We have been seeing powdery mildew on the leaves of Peony plants in some areas. Weather conditions vary greatly in areas across the country and that will change the severity of infection on some of the Peony varieties.
Some selections just do not have any problem with mildew and others have been greatly affected this year.
This time of the year it is very evident if your Peony plants have powdery mildew as it looks as if the plant was dusted with powdered sugar.
As your plants go dormant on those infected plants, cut off all infected leaves and stems all the way down to the soil line and remove all of the infected debris from the yard. By removing all of the infected plant parts, you can prevent overwintering the pathogen and your plants have a better chance of remaining clean next year.
Any of your other perennials that have leaf spots or mildew it is a great idea to do the same – remove all infected plant parts and take them to your local lawn debris recycling area to get them away from your property. It does make a difference.
Other perennials that remain clean it is a good idea to leave the stems and seeds heads on the plants over the winter to catch and sculpt the snow, and give the birds some seeds to eat.