South Bend news-times. (South Bend, Ind.) 1913-1938, 1917-04-21
Information for Farmers and Orchdrdists
DisiJecting Seed Potatoes
improves Domination,
Lessons Scab Danger

WASHINGTON, April 1.-THE
disinfection of seed potatoes by
| soaking in corrosive sublimate or in
formaldehyde is recommended by
the United States department Of ag-
ricdlture as a measure that viii tend
10 improve the termination and les
sen the danger of scab.
Such treatment is, on the whole,
profitable, but has several limita-
tons which should be clearly recog-
nized TO prevent disappointment.
The object of disinfecting seed pota-
toes is TO destroy the germs of scab
and other surface 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 partially
effects against deep pits of common
scab. Neither corrosive sublimate
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 Flu
sarian wilt nor late blight infection
in potato tubers can be reached by
any seed treatment, nor can any of
! the non-parasitic diseases of pota-
! toes, such as mosaic, leaf roll, and
curly dwarf. thus be prevented.
Select Disease Free Seed.
Clearly. therefore. the most i'm
portant precaution against these dis
| eases is to select clean, diseased free
] seed potatoes from healthy, vigorous
| plants, as determined by field in
spection during the growing season
and at harvest Seed treatment
should then be applied as an addi-
| tional precaution. Ii will not be eff
fective. however, if the soil where
the potatoes are to be planted is al
ready full of disease.
Soil conditions have an important
relation to potato tuber diseases, and
many of these are widely spread
throughout the country, and perhaps
native TO some soils. Common scab
is favored by a neutral or slightly
alkaline soil, and seldom gives
trouble in acid soils. 1t therefore
is increased by lining and by fresh
stable manure, wood ashes. and al
kaline fertilizers, such as nitrate of
soda and ground bone, while acid
phosphate and sulphate of ammonia
tend TO diminish scab.
Rhizoctoniao ccurs in 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 10 an ideal state of filth
TO minimize loss from Rhizoctonia.
Powdery scab is worst on cold.
wet or poorly drained soils. Black
leg. on the other hand, is carried by
! infected seed. No potatoes showing
deep brown discoloration at the
stem end should be planted.
Sulphur tends to prevent common
scab. 1t is not a substitute for cor
rosive sublimate or formaldehyde,
I but is a good drier for cut seed. APP
piled TO scab-infected soils at the
rate of 500 pounds per acre il re-
| duces the scab, but such heavy ap-
/ plications can not generally be rec
commended as profitable. Prelimin-
How To- Disinfect Seed.
1t is considered better to treat
potatoes before they are cut into
( seed, especially if the cut seed is to
/ be very small. Put into the solu-
| ton all the potatoes il will cover
! and keep the batch covered by the
/ solution for the period named under
/ the treatment being used.
The formaldehyde treatment con-
sists in soaking the potatoes, before
| cutting. for two hours in a solution
made by adding one pint of formal
dehyde TO so gallons of water. The
solution can be used repeatedly The
! gas treatment is no longer recon-
| mended.
! The corrosive sublimate treatment
/ is more effective than formaldehyde
particularly against Rhizoctonia, or
/ russet scab. and powdery scab. Cor
| rosive sublimate is used at the rate
of 1-1,00O for one and one-half TO
/ two hours. Dissolve two ounces Of
! the salt in hot water and dilute TO
/ Is gallons. This is a deadly poison.
/ Use with great care. 1t must be kept
/ in wood. porcelain, or glass vessels,
as il attacks metals. Seed so treated
! must not be used in the household
/ or left where animals can reach it.
How To Use the Disinfectant.
In using the corrosive sublimate
/ dip it has been found that the solu-
| ton becomes weaker each time it is
used. The degree TO which the dis