Xref: kermit rec.gardens:274949
I have a partly wooded backyard with many Black Walnut trees. Many
plants,trees and shrubs won't survive when grown close to them Does any
kind person have experience in growing anything near them?One of the
things I want to plant are hemlock trees nearby. Can anyone give me some
advice on that and/or other trees/shrubs? Thanks. S.
The roots of Black Walnut (Juglans nigra L.) and Butternut (Juglans
cinerea L.) produce a substance known as juglone
(5-hydroxy-alphanapthaquinone). Persian (English or Carpathian) walnut
trees are sometimes grafted onto black walnut rootstocks. Many plants
such as tomato, potato, blackberry, blueberry, azalea, mountain laurel,
rhododendron, red pine and apple may be injured or killed within one to
two months of growth within the root zone of these trees. The toxic zone
from a mature tree occurs on average in a 50 to 60 foot radius from the
trunk, but can be up to 80 feet. The area affected extends outward each
year as a tree enlarges. Young trees two to eight feet high can have a
root diameter twice the height of the top of the tree, with susceptible
plants dead within the root zone and dying at the margins. The juglone
toxin occurs in the leaves, bark and wood of walnut, but these contain
lower concentrations than in the roots. Juglone is poorly soluble in
water and does not move very far in the soil. [from Ohio State
University Extension Fact Sheet HYG-1148-93 by Richard C. Funt and Jane
Martin]
At
http://www.efn.org/~bsharvy/bwtol.html the Ohio State University
Extension and the American Horticultural Society have reported that R.
nudiflorum, Pinxterbloom Azalea, and Exbury Azaleas Gibraltar and Balzac
will grow near Black Walnut and Butternut trees. They also list many
other plants that will grow in the root zone of these trees.
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