Crested Wheatgrass Vigor as Affected by Black Grass Bug and Cattle Grazing

Abstract

Light to moderate populations (50-200 per m2) of black grass bugs in a seeded monoculture of crested wheatgrass appeared to reduce plant vigor. Vigor of ungrazed plants was compared to plants grazed only by black grass bugs and plants grazed by black grass bugs and cattle. Generally, vigor decreased as levels of grazing increased. Leaf length, seedhead height, root crown nonstructural carbohydrates, and plant color correlated positively with vigor while functions of axillary tillering such as basal area and seedhead density correlated negatively with vigor. Cattle grazing was not in excess of intensities recognized as proper for the area.