Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1920-05-19
DISINFECT SEED
POTATOES BE-
FORE PLANTING

Seed Treatment with Corrosive Sub
Innate Greatly Lessons the Loss
from Observation-Disclosures Of Ex-
< Periments-How to Give Treatment
Orono. Me-, May -18-The following
was issued this afternoon from the
Office Of Charles D. Woods, director
of the Maine Agricultural experiment
station at the University Of Maine:
For some years the pathologists of
the Maine Agricultural Experiment
Station have given more or less at
tention to the Rhizoctonia disease of
potatoes and the methods of its con-
troll. Ample evidence has been Sc
Of much economic importance in all
parts of the State, but some of the
worst cases of injury have been seen
in the southern and central parts. |
There is no common name for this
trouble. Rhizoctonia is the generic
name of the fungus, as originally de-
scribed. which causes it.
Every housewife who prepares po-
tatoes for the table and every observ-
ant potato grower is familiar with
one form of this fungus, although it
is not usually recognized by them as
such. The little. black or brownish-
black specks or larger, raised patches
often found closely adhering to the
surfaces of potato tubers, but which
can be removed readily by the thumb
nail or by vigorous scrubbing with a
stiff brush when the potatoes are
wet. are not particles or Jumps Of dirt,
as is often supposed, but compact
masses of threads of the Rhizoctonia
fungus. called 'sclerotia." The con-
dition which they cause is often re-
ferred to as BLACK scurf" or black
scab." These sclerotia serve the
same purpose for the fungus that the
tubers upon which they occur serve
for the propagation of the potato
plant. AS soon as and probably some
time before, the planted potato tuber
begins to sprout they begin to throw
out fungous threads which grow with
considerable rapidity If conditions are
right.
Rhizoctonia manifests itself on the
below ground parts Of the potato in
various ways, but by far the most i'm
portant Of these is in the form of an
injury or browning where the fungus
attacks the stem. Young. tender
sprouts are much more seriously in
jured. often being entirely cut off.
either before they reach the surface
or when the plants are still small.
Hence the fungous threads that grow
from the sclerotia on the potato seed
pieces are advantageously placed for
they have young, succulent potato
sprouts right at hand upon which to
grow and feed and cause destruction.
/ While the Rhizoctonia fungus is a
| normal inhabitant of all of our potato |
soils-there is probably no Maine po
tato field entirely free frcin tit is
obvious that if the sclerotia upon the
surfaces Of the seed tubers car be de-
stroyed an important step has been
taken toward removing the chief
source of injury from it. 1t has been
recognized for some time that both
the formaldchyde- and corrosive sub
Innate seed treatments for potato
scab were in varying degrees effective
in killing these sclerotia. 1t has been !
claimed, and certain unpublished ex-
periments conducted by this Station
agree with this claim, that the corro-
sive sublimate treatment Is the more /,
effective of the two for Rhizoctonia. I
New or modified quick" and easy"
methods of seed tuber disinfection !
have appeared from, time to time. One
Of these originated largely with this
Station and, while it was very prom
Using at first, difficulties arose in the i
practical application of it which
caused it to be abandoned. Hence,
even at the risk of being classed as
non progressive we have been adj
vising our correspondents to stick to
the old, established methods of rela-
lively long soaking in corrosive sub
Innate or formaldehyde solution. In
formation just received furnishes a
very satisfying justification for this
position.
For the past years Professor B. |
L. Richards of the Utah Experiment :,
Station. first in Utah and later work
ing with DR.. L. r. Jones at the Uni
versity of Wisconsin has been trying
to determine the factors which con-
troll the amount of injury caused by
Rhizoctonia, as well as the merit Of
the different methods of seed potato
disinfection. It is believed that his
conclusions are so we'll founded and
so important that Maine potato
growers should at once have the ben
eft of them. He says that the results
have convinced him and also the
pathologists and horticulturists who
have followed this work in Utah and
Wisconsin that until further evidence
is secured the one safe, practical pro-
cedure is to regard Rhizoctonia seri-
ously and for its control to treat seed
potatoes in pretty, nearly the odd
fashioned" way with rather long
soaking~in corrosive sublimate solu-
ton.
The following Is taken from
statement recently issued by Profess
sor Richards, giving a summary of
his work and the conclusions there
from. In this statement we have TAX
en- the liberty to substitute the term
corrosive sublimate for mercuric
chloride. Both mean the same thing
-mercuric chloride Is the name used
by chemists but corrosive sublimate
10, |