The good news is that powdery mildew on peonies is more of an eyesore than a health problem. However, severe cases of this chalky fungus can weaken the immune system in plants. If this is the case, it's best to remove the foliage now, before the leaves dry and fall to the ground.

How do you get rid of powdery mildew on peonies?

each of baking soda, horticultural oil (or canola), and liquid dish soap (without bleach) with a gallon (4 L.) of water. Spray on your peonies every 10 to 14 days throughout the summer months.

Why does my peony look dusty?

The white, powdery material on the peony foliage is powdery mildew. Powdery mildew is a fungal disease. Powdery mildew occurs on a large number of plants like: peonies, lilacs, viburnums, roses, garden phlox, bee balm, turfgrass and many others. Fortunately, powdery mildew seldom causes serious harm to plants.