A field experiment was conducted at Tirhut College of Agriculture, Dholi, (RAU, Samastipur, Bihar) for two consecutive years (2012-13 and 2013-14) to evaluate the efficacy of Halosulfuron methyl to control the Cyperus rotundus in Maize. The treatments consisted of new herbicide Halosulfuron methyl (75% WG) @ and g , applied at 3-4 leaf stage of Cyperus rotundus and compared with recommended 2,4-D Ethyl Ester 38% EC (900 g ), Atrazine 50% WP (500 g ) and two hand weedings at 18 and 30 DAS with untreated control. | Halosulfuron methyl 75 WG Sempra A new herbicide for the control of cyperus rotundus in maize Zea mays L. crop in Bihar