Disclosed are compounds of Formula 1, including all stereoisomers, N-oxides, and salts thereof, wherein each Y1, Y2, Y3, Y4, Z, R2, m and R3 are as defined in the disclosure. Also disclosed are compositions containing a compound of Formula 1 and methods for controlling undesired vegetation comprising contacting the undesired vegetation or its environment with an effective amount of a compound or a composition of the invention.