Peonies with a fungus - Knowledgebase Question

Teaneck, Ne
Avatar for lrlindo
Question by lrlindo
October 1, 2010
We've had our Peonies for over 35 years and this year we notice that they are covered (entire plants) with some kind of white film that looks like maybe Mildew. How can we remove this and get our healthy plants back by next spring. The Peonies usually bloom pretty pink fragrant flowers with a lot of blooms. This year we only got about 2 or 3 flowers. HELP!!!

Answer from NGA
October 1, 2010
What you describe sounds like powdery mildew, a fungal infection. It's quite common this time of year when days are warm and nights are cold. Since it's the end of the growing season for your peonies you can simply wait for the first frost to blacken the leaves and then cut the stems down to ground level and remove them from the garden. It's important to wait for that first frost which will signal the roots of your peonies to go dormant. If you simply cut off the infected foliage now, your peonies will attempt to replace the stems and leaves. This will sap the stored energy in the roots and they won't grow as well for you next year. Overcrowding, lack of sufficient sunlight and over fertilization can all contribute to the development of powdery mildew. If your plants are prone to the disease, even though they are getting lots of direct sunshine and there's good air circulation all around, you might try spraying them with a fungicide next spring to help protect your plants. Neem oil based fungicides such as Rose Defense can help control the early stages of powdery mildew and can also provide some protection for the remainder of the growing season. If you decide to use a fungicide, be sure to apply according to label directions. Best wishes with your peonies.

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