The present invention relates to a method of controlling plants or inhibiting plant growth which comprises applying to the plants or to the locus thereof a herbicidally effective amount of a compound of formula (I) wherein R1, R2, R3, R4 and R5 are as defined in claim 1； or a salt or TV-oxide thereof. Furthermore, the present invention relates to processes for preparing compounds of formula (I), to intermediates used in the preparation of compounds of formula (I), to herbicidal compositions comprising compounds of formula (I) and to certain novel pyridopyridines.
