Spend any time near the Yampa River in Moffat County and you’ll see the leafy spurge that has begun to dominate riverbank vegetation in recent decades.
Leafy spurge is an invasive plant species that was likely introduced to the area from roadside equipment or out-of-state hay as early as the 1950s, according to Yampa Valley Leafy Spurge Project volunteer Ben Beall.
The Yampa Valley Leafy Spurge Project is a community-based initiative that has been heavily involved in managing the leafy spurge infestation for the past six to seven years.
The Yampa Valley experienced a huge spread of leafy spurge in 2011, when the river banks were flooded, uprooting established leafy spurge plants and carrying roots and seeds downstream.
Once you identify the bright green flowering plant that lines the banks of the river, it’s almost impossible to miss.
Leafy Spurge project volunteer John Husband explained that since the plant is not native to northwestern Colorado, it has no natural predators to keep it from crowding out other vegetation. Leafy spurge has a strong reproductive strategy, so once it becomes established it is extremely difficult to eradicate.
Beall explained that simply picking the plant isn’t effective, and there’s a milky sap inside the stem that makes it poisonous to the touch to humans. The plant is also poisonous to animals, including horses and cattle, as well as deer and elk.
Because leafy spurge crowds out other plant species, it can be difficult for stray animals to forage near certain areas of the river, and this can impact pastures and hay fields near the river. river.
The goal of the leafy spurge project is to reduce seed flow and prevent the plant from spreading.
“Pulling him out is not an effective strategy,” Beall said. “But it’s being used as a placeholder until we have a better solution.”
One of the most common ways to control invasive plant species in agriculture is through the use of herbicides. However, herbicides are not the ideal solution for several reasons. Herbicides are not selective and often kill everything where they are applied. Although herbicides can kill everything, they do not prevent invasive plants from returning.
Herbicides are also not suitable for use near the river, as the chemicals can contaminate the water source.
“We’re looking for a holistic approach,” Beall said.
There are other more natural methods that can be used to control the spread of the plant. The leafy spurge is native to Europe and Asia, but it does not take over those continents as it does in northwest Colorado, as it has natural predators to control its growth.
One of leafy spurge’s natural predators is the leafy spurge beetle, which feeds on the plant, causing it to produce fewer flowers and seeds.
According to Beall, the project group did some research to find that the leafy beetles were released about 30 years ago in 1989. After the beetles were released, however, there was little or no monitoring to determine the effect.
This is where the Yampa Valley Leafy Spurge project came in to better understand the impact of beetles.
The group worked with several local and regional partners — including the Bureau of Land Management, Colorado Parks and Wildlife, and private landowners — to take a closer look at the effect of these biocontrols on the invasive plant.
By mapping the area and monitoring along the river, the project group found that leafy spurge beetles persisted in small numbers. The group also found some areas where the leafy spurge was showing signs of distress, meaning the plants weren’t flowering and seeding as much.
Now that the group has helped prove that biocontrols can be effective, it could help boost local efforts to control the plant.
The goal would be to achieve higher established levels of leafy spurge. Beetles are host specific, or they have evolved so closely with that specific plant that they do not eat other plants.
It is thought that increasing the number of beetles would have little effect on other plants in the area while reducing the amount of leafy spurge and leaving more room for native species to thrive.
Project volunteer Pete Williams explained that biological controls are about limiting invasive species so they don’t have such an impact, rather than eliminating them all together.
“We’re looking for a more even wave where the plant is stressed,” Williams said. “The leafy spurge got a free ride, and we need them to be more demure.”
Yampa Valley Leafy Spurge Project volunteers hold a river float at least once a year to raise awareness about leafy spurge and the work being done on this project. One of the ways the community can help is to involve more volunteers.
Anyone who is passionate about the outdoors and keeping the Yampa River healthy is invited to attend a meeting for the Leafy Spurge Project. Project updates and meeting information are available on the website at http://www.YampaRiverLeafySpurgeproject.com.