Peonies are susceptible to a fungal disease that can cause a rust appearance on peony leaves. Use a fungicide to treat the problem.
About the Author
Tammy Wood has been writing for more than 15 years, and has been published in the Chicken Soup For the Soul books, "Parenting" magazine and several websites. Wood serves as the director of online marketing for 12 organizations and creative director for BTC Interactive, a newsletter and article archive. She received a degree in business management from the University of Washington.