There is something wrong with two of my peonies. The leaves are shriveled and curling but there are no visible insects on it. On one of the peonies the edges of the leaves are black. What can I do? They came from my mother’s garden so I really want to save them!
Thank you for contacting Toronto Master Gardeners. Unfortunately, I believe your peonies suffer from a fungal disease called Peony wilt (Botrytis paeoniae) which occurs in the spring and early summer. Cool wet weather encourages the growth and spread of this fungus. And insects-especially ants- carry it from one stem to another, and one plant to another.
If you recently transplanted the peonies from your mother’s garden, the fungal spores may have arrived with the plants. If you have had them for a few years, likely the spores arrived from insects/mulch from outside your yard. The spores winter over in the soil and on debris around the plant. Now that you have the fungus, adding mulch, manure or compost is not appropriate as these soil enrichers facilitate this fungal growth in the ground.
Depending upon the variety of peony and it’s previous health, it may survive this fungal infection. I suggest you cut off all the diseased stems and leaves. Discard them in the regular garbage (not composting). This may leave you with only the root. Carefully rake the area where the peonies grow removing all debris and discarding it in the garbage. You might remove and dispose of the top 5 cm of the soil as well replacing with bagged garden soil processed to remove pathogens.
Since these are important plants to you, you might consider removing them from the soil entirely after you have cut off all the diseased material. Then wash the root and any healthy stems in water to remove all the soil; dry it well (lightly shaking, paper towels and sunlight) and replant the peony root in new commercial potting soil in a pot of significant size to allow some growth. Place the pot in a sunny spot. If/ when you see new shoots you may wish to spray the plant with a commercial non-chemical fungicide approved for sale in Ontario. Water the soil avoiding wetting any leaves and stems as the plant regrows. Replant in the early fall in another area.
Check any other peony in your garden for similar symptoms no matter where it is located.
The links below contain more information than you may need but do make interesting reading. I too share the joy of having ‘family’ plants in my garden.
https://www.torontomastergardeners.ca/askagardener/peony/
https://americanpeonysociety.org/learn/diseases-and-pests
https://www.rhs.org.uk/disease/peony-wilt
https://www.extension.iastate.edu/news/yard-and-garden-caring-peonies
14/05/23