A herbicidal compound of Formula: or an agronomically acceptable salt of said compound, wherein:- R 1 is selected from the group consisting of hydrogen, C 1 -C 6 alkyl, C 1 -C 6 haloalkyl, C 1 -C 3 alkoxy-C 1 -C 3 alkyl, C 1 -C 3 alkoxy-C 1 -C 3 alkoxy-C 1 -C 3 -alkyl, C 1 -C 3 alkoxy-C 1 -C 3 -haloalkyl, C 1 -C 3 -alkoxy-C 1 -C 3 -alkoxy-C 1 -C 3 -haloalkyl, C 4 -C 6 -oxasubstituted cycloalkoxy-C 1 -C 3 -alkyl, C 4 -C 6 -oxasubstituted cycloalkyl-C 1 -C 3 -alkoxy-C 1 -C 3 -alkyl, C 4 -C 6 -oxasubstituted cycloalkoxy-C 1 -C 3 -haloalkyl, C 4 -C 6 -oxasubstituted cycloalkyl-C 1 -C 3 -alkoxy-C 1 -C 3 -haloalkyl, (C 1 -C 3 alkanesulfonyl-C 1 -C 3 alkylamino)-C 1 -C 3 alkyl, (C 1 -C 3 alkanesulfonyl-C 3 -C 4 cycloalkylamino)-C 1 -C 3 alkyl, C 1 -C 6 alkylcarbonyl-C 1 -C 3 alkyl, C 3 -C 6 cycloalkyl-C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 2 -C 6 -alkenyl, C 2 -C 6 -haloalkenyl, cyano-C 1 -C 6 -alkyl, arylcarbonyl-C 1 -C 3 -alkyl (wherein the aryl may be optionally substituted with one or more substituents from the group consisting of halo, C 1 -C 3 -alkoxy, C 1 -C 3 -alkyl, C 1 -C 3 haloalkyl), aryl-C 1 -C 6 alkyl, aryloxy-C 1 -C 6 alkyl (wherein both cases the aryl may be optionally substituted with one or more substituents from the group consisting of halo, C 1 -C 3 -alkoxy, C 1 -C 3 -alkyl, C 1 -C 3 haloalkyl), and a three- to ten-membered mono- or bicyclic ring system, which may be aromatic, saturated or partially saturated and can contain from 1 to 4 heteroatoms each independently selected from the group consisting of nitrogen, oxygen and sulphur the ring system being optionally substituted by one or more substituents selected from the group consisting of C 1 -C 3 alkyl, C 1 -C 3 haloalkyl, C 1 -C 3 alkenyl, C 1 -C 3 alkynyl, C 1 -C 3 alkoxy, C 1 -C 3 haloalkoxy, C 1 -C 6 alkyl-S p-, C 1 -C 6 haloalkyl-S p-, aryl, aryl-S p, heteroaryl-S p, aryloxy, heteroaryloxy, C 1 -C 3 alkoxycarbonyl, C 1 -C 3 alkylamino-S p-, C 1 -C 3 alkylamino-S p-C 1 -C 3 alkyl, C 1 -C 3 dialkylamino-S p-, C 1 -C 3 dialkylamino-S p-C 1 -C 3 alkyl, C 1 -C 3 alkylaminocarbonyl-, C 1 -C 3 alkylaminocarbonyl-C 1 -C 3 alkyl, C 1 -C 3 dialkylaminocarbonyl, C 1 -C 3 dialkylaminocarbonyl-C 1 -C 3 alkyl, C 1 -C 3 alkylcarbonylamino, C 1 -C 3 alkyl-S p-amino, cyano and nitro; the heteroaryl substituents containing one to three heteroatoms each independently selected from the group consisting of oxygen, nitrogen and sulphur, and wherein the aryl or heteroaryl component may be optionally substituted by one or more substituents selected from the group consisting of halo, C 1 -C 3 alkyl, C 1 -C 3 haloalkyl, C 1 -C 3 alkoxy, C 1 -C 3 haloalkoxy, phenyl, cyano and nitro; R 2 is selected from the group consisting of hydrogen, halogen, cyano, nitro, C 1 -C 6 alkyl, C 3 -C 6 cycloalkyl, C 2 -C 6 -alkenyl, C 2 -C 6 alkynyl, C 1 -C 6 haloalkyl, C 1 -C 6 alkoxy, C 1 -C 3 haloalkoxy, C 1 -C 6 alkoxy-C 1 -C 3 alkyl, C 1 -C 6 alkyl-S p-and C 1 -C 6 haloalkyl-S p-; p = 0, 1 or 2; A 1 is selected from the group consisting of O, C and (CR e R f); and R a, R b, R c, R d, R e and R f are each independently selected from the group consisting of hydrogen and C 1 -C 4 alkyl wherein R a and R c may together form a C 1 -C 3 alkylene chain.