The Elbert County tribune., 1907-07-18
Potato Troubles.

AVSotV AAOO0hCSs
The prospect for record crop Of pota
toes in some of the districts this year is
not very encouraging, according TO re
ports received at the Colorado Agricul
tural College. The little flea beetle has
been particularly destructive to potato
vines so far this season. Their numbers
light winter, are much greater than us
ual. The cold, backward season has
caused the insects to appear later than
usual, SO that where they are usually
mostly gone by the time the plants come
through the ground, this season, in most
fields. the plants were up about the time
the beetles appeared, SO that the maxi
mum Of damage from them has resulted.
These insects at this time Of year live by
eating the foliage OF potato, tomato, and
other closely related plants. They do
not eat the stem Of the plant off at the
surface OF the ground, as is so frequently
stated by growers. The damage from
this brood Of the insects comes simply
from the reducing of the leaf surface by
the insects eating holes in the leaves.
Very soon now the beetles will lay eggs
on the underground stems, or new tub
ers, that are forming. and the resulting
larvae will feed upon them, causing the
pimpley appearance that was SO notice
able on nearly all the potatoes OF last
season.
The time has passed for any remedy.
III we had known that the insects were
coming in such numbers, Bordeaux mix
ture and an arsenite might have been
sprayed on the vines. This remedy kills
some OF the insects. but helps more as a
preventive. The insects do not like the
material, and will move on to more con
genial surroundings.
The serious trouble with the potato
fields, however, is not due so much to
insect attack as to the seed tubers in
the ground. IL the weak, sickly plants
be dug, the seed tuber will be found de
cayed. This decay begins on the outer
surface and eats its way through to the
skin. Those tubers that were attacked
when first planted did not sprout at all;
Others sprouted, but were cut off before
sufficient roots we're developed to sup
port the plant. In many cases the dis
ease has followed from the old seed tub
er up the stem Of the plant and destroy
ed it even after the plant has grown
several inches above ground Some
fields are so badly affected from this
trouble that they are being plowed up
and sown to grain crops. In others the
loss is from 10 to 80 per cent.
Microscopic inspection of these dis
thStu tuDtIS anu pldntS SHOWS tue pres
ence of one of the many species OF "Fus
arum." This is undoubtedly the same
fungus that has caused the dry rot OF
potatoes in the dugouts.
Two or three peculiar things about the
attack OF the disease are noticeable
First, fields that grew potatoes last year
are much more affected than alfalfa
land. This can be explained from the
fact that the crop last year was damaged
by this fungus, as well as by "Rhizoc-
tonia." The "F'usarium' fungi are ordi
narily saprophitic, so easily lived over
winter in the decaying potato tops and
other vegetation.
Second, soft seed and the green seed
from the mountains seem to be affected
more than either home grown or eastern
seed. This is probably owing to the les
sened power of resistance OF the imma
ture seed.
Third, whole seed, so far as our OBJ
servation goes, are not affected by the
disease at all.
1t is. too early in the season to predict
what the outcome of this attack will be,
but from our observations we may safely
draw conclusions. Ii this disease per.
sists, it will hardly pay to plant potatoes
two successive years on the same land
1t may be necessary to follow the plan
whole potatoes. Probably "a more efiic-
lent method of control OF the disease
will be the careful handling of the seed
during the winter. AS the fungus pass.
es most Of its life history as saphro.
phyte, our dugouts are favorable places
for the propagation Of the disease The
dugouts should be thoroughly cleaned
OF all old tubers and soil, and then be
fumigated and sprayed with strong so.
luton OF copper sulphate (blue stone)
before storing in the fall Treatment OF
cut seed with lime, dry Bordeaux mix
ture, and sulphur, have not proved ben.
eficial for this purpose this season. Pos
sibly treatment of seed with formalin
may do some good, il care is exercised to
see that all tools and the planters are
also thoroughly treated before being
used, and the potatoes are planted on
soil that has not grown potatoes for sew.
eral seasons. E. r. BENNETT.