Leafy Spurge (Euphorbia esula) Control, Forage Production, and Economic Return with Fall-Applied Herbicides

Leafy spurge control and forage production after various fall-applied herbicide treatment rotations were evaluated in a bluegrass pasture and a mixed grass prairie. Dicamba at 2 kg ae/ha or picloram at 0.6 kg ae/ha alone or combined with 2,4-D at 1 kg ae/ha applied annually for 3 yr provided consistent leafy spurge control of 85% or better, but forage production was greater at the bluegrass pasture site than the mixed grass prairie site. Glyphosate plus 2,4-D at 0.4 plus 0.7 kg ae/ha applied annually or rotated with picloram plus 2,4-D or dicamba provided 90% or better leafy spurge control after 3 yr at the bluegrass pasture. Control was 50% or less at the mixed grass prairie site where forage production was severely reduced by glyphosate plus 2,4-D. All treatments on the bluegrass pasture provided a positive economic return averaging $227/ha after 3 yr. Picloram or picloram plus 2,4-D at the mixed grass prairie site provided net returns averaging $285/ha, but treatment rotations that included glyphosate plus 2,4-D one or more times in 3 yr averaged a net loss of $32/ha due to severe grass injury.