St. Tammany farmer. [volume] (Covington, La.) 1874-current, 1907-08-24
SOUTHERN
AGRICULTURE


The wilt Of cotton, often called
"b1ack-root," is In many ways one OF
the most troublesome cotton diseases
now known. # is not so well known
throughout the state that a very brief
description Of the most important sys-
TENS of the trouble will here suffice.
It makes its first appearance at about
this time of the year, and if appearing
for the first time in any given field
will be confined to small area. From
this area, however, it will be distribut-
ed year after year through the agency
of plows and mules passing over the
ground The plants attacked soon ap-
pear to be dwarfed and somewhat I'M
healthy; the leaves turn yellowish at
the margins and this yellowish color
proceeds slowly towards the center
of the leaf. The vines in such cases
may long lCmain green and healthy.
Some plants may wilt and die in a
very short time, but others may send
out new shoots down close to the
ground and outgrow the attack. The
final test is to be found in an examina-
ton of cross section of the stem or
root If affected with the wilt the
woody part will appear to be stained
a brownish color.
The wilt is due to the attack of the
fungus called Neocosmospora vasin'
fecta. This fungus lives in the soil
and apparently can retain it's vitality
in the soil for five years, or even
longer. It first enters the plant
| through it's smaller roots, and 1t Is
supposed that the nematode worm is
an important agent in Wounding the
roots, which they enter, thus permit
ting the ready entrance of the wilt
fungus into the root. It is at least GER
tain that sandy soils infected with this
nematode worm that causes the root
knot disease Of cowpeas, cotton and
q host of other plans, are more apt to
become infected with this wilt fungus.
A great many farmers have in fact
learned for themselves this connection
between the nematode worm and the
wilt. But 1t is also to be borne in
mind that the wilt fungus can enter
the cotton roots without any assistance
lit is in fact an aggressive parasite.
Having gained entrance into the cot
ton root it then grows in the woody
vessels, or ducts, of the root and stem
and finally, by plugging up these nat
ural water channels of the plant,
causes the whiting" symptoms above
mentioned.
The above facts suggest certain
measures that every farmer can read
lily apply 20 his fields with advantage
in the control of this dangerous cotton
enemy.
Crop Rotation-It must be remem-
bered that this fungus causes wilt
disease in okra also and hence this
plant should not be grown in rotation
with cotton. In fact soil once infected
should NOT be planted for several years
| to cotton, okra OF any other crop that
is subject to the wilt disease.
Destruction Of Fflt-Infected Plants
Cotton stalks affected with the wilt
should be pulled up and burned at
once. This procedure will greatly re-
duce the spore production of the fun
| gus and thus reduce its spread
| throughout your fields.
Quarantine Infected Areas-The or.
binary grazing of cattle over infected
fields will tend to carry the disease
from infected to non-infected areas
This is done by the adherence Of the
spores and vegetatfve portions of the
| fungus to the feet of the cattle. In
fact, an infected area should be al
once placed under regular quarantine
regulations. For if you plow aeros:
an infected area into the balance OIL
your field you will certainly carry
some Of the fungus along on the p1ov
and thus spread the disease. The
ordinary means the fungus has Of
spreading is by its growth in the sol
and hence a somewhat larger area
should be quarantined than that &C
tually having on it infected plants.