Answer: Thompson's Seedless is prone to powdery mildew. To help avoid the problem, provide as much direct sunshine as possible and as much air circulation as you can around your grapevines. If mildew attacks, control by spraying with water to wash spores off, or pick off infected leaves and destroy them. You can also control powdery mildew with sulfur sprays or neem oil.
Q&A Library Searching Tips