Answer: Sounds like a fungal disease called powdery mildew. This happens when plants are overcrowded or when days are warm and nights are cool - or a combination of these factors. The material benomyl, or Benlate, is the most effective fungicide for the control of powdery mildew, but if the disease has progressed too far, your cucumber and pumpkin plants may die. Next year choose the most disease resistant varieties you can find. Good luck with your veggies.
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