You could check out spraying with milk! Some people have had great success with it on their veggies.

Linda

Ohio, the good news is that there are hundreds of different variants of powdery mildew and they are host specific. That means that the PM that has affected your roses will not/cannot mess with your cucurbits at all.

The bad news is that the PM strains that affect curcubits are ubiquitous; once conditions are right........

My first choice against PM on most plants is plain water. A brief syringe from the hose rinses off PM spores very effectively. I'll add a little horticultural oil sometimes.

Green Cure is not a preventative but a curative, so don't waste your resources that way. I've never used Antinovate so have no idea about the expense. Water or horticultural oil has always worked for me, neem as a curative if needed.

I'm a user of Surround WP on my cucurbits, too, and PM spores will not penetrate the clay film.

afaik powdery mildew is airborn and extremely difficult to prevent. I have used milk in the past and it seemed to work but needed daily applications. I also used half & half same results. It didn't affect the fruit so I now just cut off affected leaves and live with it.

The are some things you can spray but I believe they need to be sprayed before the mildew attaches to the leaves.

There are about a bazillion different strains of powdery mildew but they tend to be rather plant specific. So the powdery mildew on your roses (Sphaerotheca pannosa var. rosae) is not the same sort of powdery mildew that affects cucurbits (squashes, melons, cucumbers, etc. (Podosphaera xanthii and Erysiphe cichoracearum). I would not be concerned about one plant affecting the other, although the melons and cukes can certainly pass on their type of PM to any of their cousins :-)

Spraying preventatively is the ONLY way to control PM. If you wait until you see signs of it before spraying, it is already well established. Milk, baking soda solution, neem or other horticultural oil or most other prepared spray fungicides (e.g. Actinovate) should help to keep things under control. I will say that cucurbits developing PM, especially later in the season, is almost a given - they are extremely prone to this pathogen.

Some strains do cross plant types, though. Last year an infected pumpkin plant next to my catnip infected the catnip plants; it overwintered and this year the catnip still has it, with no pumpkin plant in sight.

It's very common for several types of PM to be infecting their host plants at the same time. In other words, the pumpkin had its own infection while the catnip had its, but they didn't pass it back and forth.

As long as the conditions are right for this fungus, any susceptible plant can become infected....but with its own particular strain. They don't "catch" it from an unrelated plant.

I appreciate all the responses I've gotten to this post. You all are very helpful. Thank you.