The Republican journal., 1908-09-17
Two Potato Diseases New To Maine.
A Caution to Shippers Of Seed Potatoes

As result of Investigations conduct
ed by the Maine Agricultural Expert
ment Station, the Fusarium dry rot 7
wilt and "black-leg," two diseases
the yotato stem and tuber not hilbert 0
credited to the State, have been found
to exist in several localities. Since on e
of these is distributed by means of the
seed and the other is probably spread
| in the same manner, it is important
that the growers at once learn to rec
ognize them. So far as observed, no
serious damage has, except on few
small fields, resulted from either of
these diseases. They both are, how
ever, more or less distributed, and prob
ably have existed in the State for some
little time.
The danger from these diseases is not
SO much to Maine crops alone, but
from their possible effect upon the seed
trade in the South, where black-leg ap-
pears to be much more destructive
than with us. Already the Station has
received complaints from two different
sources, stating that black-leg has de-
veloped most seriously on fields plant
ed to Maine-grOWn seed and on land
the disease had not previously been OBJ
served.
The appearance of affected plants
| above ground is somewhat similar in
both diseases. The plants appear more
or less unthrifty, varying with the Sc
verify of the attack. The branches
and leaves, instead of spreading out
normally, tend to grow upward, form
| ing a somewhat more compact top, fire.
quently with the young leaves incurred
and folding up along the mid-rib.
Later they may become lighter green
or even yellow, and the whole plant
gradually dies. If the disease progress
es rapidly, the stem may fan over quite
suddenly and wilt, without any previ-
Gus signs of disease other than the alb
| normal upward trend of the foliage
mentioned above. 1t should be noted
! that any other severe injury to the
stem just above or below ground is apt
| to produce very similar effect upon
the appearance of the plant. However,
each disease is easily diagnosed by pull
ing up and examining the portions OF
| the plant below ground.
| In the case of the FusaEium disease,
| the underground portions of the stem
will show discolored or brown, dry
| patches or streaks. The roots are brit
tie and weak, and in some cases are
covered with white, pink, or even red
dish growth. The Fusarium disease
/ also attacks the tubers, and experiment
has shown that it is by this means that
the disease is spread. Like the late
blight, it causes d dry rot of the tuber,
but the first symptoms of disease are
nearly always at the stem end, in the
form of brownish or blackened ring a
short distance below the surface. At
/ this stage the tuber may appear per-
| fectly sound and healthy externally.
/ Later there is a general discoloration
of the flesh along and decided shrink
ing of the tuber. The skin becomes
Wrinkled around the stem end, and the
tuber becomes very light and often
nearly as hard as wood Infected pota-
toes may appear perfectly sound when
placed in storage, and come out as de-
scribed above. If introduced into the
soil, the disease may persist for some
time. 1t is caused by parasitic fun
| gus.
Backlog, as its name indicates, is
characterized by a pronounced blacken-
ing of the stem below ground, usually
running up an inch or more above the
surface. Sometimes, under favorable
conditions, the inky-black discoloration
may follow up portion of the stem
! for several inches above ground. Dur
! ing the active progress of the disease
the invaded tissues show soft, wet
decay, but this apparently does not at
tack the fbrous portions of the stem.
Later the diseased portions may dry
out, but the stem retains most of the
, black color. Usually the seed tuber is
entirely decayed by a soft rot, and not
infrequently, if young tubers had been
! formed before the complete invasion of
, the stem, they are also affected in the
same manner. Almost without excep-
ton, the disease begins on the stem at
its junction with the seed tuber and
progresses upward. Similar troubles
elsewhere have been attributed to a
fungus, but there is every reason to
think that the disease here described as
| "black-leg" is of a bacterial nature. III
! fact, pure cultures of bacteria have re-
| Gently been isolated at the Maine Sta,
| ton from diseased stems which are
able to produce very rapid and COM
plete soft decay of potato tubers. There
is considerable evidence which suggests
that black-leg is carried on the tubers,
develops first in the seed piece after
planting, and spreads from that to the
stem.
| From the above it is evident that if
the Maine potato growers wish to re-
other States, particularly in the South,
they should take every precaution to
prevent the spread of both of these dis
eases, and endeavor to stamp them out
wherever they have gained a foothold,
no matter how slight. All seed for
planting should be selected from healthy
fields, and all seed tubers showing any
decayed areas whatever should be re-
| jected for planting. Each shipper who
values his seed trade should make
careful inspection several times during
the summer, from July on, of those
| fields from which he intends to draw
his supply of seed, and then ship only
from those fields which such inspection
shows to be free from the Fusarium
disease and black-leg. If these precau-
tions are followed, and infected fields
are given over to other crops for few
years, it is probable that the danger
from both diseases can be reduced to IL
minimum, if they are not both entirely
eradicated. Unfortunately, spraying is
practically of no value in fighting
diseases of this nature.
WILLIAMS KIDNEY PILLS.
Have you neglected your Kidneys? Have
| you overWOrked your nervous system and