Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1914-11-17

subject has been issued by the Maine
Agricultural Experiment Station at
Orono, Chas. d. Woods, director;
The fungus formerly known as Rhiz-
| octonia solani Kuhn, more recently as
Cortfcium vagum var. solani Burt and
| considered by some writers as identi-
cal with Hypochnus solani P. & d.
Is common inhabitant of New Eng
| land potato soils. In fact its occur
renee Is so universal that 1t is practi-
cally impossible in most localities in
this part of the country to examine a
| barrel Of potatoes without finding from
a few to many tubers carrying at least
| some sclerotia of the Rhizoctonia stage
of the fungus. Every housewife who
prepares potatoes for the table is ia
miliar with the fungus in this form,
| but the sclerotia are commonly con-
sidered to be closely adhering particles
of black soil which for some reason
are difficult to wash off from the sur
face of the potato. The fact that these
hard, brownish or black, often fiat
tened, closely oppressed bodies, whiGh
vary greatly in size and shape, are
made up of closely interviewer threads
of fungus which serve as means
of carrying this fungus over winter
and of distributing it from place to
place, is not generally understood by
those who grow potatoes or prepare
them for the table.
While the appearance of such pota
toes is affected and extra labor is re-
quired to wash them, the sclerotia are
entirely superficial and not even the
skin of the tuber is injured Although
Rhizoctonia has been classed as an
active parasite of the potato in some
localities in this and other countries
the senior writer has, in the past,
shared the opinion of certain other
students of the subject with whom he
has conferred, that it is not an impor-
tant factor in potato diseases in New
England. Work which we have done
and observations which we have made
recently in Maine, however, lead us to
the conclusion that this position Is by
no means in accord with the facts.
Economic Importance of the Rhizoe-
tonia Disease of Potatoes.
In the bulletin there is given the re-
suits of series of field and greenhouse
experiments The discussion there
given is based upon observations made
on one field with one variety of pota-
periments were made with the same
strain of Irish Cobblers produced on
the field in question during two differ
ent seasons. If the disease occurred
in this State with equal severity gem
orally, especially in the sections large
ly given over to potato raising, the
growers would have long since gone
out of business and Maine would not
l.4l "A l.
potato producing state. However.
this does not mean that what we have
described Is necessarily an isolated
case, although it is undoubtedly more
severe than the average. The writer's
predict that a more thorough study of
the situation with regard to Rhizoc-
tonia in New England and other parts
of the country will show that it is by
no means negligible fastor as a cause
of potato diseases in the United States.
By the nature of its attacks Rhizoc-
tonia produces a most insidious type
of potato disease. In cases like the
one described not enough plants are
killed outright before they reach the
surface to excite suspicion on account
of the missing hills. The one or two
per cent of plants which early in the
summer are seen to be much under the
average size are accounted for as due
to weak stock" or it is explained that
these are the plants where the seed
pieces fell with the eye down. Except
to a critical observer the majority of
the plants may appear normal and I'M
less, a period of dry weather occurs
they, may look reasonably healthy and
vigorous nearly or quite to the average
time of harvest, when the owner dis
covers for the first time that something
is wrong.
While no other case has been seen
where the disease was so common and
widespread as on the field at Highmoor
Farm during the summer of 1913, it has
been found to some extent in quite
percentage of the fields of Irish Cob
blers which have been examined in the
central and southern parts of the State
during the past two seasons. Judging
from yet too limited observations upon
which to base definite conclusions the
disease does not occur as generally or
in so severe form in Aroostook
County as in some sections farther
south Observations made and speci-
mems collected by Mr.. c. A. Day and
Mr.. M. d. Jones, in charge of farm
demonstration work for the College of
Agriculture in Washington and Pc
nobscot Counties, would seem to indi-
cate that it is widespread and common
in some parts of the State and Is no
doubt an important factor In cutting
down the yields of Irish Cobblers in
this section. It is well known that
yields of Irish Cobblers are frequently
disappointing farther west in the cent
raj part of the State, where good crops
of Green Mountains and certain other
late varieties are secured without diff
Guilty. No doubt climatic conditions
have something to do with this but
there is every reason to believe that
Rhizoctonia contributes it's share in
bringing about these undesirable re-
suits the same as it did at Highmoor
Farm, which is located in the same
section.
That there is considerable difference
In the resistance of different varieties