(Question)
Peony plant, mostly sunny spot, well drained soil, began to have curled deformed leaves as it transitioned from red shoots to stalks and leaves. No buds, and patches of the plant are looking quite deformed and affected stalks now turning brown and rotting through and falling off. The leaves otherwise are quite green and spot free, just deformed. I have not seen any bugs or worms. Please see picture of one of the stalks. I would like to treat / save the plant if possible, but don’t know how – i prefer natural treatment if possible and one that win’t kill off all bugs, bees etc. thank you so much!
(Answer)
Hello,
Thanks for reaching out to Toronto Master Gardeners about your peony. From the photo and information you provided, it looks like your peony may be infected with a fungal disease, perhaps “Botrytis blight” (a common fungus of peonies) or “Phytophthora blight.”
Fungal infections are common after cool, rainy springs or when plants sit in wet soil. I’m glad your peony is planted in well draining soil. Since good air circulation can help prevent fungal infections, aim to space your plants at least 3 feet apart and consider thinning out any crowded parts. When watering, direct the water towards the base of the plant and avoid splashing leaves and flowers as much as you can.
To remove the fungus, cut the rotted parts of your peony back to the ground. Fungus can spread on garden tools so sterilize your tools each time you use them. Throw the rotted plant parts in your garbage, rather than your compost pile, to avoid spreading the fungus. You could even put the plant material in a plastic bag and leave it in sun for a few days to solarize it before putting it in the garbage.
If cutting your peony back doesn’t take care of the fungus, you can spray the foliage, the base of the plant and even the soil surrounding the plant with a fungicide. You will likely need to repeat the spray every 7-10 days. Follow the directions for treatment listed on the package.
To read more about diseases affecting peonies here is a link to the Missouri Botanical Garden
and a link to Iowa State University. Finally, here is a link to Cornell University
about Botrytis blight in peonies.
Please be aware that American resources frequently recommend pesticides not available to us in Ontario for environmental reasons under the Ontario Pesticide Law.
Good luck with your peony!
May 29, 2024