Evaluation of herbicide combinations for controlling complex weed flora in wheat

Abstract

A field experiment was conducted during the Rabi seasons of 2014–15 and 2015–16 on a silty clay loam soil at Palampur. Avena ludoviciana (36.3%), Phalaris minor (27.5%), Lolium temulentum (13.9%), Anagallis arvensis (10%) and Coronopus didymus (6.9) were the major weeds. Herbicide combinations (pendimethalin 1.0 kg/ha + metribuzin 175 g/ha, pendimethalin 1.0 kg/ha fb sulfosulfuron 18 g/ha, sulfosulfuron 20 g/ha + metsulfuron 4 g/ha, pinoxaden 60 g/ha + metsulfuron 4 g/ha, clodinafop 60 g/ha + metsulfuron 4 g/ha, isoproturon 1.0 kg/ha + 2, 4-D 0.5 kg/ha) were superior to sole application of herbicides (pendimethalin 1.25 kg/ha, sulfosulfuron 25 g/ha, metribuzin 210 g/ha and clodinafop 60 g/ha) in reducing weed count and dry weight and increasing plant height, number of tillers, crop dry matter, yield attributes and yield of wheat. Clodinafop + metsulfuron, pinoxaden + metsulfuron and pendimethalin fb metsulfuron being better than other combinations gave 28.6, 22.5 and 23.1% higher grain yield of wheat over hand weeding twice. Weeds reduced the grain yield by 51.9%. With unit increase in weed count per m2, the wheat grain yield was decreased by 13.3 kg/ha. The cost of weed control under herbicidal treatments was 9.0–28.9% of that under hand weeding lowest being under metribuzin and highest under pendimethalin fb sulfosulfuron. Clodinafop + metsulfuron gave the highest net returns due to weed control and marginal benefit: cost ratio (MBCR). Clodinafop + metsulfuron resulted in highest weed control efficiency (WCE), weed control index (WCI), crop resistance index (CRI), treatment efficiency index, crop intensity index and weed index. Weed management index, agronomic management index and integrated weed management index were highest under sulfosulfuron followed by clodinafop + metsulfuron. Based on overall impact index clodinafop + metsulfuron, pinoxaden + metsulfuron, sulfosulfuron + metsulfuron, pendimethalin fb sulfosulfuron and pendimethalin + metribuzin were recommended for effective weed management in wheat under mid hill conditions of Himachal Pradesh.