italian ryegrass (lolium multiflorum) is cultivated as forage and/or cover crop in no-till system. however, it is also a serious weed in wheat and other winter cereals in southern brazil. experiments were conducted at greenhouse and field conditions to evaluate the susceptibility of two ryegrass biotype to glyphosate as well as the efficacy of other herbicides on the post-emergence control of the species for sowing wheat under no-till system. the experimental design was a completely randomized design for the greenhouse experiment and a completely randomized block design for the field experiment. herbicides with different mechanisms of action were evaluated on the weed control: glyphosate, glufosinate, clethodim, haloxyfop-r and diclofop, paraquat and paraquat+diuron. the results obtained under greenhouse conditions indicated the glyphosate susceptible biotype was controlled by the rate of 360 g e.a. ha-1. the resistant ryegrass biotype had no reduction in dry matter production and less than 15 % phytotoxicity caused by glyphosate up to 1,440 g e.a. ha-1. however, glyphosate rates between 1440 and 5,760 g e.a. ha-1 reduced dry matter accumulation and resulted in toxicities under45%. under field conditions, the best lolium multiflorum control was given by clethodim 79.2 g ha-1 and diuron + paraquat at 300+600 g ha1, respectively. the results obtained in these studies indicated that the population was composed predominantly by a biotype resistant to epsps inhibitor herbicides.