Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 10, 1999
Publication Date: N/A
Technical Abstract: Leafy spurge (Euphorbia esula L.) is a noxious weed believed to have been introduced into the Northern Great Plains in wheat seed brought from Europe by early farm immigrants. This invasive weed has since infested thousands of acres of native rangeland in the Northern Great Plains and the western United States. On rangeland, tillage is not an option and the use of herbicides is expensive and can damage or kill associated plants. Natural insect enemies of leafy spurge in Europe were screened for safety and effectiveness and introduced on native rangeland in the Northern Great Plains and western United States. Over time, insects have resulted in significant and successful control of leafy spurge. In 1939 and 1942, researchers reported on using sheep to control leafy spurge. Goats have also been used to control leafy spurge on rangeland, but they seem to have a narrower area of application than sheep. Since the early 1950s, sheep have been used to control leafy spurge on rangeland with varying degrees of success. Overall, sheep grazing has been shown to control leafy spurge while resulting in an economic return to the farm or ranch operation. Sheep have been suggested as a biological control agent for leafy spurge but too often insects are considered the only biological control agent. On leafy spurge infested rangeland where livestock grazing is not possible, colonies of insects are very important to long term leafy spurge control. However, on working farm or ranch units, insect colonies along with sheep will be needed to offer a biological control method for spurge while providing an economic return to the operation.