The Blackfoot optimist. [volume] (Blackfoot, Idaho) 1907-1918, 1913-05-22
POTATO SCAB
AND IT'S CONTROL
BY DisinfectinQ the Tubers With
Formaldehyde

BY Dlsinfectino the Tubers With
Formaldehyde
BY Frank D. Kern In The
Country Gentleman
Rough, scabby potatoes are familiar
to every one who deals with them in
the home, market or field. This scab-
by condition is unsightly and unprofit-
able. In some parts of the country the
malady is considered the most serious
enemy of the crop. The scabby sur
face is not accidental or haphazard,
but is the result Of the attack of a
distinct disease, which, deriving It's
name from the most conspicuous and
important symptom, is commonly
known as potato scab. This disease il
responsible for heavy losses every
year to potato-growers. First, there
is a considerable reduction in yield
owing to the injury which the disease
works to the underground portions Of
the plant, and, second, there is such
q lowering of quality that many po-
tatoes are unmarketable.
Potato scab is caused by the at.
tack of a minute fun2ous parasite.
Sometimes when the potatoes are
taken from the ground the delicate,
mold-like growth Of the fungus can be
seen at the margins Of the roughen-
ed, sunken spots. The disease is
carried through the winter by germs
or spores which may remain in the old
scab spots or, mixed with dust and
dirt, may be clinging to smooth sur
faces. These spores also live over in
the soil from year to year. They are
even capable of passing through the
digestive systems of animals without
losing their power Of growth, SO man
ure from stock fed scabby potatoes be-
comes a source of infection for the
soil
Knowing that the parasite winters
in the scabby spots and even on sound
surfaces, it will readily be seen that
the greatest source of infection is in
the seed potatoes. If potatoes free
from scab are planted in soil free from
1t the resulting crop cannot help but
be perfectly sound.
Several disinfection treatments have
been devised, but the safest and most
reliable is by the use of formaldehyde
Formaldehyde, sometimes called for
malin, Is colorless liquid with a pene
trating odor, which, largely disappears
in the diluted form employed in pota-
to- scab treatment. 1t is a solution
OF gas in water, and when Of full
strength should contain forty per cent
OF formaldehyde gas by volume or
The Best Arrangements for Dip
ping Potatoes
Seed potatoes may be disinfected by
soaking them for two hours in a solu-
ton OF fOrmaldehyde, at the rate of
one pint to thirty gallons of water
The actual method Of this treatment
may vary with the conveniences at
hand or the ingenuity of the operator
In small quantities the potatoes may
be placed in sacks and suspended in
tanks or barrels. In somewhat larg-
er quantities the potatoes may be plac
ed directly in barrels provided with
faucets. Half the barrels may be fill d
with the solution, which after the
required treatment may be drawn off
and placed in the remaining barrels.
Meantime the treated potatoes may he
removed and the barrels refilled. II
kept free from dirt and foreign sub
stances the formaldehyde solution may
be used repeatedly. II it becomes
dirty it is advisable to increase the
length of treatment slightly after the
first two or three applications.
After treatment the potatoes are
ready to be cut and planted in the
usual way, either at once or later.
Care must be taken in handling them
not to permit reinfection. They should
not be put into sacks. bins or wagons
which have not been disinfected with
formaldehyde.
When it is desired to treat pota-
toes on large scale the Tornado
hyde-gas method has been found more
economical in time and labor. By
this method the formaldehyde gas is
liberated by mixing the commercial
solution with potassium permanganate
in an alright room or shed. The
potatoes are placed in shallow, Stat
ted bins or bushel crates and stacked
up SO there may be free circulation
Of the gas on all sides. Care must
rooms may be lined with building pa
per, using lath to fasten it down at
the joints.
For each thousand cubic feet of
space three pints Of formaldehyde and
twenty-three ounces Of potassium
permanganate are used. Since the
gas is more effective in moist air it
is recommended that the floors and
walls be sprinkled just before treat
ment. The potatoes should not be
wet
The permanganate should be spread
out in a thin layer on the bottom of
a pail or deep pan in the middle of
the room. The formaldehyde may be
added and the pan given quick tilt
Then the operator must leave the
room and close it tightly, for the
irritating gas will be rapidly liberated.
The treatment should continue for
about twenty-four hours. No crates
of potatoes should be placed directly
over the generating pan or within
distance of three or four feet. This
method should not be applied on a
cold day; it is best that the tempera-
ture be above fifty degrees.
The fact that the scab germs may
be killed should by no means be in
terpreted to mean that badly affected
potatoes may be made into good seed
by the treatment. Very scabby pota-
toes sometimes have the eyes partially
destroyed and often lack vitality. The
best potatoes from q scabby crop can
however, be used with safety after
applying the treatment, and il plant
ed on q clean soil should produce a
CrOD practically FREQ from ocoh II 20