Fineline Buckthorn and Black Walnut

Asked March 6, 2019, 9:37 AM EST

I am thinking of planting some Fineline Buckthorn to my yard but they would be relatively close to a Black Walnut. I cannot find the Fineline Buckthorn on any of the Black Walnut lists. Is there any experience to suggest that the Fineline Buckthorn is either tolerant or not tolerant of the juglone from the Black Walnut?

Ottawa County Michigan

5 Responses

The information seems to be lacking on Fineline buckthorn, Frangula alnus (aka Rhamnus frangula) when it comes to black walnut toxicity. There i some vague information on the common buckthorn (Rhamnus cathartica); however, the species glossy buckthorn, (Frangula alnus) has been reclassified so it isn't applicable. Most likely there has not been any actual research on this shrub. I have requested some information but won't have an answer for a day or two and will get back to you.

I contacted one of the nurseries that produces “Fineline” and they said they had anecdotal evidence saying it is tolerant. Still awaiting answer from another nursery. Will let you know.

Excellent. Thanks for your help on this. Hope others can confirm the tolerance.

Here is the response from another grower of this cultivar:
"Determining whether or not a plant tolerates black walnut is always a bit of a game. There is little actual research to determine which plants can actually tolerate, and the lists that you do find out there generally are based on little more than observations in gardens, arboreta, and college campuses. I searched through all of the reliable resources I have access to and unfortunately cannot find any confirmation that Fine Line or any species of Rhamnus is or is not resistant to juglone, the chemical produced by black walnuts. If you want to try planting it, you certainly can - it is pretty widely agreed that tolerance to black walnut is tied to cultural conditions (how much water the plants get, especially - a well-irrigated site gives plants a better chance than a dry one) and to what part of the walnut the plant is exposed to (fallen leaves and fruits are the most difficult; simply being in the presence of roots isn't always problematic for all plants). If you plant it and it starts doing poorly, you'll typically have time to move it to a better location - it won't just suddenly die."

Very helpful. Thanks. If I end up getting results myself I'll let you know.