Glyphosate is a non-selective herbicide that inhibits the production of essential amino acids for plant survival. This herbicide is available in the market in different formulations that can produce different results for weed control. The mixture of herbicides is an important option to control herbicide resistant weeds, and it is an alternative to mixing ACCase inhibiting herbicides with glyphosate. This work was carried by applying different mixtures of four grass herbicides and 3 glyphosate formulations sprayed at two stages of development of sourgrass. Chemical control was evaluated by visual injury rating at 7, 14 and 28 days after application, and by measuring the fresh weight of the plants at 28 days after the application. The mixtures were classified as antagonistic, synergist or additive according to the model proposed by Colby. All the treatments were effective in the early control of sourgrass except for the application of glyphosate alone. In late applications with more developed plants, the mixture of quizalofop with glyphosate salts (ammonium and potassium) showed better control, but other control measures plus the herbicide mixture should be taken.
grass herbicides; Digitaria insularis; herbicide association
