A tree stump excavation tool for use mounted for rotation from an excavation machine arm has first and second side plates extending from a body and a unitary plate mounted to lower ends of the side plates. The unitary plate has a generally helical profile and defines a blade with multiple, pointed teeth integrally formed along its forward edge. The teeth, disposed for cutting engagement with a substrate of soil and stump roots, are laterally spaced apart along the axis of rotation of the tool and angularly spaced in a direction of substrate ripping motion, wherein the teeth are engaged separately and in sequence for cutting the substrate. An excavation machine with a tree stump excavation tool is also described.