Evaluation of Preemergent Herbicides for Chloris virgata Control in Mungbean

Chloris virgata is a problematic weed in mungbean crops due to its high seed production, resistance to glyphosate and high dispersal ability. Pot and field experiments were conducted in 2020 and 2021 to evaluate a range of preemergent (PRE) herbicides for C. virgata control in mungbean. In the field and pot studies, isoxaflutole 75 g ai ha^-1 caused crop injury, and in the field experiment, it reduced mungbean yield by 61% compared with the best treatment (pyroxasulfone 100 g ai ha^-1). In the field and pot experiments, dimethenamid-P 720 g ai ha^-1, pyroxasulfone 100 g ai ha^-1 and S-metolachlor 1400 g ai ha^-1 provided >88% control of C. virgata (for reduced biomass) and in the field experiment, these herbicides resulted in improved yield by 230%, 270% and 170%, respectively, compared with nontreated control (250 kg ha^-1). Similarly, pendimethalin 1000 g ai ha^-1 and trifluralin 600 g ai ha^-1 provided >89% control (biomass) of C. virgata, and in the field experiment, these resulted in improved yields of 230% and 160%, respectively, compared with the nontreated control. PRE herbicides such as diuron 750 g ai ha^-1, linuron 1100 g ai ha^-1, metribuzin 360 g ha^-1, terbuthylazine 750 g ai ha^-1, imazapic 48 g ai ha^-1 and imazethapyr 70 g ha^-1 although did not cause crop injury; however, these herbicides did not control C. virgata. Flumioxazin 90 g ai ha^-1 caused reduced biomass of C. virgata by 80% compared with the nontreated control, and in the field experiment, it resulted in improved yield by 140% compared with the nontreated control. This study suggests the potential use of herbicides, such as dimethenamid-P, pyroxasulfone and S-metolachlor in addition to pendimethalin and trifluralin, for C. virgata control in mungbean. Further studies are needed to determine the efficacy of dimethenamid-P, S-metolachlor and pyroxasulfone for controlling other troublesome weeds in mungbean.