Gossypium

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For information on the history and uses of cotton fibre, see cotton.

Gossypium

Gossypium barbadense

Scientific classification

Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Malvales
Family:	Malvaceae
Genus:	Gossypium L.

Species

See text.

Gossypium is a genus of 39-40 species of shrubs in the family Malvaceae, native to the tropical and subtropical regions of both the Old World and the New World. The cotton plants, sources of commercial cotton fabric, are included in this genus.

Cotton shrubs can grow up to 3 m (10 ft) high. The leaves are broad and lobed, with three to five (or rarely seven) lobes. The seeds are contained in a capsule called a boll, each seed surrounded by downy fibres called lint. Commercial species of cotton plant are G. hirsutum (90% of world production), G. barbadense (8%), G. arboreum and G. herbaceum (together, 2%). While the lint (fiber) naturally occurs in colors of white, brown, and green, fears of contaminating the genetics of white cotton has led many cotton-growing locations to ban growing of coloured cotton varieties.

1 Species of Gossypium
2 Cotton pests and diseases
- 2.1 Pests
- 2.2 Diseases
3 Genetically modified cotton
4 Organic cotton
5 External link

[edit] Species of Gossypium

Commercial cotton species

Commercial cotton fibres, used to manufacture cloth, are derived from the fruit of the cotton plant. The following species are grown commercially:

Gossypium arboreum L. – Tree cotton, native to southern India.
Gossypium barbadense L. – known as American Pima, Creole, Egyptian, or Sea island cotton, native to tropical South America.
Gossypium herbaceum L. – Levant cotton, native to southern Africa
Gossypium hirsutum L. – Upland cotton, native to Central America, Mexico, the Caribbean and southern Florida - most commonly grown species in the world.

Non-commercial species

Gossypium australe F.Muell – Endemic to north-western Australia
Gossypium darwinii - Darwin's cotton, found only on the Galapagos Islands
Gossypium sturtianum J.H. Willis – Sturt's Desert Rose, native to Australia.
Gossypium thurberi Tod. – Arizona wild cotton, native to Arizona and northern Mexico.
Gossypium tomentosum Nutt. ex Seem – Ma‘o or Hawaiian cotton, endemic to the Hawaiian Islands.

Cotton field in Sukhum Botanical Garden, photo ca. 1912

[edit] Cotton pests and diseases

[edit] Pests

Boll weevil, Anthonomus grandis
Cotton aphid, Aphis gossypii
Cotton bollworm, Helicoverpa armigera, and native budworm Helicoverpa punctigera are caterpillars that damage cotton crops.

Some other Lepidoptera larvae also feed on cotton - see list of Lepidoptera which feed on Cotton plants.

Green mirid (Creontiades dilutus), a sucking insect
Spider mites, Tetranychus urticae, T. ludeni and T. lambi
Thrips, Thrips tabaci and Frankliniella schultzei

[edit] Diseases

Alternaria leaf spot, caused by Alternaria macrospora and Alternaria alternata
Anthracnose boll rot, caused by Colletotrichum gossypii
Black root rot, caused by the fungus Thielaviopsis basicola
Blight caused by Xanthomonas campestris pv. malvacearum
Fusarium boll rot caused by Fusarium spp.
Phytophthora boll rot, caused by Phytophthora nicotianae var. parasitica
Sclerotinia boll rot, caused by fungus Sclerotinia sclerotiorum

[edit] Genetically modified cotton

Genetically modified (GM) cotton was developed to reduce the heavy reliance on pesticides. GM cotton is widely used throughout the world with claims of requiring up to 80% less pesticide than ordinary cotton. The International Service for the Acquisition of Agri-Biotech Applications (ISAAA) said that worldwide GM cotton was planted on an area of 67,000 km² in 2002. This is 20% of the worldwide total area planted in cotton. The US cotton crop was 73% GM in 2003.

The initial introduction of GM cotton proved to be a commercial disaster in Australia - the yields were far lower than predicted, and the cotton plants were cross-pollinated with other varieties of cotton. However the introduction of a second variety of GM cotton led to 15% of Australian cotton being GM in 2003 with 80% of the crop being GM in 2004 when the original variety was banned.

[edit] Organic cotton

Organic cotton is cotton grown without pesticides or chemical additives to fertiliser, relying instead on methods with less ecological impact. Organic cotton is used to manufacture everything from handkerchiefs to kimono robes. Different levels of certification exist, but at a minimum, a crop must be grown in soil that has been chemical-free for at least three years.