Duration of juglone (walnut root residue) in soil?

Marlin L Burkholder gleneco1 at juno.com
Sat Dec 22 02:00:57 EST 2001

Last spring I erected a small hoophouse with one end approximately 40
feet from a walnut tree.  It was one of those little oversights one
occasionally makes when the walnut tree is on the other side of a fence
and among several locust trees and not that noticeable.  I knew it was
there but I just didn't think about it when I was siteing the hoophouse. 
I grew tomatoes in the hoophouse during the summer and encountered no

I'm now thinking of possibly doubling the length of the present hoophouse
and or constructing another one beside it which would be at least double
the size of the first one.  This project will only be persued after I
have worked the kinks out of managing the present one and determined if I
have a market for winter produced salad greens and season extended hot
weather crops which would make it profitable.  This step is probably
several years away.

Here is the problem.  Due to the way the land slopes in the vicinity, and
the fact that I need the space adjacent to the one end and side for
accessability to other activities, the direction I would have to go in
extending the present hoophouse would  put it even closer to the walnut
tree (20 feet) and if I were to construct the 2nd hoophouse, part of that
structure would also fall within the 80 foot danger zone which I have
read should be avoided for planting tomatoes and other juglone sensitive
crops in the vicinity of walnut trees.

The tree in question is not a particularly valuable timber tree, so the
logical solution is to remove the tree.  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

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