Seletividade e eficácia de herbicidas aplicados na cultura da cevada para o controle de plantas daninhas

Abstract

Ryegrass, white and black oats, and turnip are weeds that cause high productivity losses when infesting barley crops, requiring adequate control. In this study, we aimed to evaluate the effectiveness and selectivity of herbicides applied to the barley cultivar BRS Cauê for weed control. Two field experiments were conducted in randomized blocks with four replications. The treatments used were oxyfluorfen (600 g ha -1 ), pendimethalin (800 g ha -1 ), and flumioxazin (50 g ha -1 ) applied in pre-emergence, and iodosulfuron (5.0 g ha -1 ), pyroxsulam (18 g ha -1 ), metsulfuronmethyl (4.0 g ha -1 ), and clodinafop-propargil (60.0 g ha -1 ) applied in post-emergence treatment of the species, plus two witnesses, one weeded and the other infested. Variables such as ear length, whole grains, empty grains, number of ears, final weight, and productivity were evaluated. The oxyfluofen herbicide applied alone in preemergence or associated with post-emergence, iodosulfuron, pyroxsulam, metsulfuron-methyl, and clodinafop-propagyl caused the highest phytotoxicity to barley cultivar BRS Cauê. In general, the application of flumioxazin + metsulfuron-methyl showed the most significant damage to the physiological variables of the barley cultivar BRS Cauê. The use of oxyfluorfen, pendimethalin, and flumioxazin in preemergence and associated with clodinafop-propargyl in post-emergence resulted in the best controls of ryegrass and oats, from the beginning to the end of the weed cycle. The best turnip control was obtained with the pre-emergence application of oxyfluorfen and combined with iodosulfuron-methyl and pyroxsulam herbicides in postemergence. Both in the selectivity and efficacy experiment, the treatment that stood out with the best effects on barley grain yield components, cultivar BRS Cauê, was flumioxazin+iodosulfuron-methyl.