Abstract: A mobile brush cutter including a vehicle; a boom having one end pivotally supported by the vehicle; a hydraulic power system mounted on the vehicle and having controls operable by an operator thereof; a cutter supported by an opposite end of the boom and operatively coupled to the hydraulic power system, the cutter comprising an elongated bed knife having one end connected to the opposite end of the boom and having bed teeth that define longitudinally spaced apart slots for receiving stalks and a moving knife juxtaposed to the bed knife and mounted for longitudinal reciprocating movement relative thereto, the moving knife having moving teeth that define a plurality of cutting edges each shaped and arranged to reciprocate through a cutting zone transversely adjacent to a different one of the slots; and a retainer assembly fixed to said bed knife and shaped and arranged for sliding engagement with outer end portions of the moving teeth so as to prevent transverse separation thereof from the bed knife.