The Grangeville globe. [volume] (Grangeville, Idaho) 1907-1922, 1917-04-12

Soaking In Dlsinfecting solution Tends
to Improve termination and Les
sens Danger OF Scab.

IUlIeU JtAlt1c department. VI 0SA tNuA-
ture as measure that viii tend TO
! improve the termination and lessen
| the danger Ok scab.
Such treatment is, on the whole,
profitable, but has several limitations
which should be clearly recognized to
prevent disappointment. The object
Of disinfecting seed potatoes is to des-
troy the germs of scab and other sur
face parasites which might otherwise
be planted with the seed and infect the
new crop Only surface infections are
reached by this method 1t Is only par
TALLY effective against deep pits Of
common scaB. Neither corrosive sub
Innate nor formaldehyde, as ordinarily
used, will destroy silver scurf. Either
one will kill surface infections Of
blackleg, but neither will reach the
internal infections common In tubers
from blackleg hills. Neither Fusarium
wilt nor late blight infection In potato
tubers can be reached by any seed
treatment, nor can any of the nonpar-
asitic diseases of potatoes, such as
mosaic, leaf roll and curly dwarf, thus
be prevented. See Farmers Bulletin
544 for descriptions Of these troubles.
Select Disease-Free Seed.
Clearly, therefore, the most import
ant precautipn 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 harvest.
Seed treatment should then be applied
as an additional precaution. 1t will
not be effective, however, IL the soil
where the potatoes are to be planted
Is already full of disease.
Soil Conditions and Potato Diseases.
Soil conditions have an important
relation to potato tuber diseases, and
many Of these are widely spread thru
out the country, and perhaps native
to some soils. Common scab is favored
by neutral or, slightly alkaline soil,
and seldom gives trouble In acid soils.
1t, therefore, Is increased by lining
and by fresh stable manure, wood ash
es, and alkaline fertilizers, such as
nitrate of soda and ground bone, while
acid phosphate and sulphate Of am
monia tend TO diminish scab.
Rhizoct0nia occurs to some extent In
nearly all soils, but appears to attack
potatoes most when the conditions are
unfavorable to the best development
Of the potato plant Bring the land to
an ideal state Of filth to minimize loss
from Rhizodtonia.
Powdery scab is worst on cold, wet,
or poorly drained soils. Blackleg, on
the other hand, is carried by infective
seed. No potatoes showing deep
brown disc0loration at the stem end
should be planted.
Sulphur tends to prevent common
scab. 1t is not q substitute for cor
rosive sublimate or f0rmaldehyde, but
is good drier for cut seed. Applied
to scab-infetted soils at the rate Of 500
pounds per acre, it reuuces the scab,
but such heavy applications can not
generally be recommended as profita-
Bile. Preliminary experimental trials
are advised
How to Disinfect Seed.
1t is considered better to treat DO
tatoes before they are cut into seed,
especially IL the cut seed is to be very
small. Put into the solution all the
potatoes 1t will cover and keep the
batch covered by the solution for the
period named under the treatment be-
ing used.
The formRldehyde treatment consists
IN soaking the potatoes, before cutting,
for two hours in solution made by
adding l Pint of formaldehyde to 80
gallons OF water. The solution can be
used repeatedly. The gas treatment
is no longer recommended.
The orrosive-sublimate treatment is
more effective than formaldehyde, par
ticularly against Rhizoctonia, or rus
set scab, and powdery scab. Corrosive
sublimate ~ used at the rate of IL, 900
for one and one-half to two hours.
Dissolve ounces of the salt In hot
water and dilute to is gallons. This
Is. deadly poison. Use with great
care. 1t must be kept in wood, por-
celain, or glass vessels, as 1t attacks
metal. Seed so treated must not be
used in the household. or left where
animals can reach it. q
In using the corrosive sublimate dip.
1t has been found that the solution be-
comes weaker each time it is used.
The degree to which the disinfectant
IS taken out of the solution varies
according to the amount of dirt on
the potatoes, the character of the wa
ter, and the kind of container For
practical purposes it win be sufficient
to add ! ounce of dissolved corrosive
sublimate to each 80 gallons Of solu-
ton after each batch of potatoes has
been treated. When this has been done
TOUR times throw away the old s0lu-
ton and prepare new solution.
To treat large quantities of pota-
toes set several barrels on slightly
elevated platform. Fit a plug in a
hole In the bottom Of each barrel, fill
with potatoes, cover with solution, let
stand two hours, draw or solution, and
pour into another barrel Increase
the number OF barrels in proportion to
the quantity to be treated. Another
method Is to use large wooden vat
or trough, into which the potatoes in
sacks are lowered by rope and pulley
and later hauled out. drained and
dried on Slated racks.
Seed potatoes may be treated sew
erai weeks before planting, provided
they are pot reinfected by storing in
old containers or storage bins.
Sproutef potatoes are injured by
treatment, but will throw out new
sprouts. in general, however, potatoes
will not Ne injured by following the
above directions. Many growers be-