I have white stuff on my zukes, yellow summer, table king bush and spaghetti squash. I know what powdery mildew is and this is not it. Plus I'm watering them with diluted raw goats milk often so I can assume that it's not. It's only on a few plants of each kind. The wilted leaves are from lack of waters... they perked up after watering :) Also one table king plant started to wilt severely from the middle (young leaves). Will post pic later. We are in NE AZ.