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Title: What have the mechanisms of resistance to glyphosate taught us?

Author
item Shaner, Dale
item LINDERMEYER, BRADLEY - Colorado State University
item OSTLIE, MICHAEL - Colorado State University

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/24/2011
Publication Date: 8/12/2011
Citation: Shaner, D.L., Lindermeyer, B., Ostlie, M. 2011. What have the mechanisms of resistance to glyphosate taught us? Pest Management Science. 68:3-9.

Interpretive Summary: Glyphosate resistant weeds are a serious problem facing farmers who use glyphosate-resistant crops. Glyphosate resistance has been selected in 21 species world wide and there are multiple mechanisms of resistance that have been selected including alterations of the target site and reduced translocation. In this paper, we review the different mechanisms of glyphosate resistance that have been discovered and suggest how this information can be used to better manage glyphosate to retain it’s utility as well as how we can use our experience from the selection of glyphosate resistance to manage new herbicide resistant crops that are being developed as well as new herbicide mechanisms of action that will be discovered in the future.

Technical Abstract: The intensive use of glyphosate alone to manage weeds has selected populations that are glyphosate resistant. The three mechanisms of glyphosate resistance that have been elucidated are 1) target site mutations; 2) gene amplification; and 3) altered translocation due to sequestration. What have we learned from the selection of these mechanisms, and how can we apply those lessons to future herbicide resistant crops and new mechanisms of action? First, the diversity of glyphosate resistance mechanisms has helped further our understanding of the mechanism of action of glyphosate and advanced our knowledge of plant physiology. Second, the relatively rapid evolution of glyphosate resistant weed populations provides further evidence that no herbicide is invulnerable to resistance. Third, as new herbicide resistant crops are developed and new mechanisms of action are discovered, the weed science community needs to ensure that we apply the lessons we have learned on resistance management from the experience with glyphosate. Every new weed management system needs to be evaluated during development for its potential to select for resistance and stewardship programs should be in place when the new program is introduced.