Leafy spurge (Euphorbia esula) 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 Milton Seaman Reservoir, and is a widespread problem from Bellvue through Rist Canyon, and on a multitude of pastures in and around LaPorte and north of Fort Collins.
By Tim D’Amato
Land Stewardship Manager
Larimer County Dept. of Natural Resources
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. The plant has since spread to thousands of surrounding acres. Leafy spurge reproduces by spreading roots, and seed spread by animals and floating along irrigation ditches and rivers. 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.
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 5 million acres in the U.S. 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.
How do we get a handle on controlling this invasive species? Education is a good start. Residents need to learn how to identify noxious weed species and realize how costly they can be. Weed seed moves in many different ways — wind, water, vehicles, bird droppings, in the fur and manure of livestock and wildlife, and in hay grown in infested pastures. When residents understand their weed problem becomes their neighbor’s weed problem and threatens our natural areas, they will more likely take responsibility for managing their weeds.
With a cooperative effort from private landowners, public land managers, ditch companies and others we can start to control leafy spurge where it exists and prevent further spread in Larimer County. For information on noxious weed identification and management, site visits, educational presentations, and enforcement procedures contact the Larimer County Weed District at 970-498-5768.