Under evironmental controlled conditions experiments were conducted to determine the efficacy of carfentrazone-ethyl in tank mixture with glyphosate to control six weed species. Glyphosate alone at 720 g ha-1 was effective in controlling Amaranthus hybridus (100%), Desmodium tortuosum (100%), Bidens pilosa (99%), Eleusine indica (96%), Digitaria horizontalis (100%) and Commelina benghalensis (93%) at 21 DAA. Carfentrazone-ethyl alone controlled only C. benghalensis. efficiently. Glyphosate mixtures (252 and 720 g ha-1) with carfentrazone-ethyl at 15 and 30 g ha¹ showed an additive effect in controlling A. hybridus, D. tortuosum and Bidens pilosa, except for glyphosate mixture at 252 g ha-1 with carfentrazone-ethyl at 15 and 30 g ha-1, which showed synergism in controlling D. tortuosum. The addition of the two carfentrazone-ethyl doses antagonized the effect of the smallest dose (252 g ha-1) of glyphosate on E. indica control. However, the largest glyphosate dose (720 g ha-1) provided additive effect when mixed with both carfentrazone-ethyl doses. For D. horizontalis, carfentrazone-ethyl mixtures with glyphosate in the smallest dose (252 g ha-1) had a synergistic effect in the control of this species, also showing and additive effect in the mixture with glyphosate at 720 g ha-1. Carfentrazone-ethyl mixture with glyphosate provided an additive effect in C. benghalensis control, regardless of dose combinations. The results of this experiment indicate that carfentrazone-ethyl presents a differentiated behavior when interacting with glyphosate, depending on the weed species and the herbicide dose used in the tank mixtures, being complementary in tank-mix combinations with glyphosate, since it showed an antagonistic effect in few combinations, with its additive effect prevailing in the mixture with glyphosate for the control of the evaluated species.
herbicide; antagonism; synergism
