Herbicidal compounds ##STR1## in which Q represents a group --C(O)--C(CN).dbd.CH--NR.sup.1 R.sup.2, R.sup.1 and R.sup.2 each independently represents alkyl, or together represent alkylene optionally interrupted by oxygen, m is O or m is an integer from 1 to 3 and the or each Y independently represents halogen or alkyl and n is O or n is an integer from 1 to 5 and the or each X independently represents halogen, alkyl, haloalkyl, cyanoalkyl, alkenyl, alkynyl, alkoxy, haloalkoxy, haloalkylthio, alkenyloxy, alkynyloxy, alkylthio, alkenylthio, alkynylthio, cyano, nitro, alkylsulphonyl, alkysulphinyl, sulphonamido, or phenyl optionally substituted by alkyl, haloalkyl, alkoxy or halogen.