Neem oil can be used to prevent powdery mildew, if the disease has been a problem in the garden during previous seasons. Neem is an effective control, if applied at the first symptoms, such as small white spots forming on leaves. This natural fungicide acts by killing the powdery mildew spores on leaves.

How long does neem oil take to kill powdery mildew?

The claim is that neem oil can treat powdery mildew in 24 hours but my experience has been that you will see results immediately. Powdery mildew is a parasitic fungus that attaches to plants and sends down roots into the plant cells to feed.

How do you use neem oil for powdery mildew?

Neem oil is labeled for control of powdery mildew, rust, blackspot, botrytis, downy mildew and other diseases. Spraying with 2.5 Tablespoons per gallon of water every 7 to 14 days is recommended.