Carboxamides Ia, Ib, Ic and Id (X = 0, S; R1 = H, halogen, substituted or unsubstituted alkyl, substi- tuted or unsubstituted benzyl, alkoxy, alkylthio, haloalkoxy, haloalkyl- thio, substituted or unsubstituted phenyl, substituted or unsubstituted phenoxy or phenylthio, a substituted or unsubstituted 5- or 6-membered heterocyclic radical containing one or two heteroatoms, cycloalkyl- substituted alkyl, substituted or unsubstituted alkenyl which may be epoxidized, substituted or unsubstituted alkynyl, substituted or unsubstituted cycloalkyl or cycloalkenyl; R1' - cycloalkyl-substituted alkyl, substituted or unsubstituted alkenyl which may be epoxidized, substituted or unsubstituted cycloalkenyl; R2 = CHO, 4,5-dihydrooxazol-2- yl, COYR5, CONR6R7; Y = 0, S; R5 = H, substituted or unsubstituted alkyl, cycloalkyl, substituted or unsubstituted alkenyl, substituted or unsub- stituted cycloalkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted phenyl, a 5- or 6-membered heterocyclic radical contain- ing up to 3 heteroatoms, benzotriazole, N-phthalimido, tetrahydrophthal- imido, succinimido, maleiimido, 2,2-dimethyl-1,3-dioxolan-4-ylmethyl, 1,3-dioxolan-2-on-4-ylmethyl, and when Y = 0: one equivalent of a cation from the group of the alkali or alkaline earth metals, Mn, Cu, Fe, ammonium and substituted ammonium, a radical -N=CR8R9 or -W-Z; R8, R9 = H, substituted or unsubstituted alkyl, substituted or unsubstituted halo- alkyl, cycloalkyl, alkoxy, furanyl, substituted or unsubstituted phenyl; R8+R9 = 4-7-membered methylene chain; W = alkylene chain, ethoxyethylen e chain, butylene, butynylene chain; Z = a molecular moiety bonded to W in the .omega.-position and is the same as that linked to W in the .alpha.- position of W; R6=H, alkyl, cycloalkyl; R7=H; alkyl; -C(0-alkyl)=N-H or -C(0-alkyl)=N- alkyl; R6+R7 = 4-5-membered methylene chain; R3 = H, substituted or unsub- stituted alkyl, substituted or unsubstituted cycloalkyl; R4 = H, OH, alkoxy, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted alkenyl, substituted or unsub- stituted alkynyl, di-(C1-C4)-alkylamino, a substituted or unsubstituted 5- or 6-membered heterocyclic radical containing one or two heteroatoms, sub- stituted or unsubstituted phenyl, substituted or unsubstituted naphthyl; R3+R4 = 4-7-membered methylene chain which may be interrupted by 0, S o r N-CH3, or -(CH2) 3-CO-) and their environmentally tolerated salts. 40 The compounds Ia to Id are suitable as herbicides.