for the nymphs feeding on the undersides of the leaves.
Keep the area around your table grape vines clean and free of weeds, leaves or other debris. Hoe away weeds and rake away all debris from around your table grape vines before spring to remove protection and feeding areas for the leafhoppers.
Spray your table grape vines with an appropriate insecticide, such as imidacloprid (Provado or Admire), acetamiprid (Assail), carbaryl (Sevin) or dinotefuran (Venom). In a clean garden sprayer, mix 1 tsp. of the powder-form or liquid-concentrate insecticide with 1 gallon of water.
Spray the entire table grape vine with the insecticide and thoroughly cover the undersides of the leaves with the spray. Apply the insecticide about seven to 10 days after bloom, when the unfertilized berries fall from the clusters.
Apply the insecticide again about seven to 10 days later. Apply subsequent treatments spaced about one week apart until harvest if you still see leafhoppers on your table grape vines.