The independent-reporter. [volume] (Skowhegan, Me.) 1909-1955, 1912-06-13
DISEASES OF APPLE TREES.
A Number of Different Fungi Found
Associated With the Disease. OF
Interest TO Fruit Growers.

For number of years the Maine
Agricultural Experiment Station has
been giving attention to the causes Of
disease in the bark of apple trees.
Such diseases cause a large amount
of loss because the bark is frequently
killed to such an extent as to girdle
the branches and this leads TO their
death so that the tree is finally de-
stroyed.
Examination of branches affected
by canker from different parts of the
State showed that a number of differ
ent fungi were found associated with
the disease. These fungi have been
studied in the laboratory and inocu-
lations have been made with each of
them in order to determine the ex-
tent to which each Is able to cause
disease.
As a result of these studies. it has
been found that at least three fungi
/ found in Maine orchards are able to
be grown In the living bark of apple
trees and cause disease which may
result in the death of the trees. Two
other fungi have been found which
are very common on diseased bark
and small dead branches but these
have not grown to any extent when
placed in wounds in healthy apple
bark. 1t seems that these two fungi
are only able to grow on branches
which have become weakened In some
way as in the case of trees which
have not been given proper care
OF the three fungi which spread
rather rapidly when placed in wounds
on healthy branches, the one which
disease Is the same fungus which
causes the leaf-spot of the apple and
the black rot of the fruit So far as
known this fungus always enters the
bark through wounds. When the fun
gus has begun to grow within the
wound it spreads into the healthy
bark and kills it so that instead of
the wound healing over as it would
do If the fungus were not present
the area of diseased bark becomes
larger from year to year. After a
considerable area of bark has been
killed the fungus begins to produce
spores and thus the material is pro-
vided for the infection of new wounds
in the bark as we'll as of the leaves
and fruit
In order to prevent the spread OF
apple canker, it is necessary to re-
move and burn all diseased wood
which may carry the spores of the
fungi which cause diseases. Care
should be taken to make wounds in
such a way that they will heal readily
and each wound should be disinfeet-
ed with a solution of copper sulpha'e,
one ounce to one gallon of water and
then painted over with white lead in
boiled linseed oil Each wound
should be disinfected because The
tools which have been used in work
ing on diseased branches are likely
to carry the fungus to healthy
branches unless this preeaution is
taken.
While there are a number of fungi
which cause canker the same methods
of control apply to all. In addition
to the removal of the dead wood and
bark which carry the spores of the
fungi, spraying should be practised
The spraying which is done for the
control of apple scab is of great i'm
portance in the control of canker.
This is due to the fact that the fungi
which cause canker are producing
large quantities of spores at just the
time when these applications are
made and wounds are covered by
the fungicide many infections will be
prevented. Spraying. however, can
not stop the growth of cankers which
are already established. These must
be cut out and burned in order to >des-
troy as many of the spores as possible
In the early stages, the diseased bark
may be removed and the wound dis
infected and painted over. but where
a branch is more than one-half grid
led by the fungus it will usually prove
to be best to remove the branch, cut
ting back to healthy wood.
John F. Sprague of Dover, presi-