This was one of the best articles about powdery mildew that I have read thus far. I hadn't put two and two together about shade being a factor in the proliferation of PM. I have a wrap around rose bed on the east and south sides of my house. I was told that the original old roses were planted approximately 40 years ago by the previous owner. A pine tree nearby has grown so big that now the east side only gets a few hours of sun a day. That side is where I have PM problems. Between that, age and lack of sun, those roses are no longer thriving. My experience is that fungus sprays will only PM at bay. What works best for me is to spray the canes and surrounding ground after my winter pruning and cleanup. This way I can more easily get the spray all the naked canes and any spores that have fallen to the ground. Although this does not prevent it from coming back the following year, it appears to help.
This was one of the best articles about powdery mildew that I have read thus far. I hadn't put two and two together about shade being a factor in the proliferation of PM. I have a wrap around rose bed on the east and south sides of my house. I was told that the original old roses were planted approximately 40 years ago by the previous owner. A pine tree nearby has grown so big that now the east side only gets a few hours of sun a day. That side is where I have PM problems. Between that, age and lack of sun, those roses are no longer thriving. My experience is that fungus sprays will only PM at bay. What works best for me is to spray the canes and surrounding ground after my winter pruning and cleanup. This way I can more easily get the spray all the naked canes and any spores that have fallen to the ground. Although this does not prevent it from coming back the following year, it appears to help.