Best Methods of Reducing the Number of Weevil to a Minimum--Results of
Many Experiments Conducted
Remarkable results and profitable returns have been obtained by carefully
applying the following methods of destroying the boll weevil:
1. Completely strip the cotton stalks of foliage, squares, and bolls--the
weevils' sole food supply--plow the cotton stalks under good and deep, or
burn them at the earliest possible moment.
2. During the winter, destroy the rubbish in and about the fields, which
might serve as hibernating quarters for weevils.
3. When the weevils appear on the new cotton in the spring, pick them off
and destroy them.
4. Pick up all punctured squares and destroy them for at least one month
after the first squares form on the cotton.
=Importance of Destroying the Food Supply:= The most important step in
producing cotton in boll weevil territory is the early fall destruction of
the foliage, squares, and immature punctured bolls on the cotton stalks,
which constitute the weevils' only food supply. Thousands of
experimenters, including the United States Bureau of Entomology,
Government Agents in Farm Demonstration Work, the Louisiana State Crop
Pest Commission, and thousands of successful farmers substantiate this
statement that the early fall destruction of the cotton stalks is the most
effective method that can be employed for the reduction of the number of
weevil.
An experiment conducted by the Bureau of Entomology in Calhoun County,
Texas, showed that where the stalks on 410 acres of land were destroyed
early in October, that the yield was increased $14.56 per acre. Another
experiment was conducted on opposite sides of the Guadaulope River near
Victoria, Texas. The stalks were burned on one farm the latter part of
September and on the other they were allowed to stand until planting time.
Forty acres, on the farm on which the stalks were destroyed, produced
fifteen bales of cotton. Forty acres on the other farm made three and
one-half bales.
Experiments conducted by the Louisiana State Crop Pest Commission are
summed up in the following extracts from Circular No. 28: "Where the
cotton plants were destroyed before October 15, only 3 per cent of the
weevils survived the winter to infest the next year's crop. Where the
stalks were destroyed from October 15 to October 27, an average of about
15 per cent of the weevils passed through the winter successfully. Where
the stalks were destroyed between November 1 and November 25, an average
of approximately 22 per cent of the weevil survived the winter. Postponing
the fall destruction of cotton stalks until the middle of December, or
later, permitted over 43 per cent of the weevils to survive the winter
and attack the next crop." _Where the stalks were destroyed before October
15, only 3 per cent of the weevils passed the winter. Where the stalks
remained in the field until December 15, over 43 per cent of the weevils
survived the winter._ These figures certainly emphasize very strikingly
the value of early fall destruction of the boll weevil's food supply.
=Methods of Destroying the Food Supply:= With the importance of early fall
destruction of the cotton stalks fully realized, the cotton grower has
before him the question of how best to accomplish this. There are three
methods of destroying the squares, bolls, and foliage of the cotton
stalks: 1. Pasturing; 2. Plowing under; 3. Burning.
[Illustration: A mature cotton plant that was late in fruiting. The joints
are long and the balls far out from the center and base of the stalk. The
limbs have few joints and few bolls. Height of plant, 3 feet; balls 26--10
in lower half circle. Do not plant this type in weevil territory.]
Pasturing the cotton fields is a good method of destroying squares, bolls
and foliage where the cotton fields are fenced and where a sufficient
number of cattle can be turned into a field to eat all the squares, bolls,
and foliage in a few days. However, let it be distinctly understood that
the practice of turning just a few head of cattle into a fifteen or twenty
acre cotton field accomplishes no particular good. Every cotton grower
knows from his own observation that two or three head of cattle to an
acre, even when confined entirely to the cotton field, will eat very
little of the green foliage in one week, and it must be kept in mind that
it is vital to destroy as quickly and as completely as possible the food
supply of the mature weevils and the breeding places of the immature
weevils.
Plowing cotton stalks under is an effective method of destroying the food
supply of mature weevils and ending the lives of immature weevils where
there are few stumps and roots, where the cotton stalks are small, and
where large plows and strong teams can be had. Farmers who have attempted
to plow under green cotton stalks early in the fall, laugh at the advice
sometimes given to plow under the stalks at all times and under all
conditions as a means of destroying the food supply of the weevil. They
know from experience that such advice is often better theory than practice
as the plowing under of green cotton stalks is very often a decidedly
obstinate proposition. However, where large plows and strong teams are
available, use them and completely bury the cotton stalks wherever it can
be done.
[Illustration: Velvet beans yield abundant crops and add nitrogen to the
soil. A good crop for weevil territory]
Burning the stalks is a practical method of destroying the weevils. On
many farms and plantations there are not cattle enough to strip the cotton
stalks thoroughly and completely of every particle of foliage, squares and
bolls in a short time by pasturing. It is also often impossible to
completely bury the cotton stalks. In such cases, it is absolutely
necessary to cut, dry and burn them as soon as the cotton can be picked.
By burning the stalks, the food supply of the adult weevil is destroyed,
and weevils in immature stages in the squares and bolls are destroyed. A
large majority of the adult weevils also perish in the flames, especially
when the stalks are burned after sundown, as weevils retire to the stalk
piles for the night at about that time. They seldom move about at night,
and if care is taken not to disturb them when applying the torch,
practically all will be destroyed.
Of course, if the stalks are allowed to remain until a heavy frost has
come, practically all of the mature weevils will have gone into winter
hibernating quarters and the immature weevils in the squares and small
bolls will have been frozen. Nothing will be gained in that case by
burning the stalks and the best thing that can be done will be to cut the
stalks and turn them under as deeply as possible.
=Clean Up Hibernating Quarters:= Many weevils escape from the fields but
all do not fly beyond the reach of the farmer. Surprising numbers have
been found hibernating in cracks and holes in the ground and under grass,
weeds and other trash. In January, 1907, in one instance, the United
States Bureau of Entomology found 5,870 weevils per acre of which 70 per
cent were alive. Most of the many examinations that have been made have
shown more than one thousand live weevils per acre in the cotton fields.
Many are found along the fence rows, hedges, ditch banks and in decayed
logs and dead trees. Thousands more are found hibernating in nearby
cornfields and old sorghum, cane and hay fields.
Winter plowing of all cultivated fields is therefore another effective way
of reducing the number of weevils, as the thousand or more weevils per
acre in the cracks and holes in the ground and under the grass, weeds,
trash and cornstalks can practically all be killed by deep winter
breaking.
=Picking Off the Weevils:= After the hibernating weevils emerge from their
winter quarters in the spring and reach the young cotton, there is little
further movement until the general dispersing season in August, September
and October. The fact that the weevil does not move about much except in
the fall makes it possible for the individual farmer to accomplish results
from his own efforts in fighting the pest. There is little danger of
weevils coming in from other fields until in August, by which time the
cotton crop is normally set. For this reason, there need be no fear that
time will be wasted which is spent in thoroughly picking off the weevils
from the young cotton plants before the squares begin to form.
Where the food supply of the weevil has not been destroyed early in the
fall and strength added to this blow by plowing under the corn stalks,
trash, weeds and other vegetable matter that serve as hibernating
quarters, and by destroying practically all of the weevils hibernating
along the fence rows, hedges and ditch banks, the over-wintered weevils
are often sufficiently numerous to puncture all the squares as fast as
they form. Where this is the case, no bottom crop and seldom a middle crop
of cotton will be made unless the weevils are picked off and the punctured
squares destroyed.
[Illustration: An early cotton plant. The fruit limbs are low and close
together on the stalk and the joints are short. Plants of this structure
fruit early, rapidly and are well adapted to boll weevil conditions.]
The possible progeny of a single pair of weevils, during a season, has
been estimated at 12,755,100. Nature has provided a number of agencies to
prevent such excessive multiplication; nevertheless, the picking off of a
single pair of weevils from the young cotton plants may mean millions less
later on.
Before squares form on the cotton, the over-wintered weevils that have
come out of winter quarters feed on the opening leaves or buds of the
young cotton plants. Early in the morning it is an easy matter to find the
weevils in the buds, where they can be easily picked off and destroyed.
The only reason why the weevils cannot be eradicated by thoroughly picking
them off, is that large numbers of over-wintered weevils do not emerge
until after the squares begin to form. As soon as the squares form, the
weevil gets on the inside of the bracts and feeds only by inserting its
beak deep into the squares. After the squares begin to form, it is hardly
practicable to pick the weevils off.
=Destroy All Punctured Squares:= The weevils that survive the winter are
all in the adult stage. They breed only in the squares and bolls and
therefore cannot multiply until squares form. The most conspicuous
indication of the presence of the boll weevil is the flaring of the
square. When the weevil punctures a square, it turns yellow and the bracts
flare open. The punctured squares usually fall to the ground in a few
days.
The over-wintered weevils live only a few weeks after coming out of winter
quarters in the spring, as they die shortly after breeding in the squares
and bolls. Therefore, if the young cotton plants are thoroughly picked two
or three times just before the squares begin to form, and every punctured
square is destroyed for at least one month after the first squares form,
practically all of the over-wintered weevils will be dead and hence there
will be few young weevils later on. If it were possible to destroy every
punctured square and boll, and thereby prevent the appearance of new
broods, the weevil pest could be exterminated in one year. At any rate,
the results that can be accomplished behoove every farmer to work
carefully and painstakingly to destroy all the punctured squares possible
before the new broods of weevils are hatched.
During the growing season, many weevils can be destroyed by co-operating
with the natural agencies that tend to reduce their number. For instance,
the weevils in the punctured squares that fall on the hot ground in July
and August and are not shaded, are usually killed at once by the heat or
will starve for lack of food, because of the hardening of the square. By
using a brush on the cultivators to agitate the plants when cultivating
the crop, many punctured squares will be knocked off onto the hot ground
sooner than they would naturally fall off. At the same time, some of the
adult weevils will also be shaken off onto the hot ground. When an adult
weevil is thrown on a surface of finely pulverized, hot soil, it is killed
almost instantly.
=Attempts to Destroy Weevils with Poison:= In territory newly infested
with the boll weevil, attempts continue to be made to destroy the weevils
by poisoning. Of course the farmers soon learn better, but the experience
is very expensive. If advocates of poison would only remember that after
the squares begin to form on the cotton, the boll weevils feed only by
inserting their beaks deeply into the squares or bolls, they would realize
that it is impossible to place poison where the weevils will feed upon it.
In all the experiments performed in the field by the United States Bureau
of Entomology, very heavy applications throughout the season have failed
to show any advantage in the use of poison. Therefore, do not waste any
money on poisons.
=Not Attracted by Light:= The weevil seldom moves at night. It is inactive
after sundown. The weevil is never attracted to lights and hence the use
of a trap lantern has no effect on them.
[Illustration: Good corn must be grown in weevil territory]