Fire Blight in Peonies
I transplanted/split several peonie bushes last fall. Some from in my yard and others from neighbors. Many of them in the front yard are doing beautifully well. The plants are large and the flowers are blooming. However, I placed a couple in my back yard and I just noticed that though the plants were large and loaded with buds, they appear to be dying or dead. The plants are all curled up and the buds even look dead. My neighbor said it appears to be a "fire blight". Plant looks like it has been scorched by heat.....yet they are in partial shade. Shall I pull and destroy them?? If I plant a peony or another plant in that area, is it likely they will get it too???
McLean County North Dakota
A few factors could be involved here.
The most common peony disease is botrytis (gray mold). It can show scorched patches on its leaves and a purplish discoloration at the base of the stems. I encourage you to go to GOOGLE Images to see photos of this disease. In the end, the disease will generate gray, powdery spores on the leaves and flower buds.
Scorching of a plant can also be due to Phytophthora root rot. This is often the case with peonies planted in wet, poorly drained soil. This is not common in our state since our weather is typically dry (although our spring this year has been very wet).
Whenever anyone mentions leaf curl at this time of year I have to mention the possibility of herbicide drift. In many of the cases, the leaves will be severely curled and distorted. Weed killers used to kill dandelions and other types of weeds can do this. This drift would likely affect other nearby plants in the landscape (which you did not mention).
Fire blight is a generic term, but we generally do not use this term for peony diseases ("fire blight" is more often associated with apple, crabapple, and cotoneaster).
I encourage you to look at this publication "Peony Problems" from the Missouri Botanical Garden and see if any of the photos matches what you see:
Recommendations for management are available here:
We generally recommend cleaning up the garden at the end of the year; fungicide sprays at the first sign of infection; and making sure the garden is well-drained.
For now, I would trim out any dead tissue. Get that tissue out of the garden. Depending on what you have left, start to use fungicide sprays to protect the rest of the foliage. Make sure the site is well drained -- this may require you to move the plants in September, if not earlier. Avoid overhead watering since this causes diseases to spread.
If the plants are a total loss, you should pull and destroy them. I would not plant any new peonies in that area for a few years.
Peonies prefer full sun.
If you have any more information or photos to share, please contact me at my e-mail address below.