A couple of my peony bushes which are in full sun are experiencing curled up leaves but not all are affected. They have been watered a couple of times.
(Answer) According to an article from the University of Minnesota (https://www.extension.umn.edu/garden/yard-garden/flowers/diseases-of-peony/index.html), there are several virus diseases of peonies one of which is leaf curl. Viruses may cause patterns of dark and light green on the leaves, stunting, leaf curl, or just a reduction in vigor. Virus-infected peonies may grow and bloom normally except for the strange patterns on the leaves or other subtle symptoms. No treatment is suggested to help cure a virus-infected peony. If symptoms are severe, and growth and flowering are greatly reduced, the plant can be removed and discarded. Other suggestions that might help would be to ensure that there is adequate air circulation where your peonies are located. When watering, water only at the base of the plant and do not get the leaves wet. In the fall, cut any diseased plants back to the ground or just below the ground and dispose of the infected material. Add well-composted organic material as a light mulch in early fall to help add nutrients and improve the soil. This organic compost can be lightly worked into the top inch or two of soil.