Eficácia de herbicidas em condições controladas para o controle de gramíneas infestantes de canaviais em estiagem

Chemical control of weeds in sugarcane crop may be performed in dry season, mainly due to agricultural operations planning, and logistics in relation to the use of equipment and labor. This study aimed to evaluate the agronomic efficacy of herbicides for controlling sugarcane grass weeds by using different periods of water restriction. Evaluated weeds were Digitaria nuda , Panicum maximum and Brachiaria decumbens . Herbicides treatments applied in total pre-emergency condition were: diuron + hexazinone + sulfometuron-methyl (1387 + 391 + 33.35; 1507.5 + 425 + 36.25 1658.25 + 467.5 + 39.87 and 1809 + 510 + 43.5 g a.i. ha -1 ; amicarbazone (1190 g a.i. ha -1 ); amicarbazone + isoxaflutole (840 + 82.5 g a.i. ha -1 ) and an check without application. After application, plots were submitted to 0, 30, 60 and 90 days of water restriction. Control visual evaluations were performed 28 days after humidity restoration, with the weeds biomass determination. All studied doses of diuron + hexazinone + sulfometuron-methyl were effective in controlling the plants studied in all water restriction periods. Amicarbazone sprayed alone was not efficient on weeds control under the condition of 60 days with water restriction. Amicarbazone + isoxaflutole presented satisfactory weeds control, except for Digitaria nuda , in 60 days of water restriction.