There are natural products for getting rid of powdery mildew, although this is a bit late for your post last year.
First of all, don't panic! At the first sign of trouble, clip off and destroy all affected leaves. If the plant is already covered by the time you realize the stuff is there, cut the plant right down, leaveing no leaves, if it is early enough in the spring the plants will continue to grow, even though it looks as if it is done for.
Here are some tips to prevent this from happening this year. Powdery mildew is usually crowding which causes poor air circulation, when you water, aim the hose at the ground, I use soaker hoses by laying them in between two rows of produce when I plant the seeds. This way, you are not going to disturb the new seedlings, and while this may be expensive to start, what I did was buy a few soaker hoses each year until I had enough for my whole garden and now I don't use a sprinkler or spray hose at all. For another thing, in these green days, watering via sprinklers and hoses is wasteful and expensive.
Powedery mildew usually starts when the days are hot and the nights are still chilly and condensation sits on the leaves.
To receive a recipe for dealing with powdery mildew, e-mail me.
