Outcomes of net-present value analyses were projected for patterned applications of herbicide sprays and pellets to mixed brush in south Texas. Picloram + 2,4,5-T (1:1) were applied but 1987 costs of triclopyr + picloram sprays, currently registered and considered the biological equivalent treatment, were used for analyses. Projected internal rates of return (IRR) ranged from 7.3 to 8.5% when 60 to 65% of the landscape was sprayed in a variable-rate pattern (VRP) at 0, 0.6, and 1.1 kg/ha; sprayed in strips with the higher dosage alternating with untreated strips; or completely sprayed with 1.1 kg/ha. Investment capital requirements were reduced when the VRP or strips were used by 49% and 35%, respectively, compared to complete treatment of the landscape with herbicide sprays. Treatment of 80% of landscapes at 2 locations with tebuthiuron in VRPs generated IRRs roughly equivalent to those from 2.2 kg ai/ha of tebuthiuron pellets applied in strips. Complete treatment of management units with 2.2 kg/ha of the pellets generated more additional beef and higher IRRs than did treatment with either pattern, but required from 50% to 75% greater investments of capital. Economic response also differed among sites of differing forage production capabilities and between otherwise similar sites because of variation in botanical composition of the brush stands. For example, IRRs at the locations, respectively, were 6.3 and 1.3% when 2.2 kg/ha of tebuthiuron were applied to sites with deep soils (drainages), 3.1 and <0% following treatment of uplands, and were negative following application to shallow ridges. Sites with a greater proportion of the woody cover contributed by tebuthiuron-susceptible species such as whitebrush yielded greater IRRs from the investment than did sites with heavy cover of honey mesquite (tebuthiuron tolerant).

A large, truck-mounted screen was constructed to aid in measurement of total leaf area of individual honey mesquite (Prosopis glandulosa Torr.) trees. The screen, which measured 4.6 m × 6.2 m, was constructed with a white tarp supported by a PVC and steel frame, and mounted via steel brackets to one side of a crew-cab truck. To alleviate problems with wind and to facilitate transport, the tarp was attached only at the top of the frame and could be raised and lowered as required. The screen could be transported in the unassembled condition using a standard truck transport frame. The assembled screen was used in a natural rangeland setting to provide a consistent background for photography of individual trees. A 35-mm camera and a portable VCR recorder were used to obtain 2 dimensional images of the tree canopy, which were then digitized. These values were related to whole plant leaf area by harvesting entire trees. A crew of 4 was required to assemble the screen and photograph about 35 trees within 4 hours.