Duration of juglone (walnut root residue) in soil?

Bill Shoemaker wshoemak at inil.com
Fri Dec 28 08:56:09 EST 2001

>My question is, even if I
>immediately cut the tree,  will I still be haunted with lingering juglone
>in the soil where I have located the present hoophouse and would like to
>build the others provided the opportunities for hoophouse production
>continues to look attractive.  If there is potential for a lingering
>juglone residue problem in the soil after removal of a walnut tree, how
>many years could I expect it to take for the residue to dissapate enough
>for me to safely grow my tomatoes?
>Marlin Burkholder, Virginia


    I've run into this problem in northern Illinois recently so I've
explored it a little bit. There is no way anyone can give you a concise
response. There are too many variables, such as juglone concentration in the
tree tissue, actual distribution of the root system, conditions for
breakdown of the tree tissue after removal, actual accumulation of juglone
in the soil, etc.. However, a general rule of thumb is 3-5 years, with
declining influence over those years. It is doubtful you can do anything to
remediate the situation, other than remove the tree.

Bill Shoemaker
Sr Research Specialist, Food Crops
Univ of Illinois - St Charles Hort Research Center

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