Glyphosate resistance was first reported in 1996 from rigid ryegrasss in an orchard in Australia. Subsequently, several additional glyphosate-resistant weed populations have been identified: rigid ryegrass in a wheat production system in Australia and in California; Italian ryegrass in Chile; goosegrass in Malaysia; and horseweed (marestail) in the eastern, midwestern, and southeastern United States. The resistance mechanism in goosegrass is due to an altered target site, whereas the mechanism in the other weeds is under investigation.
Iowa State University
Hartzler, Robert G. and Owen, Michael D., "Status and concerns for glyphosate resistance" (2003). Integrated Crop Management News. 1687.
The Iowa State University Digital Repository provides access to Integrated Crop Management News for historical purposes only. Users are hereby notified that the content may be inaccurate, out of date, incomplete and/or may not meet the needs and requirements of the user. Users should make their own assessment of the information and whether it is suitable for their intended purpose. For current information on integrated crop management from Iowa State University Extension and Outreach, please visit https://crops.extension.iastate.edu/.