Tolerance of kidney beans (Phaseolus vulgaris) to bentazon alone and when mixed with imazamox
Tolerance of Montcalm and Redhawk kidney beans to bentazon, imazamox plus fomesafen and imazamox plus bentazon applied postemergence at the maximum label rate in soybeans and twice that rate were studied at two Ontario locations (Exeter and Ridgetown) in 2001 and 2002. There were no differences between the two cultivars in their response to the herbicides tested. At Exeter in 2001, bentazon reduced plant height by 10 and 12% and yield by 33 and 22% at the label and twice that rate, respectively. Yield was also reduced by 11% at Exeter in 2002 at twice the label rate. Imazamox plus fomesafen reduced plant height equally by 14% and yield was reduced by 22 and 30% at the label rate and twice the label rate, respectively, at Exeter in 2001. Imazamox plus bentazon in Exeter in 2001 reduced plant height equally by 8% and yield by 20 and 14% at the label rate and twice the label rate, respectively. There were no negative effects on plant height, dry weight and yield at the other site-yrs. This research suggests that bentazon, imazamox plus fomesafen and imazamox plus bentazon applied postemergence can cause severe crop injury and yield reduction in kidney bean production under certain environmental conditions. Key words: Bentazon, crop tolerance, fomesafen; imazamox, Montcalm, Phaseolus vulgaris, Redhawk.