For the past several years, as the summer heats up, my peonies develop black spot on the leaves, covered with it actually. I am trying to garden organically. What can I do to prevent or treat the fungal diseases that must be in the plant. Its not just my peonies. I get fungal diseases on my roses, hydrangeas and other plants that aren't coming to mind. We have endured very hot and dry summers for the past few years. Nothing I can do about that... I water them with soaker hoses. After the leaves die down I do remove them and throw them away. Should I prematurely cut the plants back before they die back?