cosmos with white on leaves

by Carol
(Coastal Maine)

Last year I planted cosmos and, for the first time, had bushy, gorgeous growing plants. Great cut flowers! (I hadn't planted Cosmos in years!) I usually put snapdragons in that spot in back of petunias and alyssum. I would love to plant them again but found toward mid August that the "leaves" on the cosmos turned white. Would that be powdery mildew? If in fact, it was, should I try again? What do you recommend for the mildew? I live in zone 5 and on the coast of Maine. The "foggy season" usually is better by August so I am wondering about my guess.

Doug says that I think you're probably right about the powdery mildew. White over leaves is a pretty clear sign - particularly if it looks like a dusting of baby powder. You can read about powdery midlew right here and how to take care of it.