All those fallen walnuts can be quite an annoyance. Photo: thehorse.com
Question: What product could I use to treat my black walnut to prevent it from producing nuts? The nuts really upset my neighbor. It’s a magnificent tree, 60 feet (18 m) tall, but nuts are unwanted.
Jean Lafontaine
Answer: This is not something most gardeners would consider doing, but it turns out it is quite possible.
There are plant hormone products that can prevent trees from producing fruit (and nuts are fruit). These products, like Florel Growth Regulator (active ingredient: ethephon) and Fruitone N or App-L-Set (naphthalene acetic acid or NAA), essentially overdose flowers with hormones and can therefore cause the fruit to abort. They’re mostly used in orchards to control fruit production, but can be used in the home garden.
None of these products is specifically recommended for walnut trees, but they are known to work on a wide variety of trees, from apples to willows and horse chestnuts and so you’ll probably need to experiment a bit. Usually, they need to be applied around the middle or the end of the flowering period or sometimes just as the fruits start to form. An application at the wrong time may have no effect or may even stimulate increased fruit production. So, for the first year, you may have to limit your treatment to individual branches to find out at what point the product is the most effective on walnut trees.
Also, be aware that these products can disrupt the growth of the tree, causing, for example, changes in its branching. Again, you have to try them out to see.
You’ll have to cover yourself with protective clothing from head to toe and keep other people and pets away from the area during treatment. It may be necessary to cover other fruit trees in the area with a tarp while spraying. And it will take a powerful sprayer to reach all the branches of a 60-foot (18-m) walnut tree!
Unless there are a lot of orchards in your area, in which case you might find one of these products in a local agricultural store, you’ll probably have to order these plant hormones online.
But…
That’s a lot of effort to keep a neighbor happy. Have you ever considered offering to go pick up the nuts that fall on their property instead? With a nut gatherer, it’s easy to quickly harvest nuts from the ground.
Or, if no compromise seems possible, it might be wiser to cut the tree down. Then you could plant another tree … well away from the property line. When a tree is in the wrong place, removal is often the only logical solution.
I found an article a couple years ago that suggested using Epsom salt. It worked very well for out black walnut trees, but I haven’t been able to find the information since. I used a round metal stake to drive holes 10-15″ deep and filled them with Epsom salt. I think I spaced them about 4-5 feet apart under the canopy. The trees I treated produced no nuts! Need to do this before the trees bud.
Thanks! I’ll look for the article.
I too would like to stop my walnuts from falling. However spraying and 80′ high tree is not an option. Any suggestions? I was thinking or something that could be applied to the ground around the tree and let the tree absorb it.
I know of no such product, but possibly a nut nursery would be aware of one.
In our wooded area my old and very tall black walnut tree is nearly on the property line from which my neighbor has built a deck just a few feet away. In this mast year the number and size of nuts falling on her deck was remarkable, making loud noises, staining the deck and preventing her from having parties on that side of it (it is a large deck). To make a point her husband wears a hard hat when in the area. They want to cut the branches hanging over their deck, reducing the canopy by nearly half on that side of the tree. It will distort the tree and cutting too much will weaken it so that it may die. There is probably $1,000 of wood in the tree. I am against cutting for something that happens so infrequently. If she didn’t care about visuals, possibly a gazebo-like structure or net could be strung to divert the falling nuts from the deck to the ground. I do have two black walnut trees, the loss of either will be significant to me.
That would indeed be a lot of pruning. I hope you can come to some sort of agreement!
Like you mention, timing is critical. I never liked this stuff, but we used it in olive trees in landscape situations. (If I had an olive tree in my garden, I would want all the olives I could get.) On the farm, we used in on the rhododendrons, because it is faster than pinching. It does not work well for rhododendrons though, and must be a rich (and caustic) concentrate.
The nuts are hard to extract but delicious. We used to crush the outside pulp by driving on them, then crack the hard shells and make highly aromatic baked good with the flesh. It seems a shame to kill a tree, when collecting the mess for your neighbor and sharing the bounty might be a blessing in disguise.
That is nuts!
You can eat or sale them.