The true northerner. [volume] (Paw Paw, Mich.) 1855-1920, 1906-05-04
Late Biighf, or Rot.


tubers. Generally the FIRST noticeable
effect upon the leaves is the appearance
of brownish or blackish areas, which
soon become soft and foul smelling. So
sudden is the appearance of the disease
in some cases that fields that one day
look green and healthy may within the
next day or two become blackened as
though swept by fire. The rapid spread
of the disease, which is caused by par
asitic fungus, is dependent in a large
measure upon certain conditions of mois-
ture and heat. A daily mean or normal
temperature of from 72o to 74oF.
for any considerable time accompanied
by moist weather, furnishes the best
conditions for the spread Of the parasite.
On the other hand if the daily mean or
normal temperature exceeds TX for a
few days the development of the disease
is very soon checked. This fact ex
plains why the fungus seldom occurs to
any serious extent in sections where the
mean or normal daily temperature ex-
ceeds 70 Q for any length of time and prob
ably why it occurs later than the dis
ease discussed under the former heading.
The tubers affected with the disease
show depressed, dark colored areas on
the surface, while within are streaks of
brownish or blackish color. Other dis
eases may produce similar effects, so
that in this case the changes are not so
characteristic as those shown by the
leaves. For many years it was believed
was due to this disease, but recent inves-
LEGATIONS have shown that view TO be
erroneous.
The same treatment as recommended
for early blight should be followed here
and will be found to prevent the blight
ing of the tops and rotting of the tubers.
In regions where late blight is known to
occur, care should be taken to begin use
of Bordeaux mixture before the attacks
of the fungus. In all this work it must
constantly be kept in mind that the
main object is prevention rather than
cure. Benefit will undoubtedly result
if only clean, healthy potatoes are used
for seed. Decayed and discolored tubers
should be fed to the hogs, as it is poor
policy to plant them.
BROWN ROT.
This disease occurs in many parts OF
the South, and, in addition to attacking
the potato, seriously Injuries the egg plant
and tomatoes. In case of the potato,
the leaves, stems, and tubers are affected.
The disease usually manifests itself by a
sudden willing of the foliage and soon
the whole plant may become affected,
the leaves and stems shriveling and then
turning black or brown. The disease
reaches the tubers through the stems,
producing a brown or black discolora
ton of the tissues and ultimately com-
plete breaking down or rotting of all the
parts. Brown rot is caused by a bacillus,
minute organism, which multiplies in
the tissues and through its actions pro-
duces the effects mentioned. Various
insects, such as the Colorado beetles, flea
beetles, and blister beetles, serve as
carriers of the disease. These insects
may feed on a diseased plant and in
their visits to adjoining healthy ones
infect the tissues through bites and pos
sibly in other ways.
! TREATMENT.
Throughout the South, namely, in
South Carolina, Mississippi, Alabama.
and adjacent states where this disease is
known to occur, a thorough system of
spraying such as recommended for early
blight, should be followed. In addition,
all diseased vines should be removed and
destroyed as soon as possible, and the
tubers should be dug and either used at
once or stored in cool dry place. In
planting it would be well to avoid land
which has Just been used for tomatoes
or egg plants, and finally seed tubers
from localities where the disease is alb
sent should be USED if practicable.
ITO RE CoNTINUFD)