In order to evaluate the rates of glyphosate herbicide applyed alone or in mixed in 2,4-D ester herbicide to control native pasture for black oat no-till seeding, an experiment in the Federal University of Santa Maria/RS, Brazil, was carried out in 1996. The following treatments were tested: glyphosate at 720, 1080, 1440 e 1800 g ha-1 of acid equivalent, alone or in mixture with 320 g ha-1 of 2,4-D, sprayed at 100 l ha-1 volume, and unsprayed control. The main plants species out of 47 identified were: Paspalum maculosum, Paspalum plicatulum, Paspalum nicorae, Paspalum notatum var. notatum biotype "A" and Vernonia nudiflora. The results showed no difference in spraying glyphosate alone or in mixture with 2,4-D. The average chemical control were 70, 86, 92 and 94% for glyphosate 720, 1080, 1440 and 1800 g ha-1. Black oat dry mass were increased with the increase in glyphosate doses until 1440 and decreased after that. V. nudiflora was not controlled with glyphosate. P. notatum var. notatum biotype "A", P. nicorae and P. notatum with intense pilosity was controlled with glyphosate of 1440 g ha-1. Other Paspalum species required only 1080 g ha-1 of glyphosate for adequate control.
glyphosate; 2,4-D; Paspalum; Avena strigosa