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"Burnt" looking plants #305499 - Ask Extension

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"Burnt" looking plants #305499

Asked March 08, 2016, 10:04 AM EST

I had some questions about my garden. If you can help, or point me in the right direction, that would be awesome! In 2014, one of my peonies started getting black spots on the leaves, then in 2015 it started out having the black spots, then the plant started to look almost burnt. It is completely dead looking now with almost crispy burnt looking leaves and stems. I think whatever started on my peony spread to my rhubarb, tomatoes, basil, peppers, and possibly my daylillies by the fall of 2015. My rhubarb stalks looked like they were getting holes in them and would fall over. The rhubarb was sickly looking, but I couldn't tell for sure if it was bugs or something else. My daylillies leaves were just yellow and sickly looking, but never looked "burnt." The basil and tomatoes were burnt looking. Whatever it is seems to have spread all over my landscape and garden. Plants it didn't bother were cilantro, calendula, onions, and possibly zinnia (kids picked them out of the ground before the rest of the garden got bad). I live in Rockford, MI. I grew all the annuals from seed. I generally like to do things naturally, but will use a spray if that is the only option to get rid of whatever is going on. Questions: 1. Do you know what could cause this? I think maybe a fungus or something? 2. Should I do some sort of testing on the plants? 3. What can I do about it? I only used half of my garden this year, so I could garden on the other half, but I don't want whatever is going on to spread. 4. I was going to cover my garden beds with straw, but I don't want to harbor any plant diseases. Is straw OK to use as mulch? 5. Should I throw out all of the plant material in my compost pile? I had put some of the plant material in there before I realized something abnormal was going on in my garden. 6. Is there any hope for my peonies? Any help would be very much appreciated! I'm wanting to start planning my garden again this year, but i need to figure out what is going on first. I wish I would have thought to take pictures of the plants to help ID the problem. Thanks in advance for your help! Stephanie Eckstorm

Kent County Michigan

Expert Response

From what you describe, it sounds like the peonies got a fungal disease called Botrytis.  It much more common with the increased humidity of the last number of summers.  It can be confirmed by a covering of gray mold on diseased tissue.  But that would have to be confirmed by you sending a sample to the MSU Diagnostic Clinic: www.pestid.msu.edu    Otherwise, this is a guess.  It can be controlled by using a fungicide like Mancozeb or Dithane  and spraying just as new red shoots are breaking the ground in the spring and then about two weeks later.  A third application may be needed. But there are no organic products that I am aware of. But sanitation is the key.  Cleaning up all leaf and stem parts in the fall and burning or burying them must be done.  Not heaping mulch up on the stems during the growing season because you want good air circulation is important.  If you mulch peonies over the winter, remove that mulch and destroy it.  Make sure that there is good air circulation around the plants and the plants are not crowded.  But the best solution is sending a sample to the Diagnostic Clinic. The burned appearance is darkened, dried-out tissue that appears to be burned but is just dead.

But the huge list of other plants with problems should not be affected by the peony problem.  These are other problems.  When you say that the rhubarb is so weak and yellow, it falls over, is it in at least eight hours of full sun a day?  Is it being fertilized?  Is it so old that it has lost vigor?

The peonies are one problem.  The rest of the plants cannot be treated the same way. Since there are no photos, I cannot guess.  But tomatoes do not get the same problems or even insects as rhubarb or daylilies.

Gretchen Voyle Replied March 08, 2016, 10:38 AM EST

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