Powdery mildew is a common fungal disease of plants in our area that occurs this time of year. It’s named for the grayish white powder consisting of fungus strands on the leaves of the plant. The fungus uses the host plant for its food supply by sending root-like structures into the leaves and stems.
Powdery mildew likes the humid conditions we experience in New England on warm days and cool nights. Some particularly sensitive plants are apples, roses, grapes, peas, potatoes, phlox, squash and zinnias, though there are many more. It’s common for it to start in crowded plantings where air circulation is poor and in damp, shaded areas.
you’ve had powdery mildew on your plants in previous years, it’s likely
to return this year. There are, however, some practices you can
institute that can reduce or even prevent future infestations.
Additionally, many resistant varieties have been developed. For
information and to learn what some of these plants are, click on the
website links at the end of this article. You may also want to check for
resistant varieties at your favorite garden center.