May 28 , 2020
Problem: Powdery mildew leaves a telltale white dusty coating on leaves, stems and flowers. Caused by a fungus, it affects a number of plants, including lilacs, apples, grapes, cucumbers, peas, phlox, daisies and roses.
Solution: Rake up and destroy infected leaves to reduce the spread of spores. Also, give plants good drainage and ample air circulation. Avoid overhead watering at night; mid-morning is preferred to allow foliage to dry before evening. Commercial fungicides are available for powdery mildew, or you can spray with a solution of one tsp. baking soda and one quart of water as recommended by George “Doc” and Katy Abraham, authors of The Green Thumb Garden Handbook.
Lilac, a highly aromatic plant, is a common victim of powdery mildew.