| Weeds are a threat to establishing and maintaining successful pasture systems. Because of environmental constraints, the use of public lands for livestock grazing has been curtailed. As the use of privately owned pastures for livestock production increases, it will become more important to study the effects weeds have on pasture systems.;In the summers of 1997--1999, pastures in Utah, Idaho, and Wyoming were surveyed to determine the weed spectrum. Five field studies were established to measure the impacts of weeds on pasture productivity and the effectiveness of pasture herbicides.;Sixty-one weedy plant species were identified in seedling pastures. One hundred thirty-one weedy plant species were identified in established pastures. Forty-seven of the weeds identified were poisonous to livestock.;Herbicides generally controlled broadleaf weeds well in pastures. The economic value of herbicides for pasture weed control varied. |
