South Bend news-times. (South Bend, Ind.) 1913-1938, 1917-02-05
NE VI DISEASE
ATTACKS POTATO
SCOurge Is Associated With
Lack of Potash in Fer
tiIiZerS Used.

A potato disease appearing on
certain soils and apparently asso-
ciated with the lack OF potash in the
commercial fertilizers used was pre-
valent last summer in various sec
tions of the east. According tc spe-
cialists of the bureau of plant in
dustry. United States department Of
agriculture, the trouble was largely
controlled by the use of stable man
ure. The disease may be expected to
appear again with increased severity
during the coming season in many
potato growing sections, from Maine
TO Virginia, and probably also far
ther south. 1t was first noted in
scattered fields in 1915. In 1916 il
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 de
velop a 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 well
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 level follow The yield,
of course, is much reduced.
The disease is found more COM
monty on fields Of early maturing
varieties but is not restricted 10
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 well
as other features Of the trouble. are
being Investigated by the depart
ment experts in cooperation with the
Maine agricultural experiment sta
ton.
Soils which originally supported
the growth Of soft woods. or mixed
growth lands" developed the dis
eased condition in its most severe
type, while the hardwood ridges
showed it least or not at all The
trouble appeared first in the swales
or lowlands, where the natural
drainage was not so good as on the
higher ridge land When the dis
ease appeared at all on the higher
ground. il was Of a less severe type.
Specific fungi are frequently found
on the stems of the collapsing plants
and some of these most constantly
groups. Their relation TO the trou-
bic is being investigated, but the
present indications suggest that they
are not the primary cause but have
attacked the plants already serious
~ weakened by other agencies.
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 en-
urelY 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 il
is due 70 insufficient potash. or, per
haps. in some soils at least 10 an
excess Of nitrates in the presence Of
minimum potash supply. Farmers
who are unable to secure potash
fertilizer for their potato fields but
who have stable manure may insure
their crops against attack by its use
IN sections where certain types Of
soil have been observed 20 suffer
from the disease under discussion.
and il is advisable 10 plant potatoes
on these types next year, IL is strong
Is recommended that potash fertil-
GERS or stable manure be applied IL
either are obtainable.