The Florida agriculturist., 1907-11-06

ing disease of the cotton plant, which
is becoming quite severe west of the
Mississippi River:
Wilt, blackheart or black-root is a
disease of cotton caused by fungus
Erw Sm) which lives in the soil of in
fected fields, and enters the cotton
plant through one or more Of it's small
roots. After gaining an entrance, the
minute threads of the fungus grow up
ward in the water-carrying ducts of the
plant, filling them and choking off the
proper supply of water and food e1e-
ments from the soil. This causes the
leaves to wilt, turn yellow and drop off
-one indication Of the wilt disease
The fungus also produces a discolora-
ton of the walls of the water vessels,
SO that the wood of the diseased plant
is seen to be dark brown when the root
or stem is cut across. This appearance
is characteristic of this disease and
gives it the names b1ack-root and black
in some localities.
The brown color of the wood serves
to distinguish cotton wilt from cotton
rust, an entirely different disease which
IS sometimes confused with the wilt
Rust is not caused primarily by any
fungus, but is due to bad drainage, lack
OF vegetable humus in the soil, defcien-
cy OF potash, or to some other unfavor-
able condition of the soil.
Cotton wilt may attack single plant
here and there in field, or the majori-
ty Of the plants in rather extensive
area. The fungus spreads from root
to root by the growth of it's micro
scopic threads through the soil, where
they feed upon decaying vegetable mat
ter. Injuries to the roots of cotton,
such as might be caused by deep cult1
vat1on, by the attacks of root-worms,
ETC., enable the fungus to make an
easy entrance, and occasion a larger
amount Of loss from wilt than would
otherwise occur. The fungus also pro-
duces in the soil, and more especially
upon the dead cotton stalks, numerous
spores which are microscopic in size
and have an office similar to that of the
seed of higher plants in multiplying
and spreading the fungus, which is it.
self plant of very low order Dur
ing damp weather a pinkish coating
made up Of millions of these dust-1ike
spores may be seen on the surface Of
dead cotton stalks; these become dry.
and the wind scatters them far and
wide. The spores may be easily car
r1ed on the lint and seed, and it is pos
slble that infection may be spread to
distant localities in this way, although
1t has not been established that this
IS usual mode Of transmission. Arti-
t1c1ally, the fungus may be spread BY
means OF dirt carried from an infected
held on the feet of workmen, of stock,
or on farming implements.
Besides cotton the fungus is known
to attack only one plant, okra. It GER
ta1nly does not attack other common
crop plants, such as corn, cowpeas.
velvet beans, oats, grasses, etc. Cow
peas are, however, subject to similar
Wilt disease which. is caused by fun
gus very closely related to the one
causing cotton wilt. But the cotton
fungus can not affect cowpeas, and the
coWpea fungus can not affect cotton.
However, it is possible for both FUNGI
TO exist side by side in a particular
SPOT; and both cotton and cowDea will
ipfsatT 61 eourSe, develop wilt on such doubly
NotT Cotton wilt is known to occur in
Mort9 z, carolina, South Carolina, Geor.
I5 ga, rloTIda' r Alabama, Mississippi, Ar
NdnSaS' lexas and Louisiana.
90 rTom rd: what has already been said re-
th Ehalqlng the nature Of the disease. and
.15 ~1o 1dOltS OF the cauSative organism. if