Crop protection agents based on 1-aryl- or 1-hetarylimidazose carboxylic esters

A herbicidal composition containing at least one compound selected from the compounds of the formulae Ia and Ib ##STR40## where R.sup.1 is halogen or C.sub.1 -C.sub.4 -alkyl which may bear from one to three chlorine atoms,

• R.sup.2 is C.sub.1 -C.sub.6 -alkyl which may bear from one to three of the radicals halogen, C.sub.1 -C.sub.4 -alkoxy and/or C.sub.1 -C.sub.4 -alkoxy-C.sub.1 -C.sub.4 -alkoxy, or is C.sub.3 -C.sub.6 -alkenyl, C.sub.3 -C.sub.6 -alkynyl or C.sub.3 -C.sub.6 -cycloalkyl,
• R.sup.3 is hydrogen or C.sub.1 -C.sub.4 -alkyl,
• R.sup.4 is a phenyl ring or a 5- or 6 membered heteroaromatic ring selected from the group consisting of pyrrole, pyrazole, imidazole, furan, thiozole, isoxazole, isothiazole, pyridine, pyridazine, pyrimidine or pyrazine, and these aromatic rings may bear from one to three of the following groups:
• halogen, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -haloalkyl, C.sub.1 -C.sub.4 -alkoxy, C.sub.1 -C.sub.4 -haloalkoxy, C.sub.1 -C.sub.4 -alkylthio, C.sub.1 -C.sub.4 -alkylsulfinyl, C.sub.1 -C.sub.4 -alkylsulfonyl, C.sub.1 -C.sub.4 -alkylcarbonyl, C.sub.1 -C.sub.4 -alkoxycarbonyl, carboxyl, nitro and/ cyano and at least one herbicidally active ingredient selected from the group consisting of
• a) 2-(4-heteroaryloxy)- or 2-(4-aryloxy)phenoxyacetic acid derivatives of the formula IV ##STR41## where R.sup.a is phenyl, pyridyl, benzoxazyl, benzothiazyl or benzopyrazinyl, and these aromatic ring systems may bear up to two of the following radicals:
• halogen, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -haloalkyl and/or C.sub.1 -C.sub.4 -haloalkoxy,
• R.sup.b is hydrogen, C.sub.1 -C.sub.5 -alkyl, C.sub.3 -C.sub.5 -alkylideneimino, C.sub.3 -C.sub.5 -alkylideneiminooxy-C.sub.2 -C.sub.3 -alkyl, or one equivalent of a plant-tolerated cation, and
• R.sup.c is hydrogen or methyl, and
• b) cyclohexenone derivatives of the formula V ##STR42## where R.sup.d is C.sub.1 -C.sub.4 -alkyl;
• R.sup.e is C.sub.1 -C.sub.4 -alkyl, C.sub.3 -C.sub.4 -alkenyl, C.sub.3 -C.sub.4 -alkynyl, C.sub.3 -C.sub.4 -haloalkenyl or thenyl which may carry a halogen atom;
• R.sup.f is C.sub.1 -C.sub.4 -alkyl which is unsubstituted or monosubstituted by C.sub.1 -C.sub.4 -alkylthio or C.sub.1 -C.sub.4 -alkoxy;
• a 5- or 6-membered saturated or monounsaturated ring system, which in addition to carbon members may contain an oxygen or a sulfur atom or a sulfoxyl or sulfonyl group, and this ring may bear from one to three of the following radicals:
• hydroxyl, halogen, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -haloalkyl, C.sub.1 -C.sub.4 -alkoxy and/or C.sub.1 -C.sub.4 -alkylthio;
• a 10-membered saturated or monounsaturated heterocyclic structure containing two oxygen or sulfur atoms and which is unsubstituted or mono- to trisubstituted by C.sub.1 -C.sub.4 -alkyls and/or methoxy groups;
• phenyl, pyridyl or isoxazolyl, and these groups may bear up to three of the following groups:
• C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -haloalkyl, C.sub.1 -C.sub.4 -alkoxy, C.sub.1 -C.sub.4 -alkylthio, C.sub.3 -C.sub.6 -alkenyloxy, C.sub.3 -C.sub.6 -alkynyloxy, C.sub.1 -C.sub.4 -alkoxy-C.sub.1 -C.sub.3 -alkyl, C.sub.1 -C.sub.4 -dialkoxy-C.sub.1 -C.sub.3 -alkyl, formyl, halogen and/or benzolyamino;
• R.sup.g is hydrogen, hydroxy or, when R.sup.f is C.sub.1 -C.sub.6 -alkyl, C.sub.1 -C.sub.6 -alkyl;
• R.sup.h is hydrogen, cyano, halogen or C.sub.1 -C.sub.4 -alkoxycarbonyl and
• R.sup.i is hydrogen or one equivalent of an environmental compatible cation.