Q: I noticed yesterday that my peonies were turning black and withered. I was so happy to see them come up looking beautiful and healthy after all the strange weather. I have not fertilized them, as the dogs are attracted to fertilizer and it is not healthy for them to eat. What should I do?
A: This sounds like botrytis blight, a fungal disease. Remove all of the blackened leaves and flowers and clean up the area around the plant. Bag and throw the diseased plant material away.
Pure neem-oil could be used on the plants, but most of the problem can be taken care of with good sanitation and removing any diseased leaves.
Organic fertilizers such as compost (which breaks down very slowly and usually does not attract dogs) will help the plant. Liquid fish emulsion may attract your dogs, but they won’t be able to eat much.
Clean up and cut the peonies down to the ground in the fall.
— Sheryl Casteen, OSU Extension master gardener