Atlanta tri-weekly journal. [volume] (Atlanta, Ga.) 1920-19??, 1923-08-21
COTTON LEAF WORM
CONTROL. EXP A|NED;
PEST IS SPREADING
BY B. r. COAD

TALLULAH, La, Aug. ia
few weeks ago the cotton leaf worm
or cotton army worm alabama Ar
gillacea Huhn.) appeared in very I'M
usual numbers in extreme south
Texas, and scattered infestations ex-
tended northward and eastward into
Oklahoma and Louisiana. The Sec
ond generation Of this species is now
appearing, and a very unusual
spread is indicated. Reports of
worms becoming sufficiently ahun-
dant to start defoliation have been
received during the past weeks from
practically all over Louisiana and
the major portion Of Arkansas, and
Mississippi, in spite OF the fact that
the moths from the first genera
ton have apparently just started
spreading. In all probability the
area subject to damage by the pres
ent generation Of worms will be
even larger and the lateness Of the
cotton crop in many districts is go
ing to make necessary the extensive
control measures.
AS regards the arsenicai supply
situation, this is probably somewhat
bteter than was the case last year.
There are still some available stocks
Of calcium arsenate, particularly in
the eastern states, but apparently
the amount available is not much,
If any, in excess of the quantities
which would be needed to meet the
demand for boil weevil control. Of
course, where this material is being
used TO control the boil weevil the
worm will not develop as long as it's
use is continued, but many places
where no poisoning is being done for
the boil weevil probably will need
treatment for the leaf worm. Stocks
of miscellaneous arsenicale, such as
Paris green, etc, are rather low,
and in all probability, if the worm
infestation develops as indicated, an
acute shortage of poisons will ensue.
POisOns to Use on Worms
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 devel-
oped, it was very largely adopted
for the same purpose with very
satisfactory results. 1t did not burn
burn the cotton plants in the slight
est and adhered to the plants bet
ter than Paris green, but unfortu-
nately was not as poisonous to the
worms.
In the past few years calcium
arsenate has been used very extern
sively for worm control with very
satisfactory results. 1t is not inju-
rious to the cotton plant and is
very nearly as poinsonous to the
worms as Paris green. In addition,
however, there are many other ar
senicals which can be used for leaf
worm control with satisfactory re-
suits. These include such as zinc
arsenite, magnesium arsenate, Lon
don purple and numerous trade
mixtures of arsenicals. The arseIi-
icals which should be avoided are
the highly soluble ones, such as So
dunn and potassium arsenate and
arsenite, which are very injurious to
the plants. The following outline
CON6IS Tie uldnu6E III which JnGS6
materials should be used.
Calcium arsenate should be applied
at the rate Of about four pounds
per acre, either straight or diluted
with one part of lime.
Lead arsenate should be applied
without diluton at the rate of four
to five pounds per acre.
Paris green should always be
mixed in the following proportions:
One part Paris green, one part -four
and from one to five parts Of lime.
The flour will make the mixture
stick to the plant and the lime
will reduce the chance of plant in.
jury. The mixture should be used
at such a rate that about two
pounds of Paris green per acre will
be applied.
London purple should be used in
the same manner as Paris green.
Magnesium arsenate should be
used straight or mixed with one
part of lime, at the rate of about
five pounds of poison per acre
Zinc arsenite should be used with
one part Of lime and applied at the
rate of about four pounds per acre
of the poison.
The other miscellaneous arsenicals
generally contain some free arsenic,
and it is better to use them with
the addition of one or two parts
Of lime. as a safeguard against
plant injury.
The old standard method for treat
ing the cotton leaf worm is the ''bag
and pole" with which every one is
familiar. and this is still good when
ever other equipment is not avail
able. Practically all of these chemi-
Gals can be applied with the bag
and pole, but it should be remem-
bered that such chemicals as lead,
arsenate, calcium arsenate, etc, are
of a more sticky nature than Paris
green, and consequently the bags for
applying these should be made of
cloth of a more open weave than
those used for Paris green. In addi-
ton. any standard cotton busting
machine ordinarily used for boil wee