Control of Larkspur with Herbicides Plus Nitrogen Fertilizer

Abstract

Past attempts using herbicides to control larkspur (Delphinium barbeyi), one of the most serious poisonous plant problems to cattle in the Western United States, have been less than satisfactory. Preliminary research reported herein suggests that 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) plus ammonium sulfate placed around the base of the plant or urea and 2,4,5-T sprayed on the plant may give good control of larkspur with a single treatment during any stage of growth. Some results also indicate that nitrogen fertilizer alone may be an effective control for larkspur.