More About Juglone Black Walnut Toxicity
In No Guff Vegetable Gardening we tell readers that black walnut toxicity can cause a headache in the vegetable garden. Here is more information about dealing with black walnut toxicity.
The stately black walnut tree gives off a substance called juglone.In areas where Carolinian tree species grow, the black sheep of the forest (and the vegetable garden) is the black walnut tree. Too bad, because it’s a stately tree! While its walnut-family cousins—which include butternut, English walnut, pecan, and hickory—also give off juglone, it’s the black walnut that is the worst offender.
If you have a black walnut tree, be on the lookout for symptoms including stunting, yellowing, wilting, and even death. Even if you don’t have a black walnut tree—if your neighbour has a tree—keep in mind that sensitive vegetable plants might be affected anywhere in the root zone of the tree (as the roots give off juglone). With a mature black walnut tree, this root zone can extend 50 feet.
Here are some coping tactics for the juglone-affected vegetable gardener:
- Raised beds give some relief from symptoms (though if walnut roots grow into the raised beds, they’ll bring juglone with them)
- Keep fallen black walnut leaves and nuts away from growing areas
- Do not add leaves or nuts to the compost pile if you’re using the compost on the garden
Do not add black walnut leaves, nuts, or hulls to the compost pile if you're planning to use the compost on the vegetable garden.
Some sensitive plants include:
- cabbage, eggplant, pepper, potato, and tomato
Some tolerant plants include:
- beans, beets, carrots, corn, onions, parsnips, squash
Donna says: Well Steve, if you lived in Calgary you wouldn’t have to worry about black walnut trees! It’s too cold for them here.
MORE: SEE WHAT WE SAY in No Guff Vegetable Gardening about black walnut toxicity and juglone.
Garden Coaches Chat: No Guff. Lots of fun.
Donna Balzer and Steven Biggs
Garden Coaches