Leafy Spurge (Euphorbia esula) Control with Imidazolinone and Sulfonylurea Herbicides

Abstract

Experiments were conducted to determine the efficacy of imidazolinone and sulfonylurea herbicides applied alone or in combination to control leafy spurge. Imazapyr (840 g ai/ha), imazethapyr (140 g/ha), sulfometuron (100 g/ha), and chlorsulfuron (20 g/ha) were applied in the fall on rangeland sites near Ainsworth and Columbus, NE. Imidazolinone and sulfonylurea herbicide combinations did not improve leafy spurge control nor affect forage grass yields when compared with herbicides applied alone. Imazapyr and sulfometuron were the most efficacious, providing greater than 80% leafy spurge control 9 mo after treatment (MAT). Imazethapyr provided 80% control of leafy spurge 9 MAT when applied to a coarse textured, low organic matter soil. In contrast, leafy spurge control was only 15% when imazethapyr was applied to a fine textured soil. Chlorsulfuron did not control leafy spurge, regardless of site characteristics. Imazapyr reduced perennial grass yields by more than 60%.