It seems that we have had a powdery mildew infection on our squash and zucchini plants every spring for the past 5 years. Since I wrote this article last year about measures to take to prevent powder mildew , we have been powdery mildew free! In reallity we were probably helped out this year by the weather, as well as our preventive measures. We followed most of the guidelines already, but I wanted to share a couple of things that seem to make the biggest difference from my experience.
Here in Florida our sub-tropical (seems to be getting more tropical every year) climate makes a nice environment for many fungal infections. Hot temperatures and high humidity combined with nice green cucurbits like zucchini, squash, pumpkins, and gourds, make a very inviting environment for podwery mildew. The spores travel on the wind, and when they land in such an ideal spot, they try to set up camp. I believe that cucurbits have some natural resistance to fungal infections, but if the fungus gets even a slight advantage, it will win in the end.
One thing I have noticed is that older plants, seem to be more succeptable to infections than younger plants which are at the peak of vegetable production. One thing I did this year that I believe helped a great deal, was pulling out plants as soon as they appeared to by winding down production. If a plant which had had been producing for several weeks, had no new flowers or fruits on it, or had some leaves browning, I pulled them out and tossed them in the compost pile. The second thing, which I think is critical to powdery mildew prevention, is taking care not to let the plants go overnight with wet leaves. We got some help this year from mother nature, who didn't hit us this year with a lot of rain after dark. We took care to water the plants only when the foilage would have time to dry before night fall.
I will continue to follow these powdery mildew prevention practices and cotinue to post our results. We still have several gourd plants growing and may be planting some summer squash soon, and some pumpkins not long after that. I will let you know how it goes, my hope is to make it through the entire year with no pwdery mildew!