Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1915-05-06
TREATMENT FOR THE
POTATO RHIzOCTONIA
Attempt this Disease by the Use of Seed and
Soil Distinction

Crono. Ne. Nay i.-In the summe.
Ct 1912 the Maine Agricultural EIper-
inent Station had & field Of Irish Cop
bier potatoes al E.ghr1oor Farm. which
throughout me first part Of the sea
sou appeared perfectly normal and
healthy to the average observer. How.
ever, when dry weather came On II
August the leaves began 70 show
signs Of premature ripening and died
rather suddenly some three weeks o.
more before the normal period Of ma
tu-i:y. The yield was consequently ma
terially reduced. The condition Of
these potatoes did not come 10 the
attention Of the Station pathologisl
until the plants were practically ali
dead, and consequently very little in
formation could be obtained Is to the
probable cause Of the trouble.
The field had been very thoroughly
and carefully sprayed SO the POSSIBLE
ties Of blight were excluded Potato
Hea beetles were quite prevalent in
ing g. large amount Of damage on un-
sprayed and less thoroughly sprayed
fields. While bordeaux mixture acts
as a repellant for these insects, IL does
not keep them off entirely, aad the
possibility was suggested that on &C
count Of their great numbers they
might have been a factor in causing
the early death Of the potatoes. In
the light OF succeeding events II is eF-
ident that they were not the primary
cause Of the trouble.
When the potatoes were dug il vas
found that the scle-otia Of the Rhizoc-
tonia fungus were exceedingly common
on the surface Of the tubers- These
scIerotia are the compact masses OF
the threads OF the fungus in which
form it lives oyer winter. and are
usually supposed To be closely adher-
ing particles Of black or dark brown
soil which are difficult to wash off
This growth on the potato is some
times spoken Of as BLACK scurf.'
With the idea Of obtaining more ac-
curate information as TO the cause
Of the trouble in 1912. some two acres
Of the field were again planted to po-
tatoes in 1913, using for seed some
cf the potatoes produced on the field
the year before. This, however. was
disinfected with forrnaldehyde both
seasons. The field was divided up into
plots which received different treat
ments with regard TO spraying, and an
unsprayed check plot was included.
Again the plants on the entire field
died early, following a period Of dry
was much below normal. The COM
parison Of the different plots indi-
Gated that thoroughness Of spraying
or lack Of spraying was not the
fundamental cause Of the difii-
Guilty. However, careful study
Of conditions throughout the season
supplemented observations on many
other fields. and by a series Of green
house experiments showed quite con-
clusively that the Rhizoctonia fungus
was the primary cause Of the trouble.
Details Of this part Of the investiga-
ton have already been published in
one Of the regular Station bulletins.
In 1914 an attempt was made to
study the effect Of certain seed and
soil disinfectants in controlling this
disease. The fact that 1t developed Sc
r!ously two years in succession on a
field where the seed had been treated
with formaldehyde seemed to indicate
that this material was not effective as
a means Of control, but there remained
the possibility that the majority Of
s~Hn es-h
the fungus being present In the soil
rather than on the seed used. How
ever, tests with sterilized soil in the
greenhouse indicated that the usual
treatment with formaldehyde did not
always kill the sclerotia upon the sur
face OF the tubers. Certain work done
at the New York Agricultural Expert
ment Station had given even more un-
satisfactory results. Hence, little could
be expected from formaldchyde. Some
very successful laboratory tests had
been reported by the New York Sta
ton in killing the sclerotia upon the
seed tubers by the ordinary corrosive
sublimate treatment. There was prac-
tically no data available regarding the
effectiveness Of sulphur.
For a field test last season a half
acre Of pasture land was plowed UP
and planted with Rhizoctonia- infested
seed. An aged neighbor claimed to
have positive information that this
land had not been cultivated for from
sixty to seventy-five years. The sod
consisted largely Of the Kentucky
blpe grass. Five ons-fenth acre plots
wsto planted . follows: First, seed