Botyris infection of peonies - Ask Extension
All my peonies (~5 plants) that are over 30 years old at least, and that have bloomed and thrived each year with only some compost amendments, have al...
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Botyris infection of peonies #884006
Asked September 04, 2024, 9:54 AM EDT
All my peonies (~5 plants) that are over 30 years old at least, and that have bloomed and thrived each year with only some compost amendments, have all developed what I think is Botyris on their leaves. What can I do to save these plants?
Many thanks for all your help in the past, too!
Cynthia
Washington County Vermont
Expert Response
Hello Cynthia, and thank you for contacting us here at the UVM Extension Master Gardener Program with your question.
I am sorry to hear that you are having problems with your peonies. I too have some long-established peony beds, and these past few wet summers are resulting in new challenges.
Thank you for including the photo. Your images seem to match up with materials we can locate online (see below for links) and my colleague, Virginia, gathered this information about confirming and treating the specific blight:
For Botrytis, fuzzy, gray fungal spores are visible after the plants are moistened. Have you been able to see that grayish fuzz during any of these humid or wet days? There are two possible botrytis infections for peonies, with slightly different control recommendations:
1. Botrytis cinerea, which causes disease on many plants
2. Botrytis paeoniae, which infects only peonies
To help you diagnose the blight in your gardens, here are descriptions and photos:
Diseases of Peony from University of Minnesota Extension
Botrytis Blight of Peonies from Cornell University
Peony Problems from University of Illinois Extension
You can also cut away diseased plant parts during dry days - so few this summer! - now and throughout a growing season. Remember to sanitize pruning tools with a 10% bleach solution or 70% rubbing alcohol before using the tools again on healthy plants.
There are fungicides that can help protect your plants from Botrytis blight (see more details in the links above about making sure they contain "Mancozeb" or some type of copper), usually best applied early in the growing season. They will be labeled for this use, and will contain specific directions about where and when to apply, if you choose to use them.
The good news is that your plants look to still be strong, so taking care to clear the bed this fall and discard - not compost - the stems, leaves, and any fallen leafy material you clear from the peony bed will set you up for next season.
Thanks again for your question - we are always happy to help our fellow Vermont gardeners!
I am sorry to hear that you are having problems with your peonies. I too have some long-established peony beds, and these past few wet summers are resulting in new challenges.
Thank you for including the photo. Your images seem to match up with materials we can locate online (see below for links) and my colleague, Virginia, gathered this information about confirming and treating the specific blight:
For Botrytis, fuzzy, gray fungal spores are visible after the plants are moistened. Have you been able to see that grayish fuzz during any of these humid or wet days? There are two possible botrytis infections for peonies, with slightly different control recommendations:
1. Botrytis cinerea, which causes disease on many plants
2. Botrytis paeoniae, which infects only peonies
To help you diagnose the blight in your gardens, here are descriptions and photos:
Diseases of Peony from University of Minnesota Extension
Botrytis Blight of Peonies from Cornell University
Peony Problems from University of Illinois Extension
You can also cut away diseased plant parts during dry days - so few this summer! - now and throughout a growing season. Remember to sanitize pruning tools with a 10% bleach solution or 70% rubbing alcohol before using the tools again on healthy plants.
There are fungicides that can help protect your plants from Botrytis blight (see more details in the links above about making sure they contain "Mancozeb" or some type of copper), usually best applied early in the growing season. They will be labeled for this use, and will contain specific directions about where and when to apply, if you choose to use them.
The good news is that your plants look to still be strong, so taking care to clear the bed this fall and discard - not compost - the stems, leaves, and any fallen leafy material you clear from the peony bed will set you up for next season.
Thanks again for your question - we are always happy to help our fellow Vermont gardeners!
Thank you so much for this comprehensive and very helpful reply. I am so grateful for this Master Gardener resource--it is the best!!
Cynthia
Your welcome, Cynthia! Glad it was helpful.
