Location: Water Management and Systems Research
Title: Lessons Learned From the History of Herbicide Resistance Author
|Shaner, Dale -|
Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 23, 2013
Publication Date: N/A
Interpretive Summary: Herbicide resistance in weeds is becoming an increasing problem. Management practices will need to be changed to lessen the dependence on herbicide to reduce the selection pressure on weed populations by the herbicides. This paper reviews the history of the selection of herbicide resistance since the introduction of herbicides in the 1950s. Understanding how we got into our current situation is vital to developing new methods for managing weeds.
Technical Abstract: The selection of herbicide resistant weed populations began with the introduction of synthetic herbicides in the late 1940s. For the first 20 years after introduction, there were limited reported cases of resistance. This changed in 1968 with the discovery of triazine resistant common groundsel. Over the next 15 years the cases of herbicide resistant weeds increased, primarily to triazine. Although triazine resistance was serious, the resistant biotypes were highly unfit and were easily controlled with alternative herbicides. Weed scientists thought that this would be the case for future herbicide resistant cases and there was not much concern, although the companies affected by triazine resistance were active in trying to detect and manage resistance. It was not until the late 1980s with the discovery of resistance to Acetyl Co-A carboxylase (ACCase) and acetolactate synthase (ALS) inhibitors that herbicide resistance attracted much more attention, particularly from industry. The rapid evolution of resistance to these classes of herbicides affected many companies, who responded by first establishing working groups to address resistance to specific classes of herbicides and then the Herbicide Resistance Action Committee (HRAC). The goal of these groups was to act as a forum for the exchange of information on herbicide resistance selection and to develop guidelines for managing resistance in cooperation with academia and governmental agencies. Despite these efforts, resistance continued to increase. The introduction of glyphosate resistant crops in the 1995 provided a brief respite from herbicide resistance, and farmers rapidly adopted this relatively simple and reliable weed management system. There were many warnings by academia and some companies that the glyphosate resistant cropping system was not sustainable, but this advice was not heeded. The selection of glyphosate resistant weeds dramatically changed weed management in multiple areas and renewed emphasis on herbicide resistance management. The lesson learned from our experience with herbicide resistance is that no herbicide is invulnerable to selecting for resistance and that over-reliance on a weed management system based solely on herbicides is not sustainable. Hopefully we have learned that a diverse weed management program that combines multiple methods is the only system that will work for the long term.