LEAFY SPURGE (EUPHORBIA-ESULA) CONTROL WITH IMIDAZOLINONE AND SULFONYLUREA HERBICIDES

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), sulfome turon (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 cont rol nor affect forage grass yields when compared with herbicides appli ed alone. Imazapyr and sulfometuron were the most efficacious, providi ng greater than 80% leafy spurge control 9 mo after treatment (MAT). I mazethapyr 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 s oil. Chlorsulfuron did not control leafy spurge, regardless of site ch aracteristics. Imazapyr reduced perennial grass yields by more than 60 %. Nomenclature: Chlorsulfuron, -[[(4-methoxy-6-methyl-1,3,5-triazin-2 -yl)amino]?? carbonyl]benzenesulfonamide; 4,5-dihydro-4-methyl-4-(1-me thylethyl)-5-oxo-1H-?? imidazol-2-yl]-3-pyridinecarboxylic acid; imaze thapyr, -oxo-1H-imidazol-2-yl]-5-ethyl-3-pyridinecarboxlic acid; sulfo meturon, hyl-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]?? benzoic ac id; leafy spurge, Euphorbia esula L. #3 EPHES.