| ABSTRACT Ryegrass is a weed of annual cycle that is present in winter crops, in orchards and vineyards of the South region of Brazil. The species is normally controlled by the glyphosate herbicide, but the continuous use of this product caused the selection of resistant biotypes. The use of ACCase inhibitor herbicides is the main alternative for the control of this species, but it has not been satisfactory in some places, thus causing suspicion of resistance to this action mechanism. Thus, the objective of this paper was to evaluate the occurrence and geographic distribution of ryegrass biotypes that are resistant to the clethodim herbicide in the state of Rio Grande do Sul. For that, seeds of ryegrass plants that survived the application of clethodim were... |
