A 4,5-dichloro-imidazole derivative of the formula ##STR1## in which X represents a ##STR2## in which R.sup.1 represents hydrogen, alkyl with 1 to 8 carbon atoms, alkenyl with up to 8 carbon atoms or the formyl group,R.sup.3 represents cycloalkyl with 5 to 7 carbon atoms in the ring which is optionally substituted by alkyl with 1 to 6 carbon atoms or represents phenyl which may optionally carry one or more substituents selected from halogen, alkyl with 1 to 4 carbon atoms, alkoxy with 1 to 4 carbon atoms, alkylmercapto with 1 to 4 carbon atoms and trifluoromethyl, andR represents alkyl with 1 to 12 carbon atoms or alkenyl or alkynyl each with up to 12 carbon atoms, it being possible for each of these alkyl, alkenyl and alkynyl radicals to carry one or more substituents, or represents cycloalkyl with 5 to 7 carbon atoms in the ring or represents a phenyl radical which is at least disubstituted;and the use of such novel 4,5-dichloro-imidazole derivatives as plant growth protection agents especially as a herbicide, plant growth regulant, insecticide or acaricide.