The Opelousas courier., 1895-01-19
REQ RUST IN COTTON.
An Unhealthy Condition Due to Attack
Of Insects-Vigorous Growth the True
Rou,o6v

of Insects-yigorous Growth the True
Remedy.
A farmer in eastern North Carolina
sent US last summer some cotton
leaves affected, as he said, by the
red rust. A brief examination
showed that there was no rust
at all, that is, none of the usual
fungous growths commonly called
rusts. The leaves were badly infested
with the so-called red spider" (Tetran-
ychus telarius) one of the mites, The
brilliant red color and almost micro
scopic size Of the insects. together
with their multitude, gave the leaves,
particularly on the under side, a red
color. The unhealthy condition of the
leaves was due to the attacks of the
insects. These red mites infest any
plant in a hot and arid temperature,
and arc therefore more destructive in
dry hot weather than when it is cool
and moist. When they become nu-
nervous, as they rapidly do under the
influence of hot and dry weather, they
destroy the vitality of the foliage com
pletely, and, as a healthy foliage is
essential to growth and productive
ness in any plant, it is evil
dent that they must give a serious
check to the plants they infect. Close
observers of plant life have often no.
ticed that plants with weakened vial.
ity soonest become the prey of inseess.
Therefore, while we cannot contlPl
the weather or the temperature. We
can put our plants from the start In
such a vigorous condition by fertiliza-
ton and by good culture as to enable
them to resist better n attacks ON
insects and fungous diseases. This
has caused some to assert that
red rust is caused by a deficiency OF
potash in the soil. While this in one
sense is true, it is not the whole truth.
Had there been an abundance of pot
ash and other elements of plant food
in the soil the vigorous vitality OF the
plants would have enabled them to
resist the influence of the insects until
a change in the weather conditions
would have checked their operations.
Cotton well supplied with kainit and
acid phosphate will undoubtedly
suffer less from this red rust,
not because potash drives the mites,
but because a fully nourished
plant can better overcome untoward
circumstances than a weak n can.
These red spiders are sometimes
troublesome to plantscuitivated under
glass, but there we can at once attack
them with water or sulphur fumes,
while in the field it is seldom practica-
BILE to use any remedies. Therefore
the growth of the plants Is to make
them resistant to their attacks. In
nearly all of the cotton lands of the
south Atlantic coast the soil is natur-
ally deficient in potash. Hence the
wisdom of using kainit and other
forms of potash fertilizers, witha good
addition of phosphoric acid in the
readily accessible form of acid phos-
phate, to give that vigorous growth
cannot supply. Some of our best
growers are of the opinion that the
vicinity of red clover causes rust in
cotton. One intelligent gentleman as
serted that he could carry a bunch of
red clover across a cotton field. and in
a few days could trace the path by the
red rust. Surprising he referred to
some sort of fungous growth we could
not account for his opinion, but can
see that if the clover was infested
as it is apt to be, on a sandy soil,
with the red spider, which is one Of
the most common causes of it's de-
struction on such lands in the south,
the insects might be readily trans
ferred to the cotton. This will also
account for the fact that on our red
clay soils which are well adapted to
clover, and where in most seasons it
resists the red spider, no such infu-
ence has been observed on the cotton.
The weakened condition of the clover
on these sandy lands renders it an
easy prey to the attacks of the mites
and from their profusion on the clover
they may well be charged with infect
ing the cotton. The remedy is evil
dent as in the case of the cotton itself,
invigorate the clover on these lands in
the same way. Glover is a greedy CON
sumer Of potash and lime, and II these
sandy lands are lined, and well sup
piled with potassic fertilizers, clover
would find better conditions, grow
more vigorously and be less infected
with insects and hence not liable to
damage the cotton any more than on
the clay lands.-W. F. Massey. of the
North Carolina Experiment Station,
Raleigh, N. c.