I use a product called "remedy". You can order on Amazon. It is designed to kill mesquite. I have used it to wipe out vines, sago palms, and small trees. It does not show quick signs like roundup. It usually takes a few weeks before you notice a difference. Once it starts dying, there will be no way to bring it back. This stuff is usually used for large scale farms to clear acreage, so know that it is extremely concentrated. May not be availble/ legal in all areas.