Invasion of rootplowed rangeland by blackbrush acacia (Acacia rigidula Benth. ♯ ACARI) is a problem in south Texas. Low-energy grubbing uprooted plants 1 to 2.5 m tall in densities of 50, 150, and 300 plants/ha at rates of 3.0, 1.6, and 1.0 ha/h, respectively, yielding an average plant kill of 85%. Plants grubbed above the second major lateral root sprouted. A grubbing depth of 20 to 30 cm was necessary to assure plant death. A grubbing blade modified by the addition of ripper teeth facilitated grubbing under dry soil conditions and extended the grubbing season. Contract cost for grubbing the average density of 169 plants/ha was $20.80/ha adjusted to 1983 dollars.
