After many years of beautiful, trouble-free peonies, they are suddenly covered with powdery mildew, especially the stems. This year, there is probably nothing I can do, since the whole row (about 50 feet) is affected, but I need advice to save them for the future:
1. Should I cut back the affected stems now or wait until fall?
2. Should I treat the remaining plants and stubble with fungicide as well?
3. They look crowded. Do they need to be thinned?
4. The neighbor has new trees and bushes which reduce the light, so I suspect that to be part of the problem. Would they need to be altogether transplanted?
I HOPE TO AVOID SOLUTIONS 3 AND 4!
Thank you very much.