Daily capital journal. (Salem, Oregon) 1903-1919, 1916-04-01
POTATO SCAD;;
DISINFECT THE SEED
Agricultural Department Sug-
geStS Means Of EradiCat-
ing Disease

The treatment of seed potatoes with
formaldehyde or with corrosive subli-
mate has been recommended for many
years as a preventive of scab and other
diseases carried nthe 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 ne wcrop. 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 russet
scab, and against powdery scab. Neither
chemical, as ordinarily used, will de-
stroy silver scurf Either one will kill
surface infections of blackleg, but
neither will reach the internal infec-
tiOns 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 non-parastic diseases of po-
tatOes, such as mosaic leaf roll, and
curly dwarf, be prevented. See Farm
ers' Bulletin 544 for descriptions of
these troubles.
Clearly, therefore, the most important
precaution against these diseases is to
select clean, disease-free seed potatoes
from healthy, vigorous plants, as de-
termined by field inspection during the
growing season and at harvest. 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 planted 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 native
to some soils. Common scab is favored
by a neutral or slightly alkaline 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 nitrate Of
soda and ground bone, while acid phos-
phate and sulphate of ammonia tetnd
to diminish scab.
pL:ao.4o,,:a oo,,,,, a., ,o,,,o o,y4or+ IA,
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 .tilth to minimize loss
from Rhizoctonia.
Powdery scab is worst on cold, wet,
or poorly drained soils. Blackleg, 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. It is not a substitute for cor
rosive sublimate or formaldehyde, but
is a good drier for cut seed. Applied
to scab-infected soils at the rate of 800
pUuuuS per acre IL ltuhNto lhS oNdb1 but
such heavy applications can not be gen
orally recommended as profitable. pre-
liminary experimental trials are ad-
vised.
HOW to Disinfect Seed.
M. e--,,.,,. ..4.. ...
ne iolli1iuell u9 ,,e%.,seno Lnsa eu4fiso' 4t;
ll eVohins lno Po'"Voesi D?Ioio ouI''Hs,
a1i .@o hoGls IN oIioL,5 Soiu'loh ll"1e oy o6
auulns Pin. - M, Tha ,'a.Ieny aaI4;o NC ~ So
gSliUn' 5I' VI "S'e' rLn n' ooiasiou ont oon ~
uo'I Iope"teuly in1 5'' 'i'"'"''hV 20
no io"sei i''Oii',''i'i'u
corrosive subllmate Is used at the
rate Of l'l,OOO for one and one-half to
TWO hours. Dissolve ounces OF the
Salt IN not water ana dilute TO 10 gal
Ions. This IS a deadly poison. Use
with great care 1t must also be kept
IN wood porcelain, or glass vessels, as
1t attacks metal. 1t IS more effective
tnan formaldehyde, particularly against
hhlzoctohla ana poWuery scaD' DO not
liueS, as the stLeng'h dinllniSneS i5 WIN
e"cn ioV Vi Po'a'oes SoaAeu'
| To treat large quantities, set several