A Field experiment was conducted during Kharif season of 2021 under custard apple based agri-horti system, at agricultural farm of Rajiv Gandhi South Campus, BHU, Barkachha, Mirzapur to study the effect of herbicide on Cyperus rotundus. The experiment was carried out in randomized block design (RBD) having seven treatments replicated thrice. Application of different doses of pyroxasulfone as company sample (GSP sample) were compared with pyroxasulfone 85%WG (Market sample) 150 ml/ha, imazethapyr 1000 ml/ha, hand weeding at 20 and 40 DAS and weedy check. Application of pyroxasulfone 85%WG (GSP sample) 187.5 ml/ha, significantly reduced the density and dry weight of C. rotundus with least weed effectiveness (WE) and highest weed control efficiency (WCE) and crop resistance index (CRI). Compared to the other treatments, application of pyroxasulfone 85%WG (GSP sample) 187.5 ml/ha produced maximum net returns and hence proved to be more effective.