What to do about black areas on peonies?
Question:
In September 2021, I transplanted peony plants to a bed on the west side of our new home. They all came up, a couple even had flowers, but as time went on black areas (not spots) were seen on many of the plants. Unfortunately, I did not take a picture. I cut them down in the fall and discarded the plant material. I am now wondering what to do for them for this growing season? Is it late, cold periods or a disease? Do they need to be protected?
Answer:
Abi Griffith, Horticulture Community Education Assistant
Without a photo or a sample, a good place to start could be checking out the Extension’s Plant Disease Images page and scroll down to peonies to see if any of these look familiar. You may want to start with looking into Botrytis, which can cause darkening of leaves and stems and can be a common problem with peonies. Managing any potential fungal problems with peonies includes avoiding overhead watering or damp areas or damp, thick mulch. Also, to do exactly what you already did, which was to remove those plant parts and dispose of them out of your garden (don’t compost). You may have to wait until this next season to get a better idea of what you are dealing with, and get a photo or submit a sample to the UMaine Extension Plant Disease Diagnostic Laboratory, to properly identify the problem and give you management recommendations.
If you haven’t already, it could be a good idea to submit a standard soil test, to the UMaine Extension. This test will assess nutrient levels, pH, and organic matter content and offers gardeners important “next steps” to create the conditions for optimal plant health. A healthy plant is more resilient in the face of disease pressures.