Answer: It sounds like a fungal disease. Botrytis is most common with peonies. Prune away the brown leaves to slow the spread. Good sanitation (including prompt removal of spent flowers) and removing dead foliage at the end of the growing season will greatly reduce Botrytis problems. Fungicides are of limited effectiveness against this disease, but basic copper sulfate or Mancozeb can be applied early in the season when shoots are about six inches tall to help protect the plant. Spray all plant parts to thoroughly wet foliage and soil. Be sure to read and follow all label directions.
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