Efeito da época de aplicação de herbicidas sulfonilureias no controle de azevém anual na cultura do trigo

The adoption of weed management practices is one of the main tools that can contribute to increased grain yield in wheat crops. This study has aimed to evaluate the efficiency of the chemical group of the sulfonylurea herbicides, alone and in combination, at different times of the application, on the productivity of wheat cultivars, and control of annual ryegrass ( Lolium multiflorum L . ). The design was randomized blocks with 5 repetitions. The treatments were arranged in a 4 x 2 x 2 factorial design consisting in applying metsulfuron-methyl and iodosulfuron-methyl, alone and in combination, and control, using two commercial cultivars of wheat (Quartzo and BRS Tangara) in two application periods, 21 and 30 days after application. Cultivars phytointoxication, the level of control of annual ryegrass and the performance of agronomic traits of wheat crops were evaluated. For the control of annual ryegrass, it was found that there is a difference when using sulfonylurea herbicides, and iodosulfuron-methyl in use alone and in combination with metsulfuron-methyl is efficient in control. The application of iodosulfuron-methyl (5.0 g a.i. ha -1 ) and metsulfuron-methyl (2.4 g a.i. ha -1 ) + iodosulfuron-methyl (5.0 g a.i. ha -1 ) at 30 days after sowing resulted in higher productivity of wheat grains.