Submitted to: Rangelands
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/13/2007
Publication Date: 12/1/2007
Citation: Mitchell, R., Moffet, C.A., Sosebee, R. 2007. A physiological basis for controlling leafy spurge on nebraska rangeland. Rangelands 29(6): 12-14. Interpretive Summary: Leafy spurge is a weed that invades grasslands in the central and northern Great Plains of North America. It reduces pasture production and changes species composition by displacing native plants. Herbicides are often recommended to control leafy spurge. Leafy spurge response to herbicides depends on the growth stage and status of the plant at the time of application. We measured leafy spurge total non-structural carbohydrate (TNC) concentration for 21 months at four locations in Nebraska during 1998 and 1999, and developed a TNC trend for leafy spurge. Additionally, we applied herbicide treatments in June, August, and October to correspond with different growth stages and TNC status. The best time to apply herbicides to optimize leafy spurge mortality in Nebraska is from late September to the first killing frost.
Technical Abstract: Leafy spurge is a non-native perennial forb that invades rangeland and pasture in the central and northern Great Plains of the U.S. and Canada. It quickly increases in pastures, reduces available forage by displacing desirable plants and changing species composition, and may reduce forage use by cattle in infested areas. Herbicides are often recommended to control leafy spurge invasions. The response to herbicides depends largely on the physiological status of the target plant, which can be predicted by total non-structural carbohydrate (TNC) concentration. We measured the TNC concentration of leafy spurge for 21 months at four locations during 1998 and 1999, and developed a TNC trend for leafy spurge in Dawson County Nebraska. Additionally, we applied Picloram at 1, 2, and 4 pints per acre in mid June, mid August, and mid October to correspond with different stages of growth and TNC status. Based on leafy spurge TNC and response to picloram application, the best time to apply herbicides to optimize mortality in Nebraska is from late September to the first killing frost.