Though it is organic, neem oil kills beneficial insects like lady … This botanical pesticide is derived from the Azadirachta indica tree species and is labeled for use on downy mildew. Neem Oil Pressed from the fruits and seeds of the neem tree, which is native to the Indian subcontinent, neem oil is a popular remedy for powdery mildew because it’s organic. 70% NEEM OIL is an effective fungicide for the prevention and control of various fungal diseases including powdery mildew, black spot, downy mildew, anthracnose, rust, leaf spot, botrytis, needle rust, scab and flower, twig and tip blight, and alternaria. Controls various fungal diseases including powdery mildew, black spot, downy mildew, anthracnose, rust, leaf spot, boytris, needle rust, scab and flower, twig and tip blight, and alternaria. Years ago we would recommend neem oil for powdery mildew prevention and control. Neem oil works as a natural … Neem Oil. Neem oil fungicide • miticide • insecticide concentrate ... • As with other oil-based products, exercise care in timing applications to early morning/late evening to minimize the potential for leaf burn. However, we cannot recommend it anymore due to various discussions linking the chemical Azadirachtin, an active ingredient found in neem oil… As a preventative, apply 70% NEEM OIL … ... black spot, downy mildew… Application Note: Neem oil … Use neem oil.