The Caldwell tribune. [volume] (Caldwell, Idaho Territory [Idaho]) 1883-1928, 1912-09-20
The Dry Rot Of Potato.

NC 0Iy MOI Oh xOeANO.
One of Idaho's principal crops is
the potato. 1t is grown extensively
in nearly every section of the state. In
the southern part of the state it is one
of the most profitable crops to grow
in the young orchards and serves to
defray the expense of maintaining the
orchard from the time of planting until
the trees begin bearing. In the north
ern part of the state it is more often
grown as an independent crop.
In view Of the importance Of the
crop it would be well for the grower
to consider some of the fungus and
insect troubles Of the potato with a
view to controlling them. Unless this
is done, potato growing will sooner or
later cease to be commercial crop
in this state. Heretofore. very little
attention has been paid to the diseases
Of the potato; the attention of the
farmer and horticulturalist has been
centered almost exclusively upon or
chard crops. Very few growers have
thought Of spraying potatoes. The
Colorado beetle has not yet made its
appearance, so apparently the potato
has not been sprayed. However the
flea beetle is doing great deal Of
damage. 1t is a small dark beetle that
eats holes through the leaves until the
foliage is SO depleted that it can no
longer carry out its functions in the
development of the plant. The Early
and Late blight often follow in the
wake of the flea beetle, its perforations
in the leaves affording an excellent
entrance for the fungus.
A combined arsenical and Bordeaux
Mixture would control both insects
and increase the yield many per cent.
However, the most serious disease
which now threatens the potato in
dustry is the Fusarium blight and dry
rot. Spraying will not control the
disease. 1t is becoming abundant in
every part of the state and steps
should be taken at ONCE to stop it.
The disease may be recognized BY the
early following and premature death
Of the foliage. This is only second
airy effect Of the disease, however, and
BY the time the foliage turns yellow
the disease is well established. The
fungus 6rst attacks the main root. of
the plant just below the surface of the
ground, the root rots. becoming brown
Or black Ia color and the foliage grad
ually dies from lack Of nourishment.
Naturally the tubers stop growing. af-
ter the death of the roots and foliage.
This may occur while the tubers arr
quite small or after they are nearly
ali matured depending upon the age
Of the plant when the disease Attacks
il. ''''7T1
This ID the same fungus which a.
ways causes the rot Il the tubers.,
Often rotting does not begin until az
ter the potatoes are III storage. II
the fungus mycelium has entered the
potato tuber prior to storing, it is
sure to rot. Often, however. only the
spores are present on the tuber sur
face and in that case if the potatoes
are well dried before storage and stor-
ed in dry. cold place. the rot will
not develop to any extent. II the
storage place IS damp, or the tubers
are not well dried, then the rot will
progress rapidly. This disease enters
the potato from: the soil. probably in
troduced into the soil with the seed
tubers. Il remains in the soil and in
creases in abundance from year to |
year after it is once established. II
may be controlled if the proper meth
DDS are employed. A few general
rules will suffice.
4 |. Once the disease has been OBJ
served in field do not plant potatoes
IN that field for at least three years.
2. Do not plant any tubers infected
With the rot. The dry rot often may
be internal and not recognizable from
the outside. Its presence may be
made known by cutting the tubers
rom the stem end. If brown or black
pots are found then the disease IS
present and the tuber should not Be
5. Do not cut away an infectionl
pot and then plant the rest Of the
uber.
4. Seed tubers selected from 4 lori
rom which infected tubers have been
AIKEN should be treated with formalin
'efore planting to kill the spores that {
nay be present on the surface. /,
The disease will not spread from
!eld to field to any great extent so If /,
ne proper precautions are taken il
nay be practically eradicated. ID
O. "A. PRATT. II
Asst. in Plant Pathology, Idaho
Experiment Station. ii
$1,000 80 e5E