Try non fat milk and water in equal amounts with a little bit of dish soap but will have to water from above.

lissa - some copper fungicide will do the trick.

EG

I have used whole milk and half&half in 50/50 mix with water, both work but I had to do it everyday. I had better results with baking soda & water in a spray bottle. Make your own recipe. Or use compost tea if you have it.

Since Powdery Mildew is airborne, it is very difficult to combat. The long term solution may be to plant more cukes or find a resistant variety.

Good Luck

Ugh, powdery mildew. My arch nemesis last year. I used the milk/water mix and although it stopped the progression I was too late as it had already taken over. If it's just starting I think you'll have better luck with it than I did. Good luck!

Thing that always works for me is 1 teaspoon baking soda and 1 teaspoon Murphy's Oil Soap in a quart of water in a spray bottle. Never fails...

Thank you all! I am hoping to head this off at the pass, so I'll be trying these cures tonight.