2 of my 3 peony bushes appear to have a chalky coating on their leaves. We are in Philadelphia, and its been present for about 2 weeks, since late June. Do I need to do anything?

Answer #2 · Stephen Whatley's Answer · Hi Karen.

It's sounds like what you have is a fungal condition known as powdery mildew.

I'm not fully aware of the weather conditions you are expirencing in your zone but it has a lot to to do with determining if this is the problem. Typically,humid conditions, along with shade,which I assume your peony's are planted in, can be a prime breeding ground for powdery mildew.

This fungus will not necessarily kill the plant,but weaken them,making them more suseptable to insects and diseases. If you find that this may be what's going on,I would like to recommend a solution for eradication.

Any type of horticultural oil, Neem oil in particular, is a good,well rounded product that should be available from from your indepandent garden center,that will not only take care of fungus,but also take care of insects and mites at the same time.

If at all possible you can upload a picture,I can try to give a more definitive answer as to what might be going on.

I hope this information gets you started and please feel free to ask any more questions regarding this,or any other matter you may have about yor landscape.

Stephen Whatley.)

Answer #1 · John Heider's Answer · Karen-It sounds as though you have powdery mildew, a common fungal leaf disease of peonies. It can weaken and disfigure peonies but usually not enough to kill them or even have much of a detrimental effect on their spring blooms, as you may have found.

This mildew is a dusty white or gray coating. It usually starts out as small, typically circular spots and eventually mats the entire surface of leaves and other plant parts.

You can prune off any heavily infected foliage, pick up any fallen leaves and dispose of these so as not to infect other plants.
Plants can be sprayed with any good fungicide, but it is best to use an organic product whenever possible such as those containing Neem oil. Neem oil also prevents, controls and kills many harmful insects. Go by the instructions on the product which will probably have you applying a second application in 7 to 14 days which should take care of the mildew.

Hope this helps.
John)