Leafy spurge: perennial problem, unrelenting invader

By Tim D'Amato
Larimer County
Department of Natural Resources

Back to Gardening Articles List

One of the first weed species to become visible in the spring is leafy spurge (Euphorbia esula). Expect to see the bright yellow flowers by mid to late April.

Leafy spurge is likely the worst noxious weed problem in Fort Collins and much of Larimer County. This perennial invader has taken over many acres along the Poudre River from the middle section of the Poudre Canyon to the Weld County line and beyond. It is commonly found along the North Fork of the Poudre from Livermore to Seaman Reservoir. It is a widespread problem from Bellvue through Rist Canyon and on a multitude of pastures in and around LaPorte and north of Fort Collins.

The plant displays bright yellow bracts and flowers from April through June and can easily be identified by the milky latex found when breaking a stem or leaf.

Leafy spurge was first reported in Larimer County in a pasture near LaPorte in the early 1960s. Unfortunately it was not considered a problem at the time, was not controlled and has since spread to thousands of surrounding acres. Leafy spurge reproduces by spreading roots and seed spread by animals and by floating along irrigation ditches and rivers.

Native to Europe and western Asia, leafy spurge was introduced into the western U.S as a seed contaminate in the late 1800s. This noxious weed now infests more than five million acres in the United States and Canada, drastically reducing rangeland productivity, native plant diversity, wildlife habitat and land values.

Leafy spurge is on the state and Larimer County noxious weed lists, meaning residents are obligated to control this invasive species. Control measures in Larimer County, at a minimum, require mowing to prevent seed dispersal. Other control measures include sheep or goat grazing, insect bio-control and herbicide application.

The best way to suppress leafy spurge, or any weed, is to properly manage range or pasture. Disturbances, particularly excessive grazing, reduce the competitive ability of grasses and open the door for weed invasion.

Some new herbicides are now available that provide excellent control of leafy spurge without harming pasture grasses.

A cost-share program for purchase of herbicides is available for residents in the northern part of Larimer County. The program is being offered from January through mid June. For further information contact Virginia Johnson, NLCHPP administrative assistant, at nlchppadmin1@msn.com or call 493-3535. Visit the NLCHPP web site at www.nlchpp.org.

The Larimer County Weed District is partnering in this project and will be available for site visits to help landowners with weed species identification and management recommendations, and the district has field sprayers available through a loan program. The weed district can be contacted at 498-5768 and has information available online at www.larimer.org/weeds.

With a cooperative effort from private landowners, public land managers, ditch companies and others, residents can start to control leafy spurge where it exists and prevent further spread in Larimer County