The objective of this work was to evaluate the control of two emergence fluxes of the weeds Brachiaria plantaginea and Digitaria horizontalis by the herbicide imazapic applied under pre-emergence conditions, by analyzing the dose-response curves. The experimental design adopted was randomized blocks, with four replicates, with each plot being a 3L capacity pot, filled with clay soil plus Brachiaria plantaginea and Digitaria horizontalis seeds. Considering D as the recommended rate of imazapic (140 g ha-1), the treatments were: 4D, 2D, D, 1/2D, 1/4D, 1/8D, 1/16D and no herbicide. Visual evaluations of control at 30 and 60 Days After Infestation (DAI) and dry weight at 60 DAI were performed. After harvest of the biomass present in the plots, resulting from the first flux, the pots were seeded again followed by control evaluations at 30 and 60 Days After Re-infestation (DAR) and dry weight at 60 DAR. The results showed that imazapic inhibited the development of both weeds, reaching results higher than 80% of control in all the evaluations for the recommended dose, in both emergence fluxes; the efficacy in the control of Digitaria horizontalis was slightly superior than the control of Brachiaria plantaginea; imazapic was presented as an interesting option for management of these weeds.
Digitaria horizontalis; Brachiaria plantaginea; residual control
