Smoke tree and Black Walnut toxicity
I would like to plant a smoke tree (cotinus coggygria) in my yard, it would be approximately 30 feet past the drip line of my neighbor's large black walnut tree. I consulted various lists to try to determine sensitivity of this species to juglone, it's not listed as being a species tolerant to juglone, nor is it listed anywhere as being sensitive to it either. Sumac is also a member of this same plant family and I noted that this is not sensitive. Does anyone know if this species is ok to plant near black walnut trees?
Unfortunately, there is not a lot of research behind what plants are and aren't sensitive to juglone. Most of the information out there is anecdotal. Some plants appear on both "tolerant" and "susceptible" lists, which possibly means that other factors (soil, weather) also play a role. So all I can suggest is to try. If it fails, you will be out the cost of the plant and the time and trouble wasted planting and caring for it.
Here is an excellent discussion from Penn State: