The efficacy of mesotrione+nicosulfuron (OD 10.5%) and bentazon+MCPA (SL 46%), two new herbicides, in comparison with some commonly used herbicides in the control of broad-leaved weeds of corn

Field experiments were conducted to evaluate the efficacy of mesotrione+nicosulfuron and bentazon+MCPA, two new herbicides, in the control of broad-leaved weeds of corn in Alborz, Fars and Kermanshah provinces in 2018. The treatments consisted of mesotrione+nicosulfuron at three doses of 0.7, 1 and 1.3 L ha-1, bentazon+MCPA + weeding grass species at three doses of 1.5, 2 and 2.5 L ha-1, mesotrione+s-metolachlor+terbuthylazine at 4.5 L ha-1, nicosulfuron at 2 L ha-1, bromoxynil+MCPA at 1.5 L ha-1 + weeding grass species, rimsulfuron+nicosulfuron at 175 g ha-1, nicosulfuron at 2 L ha-1 + bromoxynil+MCPA at 0.5 L ha-1 and hand weeding control. Density and dry weight of weeds were evaluated 45 days after spraying. The results showed that mesotrione+s-metolachlor+terbuthylazine, nicosulfuron + bromoxynil+MCPA and bromoxynil+MCPA were the most effective herbicides (efficacy>85%) in control of broad-leaved weeds in all the studied provinces. Also, nicosulfuron and rimsulfuron+nicosulfuron controled broad-leaved weeds most effectively (by roughly 90% reduction in weeds dry weight) in Fars and Alborz provinces. The efficacy of 2.5 L ha-1 bentazon+MCPA in Fars and Alborz provinces were over than 85%, while this treatment led to 70% to 85% weeds control in Kermanshah province. The efficacy of none of the applied rates of mesotrione+nicosulfuron did not lead to a satisfactory control of broad-leaved weeds compared to the commonly used herbicide treatments. Moreover, bromoxynil+MCPA, nicosulfuron + bromoxynil+MCPA and manual weeding in Kermanshah and nicosulfuron in Fars resulted in the highest increase in corn grain yield by approximately 122% and 211% compared to the untreated control, respectively.