• Proper Burning Intervals for Tobosagrass in West Texas Based on Nitrogen Dynamics

      Sharrow, S. H.; Wright, H. A. (Society for Range Management, 1977-09-01)
      The time required for re-establishment of pre-fire nitrogen levels in tobosagrass (Hilaria mutica) communities in the Rolling Plains of West Texas was studied on five different ages of burns over a 2-year period. Time elapsed after burns varied from one to five growing seasons for both convex and concave topographic sites near Colorado City, Texas. Standing old growth-N returned to pre-fire levels by the end of the third growing season. However, litter-N on the soil surface took 5 years to reach pre-fire levels on concave sites and an estimated 8 years on convex sites. High variation prevented the recognition of any meaningful trends in root or soil nitrogen levels. Based on this data, tobosagrass should not be burned more frequently than 5 to 8 years, depending on the site.
    • The Black Grass Bug (Labops hesperius Uhler): Its Effect on Several Native and Introduced Grasses

      Higgins, K. M.; Bowns, J. E.; Haws, B. A. (Society for Range Management, 1977-09-01)
      Large areas of Utah's rangeland have been seeded to introduced wheatgrasses, and many of these areas are now infested with the black grass bug (Labops hesperius). A study of the effects of this insect pest on several native and introduced grasses was conducted on three experimental study plots in southwestern Utah. The data revealed that the six introduced grass species studied, growing in small monocultures, contained considerably more black grass bugs than did the native range grasses in nearby areas. Thus, the six monoculture grass species were more susceptible to grass bug damage than were the native range grasses. Moreover, variations in black grass bug populations within the six grass monocultures also revealed differences in susceptibility. Phenology comparison data revealed there was no correlation between the phenological stage of plant development and the stage of black grass bug instar development, therefore ruling out an accurate means of determining time of spraying in relation to plant maturation.
    • Weed Control-Revegetation Systems for Big Sagebrush-Downy Brome Rangelands

      Evans, R. A.; Young, J. A. (Society for Range Management, 1977-09-01)
      Chemical weed control systems integrating 2,4-D or picloram spraying for brush control and atrazine fallow for downy brome control were investigated in a series of rangeland communities. Application of both weed control techniques greatly enhanced seedling growth and increased yield of perennial grasses seeded the year after the fallow. Added nitrogen either had negligible effects or tended to negate the benefits of the weed control systems on establishment of perennial grasses. The 2,4-D/atrazine-fallow system also allowed establishment of the browse species, cliffrose, in a big sagebrush/downy brome community. Increased soil moisture available during the growing period of the fallow and seedling years, because of decreased weed competition, was the major factor for the better stands of grass and browse that resulted from chemical weed control systems.