Present invention relates to the use of the ALS inhibitor herbicides for controlling unwanted vegetation in ALS inhibitor herbicide tolerant Beta vulgaris plants, more especially, present invention relates to the use of ALS inhibitor herbicides for control of unwanted vegetation in Beta vulgaris, preferably in sugar beet growing areas in which the Beta vulgaris, preferably sugar beet comprise a mutation in codon 1705-1707 of an endogenous ALS gene encoding an ALS protein containing an amino acid that is different from tryptophan at position 569, preferably the tryptophan is substituted by leucine.