Galls, Diseases, and Pests - Oak Powdery Mildew
Erysiphe alphitoides
Powdery Mildew is a little counterintuitive in that it germinates in dry conditions rather than a wet environment. It occurs on new shoots and leaves, on more than one type of oak. Powdery Mildew is usually found as a thin layer of white powder. Leaves with the mildew deform over time and can dry up early in the season.