The Caldwell tribune. [volume] (Caldwell, Idaho Territory [Idaho]) 1883-1928, 1916-04-07
CONTROL POTATO ScAB.
Select Clean, Disease-free Seed Pota-
toes-Disinfection Treatment.

The treatment of seed potatoes with
formaldehyde or with corrosive SUBJ
Innate has been recommended for
many years as preventative OF scab
and other diseases carried on the
tubers.
Such treatment is, on the whole,
profitable, but has several limitations
which should be clearly recognized to
prevent disappointment, according to
the specialists of the department. The
object of disinfecting seed potatoes is
to destroy the germs of scab and other
surface parasites which might other
wise be planted with the seed and in
feet the new crop. Only surface in
fections are reached by this method.
1t is only partially effective against
deep pits of common scab. Formalde-
hyde is less effective than corrosive
sublimate against the black sclerotia
or resting bodies of Rhizoctonia, or
russell scab, and against powdery scab.
Neither chemical as ordinarily used,
will destroy silver scurf. Either one
will kill surface infections Of blackleg,
but neither will reach the internal in
fections common in tubers from black
leg hills. Neither fursarium wilt nor
late blight infection in potato tubers
can be reached by any seed treatment,
nor can any OF. the non-parasitic dis
eases of potatoes. such as mosaic leaf
roll, and curly dwarf. be prevented.
See Farmers Bulletin No. 544 for des-
criptions of these troubles.
ant precaution against these diseases
is to select clean. disease-free seed po-
tatoes from healthy. vigorous plants,
as determined by field inspection dur
ing the growing season and at har-
vest time. Seed treatment should then
be applied as an additional precaution.
1t will not be effective, however, if the
soil where the potatoes are to be plant
ed is already full of disease.
| Soil Conditions and Potato Diseases.
Soil conditions have an important re-
lation to potato tuber diseases. and
many of these are widely spread
| throughout the country, perhaps ma
tive to some soils. Common scab is
favored by neutral or slightly aka
line soil, and seldom gives trouble in
acid soils. 1t is therefore increased
by lining and by fresh stable manure
/ wood ashes, and alkaline fertilizers
such as mira of soda and ground
bone, while acid phosphate and sui
phate of ammonia tend to diminish
scab.
Rhizoctonia occurs to some extent
in nearly all soils. but appears to at
tack potatoes most when the condi
tons are unfavorable to the best de
velopment of the. potato plant. Bring
the land to an ideal state of filth t.
, minimize loss from Rhizoctonia.
. Powdery scab is worst on cold
wet, or poorly drained soils. Black
leg, on the other hand. is carried b,
infected seed. No potatoes showing
deep brown discoloration at the ster
end should be planted.
Sulphur tends to prevent com
mon scab. 1t is not substitute TO
corrosive sublimate or formaldehyd,
but is a good drier for cut seed. Ar
piled to scab-infected soils at the rat
of 500 pounds per acre it reduces tn
scab, but such heavy applications ca
not be generally recommended a
al trials are advised,
How to Disinfect Seed.
The formaldehyde treatment cor
cutting. for two hours in a solutio
made BY adding one pint of formald,
HYDE to 80 gallons of water. Tt
solution can be used repeatedly. Tt
gas treatment is no longer recon
mended
Corrosive sublimate is used at ii
rate of 1-l000 for one and one-half
two hours. Dissolve ounces of IL
, salt in hot water and dilute to IS ga
. Ions. This is deadly poison. u
with great care. 1t must also be Ike
. in wood. porcelain, or glass vessels,
it attacks metal. 1t is more effecti'
than formaldehyde, particular
} against Rhizoctonia and powde
scab. Do not use the same solutic
more than three times. as the streng
> diminishes with each lot of potato
soaked