Fungal disease of yard plants?

Asked August 25, 2020, 3:12 PM EDT

My prized, precious peony plants have suffered mold before, but this look to be more threatening. One bush looks like it will fail, as the leaves curl and the color fades. I have 13 bushes in all. The leaves have small holes, surrounded by brown areas. The stems do appear to have some “canker” on them. A nearby Delphenium experienced browning stems and failure to thrive, almost dead, after wonderful blooms. Below are my photos. Also included are iris, which I sprayed once with an anti-fungal and it seems to have temporarily helped. Now it is spreading again. I dispose carefully of the leaves when I clean them up. I think I see it on my lupine as well. I have been trying to save it with anti-fungal spray. It is from my late father’s yard and holds value to me. I practice good sanitary techniques, disposing of leaves properly in the fall, this year I trimmed out stems to provide better air flow. I lost all of my tulips to Botrytis blight, which was severe this spring. Although these aren’t near the the tulips, I am afraid I will have to exterminate all of my beloved peonies. Since this is so widespread across my acre lot, do I clean everything out? I am quite upset about this, as it is my hobby. Your advice is much appreciated, thank you in advance.

Saginaw County Michigan

1 Response

To get a clear ID of what is causing these symptoms, I recommend submitting a sample to the MSU Plant and Pest Diagnostic Lab. By getting a clear ID of what this is, you can decide the best management strategy that will target it and hopefully save your peonies. You can get started on submitting a sample here: https://www.canr.msu.edu/pestid/ They also encourage submitting digital images before submitting the sample.

The symptoms remind me of red spot, botrytis blight or possibly a bacterial blight. When you look at the infected areas of the leaves, do you you see any fuzzy areas or spores? That is a sign of a fungal infection.

If it ends up being a bacterial disease, disposing of the infected plants is recommended. That is why I suggest getting a test done, so you do not dispose of the plants if it is another disease that can be managed without disposing of the plants.