Glyphosate and acetolactate synthase inhibitor resistant common ragweed (Ambrosia artemisiifolia L.) in southwestern Ontario

Van Wely, A. C., Soltani, N., Robinson, D. E., Hooker, D. C., Lawton, M. B. and Sikkema, P. H. 2015. Glyphosate and acetolactate synthase inhibitor resistant common ragweed (Ambrosia artemisiifolia L.) in southwestern Ontario. Can. J. Plant Sci. 95: 335–338. Common ragweed (Ambrosia artemisiifolia L.) was found to be resistant to glyphosate in Ontario. Field surveys were conducted from 2011 to 2013 to determine the distribution of glyphosate-resistant (GR) and acetolactate synthase inhibitor resistant common ragweed. GR common ragweed was confirmed in Essex County. All GR populations were found to be resistant to acetolactate synthase-inhibiting herbicides.