The Manning times. [volume] (Manning, Clarendon County, S.C.) 1884-current, 1901-01-09

s1e somewhat resistant 20 the disease.
Snail tufts Of roots grow from each
point Of infection, doubtless on account
Of some stimulus eZerted by the fun
gus. Several short roots will thus
Start from place which would normal
ly have produced one longer branch.
Many Of tkese little roots are killed
By the fungus and others grow in their
places, so that the tufted appearance
Of the rooslets is more pronounced late
in tie season. The same result has
beer produced in the laboratory BY IN
oculating seeding cotton plants Sltn
pure cultures of the cotton VIII 1uo-
gus. Similar root tufts are found as
socisted with the wilt diseases OF okra,
cowpea watermelon and cabbage, aod
thew are believed to be characteristic OF
this class of root diseases.
In the case of cotton their presence
N the roots demonstrates the presence
Of the wilt fungus in the soil, even
when the snount is SO small that no
harm is visible aside from the reduced
growth of the plants. This dRsr6ng
Of the plants is due to the killing Of the
small roots and is often visible over 8
considerable area surrounding badly
infected spot. For this reason the loss
in wed on such field is much greater
than would appear simply from coz
sideration f the badly diseased areas,
as the dEsr6ng due to the pjlriug of
the small roots considerably curssils the
yield.
Since the publication Of bulletin No
II, the wilt disease has been produced
IN healthy cotton plants BY inoculating
the soil in which they grew with pure
cultures Of conidial stages Of 1eocos
nosporavas infects. This removes any
oouosss to the casualrelarion Of rhefun
gus to the diseasewhich might arise from
the failure Of the previous incubation
experiments. TIE plants were grown
for few weeks N pots, and then s
small quantity Of fungus from a pare
cultutuce was placed in the bottom OF
each enc. Eight days later they were
traasplanted to opsn ground. The hrss
case appeared after about thirty hVe
days. Fourteen out of twenty four
pants contracted the disease. The fuo-
gus vas ABUNDANT in the vascular bun
oles Of seven plants and they showed
all the other symptoms Of the disease.
The other seven infeoted plauts were
only slightly diseased, although the fun
gus was found in the vessels OF the
stem. The check plants, twenty hye
in number, all remained healthy. 1t
will be noted that the length Of time
between the inoauia,ion Of the soil and
the appearance of the disessein this ez
pertinent (thirty-fve to fifty days. was
prac ,ically the sans IS elapses in the
i:ld between the termination OF the
seed and the 6rss appearance OF
the disease. That larger proportion
Of the ipoculations did rot succeed is
believed to be due to the small amount
of fungus used and to the natursi resls
tance Of the plants. The cotton plan,
incubation described in bulletin No. II
were all made IN the greenhouse, and II
is now believed that the negative results
were due either to the slow growth OF
the plants or to the }sct that they were
naturally resistant.
Careful experiments have been made
with large number Of substances appll,
ed to the soil in the hepe Of killing the
fungus, but sll the results obtained
up to the present time indicate that
there is no hope Of success in the use
Of any fungicides sprayed on the plants
or applied to the soil. -,
Fields uniformly infected with wilt
disease were selected, and over twenty
different substances were applied ID
amounts SIS large as it was thought safe
to use. In many cases the expense Of
their application in suca quantities was
so great as to make their use implactlb!e
had they proved eficaclous: In other
cases, as in the use OF materials contain
ing copper, continued applications II
su,h large Qualities would be likely te
IL are the soil.