Note: Descriptions are shown in the official language in which they were submitted.
1038Z87
`` It has been known that a number of three diseases
are brought about by fungus infections of the xylem layer of the
tree. Two common examples of such infections are oak wilt and
its destruction of American Elms. In each of these cases the
disease can be spread by means of root grafts, although the most
common vector for the disease in Dutch elm disease is the elm bark
beetle. The present invention is directed to a treatment of trees
, which is prophylactic in its effects. That is, it both has pre-
ven;tative as well as curative effect,
It has long been known to treat fungus infections of -`
plants including ~rees with various types of fungicides which are
--~ introduced into the vascular system of the plant by soaking the
soil about the roots with the appropriate chemical or by injecting
into the piant the desired fungicide~ However, while prior inves- -
tigators have proposed a number of treatments purporting to act -
as a cure or control for such diseases none of them have proved
;~ satisfactory to the extent of gaining widespread and successful
usage. In order for a fungicide to be satisfactory for this in-
tended purpose it must not only act to prevent the spread of the
fungus throughout the tree and to neighboring trees but also must
do so without causing damage to the tree being treated.
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In accordance with the present invention it has been
discovered that by selecting compounds which are structurally
similar to the lignins of the trees as the treating agent the com-
pounds are compatible chelnically with the tree and tend to produce
little, if any, adverse effect upon the tree itself. By halogena-
ting these compounds--preferably with chlorine--the compounds are
made highly toxic to the vector which brings about either oak wilt
or Dutch elm disease.
The chemical structure of the lignins has been exten-
sively investigated by many individuals over a period of years.
While the structure of the lignin is not known with complete cer-
tainty it is known to be of a polymeric construction and is quite
probably a polymer of the basic building block indicated below.
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See Construction and Biosynthesis of Lignin by K.
Freudenberg et al, Springer-Verlag New York Inc.
In accordance with the invention it has been found that
j if compounds having a structure similar to that given above are
, halogenated and then introduced into the vascular system of the
tree by the injection technique, that at least temporary protec-
tion of a tree against infection by either Dutch elm or oak wilt
~ disease, respectively, can be achieved. For those trees which are
'd already infected treatment with the chemical compounds in accor-.~
dance with the present invention arrests further progress of the
diseases and dependent upon the extent of progress of the disease
can even bring about recovery of portions of the tree already
showing symptoms of the disease.
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1038Z~7
The ~ajority of the compounds in accordance with the in-
vention are insoluble or only sparingly soluble in water. There-
fore, it is necessary to prepare a solution of the active treatment
chemical in a suitable carrier that will achieve its distribution
through the circulatory system of the tree. While a number of
solvents are suitable for the purpose it has been found that
either methyl or ethyl alcohol and aqueous mixtures thereof are
particularly useful for dissolving the compounds to be used in the
treatment.
The following examples will more specifically illustrate
the nature of the treatment in accordance with the present inven-
tion.
Example I - -
The first class of compounds which will be illustrated
are the halogenated creosols. It has be~n found that creosols - -
having a structural formula as indicated below may be suitably -
treated to halogenate the same at either or both of the five and
six positions on the ring.
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A single halogenation with chlorine to produce either 5 or 6
chloro creosol produces a compound-having sufficient toxicity to
the fungus which brings about the Dutch elm disease to achieve
arrest of the spread Gf Dutch elm disease within an infected tree
or to other trees by root graft. The treatment material is effec-
tively distributed throughout the tree by the trees own vascular
~-~ system.
In treatment of a tree a solution of a creosol in
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methyl alcohol was made by mixing 100 milliliters of 6 chloro
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creosol in one gallon of methyl alcohol. The quantity injected
into a tree to achieve the desired results will, of course, de-
pend upon the size of the tree. For a 24-inch diameter trunk and
a 40-foot high tree it has been found that one gallon of solution
is a desirable amount. Larger concentration and/or larger total
amount of active ingredient may be used, but as the above concen-
tration and total amount provides the desired prophylactic treat-
ment no useful purposes are served by use of more material.
Lesser concentration levels of the active ingredient and
- 10 smaller total quantity for the same size tree may be used. How-
ever, the indicated amount is believed optimum.
For smaller or larger trees one may proportion to the
size of the tree and by simple ari~hmetic make adjustment as to
the amount to be injected.
Sampling of trees treated in accordance with the above
; procedure, which trees had previously been tested to establish theexistence of Dutch elm disease, resulted in all cases in arrest of
further spread of the disease following treatment.
s The trees so treated showed no short-term adverse effects20 to the foliage from the treatment and in the subsequent year to
treatment were free of further incursions by the Dutch elm disease. ~ -
In some instances there was an apparent increase in the number of
sucker branches and leaves in the growing season subsequent to
treatment.
Treatment with 5-chloro creosol and 5,6-dichloro
creosol ln similar concentrations and quantities per equivalent
tree size produce substantially the same beneficial results.
- Example II
-~ A second class of compounds useful in treatment of in-
30 fected trees in accordance with the invention is the Catechol
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103~287
series that has been halogenated to produce the desired toxicity
of the compound to the fungus inducing the wilt diseases. The
structural formula for the preferred compound of the Catechol
series, 6-chloro Catechol ~ g ven below:
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As in the case for the compounds illustrated in Example I above,
a quantity of this compound is dissolved in a suitable carrier,
which is typically methyl or ethyl alcohol, in the same proportions -
as in Example I and is injected into the xylem layer of the elm ~-
tree. Distribution of the compound occurs through the vascular -
system of the elm tree and is effective in preventing the initial
infection by the fungus or alternatively, if the fungus has already
infected the tree, to prevent its further spread.
Various substitutions can be made in this basic Catechol
structure to produce closely related compounds capable of achieving
the prophylactic effects of the invention. For example, a compound - -
such as 5-methyl Catechol may be suitably modified by introduction
of chlorine at either or both of the 3 and 4 positions and used in
like proportions as thé active ingredient for injection into a
~ree~ ~ikewise, homologues of the Catechol such as veratrole
which has been halogenated to produce the desired toxicity are
similarly effective in treatment of trees infected with Dutch elm
or to prevent infect~on by the Dutch elm fungusO Other related
compounds include chlorinated coniferyl alcohol, vanillin and the
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~ like.
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- Example III
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`- A substituted veratrole, 5-chloro-3,4 dimethoxytoluene,
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~ 30 was prepared and mixed in a methyl alcohol carrier in the quantity
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103~287
corresponding to that of Example I. ~lm trees were injected
with the xesulting solution in concentration and quantity corres-
ponding to those given for Example I with the results obtained
being substantially the same as those for the creosols and Cate-
chols of the previous examples.
The technique for injection of the active chemicals and
carrier may follow the prior art practices of injecting solutions
into trees for similar purposes. In the interest of introducing
the treatment chemical and carrier at a rapid rate I prefer to
introduce a quarter-inch diameter tube through the bark into the
cambium layer and then inject by means of this quarter-inch tube
the solution into the tree under approximately 100 pounds per
square inch pressure. As a fluid is compatible with the existing
structures and fluids of the tree it is rapidly disseminated
throughout the tree by this technique. The time involved is of --
very short order which provides an important economic advantage for
the treatment of numerous trees per unit time by an operator.
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