Is it just me, or does the phrase "powdery mildew" seem like a contradiction? If something is mildew-y, should it not be soggy and stinky?
At any rate, it's killing my squash plants this year, and a few of my cucumbers as well. Oddly enough, it's only on the squash plants in my raised beds, not on the gardens by the fence. It seems to grow well in hot weather, but really loves the moisture we've been having this year. I think it rains almost every day! I have a running joke with my husband that as soon as I water the garden or hang clothes on the line, it rains.
I've been doing some reading about it and about organic methods of containing it, and it seems like there's not much you can do unless you get something that will also kill beneficial organisms (sulphur and copper being included in that). So, I'm going to try spraying on a baking soda and water remedy (1 tsp baking soda in 1 quart of water) that I read about in the Rodale Organic Gardening book. I hope it works, because besides looking gross, powdery mildew can cause problems with the fruits. My guess is that it impedes photosynthesis so the plants can't put as much energy into fruit production. And I want my pumpkins!
I'm trying desperately to figure out why my parents' garden grows amazing squashes and cucumbers year after year, and mine almost always do terrible. Case in point, I planted pumpkins in their garden at the same time as I planted the same type in mine, and mine have powdery mildew (which theirs don't) and very few flowers. The ones in their garden, however, have pumpkins almost as big as my head already! Oh the fun of horticulture.