Aerial applications of pelleted tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea} at 0.5 kg/ha reduced creosotebush [Larrea tridentata (DC.) Coville] density by up to 86% and by 99% when applied at 1 kg/ha in February or March. Grass production 32 months after treatment was 174 to 305% greater in tebuthiuron-treated plots than on untreated ran gel and, but forb production in treated plots was reduced 38% or more and the poisonous half-shrub broom snakeweed [Gutierrezia sarothrae (Pursh) Britt. and Rusby] was reduced 94% or more.

Salt rabbitbrush [Chrysothamnus nauseosus (Pallas) Britt., ssp. consimilis (Greene)] and greasewood [Sarcobatus vermiculatus (Hook.) Torr.] grow slowly in early spring until mid to late May. They then begin a period of rapid growth, at which time susceptibility to foliar herbicides is probably greatest. Greasewood ceases rapid growth in mid June to early July, but salt rabbitbrush continues to grow rapidly until early August. Greasewood that resprouts after herbicide application has a longer rapid-growth period than shrubs in an untreated stand. An average leader length of 4 cm indicates that rapid growth of salt rabbitbrush is underway, and first opening of the flower buds indicates that rapid growth is over. Appearance of greasewood staminate spikes indicates that rapid growth has begun, and the first appearance of dried spikes indicates that growth has ceased. Simultaneous control of these shrubs with a single application of phenoxy herbicides may only be possible during the relatively short period when both are growing rapidly. This period may only occur from late May to mid June in some stands and years, but may occur from mid May to early July in other cases.

Woody plant encroachment restricts forage production and capacity to produce grazing livestock. Biophysical plant growth simulation and economic simulation were used to evaluate a prescribed burning range management technique. Modeling systems incorporated management practices and costs, historical climate data, vegetation and soil inventories, livestock production data, and historical regional livestock prices. The process compared baseline non-treatment return estimates to expected change in livestock returns resulting from prescribed burning. Stochastic analyses of production and price variability produced estimates of greater net returns resulting from use of prescribed burning relative to the baseline.

Tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiozol-2-yl]-N,N′-dimethylurea} pellets (20% ai) applied at 0.6, 1.1, or 2.2 kg ai/ha in the spring at two locations and in the fall at a third location on the South Texas Plains did not significantly decrease buffelgrass (Cenchrus ciliaris L. # PESCI) standing crop or foliar cover compared to untreated areas. Buffelgrass standing crop was reduced for 8 months after application of 3.3 and 4.4 kg ai/ha of tebuthiuron to a sandy clay loam in the spring, but the same rates did not reduce standing crop after application to clay loam in the fall. However, buffelgrass foliar cover was reduced following application of 3.3 kg ai/ha or more of the herbicide, regardless of soil. Tebuthiuron applied at 2.2, 3.3, or 4.4 kg ai/ha to sandy clay loam soils killed buffelgrass plants in spots, but production by larger surviving plants compensated for reduction in plant density where 2.2 or 3.3 kg ai/ha were applied.

Fringed sagebrush is a native, drought-resistant, increaser species in Saskatchewan pastures and rangelands. Conventional control by cultivating and reseeding is neither highly effective nor sustainable. Two field experiments were conducted in 1988 and 1989 through 1991 to develop a management plan for fringed sagebrush. Comparison of fringed sagebrush control using various applications of clopyralid, dicamba, dichlorprop, fluroxypyr, picloram, triclopyr and 2,4-D, showed control was sufficient using the low-cost herbicide 2,4-D isooctyl ester at 1.5 kg ai/ha. Total yield of crested wheatgrass plus smooth brome was compared and the plots subjected to two applications of 2,4-D yielded the greatest accumulation of grass over the length of the experiments. The economic threshold of fringed sagebrush is the density at which yield is reduced by approximately 290 kg/ha; above this density it is economically viable to use 2,4-D at 1.5 kg/ha to control fringed sagebrush. Grazing practices can aid greatly in management of fringed sagebrush by allowing the forage to out-compete fringed sagebrush.

Aerial applications of 20% tebuthiuron JA/-[5-(1,1- dimethylethyl) - 1, 3, 4 - thiadiazol-2 -yl] -N, N' dimethylurea pellets at 2.2 or 4.4 kg/ha in the spring to heavy brush cover in Texas Post Oak Savannah did not increase the amount of grass, compared to that of untreated pastures, until the growing season after application. By the second growing season after tebuthiuron application, however, native grass stands were composed of a higher proportion of perennial species of good-to-excellent grazing value than were stands on adjacent, untreated rangeland. Tebuthiuron at 4.4 kg/ha did not improve botanical composition of grass stands, but increased the amount of grass during the second and third growing season after application compared to those where 2.2 kg/ha were applied. Daily steer gains were increased in one experiment in the fall after application of 2.2 kg/ha of tebuthiuron in the spring, but were unchanged after two growing seasons in another. Days of available grazing were increased, however, by the second or third growing season after treatment with 2.2 kg/ha of the herbicide in both experiments.

In areas where livestock production predominates, a ‘fence-out rule’ as opposed to a ‘fence-in rule’ has been advocated due to perceived economic advantages associated with open-range livestock production; people desiring to have no livestock on their properties need to construct fences. Yet a region's total economy may be enhanced by moving away from established fence-out and cost-sharing rules. With changes in public perceptions of property rights, advances in technology, and the acquisition of new scientific information, fence rules should be expected to evolve. This paper articulates political, economic and scientific considerations in the USA that may be contemplated by citizens and elected officials for altering directives controlling livestock. To promote economic efficiency and social well-being, the paper advocates the scrutiny of existing fence-out and cost-sharing rules in a region to determine whether alternative rules should be preferred. The demise of fence-out rules in some areas in the USA and other countries could help achieve a more sustainable use of range resources.