rescue peonies from black walnut tree
I have 30-year-old peonies planted about 20 to 30' from a mature black walnut tree: bloomed gloriously but began to turn papery and foliage turned deep bronze after deadheading. I suspect poisons from tree roots have affected.the entire bed. Peonies planted on other sites are not affected. Here are my questions:
Q. Will roots survive if I cut the plants to the ground and relocate?
Q. Should I disinfect the clippers before trimming any other plants? If so, please suggest a product.
Q. I am concerned about nearby plantings which show no symptoms yet: 15' tall crape myrtle, Japanese red maples, and a considerable investment in underplantings of helioborus and lungwort. Drainage pattern is toward these plantings. Would damming this runoff across my neighbor's gravel drive do any good?
Montgomery County Pennsylvania
The assumption that the peonies might be suffering from juglone from the black walnut is reasonable since some cultivars of peony are very susceptible to juglone but there may be other causes of the decline of your peony shrub. The following link provides additional information on typical diseases associated with peonies. Transplanting the shrubs from one location to another might just move the problem. If blight or nematodes are the problem you may be exposing other plants to the same problem. Observation of the remaining plants and taking a sample of the affected plant to your local extension office would be a better approach. https://pubs.ext.vt.edu/3010/3010-1501/3010-1501.html I'm also including a link which describes black walnut and juglone effects. http://extension.psu.edu/plants/gardening/fact-sheets/trees-shrubs/landscaping-and-gardening-around-walnuts-and-other-juglone-producing-plants If juglone is the problem changes to the soil composition might mitigate the effects or transplanting to a raised bed. Hopefully the sample could be analyzed and determined if juglone is present to help determine an appropriate course of action but I'm uncertain if that is possible. Making a definitive diagnosis with limited information is not possible at this time.