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Why Bt Cotton - Pros and Cons

Bt cotton offers an opportunity to reduce use of pesticides more hazardous than the toxins produced by the Bacillus thuringiensis (Bt) bacterium. What are the risks associated with using it? What are the benefits?

Some Potential Positives

Reduced pesticide use, leading to
  • Lowered risk of poisoning people who apply pesticides or work in the fields.
  • Less danger to wildlife and environment, and fewer beneficial insects harmed.
  • Lower costs, since fewer pesticide applications may be needed
Acquiring definitive data on any of the above is often difficult.
The following table is created from the USDA, National Agricultural Statistics Service data, showing use of pesticides on cotton (both Bt and non-Bt). Since its introduction in 1996, Bt cotton use rapidly grew to 50 to 70% of cotton acreage in Arizona. Its use has coincided with a dramatic downward trend in insecticide use in Arizona cotton (Figure below). However, two new insect growth regulators were also introduced for whitefly control in 1996. Thus, the striking reductions in insecticide use in Arizona cotton since 1995 are attributable to both Bt cotton and the new, selective, whitefly controls.
graph showing decline of pesticide use from over 6 to less than 2 applications per growing season

Another estimate of insecticide use in Bt and non-Bt cotton from 1994 to 2001 can be found at:
http://cals.arizona.edu/crops/cotton/insects/cil/btconvcharts.html The methods used in collecting these data differ, Though the numbers do not exactly match, they are in the same range.

Some Potential Negatives

  • Risk of losing, via pesticide resistance, a valuable pesticide currently used in organic and conventional agriculture
  • Risk of losing markets if transgenic crops are not accepted by governments, buyers, and/or consumers
  • Possible financial or other damage to other growers intent on growing non-Bt cotton if Bt cotton contaminates their fields and they have difficulty selling their commodity profitably
  • Risk of outcrossing with native plants
  • Risk of development of adverse monopolies in agriculture
  • Risk of prolonging a crop that is inappropriate for desert ecosystems

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document located at: http://cals.arizona.edu/crops/cotton/btcotton/
The Department of Entomology
College of Agriculture and Life Sciences
The University of Arizona
Contact: BtCotton@ag.arizona.edu or Al Fournier (fournier@ag.arizona.edu)
All contents copyright ©2002. All rights reserved.
Last modified November 13, 2003