The Hood River glacier. (Hood River, Or.) 1889-1933, 1921-07-21
ANTHRACN0SE Is
FURTHER DISCUSSED
(By M. d. Armstrong;

The cankers which are seen on the
tree and the spots which appear on the
apples in the winter are started by
spore too small to be seen by the
naked eye. These begin to be given
off by the old cankers shortly after the
rains start in the fall and continue to
come from these old cankers in abund-
ance for two or three months and to a
certain extent all winter when the
weather is warm and moist. Some Of
these spores are washed and spattered
about by the rain and blown around in
the wind. If these spores chance to
light on an apple or on limb where
the bark is not too tough and dry and
the weather remains damp and moist
the spore commences to grow in the
same way as a gram of wheat; and its
roots, called mycelium, penetrate the
bark or skin of the apple and thrive in
the inner bark or tissues of the apple.
The growth of this root system de-
stroys the cells of life in that spot and
usually by March small spot can be
seen on the tree. This spot grows
quite rapidly in the inner bark during
the late winter and early spring; is of
a dark brown color and of soft
mushy texture.
After the tree growth is we'll started
in the spring the spot seems unable to
grow farther and the bark in the dis
eased portion gradually dries up and
cracks away from the healthy bark
which commences at once to grow back
over the wound. AS a rule these cank
ers reach their full size the first year
but new canker may start right be-
side the old one and appear to be
part of the original canker. The bark
in these spots appears dead but the
disease is really much alive and is ma
turing its fruiting system under the
bark. After the bark of the trees be-
comes softened by the rains in the fall
the fruiting bodies are pushed up
through the skin of the bark and then
burst and discharge the spores which
are then free to be blown or washed
about.
One of the unfortunate things about
this disease is that the old cankers,
though they do not enlarge, continue
for three successive falls to give off
spores. Thus it is that an absolute
control of the disease by spraying one
year will not prevent many new cank-
ers from coming the next year If not
sprayed. Spraying does not kill the
old cankers but simply coats the bark
of the treeSwith copper sulfate which
destroys the tender spOre when it
lodges on the bark. 1t is entirely pos
sible to clean up seriously infected
orchard in three years by thorough
spraying. At the end of his time the
old cankers will be dead. Because the
cankers are active for so long it is
easier to be rid of the source of infec-
tion by cutting out the cankered wood
where there is not too much of it in an
orchard. These cankers remain alive
on dead branches even when cut off,
and unless put under cover or de-
stroyed will continue giving off spores
when wet.
From this it is seen that if there are
cankers in an orchard which are three
years old or less that there will be
many spores present which will surely
infect the tree and if the apples are
not all picked before the rains there
will be many infections there also.
Someone is going to take loss from
these infected apples. They may have
to be repacked in the warehouse here
or they may be shipped and then rot
but wherever it occurs the growers of
Hood River are going to take the loss
eventually.
If it was only a loss to individual
growers the condition would not be
so serious, but the loss is the loss of
reputation of Hood River apples among
the buyers of our fruit which results
in a reduced demand for the apples of
all. AS Hood River is the only large
apple producing district in the North
west effected with this disease, we can
realize our position in the eyes of the
buyers of Northwest apples unless we
keep our fruit free from this disease.
Next week shall attempt to bring
to your attention the value of the sum-
mer Bordeaux, time of application and
possible damage from its use. 1t will
be generally recommended for use in
the Willamette valley this year and
also by your own Experiment Station
here for orchards seriously infected.