Shoshone journal. [volume] (Shoshone, Idaho) 1884-1931, 1922-04-14
Seed Potato Treatment
BY DIR. B. L. Richards, Associate
Botanist, Experiment Station,
Utah Agricultural College

ton more definitely upon the potato
is a product free from disease and
upon seed treatment as an aid La
clean seed production. In the process
OF seed treatment we are concerned
primarily with three diseases of the
n Utah and throughout the Inter-
mountain region: scab, stem csnker,
| tRhizoctOnia) and Black leo. The
organisms which cause these diseases
are all tuber borne and as such are
introduced each year into large areas
of clean land rendering them unfit
for potato production. 1t is definite
ly known that these organisms when
/ planted with the seed result In a de-
creased yield and in the production Of
tubers inferior both for the market
and for seed purposes. Further 1t
must be remembered that the scab
and the stem canker organisms once
introduced into the soil may live there
Indefinitely and seriously damage 9TH
er and succeeding crops.
The disease organisms as they ap-
pear on the surface of the tubers are
very resistant to the action of chem
icals and rather severe methods are
necessary to destroy them.
For treating seed potatoes two stand
ard disinfectants have been used:
formsldehyde, one pint to thirty gal
flT Ill LII
ounces to thirty gallons of water.
The formaldehyde treatment is not
effective against Rhizoctonia at ordln-
airy temperatures and is therefore not
to be generally recommended. Tie
mercuric chloride method on the other
hand when properly applied has given
uniformally good results.
A number of precautions are neces-
sary, however, in the application Of
mercuric chloride to the surface of
the potato tuber. In the first place
1t must be recognized that the potato
tuber is living structure and as such
is most resistant to the action of
mercuric chloride when in a dormant
or resting state. With the earliest
signs of sprouting the eyes Of the |
tubes becomes very liable to injury |
from this chemical and considerable |
damage may result in treatment at /
this particular stage. Early treatment |
is therefore advisable.
Again it has been determined that |
damage to the seed may result from |
the continued action Of mercuric |
chloride if the tubers are allowed to /
sinain wet for a considerable period |
after treatment. Rapid drying of the /
tlhers will eliminate this danger and |
viii further add to the effectiveness
of the treatment by depositing a
slight film of the poison on the sur.
face of the potatoes.
A further protective precaution
must be taken against too rapid re-
duction of strength of the treating So
luton. The surface of the tubers
rather rapidly abs0rbs the mercuric
sacks and any other organic nateriais
hat may be introduced with the seed.
Where necessary to use sacks a few
should be previously treated for =
hours in a solution of mercuric chlor-
de and then used repeatedly with sue
,essive lots of potatoes.
Details for treatment are as fol-
ows:
SELECT only those tubers for treat
nent which are free from burises, :
lecayed spots and internal browning
TREAT UNCUT SEED az early as
'ossible in the spring. at least ten
avs or two weeks before planting. :
void the use Of sacks IN treating.
>eep seed in a clean place and in
terile sacks after treating and drying. r
PROPER STRENGTH, Mercuric :
ounces to 80 gallons of
alter. q: 10000.
TIME OF TREATMENT. Dormant
eed l u hours If tubers have started
, sprout and show but little disease
sduce the time, bat in all cases soak
10 seed for at least u hour. Soak
ls for "A hours in cold water before
eatment will greatly aid in Destroy /
e the disease germs.
DRY POTATOES as rapidly as pos
bic after treatment For early crop,
here convenient green" the tubers
the sun for few days befor plant
z.
KEEP UP STRENGTH OF soLU-
ON by adding 3-S ounce Of mercurlc
loride after treating each four
shels OF potatoes treated for one
"a one hair hours and restore the
lume VI water 10 It's original 30 gal
rs.
DISCARD SOLUTION after the
lrd " fourth treatment where no
emieai Is added. Il H. also necos.
~ when chemical Is not added 10
'rease tie time ~ treatment l5
nutes Tor each consecutive iot trsat.