Alfalfa that was supposed to be dead 2 years ago is still growing in one field. I have hit it with a quart of Rup and full rate of Harness extra this spring. Turned it a bit brown and now its back with a vengence. Is there anything that kills alfalfa in foot tall corn?? It also survived the Rup from last years beans. Is this roundup ready alfalfa seed?? Too old to be that kind. NOW what???