Several of you have written to ask me what's wrong with your cucumber and squash vines. They have a white cast to them and you're worried it's a sign of a disease. Actually, many plants in the squash family have a natural white shading on the leaves from the fuzzy, scratchy hairs. If it's been there most of the season and the plants look healthy and happy, don't worry about it.
If the white is blotchy, powdery and spreading, like the spots on the squash leaf here, it could easily be powdery mildew. Some varieties of squash and cucs are resistant, but a lot of the old favorites still succumb in humid weather. Powdery mildew doesn't kill the plant, but it does weaken it and it makes it difficult for the plant to photosynthesize and make food. Once powdery mildew takes hold, it's hard to stop it by organic means, but the old stand-by baking soda recipe can help to keep it from spreading.
Photo: © Marie Iannotti