The cotton-worm (Aletia argillacea), bollworm (Heliothis arnager) and Mexican cottonboll-weevil (Anthonanzus grandis) are not so easily controlled, and their ravages have been costly. The cotton worm is now more easily controlled than formerly. It is a blue-green caterpillar, with black spots and stripes on its back. It is most severe in late sum mer, but is present the entire summer. There are several generations each year. The common method of combating it is to apply dry Paris green to the plants.
The cottonboll-worm is a common garden pest, attacking various crops, as corn, tomatoes, peas and squash. The caterpillar is somewhat darker than the cotton-worm, but otherwise the two are very similar in their early stages. This, too, has several generations in a season. It is most effec tively controlled by the planting of an early trap crop. Sweet corn is much used. As soon as the corn is infested it is removed and destroyed or fed to stock. Lantern traps for the moths and arsenical sprays for the worms have given limited success.
The most serious problem confronting the cot ton-grower today is the control of the Mexican cottonboll-weevil, which is threatening the de struction of the industry. The weevil is small, three-eighths inch, or less, in length, of a dark brown or black color. The eggs are laid in the young bolls, and the larva begin their work by eating the inside of the bolls. No very effective direct method of combating the weevil has been found. Its control depends on strict attention to many details in the culture of the crop, and to a modification of the farm practice. It is very important to mature the crop early, and then to clean up the plantation as soon as the cotton is picked, burning or plowing down all stalks and refuse ; this will largely control the weevil, at the same time that it improves the cropping practice. The seed should be fumigated with carbon bisulfid to be sure that the pest is not introduced in this way. Early trap-crops may be planted about places where the weevils are likely to hibernate, as about cotton-gins, and sprayed with arsenical poisons ; later the crops are destroyed. Sometimes the weevils are jarred from the trap-crop into pans, and destroyed. Volunteer cotton-plants must be destroyed. Attention must be given to the picking and destroying of infested squares. All rubbish, infested squares that have dropped, stalks remain ing at the end of the season, weeds and litter should be gathered and burned.
Among the diseases attacking the cotton-plant, wilt is controlled by planting disease-resistant seed, the burning and careful destruction of all infested plants, and the rotation of crops. Sore shin, or damping-off, is checked by liming the soil and cultivation to keep the surface mulch dry. It
is caused by excessive dampness. No remedy for anthracnose is known. Red-rust is not serious. Vigorous plants will withstand it. It is usually localized in its attacks. Crop rotation is the most effective means of controlling the root-knot fun gus (see article on "Soil Diseases," Vol. I, page 450). Angular leaf-spot attacks the plants in June and July, forming watery spots on the leaves. The growing of vigorous plants is the best insurance against infestation by it. Leaf-blight is common but not very serious. It forms a tan or light spot, surrounded by irregular reddish spots, on the older or less vigorous leaves. No remedy has been sug gested. Mildew is not serious and no treatment has been found.
Shedding of the bolls is common in unfavor able seasons. Extremes of rain and drought, or their alternation, are the probable causes. The trouble is to be prevented to some extent by maintaining good soil conditions and employing hardier varieties.
Manufacture.
The manufacture of cotton consists of the various processes in the production of thread or yarn and woven fabrics from the fiber. The spin ning of yarn and the manufacture of coarse cotton cloth has been practiced in many parts of the world from a remote period. Until slightly over a century ago, only very rude implements were used, the work being done almost entirely by hand machines. However, the industry has been completely revolutionized, and the enterprise of modern commerce has carried the cheap products of modern machinery to remote sections of the earth, rendering the hand-spun and clumsily woven cloth of earlier periods practically extinct.
There are various steps in the process of spin ning. The loose cotton from the bale is first run through an opener or picker, where it is subjected to the action of a beater, which cleans it from impurities such as broken seed, fragments of leaves, burs and stalks, dirt, and the like, sep arates the individual fibers, and delivers the cot ton at the end of the machine in a uniform layer, called a lap. The lapping machine is fed with three laps at once and the three layers are drawn out to the thickness of one, the object being to neutralize the irregularities of each layer by averaging them with those of two others. From here it goes to the carding, combing and drawing machines, which extract the very short fibers, straighten out the others, and secure a uniform distribution of them in parallel series. It is next drawn through the "slubbing-frame," the "inter mediate frame" and the "roving frame," which draw the "sliver" to a more uniform size and give it a slight twist. It then passes to the last pro cess, the spinning, where it is still more twisted.