Abstract Background Recently, biotypes of sourgrass (Digitaria insularis) were identified in Brazil with multiple resistance to EPSPs-ACCase inhibiting herbicides, which demands the recommendation of herbicides with alternative mode of action, such as glufosinate-ammonium. Objective Therefore, this work was developed with the objective of modelling the efficacy of glufosinate-ammonium on sourgrass regarding to five different phenological stages. Methods Treatments consisted of eight rates of glufosinate-ammonium (1,600, 800, 400, 200, 100, 50 and 25 g ha-1, and check plots without herbicide application) […]