Abstract: Herbicidal compositions based on aminotriazole comprising, besides the usual constituents, adjuvants and/or supports, on the one hand aminotriazole and on the other hand a proportion by weight with respect to the aminotriazole from about 1 to about 14.3%, preferably from 2.5 to 4% and, still more preferably, of about 3% of at least one triazinone of formula ##STR1## wherein R represents a linear or branched alkyl radical comprising from 1 to 4 carbon atoms, the proportion of triazinone in a given composition being selected taking into account the fact that the said composition should provide per hectare an amount of triazinone lower than 300 g, preferably lower than 200 g and still more preferably lower than or equal to 100 g.Herbicidal treatment implementing these compositions.