A cutter apparatus comprising a frame having a mounting member connectable to a piece of prime mover equipment; a cutter assembly connected to the frame, the cutter assembly comprising a support member having a first end; a drive shaft having a first end journaled to the first end of the support member; and a plurality of discrete cutter members stacked on the drive shaft so as to be engaged with an adjacent one of the cutter members, each of the cutter members having at least one cutting edge; and a drive assembly connected to the drive shaft in a way that activation of the drive assembly causes the drive shaft to rotate and thereby rotate the cutter members. The frame may have a base and an extension arm pivotally connected to the base. The support member may be pivotally connected to the extension arm.