Cotton

Cotton, subtropical plant (genus Gossypium) grown for the soft white fibers attached to its seed, which can be woven into fabric, also called cotton. Examples of woven cotton cloth dating to 3000 B.C. have been found at Mohenjo-Daro, in what is now Pakistan. Samples of prehistoric cotton have also been found in Pueblo ruins in Arizona, and some cotton fabric made before the Inca civilization still is in existence. Despite competition from synthetic fibers, cotton is one of the world's most important crops. Although the proportion grown in the United States has declined sharply, the United States has more than 11 million acres (4.5 million hectares) planted with cotton, producing about 10 million bales per year. Cotton requires about 200 days of warm, sunny weather and 25–30 in (63.5–76 cm) of rain. It is generally cultivated as an annual plant. When the pods, or bolls, burst to reveal the white fibers (lint) within them, the cotton is ready for harvesting. Since the bolls burst at different times, a field may have to be picked several times during the season.

Each cotton fiber is an elongated plant cell made up of 90% cellulose. Unlike other natural fibers, the cotton fiber has 200–400 twists per inch (500–1,000 twists per cm) along its length. These give it excellent spinning characteristics. The quality of cotton is measured in terms of the length and fineness of the lint. Egyptian-type cotton, grown mainly in Egypt, the Sudan, and Aden, is the finest, producing long fibers (more than 1 1/8 in/2.9 cm) that are strong and silky. It commands the highest prices, but constitutes only about 5% of world production. About 95% of U.S. cotton yields fibers between 7/8 in and 1 1/8 in (2.2 cm and 2.9 cm) long, and perhaps 73% of the world crop produces this fiber length. Cotton is prone to many pests and diseases that cause enormous damage to the crop (averaging nearly $300 million in the United States every year). The main insect pests are the boll weevil in the United States and the pink boll worm in India and Egypt. Destructive fungus diseases that attack the plant include fusarium and verticillium wilt and Texas root rot.