The present invention relates to a compound of the formula (I) or salt thereof in which R1 is identical or different at each occurrence and is H, halogen, CN, nitro, SF5, (C1-C8)alkyl, (C2-C8)alkenyl, (C2-C8)alkynyl, (C1-C8)alkoxy, [(C1-C8)alkyl]-carbonyl or (C1-C8)alkylsulfonyl, each of the radicals being unsubstituted or substituted,  or is S(O)p—R7, where p=0, 1 or 2 and R7 is (C1-C8)alkyl, (C1-C8)haloalkyl or NR8R9, where  R8 and R9 independently of one another are identical or different and are H, (C1-C8)alkyl, (C2-C8)alkenyl, (C7-C10)arylalkyl, (C7-C10)alkylaryl or (C6-C10)aryl, each of the last-mentioned five radicals being unsubstituted or substituted,  or is a group of the formula where R10 is (C1-C8)alkyl which is unsubstituted or substituted, and W=O or S, A is optionally substituted aryl or an optionally substituted heterocyclic radical, X is O or S, R2,R3,R4, and R5 are identical or different and are H, halogen, CN, (C1-C8)alkoxy or (C1-C8)alkyl, each of the two last-mentioned radicals being unsubstituted or substituted, m is 0 or 1, R6 is H, (C1-C8)alkyl, (C1-C8)alkoxy, (C2-C8)alkenyl or (C2-C8)alkynyl, each of the four last-mentioned radicals being unsubstituted or substituted, or is hydroxyl or an acyl radical, and B is an acyl radical, or B and R6 together form a 4- or 5-membered chain, with the exception of N-hydroxy-N-[(6-phenoxy-2-pyridyl)methyl]-acetamide and its salts. The compounds of the invention are suitable, for example, as herbicides and growth regulators.