Herbicidal quinoline-3-carbonamides

Quinoline-3-carboxamides I in which the substituents have the following meaning: R is hydrogen, alkyl, alkenyl, alkynyl or cycloalkyl, where the abovementioned organic radicals can in each case be substituted; R is hydrogen, hydroxyl, alkoxy, alkenyloxy, dialkylamino, alkyl, alkenyl, alkynyl or cycloalkyl, where the abovementioned organic radicals can in each case be substituted; or R and R together are an alkylene chain having 4 to 7 members which can be interrupted by oxygen, sulphur or N-methyl; R -R are hydrogen, alkyl, alkoxy, haloalkyl, haloalkoxy, alkylthio, haloalkylthio, halogen, cyano or nitro; X is oxygen or sulphur; with the proviso that R is not hydrogen, C1-C3-alkyl, n-butyl, 3-methylbutyl, cyclohexyl, hexyl, heptyl, octyl, 2-chlorobenzyl, 3-(dimethylamino)propyl, 3-(diethylamino)propyl, 2-morpholinoethyl and 2-(3,4-dimethoxyphenyl)ethyl if R and R to R are hydrogen and X is oxygen, and R is not benzyl if R is methyl, R to R are hydrogen and X is oxygen, and R and R together are not morpholino if R to R are hydrogen and X is oxygen.