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