Weed and Brush Control for Range Improvement

Abstract

Weeds and brush cause losses on rangelands by reducing forage production, increasing the cost of handling livestock, and increasing death losses of livestock due to poisoning and physical injury from spines and thorns. In addition, weeds and brush reduce water yields 6f watersheds, reduce accessibility of wild lands for recreationists and hunters, reduce the numbers and kinds of wildlife, and cause discom fort and stress to people through allergies and skin rash. Losses from reduced potential production caused by weeds and brush on western rangelands are estimated to total approximately $250,000,000 an nually (USDA, 1965). The weeds and brush occurring on western rangelands are as diverse as the soil types and environments of that area. They are a problem on pastures near sea level, at elevations well above 3,000 m, on very arid areas where rainfall is less than 25 cm and where rainfall is well over 125 cm annually. Although diversity is great, weeds and brush compete for light, fertilizer, and water on rangelands just as they do on cultivated lands. In many cases, competition is so severe that no range improvement can be made until this competition is re moved. This discussion will illustrate this competition, the losses caused by weeds and brush, and methods that can be used to control unwanted vegetation. I. HERBACEOUS WEEDS Herbaceous weeds occur on all rangelands. Relatively few are present on good ranges and dense stands frequently occur on poor ranges. Likewise, the density of herbaceous weeds will vary from season to season and from site to site due to climatic, edaphic, and