The invention relates to compositions (extenders) useful for prolonging the action of herbicides containing thiolcarbamate derivatives as active ingredients as well as to herbicide compositions with a prolonged action containing thiolcarbamate derivatives as active ingredients and optionally an antidote which comprises a diaminomethane derivative of the general formula (III) <IMAGE> (III) wherein the R substituents stand independently from one another for C1-6 alkyl groups or for C2-4 alkenyl groups optionally substituted by a C1-4 alkyl group; and a process for prolonging the actin of herbicide compositions containing a thiolcarbamate derivative and optionally an antidote, which comprises applying the above mentioned composition in a quantity providing the prolonged action simultaneously with or after the application of the herbicide composition.
