My Peonies are covered with a white mildew and some of them have a blight causing the foilage to turn dark. What should I do for them? Do I cut off the foilage? Will it affect next year’s growth and bloom?
Once the foliage starts to yellow, cut it off and remove it from the yard in a garbage bag. The best way to control powdery Mildew is with preventative sprayings with copper of sulfur fungicide before the symptoms show…around mid-May through mid-June. It is difficult to control once the white powdery coating on the leaves shows up. None of the should create problems for next year’s flowering cycle.