Environmental concerns of using pesticides on public lands have greatly reduced the use of herbicides to control tall larkspur (Delphinium barbeyi Huth). An alternative method of control used ammonium sulfate placed at the base of individual plants. The objective of this study was to determine the mechanism by which fertilizers kill tall larkspur. We hypothesize the salt from the fertilizers kill the plant. We applied ammonium sulfate, ammonium nitrate and sodium chloride at equivalent salt concentrations and evaluated their effect on tall larkspur plants. There was no difference among treatments in larkspur mortality (P > 0.10). The high rate of all treatments (ammonium sulfate 400 g plant-1, ammonium nitrate 264 g, and sodium chloride 180 g, at equivalent salt concentrations) killed greater than 70% of larkspur plants. We conclude the salt in fertilizers kills tall larkspur, not the nitrogen. It is necessary to place the fertilizer or salt at the base of the plant to concentrate it in the root zone, rather than broadcast it. At the end of the study, bare areas left around the dead tall larkspur plants were only 13% of the original size of the tall larkspur plants at Yampa Colo. and Cedar Ut., and 46% at Emery Ut., indicating the surrounding vegetation was quickly filling in the vacated space. The relative cost of materials per plant for both ammonium sulfate and nitrate was 12.9 cents, and 2.6 cents for salt. The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information. Migrated from OJS platform August 2020
Scholarly peer-reviewed articles published by the Society for Range Management. Access articles on a rolling-window basis from vol. 1, 1948 up to 5 years from the current year. Formerly Journal of Range Management (JRM). More recent content is available by subscription from SRM.