Controle de plantas daninhas com herbicidas alternativos na cultura do trigo

Abstract

Among the biotic factors that affect the productivity and quality of harvested wheat grains, weeds stand out. These species can compete with the crop for water, light, and nutrients, reducing productivity and increasing production costs, which in turn reduces the grower's profit margin. Thus, the objective of this work was to evaluate the selectivity and efficacy of herbicides used pre-emergence and post-emergence for weed control in wheat crops. Two trials experiments were set up, one to evaluate selectivity and the other to evaluate efficacy of herbicides applied to wheat in randomized blocks of four replicates. The pre- emergence herbicides applied were imazethapyr + flumioxazin (106 + 50 g ha-1 ), pendimethalin (800 g ha1 ) and flumioxazin (50 g ha-1 ). Iodosulfuron - methyl (5 g ha-1 ), pyroxsulam (18 g ha-1 ), metsulfuron-methyl (4 g ha-1 ), and clodinafop-propargyl (60 g ha-1 ) were applied in the postemergence of the species and two witnesses, one with weed and one with infestation. The herbicides that exhibited the highest phytotoxicity to the wheat cultivar TBIO Sinuelo were the commercial mixture of imazethapyr + flumioxazin and associated post-emergence applications of iodosulfuron-methyl, pyroxsulam, metsulfuron-methyl, and clodinafop-propargyl. In general, the application of imazethapyr + flumioxazin + metsulfuron-methyl showed the least damage to the physiological variables of wheat. Pre- emergence application of imazethapyr + flumioxazin and post-emergence application of iodosulfuron-methyl, pyroxsulam and metsulfuron - methyl resulted in the best control of beet weeds of wheat. The use of pendimenthalin and flumioxazin in combination with clodinafop- propargyl showed the best control of ryegrass. The treatments imazethapyr + flumioxazin, imazethapyr + flumioxazin + iodosulfuron-methyl, pendimenthalin + iodosulfuron-methyl, flumioxazin + iodosulfuronmethyl, imazethapyr + flumioxazin + pyroxsulam, pendimenthalin + pyroxsulam, flumioxazin + pyroxsulam, imazethapyr + flumioxazin + clodinafop – propargyl, and flumioxazin + clodinafop-propargyl were most effective in controlling the wheat weed black oat. In both trials, pendimenthalin + iodosulfuron-methyl was the treatment that showed the best effects on wheat grain yield components in terms of selectivity and efficacy.