Black Walnut Toxicity

Asked May 4, 2020, 12:01 PM EDT

Once a tree is cut down, how long does the toxicity for other plants last? Our tree was was about 14 inches in diameter at ground level and just cut down before leafing out. Thank you.

Jo Daviess County Illinois

1 Response

Dear Questioner,
A study has shown that juglone toxicity (the substance walnut trees secrete) lasts for at least two months in the soil after the tree is removed but it has also been shown that decaying walnut tree roots can release juglone into the soil for several years. There are a large number of trees, shrubs, vines and plants that are resistive to juglone toxicity though that you can plant in the area where a black walnut tree was. Just Google "plants resistive to juglone" and you will get a long list