Selectivity and efficacy of herbicides applied on barley for weed control

Abstract

Ryegrass and turnip are weeds that cause high yield losses when infesting barley, thus requiring adequate management. In this context, the aim of this study was to evaluate the selectivity of different herbicide treatments and weed control in the barley crop, cultivar BRS Cauê. Two field experiments were conducted in randomized blocks, with four replications. The treatments used were: pendimethalin (800 g•ha -1 ), sulfentrazone + diuron (175 + 350 g•ha -1 ), and imazaquim (150 g•ha -1 of a. e.) applied pre-emergence; and iodosulfuron (3.5 g•ha -1 ), pyroxsulam (18 g•ha -1 ), metsulfuron-methyl (3.96 g•ha -1 ), 2,4-D (670 g•ha -1 of a. e.), clodinafop-propargyl (48 g•ha -1 ), bentazon + imazamox (600 + 28 g•ha -1 ), saflufenacil (49 g•ha -1 ), bentazon (720 g•ha -1 ), carfentrazone-ethyl (120 g•ha -1 ), and imazamox (42 g•ha -1 ) applied post-emergence, with two controls (one weeded and the other infested). The use of the herbicide imazaquim caused high levels of phytotoxicity in barley. Gas exchange was less responsive to herbicide applications in relation to barley phytotoxicity and productivity.Clodinafop-propargil showed the best control of ryegrass, while the herbicides iodosulfuron, pyroxsulam, metsulfurom-methyl, 2,4-D, bentazon + imazamox, saflufenacil, bentazon, carfentrazone-ethyl, and imazaquim showed high efficiency in the control of turnip species. Imazaquim caused reduction of up to 74.7% in barley grain yield. On the other hand, iodosulufuron and piroxsulam allowed the highest grain yields of the barley cultivar, BRS Cauê, by promoting partial control of ryegrass and total control of turnip species, followed by clodinafop-propargyl and metsulfuron-methyl, which controlled ryegrass and turnip, respectively, allowing an increase in yield grain in relation to the infested control.