Mildew or Fungus on Canadian anemone
Can someone help me identify and treat the disease that is affecting my Canadian anemone? It is a pretty dense stand if anemone that has been there for years. When it comes up in the spring, it looks fine, but gradually develops this gray splotching on the leaves. Eventually the leaves curl up and the plant is not so healthy. I do have a sprinkler system so I'm wondering if the water falling on dense plants has something to do with it. Thanks for your help!
Canada anemone is usually a hardy plant with few problems. If your sprinklers are hitting the plant then yes, direct the sprinklers away from these plants. Keeping leaves dry is the best way to prevent diseases on leaves. There are fungicides that can help control diseases on the leaves.
From the looks of your photos this appears to be some sort of mildew. This could be downy mildew or powdery mildew- they are two different diseases. Managing them will be similar:
Plant debris should be removed from the area around the plant and buried, burned, or placed in a closed container. Plants should be spaced to ensure good air circulation around them so that when irrigated or subject to rainfall, leaf surfaces dry quickly. Overhead irrigation should not be used. If you follow these guidelines you will not have as much an issue next season.
Fungicides for powdery mildew (some may not be available to home gardeners) are
metconazole, myclobutanil, propiconazole, tebuconazole, triadimefon, and triticonazole.
Fungicides for downy mildew available to homeowners are usually copper-based fungicides- read the labels on the garden center products to see if downy mildew is listed. As always, please read and follow all directions and precautions on the products you use.
Here are links with detailed information on Canada anemone.
If you want to positively identify whether you have powdery mildew or downy mildew you can submit samples of the plants to the MSU diagnostic lab. There is a small fee for this service. You can find the sample submission form, instructions, and mailing address on their website. https://pestid.msu.edu
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