Bud wrote in :

On 2011-08-21, Zootal wrote:
Once again it is mid/late august, and the squash plants are pumping
out zukes like crazy. And, right on schedule, the powdery mildew is
starting to appear. Has anyone had any success fighting or even
eliminating powdery mildew on squash plants?

Is it damp out there? Try some sulfer powder.

It's not damp at all - summers here (Wilamette valley, Oregon) are warm and
dry. Temps in the 80s. Comfortably cool at night. And I never water
overhead, but use the hose on the ground so the leaves don't get wet.

Interesting enough, I water the cucumbers overhead, yet never have mildew
on them - just the squash.