A com. fenmedifam, desmedifam and etofumesat-contg. herbicide was modified by addn. of H3BO3, MnSO4 and/or the com. B and Mn chelates in aq. solns. and used for controlling weeds in sugar beet culture. The applied solns. were stable (very small amts. of a ppt. were observed), did effect neither morphol. nor metabolism of the beet and showed high herbicidic efficiency against the dominant weeds (destruction of 84-89% weeds in av.). The addn. of B and Mn salts to the herbicide resulted commonly in increasing the herbicide efficiency. The application of herbicide alone resulted in a small increase in sugar, Na, K and alpha-aminoacid N contents in the sugar beet. The addn. of B and Mn salts resulted in an increasing of the tendency.