INTERVALO ENTRE APLICA??ES SEQUENCIAIS PARA O CONTROLE DE CAPIM-AMARGOSO

摘要

More than one herbicide application is usually necessary to manage glyphosate-resistant sourgrass in advanced stages of development efficiently during off-season fallow periods. The objective of this study was to determine the best interval between two sequential applications to control sourgrass, based on the number of days and tiller-height after the first treatment. Two experiments were conducted based on these criteria. Experiment 1 consisted of one application of glyphosate clethodim (1140 ae ha-1 108 g ha-1) followed by glyphosate clethodim or paraquat (400 g ai ha-1) at an interval of 10, 17, 24, 31, 28, or 45 days. Experiment 2 was conducted with the same herbicide treatments, but using the tiller-height as the criteria for the second application, which were 2-5, 6-10, 11-20, 21-30, and 30 cm. None of the treatments resulted in total sourgrass control during the evaluation period. Overall, treatments with glyphosate clethodim in the second application were more efficient than paraquat. The most effective interval between sequential applications of glyphosate clethodim was observed at 17 to 24 days. For paraquat, the best interval for the second application was 6-10 days. The most effective performances based on the tiller-height were found at 620 cm tall for glyphosate clethodim and 6-10 cm tall for paraquat.