A honey mesquite drainage habitat (20% of a 1,215-ha study pasture) was aerially sprayed with 1.1 kg/ha of 2,4,5-T + picloram in the spring. Adjacent habitats (blackbrush acacia uplands, creeping mesquite flats, blrrckbrush acacia-domimted mixed brush,and creeping mesquite-mixed brush) were not sprayed. Discriminant treatment of the honey mesquite drainage habitat did not cause consistent differences in white-tailed deer use of that habitat nor did it change deer use of the pasture containing the sprayed drainage based on average daily fecal accumulation rates for 22.5 months after herbicide application. Lack of differences in deer use between sprayed and unsprayed habitats were attributed to minor impacts of sprays on forb populations during the study period, retention of ample cover screen for deer, and increased abundance of grasses on sprayed areas which presumably reduced use of preferred deer food items by cattle. The recent surge in economic potential of white-tailed deer (Odocoileus virginianus), especially in Texas, has precipitated intense interest in the potential effects of brush control on deer populations. Historically, the primary goal of brush control has been to improve range forage resources or to facilitate their use by livestock (Vallentine 1971). Consequently, most research efforts on interrelationships between brush control and white-tailed deer habitat have been oriented toward threshold levels of woody plant removal relative to their negative impacts on deer numbers. Broadcast applications of selective herbicides have little immediate effect on screening cover and complete defoliation may require a month or longer. Consequently, aerial spraying of brush apparently has less acute impact on white-tailed deer numbers than do many conventional mechanical brush control methods. Aerial spraying of approximately 80% of mixed brush in alternating strips on areas of 430 to 1,800 ha in south Texas did not cause a net change in white-tailed deer popultions (Beasom and Scifres 1977, Marshall 1978, McKenney 1978, Tanner et al. 1978). These studies, as with most in the past, evaluated treatments which weregenerally indiscriminant relative to range sites or habitats. The antithesis of the deer-threshold brush cover relationship is the minimum amount of brush that can be controlled and result in an economically justifiable response to the landowner. This view generates several additional hypotheses which have not been tested. Since vegetation response to brush control is site specific (Scifres 1980), one proposition is that treatment only of rangesites with greatest potential for herbaceous forage production (sites which frequently occupy a relatively small area) could increase livestock carrying capacities as much as, or more than, indiscriminant treatment of large portions ofa pasture or ranch. However, in At the time of the research. the authors were associate professor and professor, Department of Wildlife and Fwheries Sciences; and professor, Department of Range Science. Texas A&M University, College Station, 77843. Authors are grateful to P.H. Welder for furnishing land and herbicide treatment for the research, J.L. Mutzh and K. Caerely for their assistance in conducting the research. and Julia Scifres for manuscript typing and preparation. Manuscript received August 2, 1981. much of south and west Texas, the sites with greatest potential for producing herbaceous forages, such as the honey mesquite drainages, are also considered the most important habitat type for white-tailed deer (McMahan and lnglis 1974, Darr and Klebenow 1975). Consequently, managers often have controlled brush on all but these habitats to avoid possible reductions in deer numbers and/or quality. In such cases, resultant brush removal from a pasture may approach 70 to 90%. This research was designed to test the hypothesis that chemical brush control could be applied to the honey mesquite drainages without negatively influencingdeer numbers if adjacent habitats were not sprayed.