Removing powdery mildew

Credit: The County Clerk

Q: My peonies’ leaves have a powdery look to them…

This sounds like powdery mildew (Erysiphe polygoni), a fungus widespread on many vegetables and ornamentals late in the summer. Mildew is noticeable when plants are grown in undesirable growing conditions like excessive shade, poor air circulation, inadequate soil nutrients, high humidity, uneven soil moisture, and others. Improve growing conditions to meet plant’s needs. Remove and dispose of infected plant material at the end of growing season. Do not compost infected materials. Plants vary in their resistance so avoid susceptible cultivars.