Western wheatgrass canopy cover, live standing crop, and relative composition (based on live standing crop) were reduced under sulfonylurea herbicide treatment, ranging from 37–39%, 42–49%, and 49–55%, respectively, below auxin or mowing treatments (Fig. 1). Switchgrass incurred severe adverse impacts under sulfonylurea herbicide use, producing stand reductions ranging from 61–71%, 51–69%, 28–47%, and 27–32% for basal cover, canopy cover, live standing crop, and relative composition, respectively. Auxin herbicides also significantly reduced basal cover and canopy cover for switchgrass compared to mowing.