Just a heads up to any farmers that burn sulfur,beware of spraying any kind of foilar products that contain oils in them before using sulfur. The sulfur will stick and burn the plants. IME sulfur works very well at nipping that PM in the butt. Sulfur is more effective at preventing the formation of powdery mildew than treating a moderate-to-heavy infection. When used improperly or at to high concentration,it can cause leaf damage. Still,it is a effective method of controlling the infection. Another trick since fungi die in alkaline environment,is to adjust the ph of the leaf surface so it's alkaline. With a Ph of over 8 is one of the simplest solutions for powdery mildew. Also silica helps strengthen the stem,serves as an alkaline adjustor,and has natural fungicidal properties. Also foilar sprays can be made using fungicides such as cinnamon oil or tea,copper,garlic,herbal oils,
hydrogen peroxide,D-
limonene(citrus oil),milk,
neem oil and vinegar. Potassium bicarbonate is very effective also. Some biological controls work great against mildew. The bacterium Bacillus subtilis (strain QST713) is often known as brand name
serenade. It's safe to humans and animals,but is highly detrimental to fungi. When used weekly,it's puts powdery mildew into remission. Another strain of bacteria,Bacillus pumilus (QST 2808 strain)produces a compound that disrupts fungal development. This strain is known as Sonata. Sonata does not eradicate powdery mildew completely,but it works well in combination with
serenade or other solutions to greatly reduce an infection. Info provided by Ed Rosenthal. I'm just the messenger.