Cost-Effective Long-Term Leafy Spurge (Euphorbia esula) Control with Herbicides

Four herbicide treatments applied in the spring or fall were evaluated for leafy spurge control and forage production in eastern and western North Dakota during a 5-yr experiment. All treatments gradually reduced the leafy spurge infestation at both locations except 2,4-D at 2.2 kg ae ha-1applied annually in the spring or fall and picloram plus 2,4-D at 0.28 plus 1.1 kg ae ha-1applied annually in the fall. The most cost effective treatment was picloram plus 2,4-D applied annually in the spring which provided a net return of $284 and $108/ha in eastern and western North Dakota, respectively, and averaged 80% leafy spurge control. Picloram at 2.2 kg ha-1was reapplied only when leafy spurge control declined to less than 70% and provided a net return of $96/ha in eastern North Dakota, but a net loss of $235/ha in western North Dakota. Dicamba at 9 kg ae ha-1was applied up to four times to maintain 70% control with an average net loss of $458/ha. Total potential production and value of forage will determine if a specific treatment is cost effective in any one location.