Leafy Spurge Control and Improved Forage Production with Herbicides

Abstract

An experiment to evaluate 59 long-term leafy spurge (Euphorbia esula L.) management alternatives with resulting forage production was established at 4 sites in North Dakota in 1980. The herbicides applied included 2,4-D [(2,4-dichlorophenoxy)acetic acid], dicamba (3,6-dichloro-2-methoxybenzoic acid), and picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid). Picloram was applied as the liquid spray, granules or using a roller or pipe-wick reduced volume applicator. All original treatments applied in 1980 reduced leafy spurge density 65% or more but required retreatments in 1981 and 1982 to maintain good control. Picloram sprayed at 2.2 kg/ha followed by a herbicide retreatment provided the best leafy spurge control at 84% after 3 years, but resulted in only intermediate annual forage production. Picloram roller applied provided 84% initial leafy spurge control and increased forage production an average of 28%, but control declined rapidly without retreatment. Picloram pipe-wick applied gave poor leafy spurge control and no increase in forage production. The most cost effective treatments for both leafy spurge control and high forage production were annual applications of picloram at 0.28 kg/ha or picloram plus 2,4-D at 0.28 plus 1.1. kg/ha. These treatments increased annual forage production by 64 and 71%, respectively, and reduced leafy spurge production by 96% compared to the untreated control. Annual application of 2,4-D did not reduce the leafy spurge density but did control the top growth long enough to allow increased forage production. Several long-term management alternatives provide a choice for leafy spurge control depending on geographical location, neighboring vegetation, and economic considerations.