Cotton: clothing the world, naturally

Cotton is one of the world’s major crops and particularly important to the economies of many developing countries. Cotton itself is a fibre which protects the seed of the cotton plant, much as the flesh of an apple protects the pips. So, fruit are not only for eating. The crop has been at the forefront of the revolution in biotechnology, being the second genetically modified (GM) crop to be introduced in broadacre agriculture after soybeans in 1997.

One of the main traits in GM cotton is tolerance to applications of the non-selectiveDescription A chemical product used for eliminating all types of weeds (annual and perennial grasses and broadleaved weeds). Authoritative On-line References and Resources http://www.weeds.iastate.edu/ An invaluable source of contemporary information about herbicides and weeds from Iowa State University. herbicide glyphosate. The choice of herbicide resistance as an early target for biotechnology research indicates the importance of effective weed control in cotton. Although herbicide tolerant cotton has many advantages, it has contributed to enormous increases in the use of glyphosate and the consequent problem of glyphosate resistant weeds.

Paraquat is the alternative non-selective herbicide which can provide solutions to these weed control problems. Using paraquat can also address a number of environmental issues concerned with cotton growing, including soil erosionDescription Displacement of solids (soil, mud, rock and other particles) usually by the agents of currents such as, wind, water, or ice by downward or down-slope movement. Authoritative On-line References and Resources http://soilerosion.net/ This site brings together reliable information on soil erosion from a wide range of disciplines and sources. It aims to be the definitive internet source for those wishing to find out more about soil loss and soil conservation. and degradation, water contamination by run-offDescription The occurrence of surplus liquid (like rain) which originates up-slope and is collected beyond the ability of the soil to absorb it. The surplus liquid then flows away over the surface to reach the nearest surface water (pond, lake, river). Authoritative On-line References and Resources http://www.sowap.org/index.htm SOWAP (Soil and Water Protection) is a collaboration between industry, NGOs, universities and farmers to test a range of site-specific soil management methods, based on the concept of conservation tillage. It has looked at economic and environment aspects including effects on soil erosion and run-off. and leaching of agrochemicals, and loss of habitats and effects on biodiversityDescription The variety of life in all its forms, levels and combinations. Includes ecosystem diversity, species diversity, and genetic diversity (IUCN, UNEP and WWF, 1991). Authoritative On-line References and Resources http://earthtrends.wri.org/ EarthTrends is a comprehensive online database, maintained by the World Resources Institute, that focuses on environmental, social, and economic trends. Statistics on biodiversity indicators are available..

Paraquat can be used from preparing fields for planting to conditioning crops for harvest. Using paraquat with its distinctive mode of action in integrated weed managementDescription A decision support system for crop protection which focuses on long-term prevention or suppression of pest problems with minimum impact on human health, the environment, and non-target organisms. IPM takes into consideration all available pest control techniques and tactics (cultural, mechanical, biological, chemical). IPM emphasizes the growth of healthy crops for better productivity with the least possible disruption to agroecosystems. Authoritative On-line References and Resources http://www.ipmcenters.org "The USDA's National Site for the Regional IPM Centers' Information System provides information about US commodities, pests and pest management practices, people and issues." systems is helping to avoid problems of weed shiftsDescription A change in the weed community within a field i.e. relative abundance or type of weeds. This can be the result of a management practice like herbicide use or any other phenomenon that brings about a change in weed species composition. Species or biotypes adapted to current weed management practices increase, whereas weeds susceptible to those practices decrease. Authoritative On-line References and Resources http://www.weeds.iastate.edu/mgmt/qtr00-1/popdyn.htm A classic article on weed population dynamics on the Iowa State University Weed Science website. and resistance. Paraquat is deactivated on contact with the soil meaning that it can be sprayed to burndown weeds before planting a cotton crop without risking damage to that crop or subsequent crops in the rotation. There are no leaching, persistence or root uptake problems to restrict its use. Paraquat works well even in cold and rainy weather making it suitable for use early in the season to control weeds in conservation tillageDescription Any tillage and planting system that covers 30 percent or more of the soil surface with crop residue after planting to reduce soil erosion by water. Authoritative On-line References and Resources http://www2.ctic.purdue.edu/Core4/CT/Definitions.html Core4Conservation is part of the Purdue University-based Conservation Tillage Information Centre. systems. These systems do not rely on ploughing to control weeds. Not disturbing the soil helps prevent erosion and maintains a healthy soil.

Although paraquat is a non-selective herbicide, if small amounts land on leaves there is little or no crop damage because paraquat does not move through plants systemically like glyphosate. So, paraquat can be used for inter-row weed control to remove weeds growing between the crop rows. Paraquat can also be used effectively and safely as a harvest aid to avoid green leaves staining the cotton lint, to control entangled weeds and speed harvest by cotton pickers.