Survey of glyphosate-resistant kochia (Kochia scoparia L. Schrad.) in Alberta

Abstract

Glyphosate-resistant (GR) kochia was identified in Warner county in southern Alberta in 2011. To determine the scale of the distribution and frequency of GR kochia, a randomized stratified survey of more than 300 locations (one population per location) in southern Alberta was conducted in the fall of 2012. Mature plants were collected, seed separated, and F1 seedlings screened by spraying with glyphosate at 900 g a.e. ha-1 under greenhouse conditions. Screening confirmed 13 GR kochia sites: seven in Warner county, five in Vulcan county, and one in Taber county. The frequency of GR individuals in a population ranged from 0.3 to 98%. GR kochia were found in arid areas where chemical fallow is a significant component of the rotation. Economic and agronomic impact of this GR weed biotype is compounded because of multiple resistance to acetolactate synthase-inhibiting herbicides.