Monday, December 11, 2006

An integrated approach to sustainable management of leafy spurge Euphorbia esula L.

Ankush Joshi, ankush.joshi@ndsu.edu1, Denise L. Olson1, Rodney G. Lym2, and Donald R. Carey1. (1) North Dakota State University, Entomology Dept, Hulz Hall, NDSU, Fargo, ND, (2) North Dakota State University, Plant Science, Hulz Hall, NDSU, Fargo, ND

Most tools used against leafy spurge (Euphorbia esula L.) are not economical, practical and/or efficacious. Combinations of these tools may, however, provide sustainable and economical control of leafy spurge. Combinations of the biological control agents, Aphthona flea beetles, the herbicide imazapic, and native grass mixes against leafy spurge were evaluated at Sheyenne National Grassland in southeast North Dakota during 2001 to 2005. The treatment effect on leafy spurge stem density was measured in the spring of each experimental year. Treatment effect on the establishment of the flea beetles was determined by sweep counts in the summer of each study year. Aphthona spp. population increased to 3.2 beetles/m2 and leafy spurge stem counts decreased by 72%. A 90% reduction in leafy spurge density was observed one year after initial herbicide application. One year after this reduction, the effect of insect-herbicide interaction was significant o the leafy spurge infestation. The leafy spurge control achieved by herbicide continued three years after the herbicide application. Seeding the native grass mixes into the leafy spurge infestation did not appear to affect the flea beetle population.

Species 1: Coleoptera Chrysomelidae Aphthona lacertosa