Submitted to: Pesticide Management Science
Publication Type: Review Article
Publication Acceptance Date: December 1, 2004
Publication Date: January 19, 2005
Citation: Duke, S.O. 2005. Taking stock of herbicide-resistant crops ten years after introduction. Pesticide Management Science. 61:211-218. Technical Abstract: For several decades, herbicides have made up more than 50% of the agricultural pesticide market, reaching about 70% during the past decade. Since transgenic, bromoxynil-resistant cotton was introduced in 1995, planting of transgenic, herbicide-resistant crops (HRC) has grown substantially, revolutionizing weed management. Before 1995, several commercial HRCs were produced by biotechnology through selection for resistance in tissue culture. This strategy was technically feasible for some herbicides that targeted molecular targets with significant genotypic and phenotypic plasticity (e.g., acetyl-CoA carboxylase), but not for non-selective herbicides, such as glyphosate or glufosinate. Non-transgenic HRCs have had little commercial impact. The advent of transgene technology ushered in glyphosate- and glufosinate-resistant crops. Since the introduction of glyphosate-resistant soybean in 1996, and the subsequent introduction of other glyphosate-resistant crops, where available, they have taken a commanding share of the HRC market, especially in soybean, cotton, and canola. The high level of adoption of glyphosate-resistant crops by North American farmers has significantly reduced the value of the remaining herbicide market. This effect, along with corporate mergers, has reduced the number of new herbicides being commercialized. The future of herbicide use in developed countries is unclear. Introduction and adoption of other HRCs that can be used with other broad-spectrum herbicides has apparently been hindered by the great success of glyphosate-resistant crops. Evolution of glyphosate-resistant weeds and movement of naturally-resistant weed species into glyphosate-resistant crop fields will require increases in the use of other herbicides, but the speed with which these processes compromise the use of glyphosate alone is uncertain. The effects of this situation, as well as lack of European acceptance of transgenic HRCs, on herbicide discovery and research on other strategies for weed management will be discussed.