Diane, Thank you for the question. Peonies are susceptible to a couple of different blights brought on by cool wet weather. Iowa State has good information on growing peonies and managing diseases. Here is the link: https://yardandgarden.extension.iastate.edu/how-to/how-manage-potential-problems-growing-peonies

Also, peonies are susceptible to juglone so that may be a factor too. Particularly sensitive to juglone are ornamentals such as lilacs, peonies, rhododendrons and azaleas. The symptoms in plants sensitive to juglone range from stunting, yellowing, to partial or total wilting, to complete death. Does not appear that your peony has these symptoms.

Paul

Master Gardener volunteer