The Marlboro democrat. [volume] (Bennettsville, S.C.) 1882-1908, 1901-01-11

hkO bUluOWuht fOblbtaut W bIlO OlbSUbVt
Small tufts Of roots grow from oach
point Of infection, doubtless on account
Of somo stimulus exerted by tho fun
gus. Several short roots will thus
start from plaoo which would normal
ly havo prcduced ono longer branch.
Many Of thoso littlo roots arc killed.
by tho fungus and othors grow in their
plaoos, so that tho tuftod appearance
of tho rootlots 10 moro pronounced late
in tho season. Tho aamn result has
beon produced in tho laboratory by in.
ooulating geodling cotton plants with
puro cultures Of tho cotton wilt fun
gus. Similar root tufts arc found as
sociated with the wilt diseases Of okra,
oowpoa, watermelon and cabbage, aud
they are believed to bo characteristic Of
this class Of root diseases.
In the case of cotton thoir presonoo
Of tho wilt fungus in tho soil, oven
whom tho amount is so small that no
harm is visible aside from tho reduced
growth Of tho plants. This dwardng
Of tho plants is duo to tho killing Of tho
small roots and is often visible over
considerable aroa surrounding badly
infootod spot. For this reason tho loss
in yie,d on such fold is much creator
than would appear simply from con
sidoration Il the badly diseased areas,
as the dwaring duo to the injuring of
tho small roots considerably ourtails tho
yield.
Sinco tho publication of bulletin No
II, tho wilt disease has boon producod
in hoalthy cotton plants by inooulating
tho soil in which thoy grew with puro
cultures Of oonidial stagos Of neoooB-
mosporavas infeota. This removes any
doubtas to the oasualrelation of thefun-
gus to tho diaeasewhioh migh arise from
the failure Of tho previous incubation
experiments. The plants wero grown
for fow wooks in pots, and thon
small quantity Of fungus from pare
oultuturo was plaood in the bottom Of
each ono. Eight days lator they wero
transplantod to opon ground. The fret
case appeared after about thirty. five
days. Fourteen out Of twonty- four
plants contracted tho disease. Tho fun
gus WAS abundant in tho vascular bun
dies OF soyon plants and they showed
all the othor symptoms Of tho disease.
Tho othor scvon infected plants were
only slightly diseased, although tho fun.
gus was found in the vessols Of tho
stom. Tho chook plants, twenty-five
in number, all remainol healthy. It
will DO noted that tho longth OF time
botwoon tho incubation of the soil and
tho appearance Of tho disease in this OK
poriment (thirty-fvo to fifty days) was
practically tho Same as elapBos in the
fold between tho termination Of the
seod and tho first appearance Of
tho diaoaso. That larger proportion
Of the inooulations did not succeed is
beloved to be duo to tho small amount
Of fungus used and to the natural rasis
tanoe of tho plants. Tho cotton plant
incubation described in bulletin No. II
were all made in tho greenhouse, and it
is now beloved that tho negative results
were due other to the slow growth Of
the plants or to tho fact that they wore
naturally resistant
with largo number Of Substances appll-
cd to tho soil in tho hepo Of killing the
fungus, but all tno results obtained
up to tho present time indicate that
there is no hope of sucoess in tho use
Of any fungioides sprayed on tho plants
or applied to tho soil.
Fields uniformly infcoted with wilt
disease wero solicited, and over twonty
ditforent substances were applied in
amounts as large as it was thought safe
to use. In many cases tho expense Of
their application in such quantities was
80 great as to make their use impraotiblo
had thoy proved effioacious. In other
cases, as in tho use OF materials contain,
ing copper, oontinucd applications in
such largo quatitios would be likely to
iDjuro tho soil.