Powdery Mildew Remedies for Plants | Old Farmer's Almanac
The powdery mildew that you find on your squash is not the same as the mildew on your beans or roses. Cucurbits such as pumpkins, squash, cukes, and melons have three different powdery mildew fungi gunning for them that can thrive in both humid and dry weather. The spores of the fungi are windborne and can’t be avoided.