Tordon RTU is effective, but only available in quart containers and perhaps a bit expensive. Bonide brand Stump & Vine Killer likely is more cost effective. Keep in mind the only live part of woody materials is the thin layer of green tissue immediately under the bark, and that needs to be exposed by a fresh cut prior to applying the materials listed above. If there is a stump remaining, you can expose that green layer with a hatchet or axe and then squirt (Tordon) or brush (Stump & Vine Killer) and herbicide onto the exposed areas. If the exposed portion of a stump is dead (no green exposed by the hatchet/axe), it won't help to apply the herbicide to it.