Research and IPM

Determine the effects of different grazing regimes on soil moisture use patterns by pubescent wheatgrass, yellow starthistle, and annual grass dominated rangeland.

Determine the population dynamics of yellow starthistle following previous clopyralid applications of 1, 2, or 3 years in wheatgrass or annual grass dominated rangeland.

Measure and contrast total forage production and quality under simulated spring, early summer and continuous grazing management strategies.

Economically evaluate all grazing strategies to determine the most cost-effective method for maintaining a perennial grass stand and preventing yellow starthistle invasion.

In 2001, a severe drought resulted in complete yellow starthistle mortality in the experiment. However, pubescent wheatgrass, a drought-tolerant perennial, produced 900 kg/ha more dry matter than the downy brome that replaced yellow starthistle. Forage dry matter was higher at the later two grazing stages than the early stage. Forage quality was not different between range types (annual grass or perennial grass) and significantly decreased in both types over the growing season. Pubescent wheatgrass fall recovery was not significantly different among clipping treatments and wheatgrass recovery one year after clipping was also not significantly different between treatments.

These results suggest that pubescent wheatgrass is initially robust to clipping and provides the highest level of yellow starthistle suppression when clipped later in the season. The yellow starthistle suppression it provides is likely a more important factor than the reduction in forage quality with late season clipping. These results stress the need for large scale grazing research in perennial grass revegetated areas given the increased promotion of native grass restoration.

In 2001, a severe drought resulted in complete yellow starthistle mortality in the experiment. However, pubescent wheatgrass, a drought tolerant perennial, produced 900 kg/ha more dry matter than the downy brome that replaced yellow starthistle. Forage dry matter was higher at the later two grazing stages than the early stage. Forage quality was not different between range types (annual grass or perennial grass) and significantly decreased in both types over the growing season. Pubescent wheatgrass fall recovery was not significantly different among grazing treatments and wheatgrass recovery one year after grazing in 2000 was also not significantly different between treatments.

The results from 2000 and 2001 suggest that pubescent wheatgrass is initially robust to grazing and provides the highest level of yellow starthistle suppression when grazed later in the season. The yellow starthistle suppression it provides is likely a more important factor than the reduction in forage quality with late season grazing. However, the long-term sustainability of pubescent wheatgrass grazed during its reproductive stages is still uncertain.