Two experiments were carried out to evaluate the susceptibility of Brachiaria subquadripara and Brachiaria mutica to different herbicides applied in post-emergence. The herbicides and doses used were: glyphosate (Rodeo) at 2,400, 3,360 and 4,320 (g a.e. ha-1) plus Aterbane 0.5% v/v; glyphosate at 2,400, 3,360 and 4,320 (g a.e. ha-1) plus Silwet 0.1% v/v; imazapyr (Arsenal) at 750 and 1,500 (g a.e. ha-1), diquat (Reward) at 400 and 800 (g a.i. ha-1) with sequential application and an untreated control. The experimental plots were constituted of 60 x 60 x 45 cm water reservoirs, with 55 L of soil. Herbicides were applied when the plants reached 45 and 65 cm for B. subquadripara and B. mutica, respectively. A CO2 backpack sprayer was used with 2 bars, 110.02 XR nozzles and consumption of 200 L ha-1 spray solution. The control was visually evaluated, through percentile note scale, and plant dry mass as well. The herbicide glyphosate (doses of 3,360 and 4,320 g a.e. ha-1) showed an excellent control for the two species, regardless of the adjuvant tested. However, the plots that had received glyphosate at 2,400 g a.e. ha-1 showed only a satisfactory control. The herbicide imazapyr (doses 750 and 1,500 g a.e. ha-1) provided an effective control for B. subquadripara and a very effective control for B. mutica. The herbicide diquat, although applied twice and regardless of the dosage used, was found to be inefficient in controlling the two species.
aquatic plant; adjuvant; glyphosate; imazapyr; diquat
