The horticultural books say that the roots of juglans (walnuts)
release a poison that prevents other plants from growing near them.
Nonsense. In 30 years of observing them in my "wild" areas, I haven't
found this to be true.

Does anyone know the origin of this misinformation and why the books
keep repeating it?

Thanks,
Jack

BroJack wrote:

The horticultural books say that the roots of juglans (walnuts)
release a poison that prevents other plants from growing near them.
Nonsense. In 30 years of observing them in my "wild" areas, I haven't
found this to be true.

Does anyone know the origin of this misinformation and why the books
keep repeating it?



Juglone does not prevent all plants from growing near the walnut tree,
but some plants are inhibited. Look up "walnut wilt" on Google for a
list of susceptible plants.

In wild areas, plants that are not susceptible to juglone will
predominate around your walnut trees. However, if you try to introduce
other varieties you may run into trouble.

Dwight Sipler wrote:

Juglone does not prevent all plants from growing near the walnut tree,
but some plants are inhibited. Look up "walnut wilt" on Google for a
list of susceptible plants.

In wild areas, plants that are not susceptible to juglone will
predominate around your walnut trees. However, if you try to introduce
other varieties you may run into trouble.

For example, tomatoes. When their roots touch the roots from the walnut tree
the plants wilt and die rather quickly.
Carl

Xref: kermit balt.general:40032 rec.gardens:232739 alt.appalachian:67975

Dwight Sipler wrote:

BroJack wrote:

The horticultural books say that the roots of juglans (walnuts)
release a poison that prevents other plants from growing near them.
Nonsense. In 30 years of observing them in my "wild" areas, I haven't
found this to be true.

Does anyone know the origin of this misinformation and why the books
keep repeating it?

Juglone does not prevent all plants from growing near the walnut tree,
but some plants are inhibited. Look up "walnut wilt" on Google for a
list of susceptible plants.

In wild areas, plants that are not susceptible to juglone will
predominate around your walnut trees. However, if you try to introduce
other varieties you may run into trouble.

Interesting. One of the larger trees in my parents yard is a black
walnut and a wild cherry tree that somehow have managed to grow
together and look like just one tree from the ground up. The older and
taller it gets, the more the limbs seem to mix. One limb might have
the leaves of the wild cherry, while the limb right beside it might be
loaded with walnuts. Mom tried for years to grow a tomato in a tractor
tire casing beside the tree. While she had marginal luck, most of
those years, the casing was used as a home for various turtles and
torquoises my brother found and just had to keep as pets. The pets
grew better than the tomatoes, and were usually released (or found
their way out of the casing) to the wild when my brother deemed them
old enough. Now that I've gone all the way around the world, I'll
close by saying that now I know why Mom never was able to grow
tomatoes under that black walnut tree.

On Mon, 09 Jun 2003 11:31:33 GMT, (BroJack)
wrote:

The horticultural books say that the roots of juglans (walnuts)
release a poison that prevents other plants from growing near them.
Nonsense. In 30 years of observing them in my "wild" areas, I haven't
found this to be true.

Does anyone know the origin of this misinformation and why the books
keep repeating it?

With a wilderness of forsythia, ivy, violets, daffodils, vinca, grass,
pine trees, and heaven-knows-what growing over, under, around and
through a bunch of black walnut trees and their many offspring in my
back yard, I wondered about that, too. The problem, I believe, is that
the information is often presented as "*nothing* will grow around
black walnuts." Which is obviously false. Juglone 'poisoning' is
well-documented and I've come to believe it. There's not enough sun
under the trees to plant tomatoes anyhow.

(BroJack) wrote:

The horticultural books say that the roots of juglans (walnuts)
release a poison that prevents other plants from growing near them.
Nonsense. In 30 years of observing them in my "wild" areas, I haven't
found this to be true.
Does anyone know the origin of this misinformation and why the books
keep repeating it?

Black walnuts are allelopathic--they produce substances toxic to other
plants. Walnut roots, leaves, and other plant parts contain the
herbicide, juglone. It is toxic to many plants, especially my
rhododendrons. The squirrels keep planting black walnuts and I keep
pulling them out. The walnuts that do exist have killed several of my
rhododendron plants. I can recover the area by trenching around the
rhododendrons and severing any roots that are entering the area. Then
after a couple years it is safe to plant rhododendrons.

"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]

The Ohio State University Extension and the American Horticultural
Society [http://www.efn.org/~bsharvy/bwtol.html] 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.

The information is correct. People have misquoted it.

Another natural herbicide is juniper needles. They contain a natural
preemergence agent. That is the reason the forest floor under junipers
is barren.

--
Pardon my spam deterrent; send email to
Visit my Rhododendron and Azalea web pages at:
http://www.users.fast.net/~shenning/rhody.html
Also visit the Rhododendron and Azalea Bookstore at:
http://members.aol.com/rhodyman/rhodybooks.html
Cheers, Steve Henning in Reading, PA USA http://www.users.fast.net/~shenning

On Mon, 09 Jun 2003 11:31:33 GMT, (BroJack)
wrote:

The horticultural books say that the roots of juglans (walnuts)
release a poison that prevents other plants from growing near them.
Nonsense. In 30 years of observing them in my "wild" areas, I haven't
found this to be true.

Does anyone know the origin of this misinformation and why the books
keep repeating it?

It's not misinformation. Some plants are adapted to cope very well with
growth-suppressing hormones or natural-herbicides such as are exuded
chiefly from the roots of such plants as walnuts, many grasses,
dandylions, monkshoods, cherries, & other plants that give themselves an
"edge" by slowing down the growth rate of the plants they compete with.
Other plants are serioiusly retarded or even killed by juglone & other
natural herbicides & growth suppressants. Black walnut has vastly more
juglone than any other tree likely to be encountered, so the effect is
particularly obvious on plants sensitive to juglone (one would rarely see
nightshades or other potato-family plants thriving under a black walnut).

But I'm sure some of the cause of plant deaths under walnuts is the deep
shade & the tree roots drying out the soil very rapidly or the canopy
keeping rain from reaching the ground & autumn leaves falling so thick
they smother what ever almost got established. Yet it all gets blamed on
juglone even where there are multiple causes.

I have some rhododendrons growing inside the dripline of an enormous old
chokecherry such as also exude juglone, though a tiny fraction of what
black walnut produces. These dwarf rhodies & azaleas are doing fine (one
is doing super-fine & seems to LOVE the jugloned soil) but I can tell the
majority under the chokecherry do have some small negative effect on their
growth rate & degree of flowering. If I didn't have many specimens here &
there for comparison I might not notice the juglone effect on those few.

-paghat the ratgirl

--
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
-from Peter Newell's "Wild Flowers"
See the Garden of Paghat the Ratgirl: http://www.paghat.com/

"Frogleg" wrote in message
...
On Mon, 09 Jun 2003 11:31:33 GMT, (BroJack)
wrote:

The horticultural books say that the roots of juglans (walnuts)
release a poison that prevents other plants from growing near them.
Nonsense. In 30 years of observing them in my "wild" areas, I
haven't
found this to be true.

Does anyone know the origin of this misinformation and why the books
keep repeating it?

With a wilderness of forsythia, ivy, violets, daffodils, vinca, grass,
pine trees, and heaven-knows-what growing over, under, around and
through a bunch of black walnut trees and their many offspring in my
back yard, I wondered about that, too. The problem, I believe, is that
the information is often presented as "*nothing* will grow around
black walnuts." Which is obviously false. Juglone 'poisoning' is
well-documented and I've come to believe it. There's not enough sun
under the trees to plant tomatoes anyhow.

I've noticed that the ground under/around/near Magnolia trees is barren
as
is the situation with electric poles. Hummm....

Helen

New to the site but decided to share my own family's experience with a
black walnut. My father has a black walnut that is at least 30 years
old and it is planted near (just behind it about 5 ft.) his vegetable
garden. As the tree grows the garden decreases in size. He is unable
to grow vegetables on the end of the garden that is closest to the
black walnut.

(Laura) wrote:

New to the site but decided to share my own family's experience with a
black walnut. My father has a black walnut that is at least 30 years
old and it is planted near (just behind it about 5 ft.) his vegetable
garden. As the tree grows the garden decreases in size. He is unable
to grow vegetables on the end of the garden that is closest to the
black walnut.

Welcome Laura. The black walnut/wild cherry tree in my parents' yard
is over 30 years old. When we moved there in 1968, the limbs of both
trees were already too tall for us kids to reach and climb, but the
trunk would have held us if we could have. It's in the front yard on
one side of the driveway near the road, almost bordering a neighbor's
field/pasture. The neighbor has grown corn, millet and hay in the
field successfully, but those are the only farm-type plants other than
Mom's early tomato plants that I've seen anyone even try to grow near
the tree.

But the roots can extend beyond "under the tree."