Phenylpyridazinones

A phenylpyridazinone of the formula (I)

• wherein
• R1 represents fluorine, chlorine or bromine,
• R2 represents cyano, carbamoyl, thiocarbamoyl, fluorine, chlorine or bromine or represents respectively optionally fluorine- or chlorine-substituted alkyl, alkoxy or alkylthio having in each case 1 or 2 carbon atoms,
• R3 represents A3 or the grouping —NH—A3
• A3 represents fluorine, chlorine, bromine, or represents respectively optionally fluorine-, chlorine-, C1-C4-alkoxy-substituted alkyl, alkoxy, alkylthio, alkylsulphinyl, alkylsulphonyl, alkylamino, dialkylamino, alkoxycarbonyl or dialkoxy(thio)phosphoryl having in each case 1 to 6 carbon atoms in the alkyl groups, or
• represents respectively optionally fluorine- or chlorine-substituted alkenyl, alkenyloxy, alkenylamino, alkylideneamino, alkenyloxycarbonyl, alkinyl, akinyloxy, alkinylamino or alkinyloxycarbonyl having in each case 2 to 6 carbon atoms in the alkenyl, alkylidene or alkinyl groups;
• wherein at least one of R1, R2 and R3 is not fluorine, chlorine or bromine;
• R4, R5 and R6 are identical or different and each represents hydrogen, cyano, thiocarbamoyl, nitro, hydroxyl, mercapto, amino, fluorine, chlorine, bromine or represent respectively optionally fluorine- and/or chlorine-substituted alkyl, alkoxy, alkylthio, alkylamino or dialkylamino having in each case 1 to 4 carbon atoms in the alkyl groups, except for the compound 4-chloro-5-dimethylamino-2-(4-chloro-2-fluoro-5-propargyloxy-phenyl)-pyridazin-3-one.