• Leafy Spurge Control with Herbicides in North Dakota: 20-Year Summary

      Lym, R. G.; Messersmith, C. G. (Society for Range Management, 1985-03-01)
      Leafy spurge (Euphorbia esula L.) control by herbicides can vary from year to year due to changing environmental conditions. Data from leafy spurge control experimental and demonstrational plots with 2,4-D[(2,4-dichlorophenoxy)acetic acid], dicamba (3,6-dichloro-o-anisic acid), picloram (4-amino-3,5,6-trichloropicolinic acid) and glyphosate [N-(phosphonomethyl)glycine] were combined from 1963 through 1982. The amine and ester formulations of 2,4-D provided similar leafy spurge control. 2,4-D at rates up to 4.5 kg/ha provided less than 40% control after 1 year, and annual (spring or fall) or biannual (spring and fall) 2,4-D applications did not increase leafy spurge control. Dicamba was most effective as a liquid formulation when spring applied and as a granular formulation when fall applied. Dicamba at 9.0 kg/ha was required for satisfactory leafy spurge control for 1 year. Picloram at 2.2 kg/ha gave over 90% control of leafy spurge for 2 growing seasons regardless of formulation or time of application. Synergistic weed control was observed when 2,4-D at 1.1 kg/ha or less was applied with dicamba or picloram at 0.6 kg/ha or less. These synergistic herbicide combinations are economical on many pasture and rangeland sites infested with leafy spurge. Fall-applied glyphosate at 0.8 kg/ha or more gave good control of established leafy spurge for 1 year in shelterbelts and as a spot treatment.