The Covington leader. (Covington, Tenn.) 18??-current, 1922-08-17
BIG FIGHT AGAINST
COTTON LEAF WORM
PEST is DOING MUCH DAMAGE
IN LOUISIANA AND TEXAS
Reports Indicate That Tennessee Is
Infected and May Expect Very Sc
riOus Trouble With This Pest
Within Next Few Weeks-Crops
Should Be Watched For Invasion
of This Destructive Pest.
(By B. R. Coad, Of Delta Laboratory,
ralluIah. La

worm, or, as it is sometimes called
the cotton army worm alabama
argillacea Hubn.) from the States of
Louisiana and Texas. These reports
have increased rapidly until it is now
obvious that we may expect very Sc
rious trouble with this pest in the next
few weeks. This species does not
oyerwinter in the United States. It'll
is a native of tropical America and,
as the adult moth is very powerful
filler, it migrates into the United
States whenever it reaches degree
of great abundance in its native home.
Normally, the first generation pro
duced by the migrating moths in thel
United States is limited to the south |
western costal regions of the Gulf OIL
Mexico, and is not sufficiently album
dant to do serious damage. The
progeny Of this generation move
northward and eastward and, as al
rule, by the third generation, the en-
tire cotton belt is infested Generally
these generations are fairly well de-
fined. The present infestation, how
ever, is very peculiar in that the first
generation has spread over a remark
ably large territory and in unusual
abundance. Reports to date show the
State of Louisiana to be completely
infested and the majority of Texas is
likewise. At least the southern half
of Arkansas is now infested, and
scattering infestation occurs prac-
tically all over the State of Missis-
sippi. In addition, scattering reports
have been secured from Southwestern
Tennessee and Western Alabama.
Throughout much of this territory
the worms have already reached de-
foliating abundance and are seriously |
injuring the cotton in local spots.
which is very unusual for the first
generation and indicates an abnorm-
ally heavy infestation in the next
generation, which may be expected to
start to develop within the next 10
days. In addition. an examination Of
a majority Of fields shows re-
markable variation in the size of the
worms, the same field often yielding
all stages, from newly-hatched worms
to fully matured ones, which have
webbed up. This seems to indicate
continual immigration of moths and
the probability of more or less con-
tinuous damage of rapidly increas-
ing nature rather than distinct gene
rations as has usually been the case
in the past.
The question of just how wuch dam
age these worms can do is a very
important one in determining on con
control measures. At some points the
cotton crop is already so mature that
the worms can do little or no harm,
but this area is very limited. The
majority Of the territory where the
worms are now present in defoliatinr
abundance is still susceptible to seri-
Gus injury. Of course, the heaviest
invasion will not develop for some two
weeks yet, and there will be much
more cotton which will be beyond
damage at that time. However, there
will still be an enormous amount of
cotton which can be seriously injured
by the worms even after the first of
September, owing to the fact that so
much Of the cotton crop is from one
TO three weeks late in maturity. The
question Of whether or not to attempt
to control the worms is going to be
an individual one for each grower to
decide.
On account Of the unusually
threatening nature of this invasion
everyone should watch his cotton crop
cry closely for the first appearance
# the worms, and whenever they are
found in threatening numbers in
eld, where conditions will Justify
poisoning, control should be started
Immediately rather than waiting
lew days, when much of the cotton
viii be stripped, making it wore diff
'icult to poison the worms. Judging
from present prospects, worms will
probably be found in serious numbers
all over the cotton belt within the
next two or three weeks, and ire
mendous acreage will still be sus-
ceptible to serious damage at that
time.
The leaf worm is very susceptible
to control by the use of arsenical
poisons, but the unfortunate feature
of the situation is the fact that the
unprecedented demand for calcium
arsenate for controlling the boil
weevil this year has not only consumed
the stock of this chemical, but has
also enormously reduced the supplies
Of other arseHicals. We have just
completed a canvass of stocks of
chemicals which can be used for leaf
worm control and find an alarming
shortage. Considering every chemi-
cal which can be used, there is prob
ably not to exceed 100000 pounds
available, and this viii be far short
of the amount needed if the present
indicated infestation develops. A |
comparatively small amount of this
material is available in the South |
now, but manufacturers have been
notified of the emergency and the
majority of stocks are already roll
ing southwark.
In the early days paris green was
first adopted as a means of leaf /
worm control This gave very sat
isfactory control, but always pro-
duced more or less burning Of the
cotton plant, which was undesirable,
though not nearly as serious as the
leaf worm damage. Later, when
powdered lead arsenate was develop
ed, It was very largely adopted for
the same purpose, with very salts
factory results. It did not burn the
cotton plants in the slightest and
stuck to the plants better than paris
,-.aor h,.4 INTERCHANGEABLE, rrras MT