• Herbicides, Nitrogen, and Control of Tall Larkspur under Aspen Trees

      Cronin, E. H.; Bowns, J. E.; Johnson, A. E. (Society for Range Management, 1977-11-01)
      Tall larkspur (Delphinium barbeyi Huth.) dominates the herbaceous vegetation under quaking aspen (Populus tremuloides Michx.) on large areas of mountain summer ranges in southern Utah. These tall larkspur plants are more susceptible to single applications of 2,4,5-T and silvex than reported for the same species growing in the open subalpine meadows of central Utah. The herbicide treatments evaluated provide a means of manipulating the vegetation to produce various proportions of grasses and forbs that would be safe and desirable for cattle or for dual use by cattle and sheep. Nitrogen fertilization applied in addition to herbicide treatments did not enhance control of tall larkspur or stimulate forage production. High rates of nitrogen applied to otherwise untreated plots did not control tall larkspur, and increased forage production only the first year after application.