Powdery Mildew Of Oak

Disease Information

Powdery Mildew

This disease is caused by several fungi (Erysiphetrina, Microsphaeraalni, Phyllactiniacorylea and/or Sphaerothecalanestris).

Symptoms and damage

The symptoms consist of a white, powdery growth on both leaf surfaces. The foliage may be malformed, dropping prematurely or drying out and shriveling. Sometimes the grayish-white fungal growth changes to tan and then brown with age. Tiny black dots (fruiting bodies) may be seen in the brown felt, abundantly in some years, rarely in others.


Control is usually not practical nor warranted. Myclobutanil, triadimefon or thiophanate-methyl may be used to control powdery mildew in severe cases. Follow the directions on the label.


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