TOXICITY AMONG TREES AND PLANTS
Although quack grass will grow luxuriantly up to the trunks of both
black walnut and butternut trees, I know, from things I have seen
myself, that the roots of the latter and probably of the former have a
deadly effect on members of the evergreen family. I have seen northern
white pine and other pines, too, suddenly lose their needles and die
when, as large trees, they have been transplanted to the vicinity of
butternut trees. To save as many of these transplanted trees as
possible, it was necessary for me to sacrifice almost one hundred fine
butternut trees by cutting them off close to the ground and pruning all
the sprouts that started.
Other instances have also demonstrated to me this deleterious power of
butternut trees over evergreens. For years, I watched a struggle between
a small butternut tree and a large Mugho pine. Gradually the Mugho pine
was succumbing. At last, when the pine had lost over half its branches
on the side near the butternut, I decided to take an active part in the
fight. I cut off the trunk of the butternut and pruned off all of its
sprouts. The butternut surrendered and died. The Mugho pine took new
heart, lived and again flourished.
At another time, I transplanted several thousand Montana pines, about
thirty or forty of which came within the branch limits of a medium size
butternut tree. Within a year, these thirty or more trees had turned
brown and were completely dead, while those immediately outside the
branch area were dwarfed and not at all thrifty. The trees farther from
the butternut were unaffected and grew consistently well. A similar
condition, although not to the same degree, developed under a white oak
where more Mugho pines were growing. Another instance occurred when a
planting of several thousand Colorado blue spruce were lined out and
fell within the area affected by two butternut trees. The spruce were
all dead within a few months.
Many people have observed the detrimental effect of trees of the walnut
family on alfalfa, tomatoes and potatoes, resulting in wilting and
dying. It is the root systems of the walnut which are responsible for
this damage. Apparently, there is some chemical elaborated near the
surface of the roots, and sensitive plants, whose roots come in contact
with either roots or ground containing this factor, are injured and
sometimes killed by it. One must therefore be very cautious about
trusting these trees as protectors of many of the ornamental and garden
plants. I am certain, from my own observations, that their influence on
evergreens is strongly antagonistic.
On another basis is the association between catalpas and chestnut trees
growing adjacent to one another. Constructive symbiosis apparently
develops when a young chestnut tree is planted within the radius of the
root system of a catalpa. The latter very definitely influences the
chestnut tree to grow more vigorously than it otherwise would.
I have recorded my observations of these antagonisms and friendships
between trees and plants to show that they are a reality which should be
taken into consideration in grouping and transplanting. Such warnings
are infrequent because some people may mistake them as condemnations of
certain favorite trees. I do not intend them as such, for these plants
are often valuable and worthwhile. This ability which they have
developed through the many years of their existence is a guarantee of
the sturdiness and strength of their family and species, not at all a
quality to be condemned.
CONCLUSION
If I had written this book twenty years ago, I would have prophesied a
future for nut culture in the north, full of wonder, hope and profit. If
I had written it ten years ago, I should have filled it with
discouragement and disillusion. Now, after growing such trees for more
than 30 years, I realize that the truth lies somewhere between these
extremes, but nearer the first.
It is seldom practical to move native trees very far from their natural
range, nor is it necessary to do so in this part of the north: We have
four fine, native nut trees: the hazel, the butternut, the black walnut
and the hickory. In my experience, these four have completely
demonstrated their practical worth.
If commercialization is the primary hope of the nut tree planter, he
should first consider the large, hardy hybrids, known as hazilberts,
which I have produced between a large Wisconsin wild hazel and European
filberts. Hazilberts equal the best European filberts in every way,
without the latter's disadvantage of susceptibility to hazel blight and
its lack of hardiness. They are as hardy as the common wild hazel and
are more adaptable to environment and soil conditions than any other
native nut tree. They may be trained into trees or allowed to grow as
large bushes. Like all other filberts and hazels, they, too, need
companion plants for cross pollinization to obtain full crops of nuts.
The butternut is also a very adaptable tree. No one who is acquainted
with it, questions the quality of the butternut kernel. In a good
variety, the nuts should crack out in halves and the kernels drop out
readily.
So many good varieties of black walnuts are being propagated, I need not
say much about them, except that many of the best ones are not practical
for this climate. Nurserymen who grow them can give the best advice
about varieties to anyone selecting black walnuts for orchard planting.
Hickories are the last of these native trees to be recommended from a
commercial standpoint, as they are the most particular about soil and
climate. However, with improved propagation methods and planting
technique they should become some day as valuable as pecan plantations
have become valuable to the south.
Considering the nut tree as a dooryard tree, an ornament rather than a
business, makes it possible to include many more species as suitable for
growing in the north. For this purpose, I suggest heartnuts, chestnuts,
pecans and hiccans. The heartnut tree is always one to draw attention
and interest, picturesque in its leaves, blossoms and clusters of nuts.
Last, but certainly not least in it potentialities, is the English
walnut. I am certain that we shall have some varieties of these which
will be hardy enough to plant in the north. When these have been
completely proven, they will be a delightful addition to the number of
trees flourishing here. What family would not receive enjoyment and
satisfaction from having, in its dooryard, a gracious English walnut
tree, its spreading branches laden with nuts?
Although the commercial aspect of producing hazilberts is engrossing me
at the present time, my greatest pleasure in nut culture still comes, as
it always shall come, from actual work with these trees. It is both a
physical and mental tonic. I recommend nut tree culture to everyone who
enjoys spending his time out-of-doors, who is inspired by work of a
creative nature, and who appreciates having trees, or even one tree, of
his own. Suggested reading on Nut Tree Culture:
Nut Growing by Morris
Nut Growers' Handbook by Bush
Tree Crops by J. Russell Smith
The Nut Culturist by Fuller
Improved Nut Tree of North America by Clarence Reed
Annual Reports of N.N.G.A.
End of Project Gutenberg's Growing Nuts in the North, by Carl Weschcke