The Cook County news-herald. [volume] (Grand Marais, Cook County, Minn.) 1909-current, 1917-02-28
NEW POTATO DISEASE AP.
FEARED LAST SUMMER
Preva'ent-Last Season in Eastern
Observation-Disclosures Of Potash
or Manure to Soil Recommended,


or Manure to Soil Recommended,
A potato disease appearing on
certain soils and apparently associ-
ated with the lack of potash in the
commercial fertilizers used was pre-
valent last summer in various Sec
lions of the East. According to
specialists of the Bureau of Plant
Industry, United States Department
of Agriculture, the trouble was lar
gely controlled by the use of stable
manure. The disease may be ex-
pected to appear again with increas-
ed severity during the coming sea-
son in many potato growing sections
from Maine to Virginia, and prob
ably also farther south. 1t was first
noted in scattered fields in 1915. In
1915 it became serious and general
over considerable areas. Last year
the disease was first observed late
in June in Maryland and Virginia,
and during the latter part of July
in Maine. The affected plants first
develop downward rolling of the
leaf margins, accompanied by a pc
culiar bronzing of the surface. some
times mistaken for spray injury.
Since it occurs on unsprayed as we'll
as on sprayed plants, it can not be
due to the corrosive action of
sprays. The foliage gradually turns
brown-not yellow--and the plants
ripen prematurely. Death of the
leaves and sudden collapse of the
stems at the ground follow. The
yield, Of course, is much reduced.
The disease is found more CON-
monty on the fields of early matur-
ing varieties, but is not restricted
to them. 1t also appears first on
early planted fields.
What is more striking is the very
apparent association of the trouble
with certain soil types, at least in
Maine, where this relation, as we'll
as other features of the trouble, are
being investigated by the depart
ment experts in cooperation with
the Maine Agricultural Experiment
Station.
Soils which originally supported
the growth of soft woods, or linked
growth lands,'' developed the diseas-
ed condition in it's most severe type,
while the hardwood ridges showed
it least or not at all. The trouble
appeared first in the swales or low
lands, where the natural drainage
was not so good as on the higher
ridge land. When the disease ap-
peared at all on the higher ground,
it was of a less severe type.
Specific fungi are frequently found
on the stems of the collopsing
plants, and some of these most con-
stantly seen belong to disease-pro-
ducing groups. Their relation to the
trouble is being investigated, but the
present indications suggest that
they are not the primary cause but
have attacked the plants already
seriously weakened by other agen-
cies.
Fertilizer experiments in progress
on affected fields demonstrated that
the plots receiving potash showed
little or no signs of the trouble, even
where the other plots were entirely
dead. Stable manure also held the
disease in almost complete control.
Investigations of the trouble by
the department are incomplete, but
the present indications are that it
is due to insufficient potash, or, per,
haps, in some soils at least, to an
excess of nitrates in the presence
Of a minimum potash supply. Far
mers who are unable to secure pot
ash fertilizer for, their potato fields
but who have stable manure may in
sure their crops against attack by
it's use. In sections where certain
types of soil have been observed to
suffer from the disease under discus
sion, and it is advisable to plant
potatoes on these types next year,
it is strongly recommended that pot
ash fertilizers or stable manure be
applied if either are obtainable.