Response of Chickpea Cultivars to Imidazolinone Herbicide Applied at Different Growth Stages

POST broadleaf weed control options in chickpea are very limited on the Northern Great Plains. Field experiments were conducted in 2012 and 2013 in Saskatchewan to evaluate the response of chickpea cultivars to imidazolinone (IMI) herbicides applied at different growth stages. Conventional cultivars 'CDC Luna' and 'CDC Corinne' were compared with IMI-resistant cultivars 'CDC Alma' and 'CDC Cory'. Treatments comprised a combination of imazethapyr+imazamox herbicides at 30 and 60 g ai ha(-1) (13 and 23 rates, respectively) applied at the 2 to 4-, 5 to 8-, and 9 to 12-node growth stages. Visual injury estimates were. 50% for CDC Luna and CDC Corinne for all growth stage applications. Conventional cultivars also experienced height reduction and decreased rate of node development compared with the nontreated controls. Flowering and maturity of CDC Luna and CDC Corinne were delayed for herbicide applications at all growth stages; however, application at the 9 to 12-node stage caused the most severe delay. All treatments of IMI herbicide caused yield reduction in the conventional cultivars in 2013. In contrast, IMI-resistant cultivars CDC Alma and CDC Cory demonstrated no negative response at any growth stage of IMI herbicide application. Visual injury estimates were negligible, and height, node development, days to flowering, maturity, and yield did not differ significantly between IMI-treated plants and the respective controls. These results demonstrated the potential of in-crop use of IMI herbicide on resistant chickpea cultivars to control broadleaf weeds.