I’ve been meaning to type up this topic for a while now because I wanted to impart my 10 years of experience attempting to grow fruiting trees surrounded by black walnut (Juglans nigra) trees on all sides and the actual anecdotal outcomes involving which trees decline and perish and which don’t.
My previous orchard was surrounded by a stand of black walnuts that ranged from 20 to over 80 years old and I have, at one time or another, read every piece of online literature about which genus will grow if exposed to juglone from the walnut trees, and which will not. If you’ve invested time in this topic you know that the lists from various sources online don’t exactly match up. Some say one tree is OK and some say it is NOT OK. I don’t think there’s a lot of research where folks planted dozens of different types of fruit and waited 5-10 years to see if they eventually died or not. Well I sorta did that and now I have my own anecdote to present.
In zone 5b central New York there is only one fruit tree that I was able to grow without issue within 100 feet of an 80 year old black walnut tree, and that’s a paw paw. The paw paw still sits about 30 feet away, happy as can be.
Here’s the list of trees that suffered death by decline. I’m using the phrase “death by decline” as a stand-in for juglone poisoning because I have no scientific proof that that’s what killed them. But juglone poisoning in apples and pears which is proven to happen looks like a slow yellowing, defoliation, die-back, and ultimately non-survival overwinter:
Pear (European and Asian)
Cherry (avium and cerasus)
In my experience the apples and pears die much faster than the Prunus species (twice to three times as fast) but ultimately Prunus species all succumb. Different lists online will list various Prunus as being able to live with black walnut. I personally was never able to get a single one to survive. The longest surviving one was a dwarf cherry tree that eventually died off after 5 years.
A mystery in this is that at my new orchard has mature wild pin cherry trees next to 10 year old black walnuts. So perhaps there is some validity to some Prunus being able to survive.
Pawpaw is well known to be tolerant of juglone. I walked through Gerald Gardner’s walnut trees back in 2003. He had several dozen pawpaws planted under the drip line of the walnuts. He stated that the pawpaws thrived in that setting and produced an abundance of fruit.
If you think apples don’t like juglone, try to grow tomatoes near a walnut. They look like late blight got to them a few weeks after planting.
You’re right, our black raspberries thrived (red and gold all died).
Yes, that’s right, our serviceberry died as well. Our honeyberries didn’t die but refused to grow, so we transplanted them to a different area. Gooseberries refused to grow and eventually perished from not being able to put on enough growth to defeat the gooseberry sawfly.
My dad was obsessed with black walnut, chestnuts, butternut and other nuts so i have been dealing with that on my fruits. So far mulberry and Elderberry are doing well… with extremely stressed black walnuts that i have cut down that wont die.
I have a wet bog area that is spring fed where nothing grows literally. Black walnut grows there with ease… but i have started putting in Elderberries as they too like the same conditions. Also going to put in some swamp milkweed not sure if they are ok with juglone.
Stephan says that plums and pears are not effected as much… so i may put in some beach plums in those areas.
I have some mature Black Walnuts just outside one corner of my orchard. I laid it out with Apples the furthest from them because the literature says they’re very susceptible. I put Plum and Cherry closer, again because the literature says they’re more tolerant. So far two Cherry and two Plum trees have died, all between 20’ and perhaps 45’ from the Walnuts. Another Cherry which is a bit further up the hill and more like 50’ from those Walnuts is doing great.
I also planted two seedling “ornamental” Cherry trees my neighbor gave us, one close to a Walnut and one further away. The far one is thriving, the close one is barely hanging on.
Wild PawPaw are growing from right up against the base out to the drip line and all are doing just fine.
So yeah, “the literature” might claim that most Prunus are OK with Juglone, my experience at a smaller scale seems to mirror yours. Not so much…
I’m hopeful Mulberry will be OK, I plan to try those in that area next.
I had a feeling that others would have had identical experiences with Prunus. I think that’s the biggest false belief I had during my time at the old site based on “doing my own research” online – the idea that I could defeat the black walnut by choosing cherries, plums, and peaches instead of apples and pears. Several lists from educational cooperative extensions list the genus Prunus as good to go. I just think it’s a lack of actual scientific research that’s needed to strike that from the record.
I try to grow tomato plants near black walnut trees, and what you describe as looking like late blight occurring several weeks after planting is what I experience with some of the tomato plants. Some tomato plants in the area are growing ok, well others are struggling to survive.
I have four or so black walnut trees 25-50 feet behind my fence. They aren’t huge, they’re probably 20ish year old and don’t get great light because it’s just woods/ brush, not that productive not much nut litter. Should I still expect extreme difficulty?
In all honesty those trees would seriously bother me. To tell you how paranoid I got from working in an orchard surrounded by black walnuts; when I moved to the current orchard we have now I cut down every single black walnut on the property except one mature tree buried deep in the forested portion of our land. At the old orchard I was dealing with specimens over 50-70 years old. They were mammoth trees whose roots spread in every direction probably further than I ever realized.
If you do have control of those trees, and you really want to grow fruit and don’t care what happens to the black walnuts; my recommendation would be to take them down.
Over 50 feet is probably safe enough to not experience extreme difficulty if they’re simultaneously competing with every other plant in the brush/forest. If you’re going to let them stay there my recommendation would be to plant a test tree. Make the tree physically closest to them in your orchard plan to be an apple or pear that you’re willing to sacrifice. You’ll absolutely know if the BW trees have the reach to get to your fruit because it does happen directionally and very quickly (for apples and pears). Our black walnut trees dealt the most damage to the trees closest to their trunks (like canaries in a coal mine) they’d drop first followed by the ones next to them and so on.
Happy to answer any other questions you have about BW trees if I can.
Thanks for the response Kevin, only one is on my land but its not such a bad situation because there’s other areas I can put my fruit trees, where they’ll be 100+ feet from any walnut, or 200’ +. I’ll do some gardening that tolerates the walnut better on that side.
I know that particular cat litter, we’ve used it and composted it in our pet waste composting system. The one we used (we don’t use it anymore) was made with English walnuts. My first guess was that anything made for pets would probably be “heat treated” for all around sterilization but I couldn’t find any proof of that online, and I couldn’t find any scientific papers of what would happen to juglone if you heated it up (would it degrade? I don’t know).
The conclusion I think researchers are coming to is that in a well aerated soil environment juglone doesn’t last as long as was once believed. It does degrade over time and drop out of the soil system without something (the living tree) to replenish it.
If you wanted to know for sure you could attempt to mulch one tomato plant with it (un-used by pets) as a test. If that tomato plant survives the entire season you’ve got nothing to worry about. In my experience tomato plants wilt from the top down at the mere sight of juglone. Good luck.