Botrytis Blight on Peonies and Roses
Brown buds that fail to open on peonies and some roses, especially the white and pink flowered varieties is usually the result of botrytis blight also known as gray mold.
This fungal disease is most common in cool and rainy as well as humid weather. The disease attacks a variety of ornamental and edible plants and often is specific to the plant part infected.
Look for the fuzzy gray growth and small black specks on the dead tissue.
Remove infected parts and place in a paper bag for disposal. Don’t compost it as this can spread the disease. And only clean up during dry weather as moisture helps spread the blight.
Ongoing sanitation, fall clean up and better weather is usually enough to keep this disease under control
A bit more information: Phytophthora blight is another common disease of peonies. Both blights cause purplish black spots on the leaves and stems of peonies. Fall clean up and drier spring weather is usually enough to keep both diseases under control.