Squash got the fungus. My son thinks it is due to it being shaded in the morning when the dew is out. We are still getting Squash and Cucumbers. Radishes and Beets are in pots. We thought it was going to be a Basil-less year but they have rebounded. Tomatoes are slow this year due to a cool June.
When I lived on the coast, I had a major issue with powdery mildew on leaves. Hydrogen peroxide in a 2-3% mixture sprayed on the entire plant/tree worked quite well, with no damage to the leaves, fruit, or stems/trunks.
I’d spray this every other day for a week, then taper down to once a month. It was quite effective controlling the problem.