The invention relates to novel herbicidal agents which contain the herbicidal active substances from the group of the substituted pyrimidines and triazines and safener compounds of the formula B1 and/or B2, ##STR1## in which X' is hydrogen, halogen, (halo)alkyl, (halo)alkoxy or nitro, Z' is OR.sup.31, SR.sup.31 or NR.sup.31 R or a heterocycle having at least one N atom and up to 3 hetero atoms, R' is an alkanediyl chain, n' is a number from 1 to 5, W' is a divalent heterocyclic radical, and the remaining radicals are as defined in the description. The invention furthermore relates to a method of protecting crop plants against phytotoxic secondary effects of herbicides, which comprises applying an effective amount of at least one compound of the formula B1 and/or B2 before, after or together with at least one herbicidal active substance from, the group of the pyrimidines and triazines, to the plants, seeds of plants or the area under cultivation.