first time growing summer squash this year and although it was going like gangbusters, it is now looking a little sad. I have fruit in various stages of growth and a lot of blossoms,but the leaves are turning yellow and have a powdery mildew. new leaves are green, shiny and healthy. the mildew can be wiped off with a wet cloth but the leaf is obviously weak and pale looking. the only pests I could see are a tiny jumping black bug I will assume is a flea beetle. I also have cucumbers and have killed about 10 cucumber beetles over the course of a few days, that is the only pests I have seen. We have had rain almost daily followed by scorching heat, which makes for high humidity. what should be my course of action?