Mesquite (Prosopis juliflora) is a major unwanted plant in the Southwest. This study evaluated the herbage responses obtained from various aerial applications of 2,4,5-T on mesquites in southern New Mexico. The dead plants on the various areas ranged from 7-64% of the mesquite. Yields of perennial grasses ranged from 3-1931 kg/ha on the untreated controls and 11-2696 kg/ha on the areas sprayed with 2,4,5-T. In dense stands of mesquite, about 30% of the mesquites must be killed before grass yields are significantly increased.