Composting black walnut leaves - Ask Extension
Is it "safe" to compost black walnut leaves when the compost will be used for vegetable and blueberry gardens?
Knowledgebase
Composting black walnut leaves #854701
Asked November 04, 2023, 4:35 PM EDT
Is it "safe" to compost black walnut leaves when the compost will be used for vegetable and blueberry gardens?
Washington County Maryland
Expert Response
Microbes composting the debris will probably inactivate the juglone (the toxin in black walnut foliage, nuts, and roots) to the point where you won't need to worry about it. Even so, this is a horticulture topic with little conclusive evidence regarding the real-world risk of juglone to plant health (compared to lab experiments). You can learn more about one main counter-argument to juglone toxicity in the Washington State University publication: “Do Black Walnut Trees Have Allelopathic Effects on Other Plants?"
You could test finished compost with "sentinel" plants as an experiment next year. Tomatoes are thought to be very sensitive to juglone, which seems to cause wilting and stunting. You could plant a few sentinel tomato plants in an area where you apply the compost and observe their growth. A lack of symptoms would indicate that juglone is not going to be an issue.
Miri
You could test finished compost with "sentinel" plants as an experiment next year. Tomatoes are thought to be very sensitive to juglone, which seems to cause wilting and stunting. You could plant a few sentinel tomato plants in an area where you apply the compost and observe their growth. A lack of symptoms would indicate that juglone is not going to be an issue.
Miri
Thank you!
On 11/06/2023 11:57 AM EST Ask Extension <<personal data hidden>> wrote:
You're welcome!
