Two things have worked well for me - watering as much of the garden as possible with a drip system and using Neem oil on the infected plants AND those close by as soon as any mildew shows up. The neem oil comes in several brands so you will need to look at the labels. I do keep the garden cleaned of old plant material as well.

Thanks for the information...Will be trying this myself.

Ahhh, the dreaded powdery mildew! What a pain! My worst problem has been my perennial phlox. Every year they were beautiful, then they start to bloom, and BAM... ugly white fungus! I tried the fungal sprays, but admit that I most likely didn't spray them as often as recommended so I can't blame the product for not working................ I have not tried home remedies, but this site lists a few that I think may be worth trying... especially if your problem is with vegetable crops or an extreme case... http://gardengal.net/page11-1.html .................. I HAVE won the phlox mildew war, though... by careful garden cleaning and thinning out plants. It has worked amazingly well for me!............................. Powdery mildew spores overwinter on plant debris left in the garden. The spores begin to grow in early spring and are spread around by wind, splashing water and insects. I have controlled it by removing ALL susceptible plant material in fall, and any mildew infected material as soon as I see it. A very important key is air circulation. In spring, I thin out the phlox plants considerably, removing all the shorter growth (these will not bloom anyway)... more energy is saved for the productive growth.... Other tips... always try to get resistant varieties, blast your plants with a strong spray of water once in a while (it washes the spores off the leaves and may slow the spread up the plant), plant susceptible plants where they will get as much sun as possible, avoid wetting the leaves - water the ground.................. Best of luck! Please let us know if you find something that works for you, or if you find other tips we can use.

Mix 3% peroxide with water at 2 1/2 tsp. per gallon and spray on plants. Cinnamon is also a natural fungicide that can be sprinkled onto plants and soil.