The Hood River glacier. (Hood River, Or.) 1889-1933, 1916-02-03
APPLE SCAB, METH
obs OF FIGHTING IT
From the Mosier Bulletin

Produce News and which was read by
K. ID. Chatfield. manager of the Mosier
Fruit Growers association, at the
meeting last Saturday of the Mosier
Horticultural society:
Reports from different parts of the
West during the past season indicate
that apple seab has been unusually
severe in many sections. The loss due
to this disease alone will probably
amount this year in rough estimate to
over $500. 900 in Oregon. In many an
unsprayed orchard there could not be
found single scab.free fruit this
year, and even in orchards where the
owners did spray there was often a
serious high percentage of scab, suffi-
cient in some cases to remove all trace
of profit from the ledger. For several
years the college has been conducting
Investigations on the control of apple
scab and at the same time has been
watching the work done by practical
growers in this direction. From the
results of these Investigations and
observations the conclusion is forced
upon US that no matter how bad the
year may be for this disease, the intel
ligent application of our present
knowledge will result in satisfactory
control
So much has been written and said
on the subject of apple scab that there
is no need of describing the disease in
detail. You will understand that the
parasitic fungus which causes it lives
through the winter in the dead tissues
of the fallen apple leaves. and that in
the early spring crop of spores is
matured which are shot forcibly out
of these old leaves and then caught by
the lightest air currents, are carried to
the newly developed foliage and fruit,
causing on them the first scab infec-
tions of the season. 1t was for long
time thought that this crop of spores
did not mature until about the time
the blossoms open and that infection
could not occur earlier. In Oregon,
however, we have found that at least
in some seasons these spores may be
mature approximately month before
the blossoms open. Under such cir
cumstances if the weather conditions
are favorable infections may occur
before the cluster buds are fully
opened, often a considerable time pre-
vious to blossoming. These first in
fections will develop into typical scab
spots on the young leaves and bower
parts and in week or two there will
be a new crop of spores produced in
these spots which, as you are aware,
usually result in an exceedingly rapid
spread of the disease in the orchard,
attacking fruit and foliage alike.
There is now no longer any doubt
regarding the natural conditions which
make possible the spread of the dis
ease. Moisture is absolutely necessary
for the termination of the spores and
those climatic conditions which enable
the dew, rain or fog to remain upon
the leaves or fruit for considerable
number of hours in succession make il
possible, where spores are present, for
those spores to sprout and send their
delicate germ tubes through the cuti.
Gle, after which the infections will
take care of themselves. Anything
that promotes rapid drying of foliage
tends to prevent infection. Wind and
sunshine. even though interspersed
with showers. are unfavorable to the
disease, while cloudy or misty weather
with little wind. even though there
be practically no rain, makes possible
abundant spore termination.
Years ago. before the nature Of this
disease was yet fully understood, an
effort was made to find some means BY
which it might be prevented. Bor.
deauX mixture had been found of such
value in connection with certain other
plant diseases that it was naturally
one of the first materials tried out as
spray for the control of this malady.
AS long as twenty or twenty-five years
ago in the eastern part of this country
Bordeaux mixture was shown to be
decidedly beneficial, and the large
number of tests carried out since that
time all over the United States leave
no doubt as to its efficiency for scab
control in the mind of any one familiar
with the results. There was, however,
one drawback in connection with Bor-
deaux mixture wherever used; namely,
the tendency under certain conditions
to cause russeting of the apple fruit.
1t was thought at first the mixture
was being used too strong, but expert.
ments demonstrated the fact that in
jury would occur when weak dilutions
were used and it was found that this
could not be prevented by any change
in proportions of the ingredients. 1t
was found that this injurious effect
was present only in fruit sprayed when
young. and il is now further understood
that moist weather following the appli-
cation of Bordeaux mixture provides
the most favorable conditions for the
appearance of russeting.
Continued Next Week.