Noxious weeds are simply trouble, sometimes breaking the lifecycle of native grassland areas by crowding out important plants vital to a local ecosystem. Dalmation toadflax is an escaped ornamental weed that has found its way into Colorado pastures, meadows, roadsides and rangland.

This is an aggressive plant, producing up to 500,000 seeds per year and while most of the seeds fall within 18-inches of the plant, they can stay viable for 10 years. In Larimer County, an innovative partnership has turned a stem weevil - specifically Mecinus janthiniformis - into an effect biocontrol for that troublesome toadflax.

A coalition of groups in Colorado turned to this Mecinus janthiniformis into a potent bio control for a troublesome noxious weed.

Beetles were scattered through an area in Poudre Canyon that was burned by the High Park Fire in 2012. While the toadflax was present before the fire, noxious weeds can quickly expand after a fire possibly due to seed germination, growing seasons and lack of native vegetation as competition. The spread of Dalmation toadflax in the county resulted in a yellow hue to native grassland and forested landscape.

In 2013, the Colorado Department of Agriculture facilitated creation of the Poudre Invasive Species Partnership, made up of federal and state agencies, local entities and private landowners. This effort was performed and coordinated by the Larimer County Weed District, and included crews from CDA's Palisade Insectary, Larimer County, U.S. Forest Service and Colorado Parks and Wildlife.

Steve Ryder, CDA's state weed coordinator, explains that noxious weeds pose a threat to agriculture and Colorado's natural heritage. He adds: "The partnership was effective due to the commitment by the entities involved to battle these destructive weeds including the on-the-ground leadership and coordination by the Larimer County Weed District."

The partnership’s first goal was to establish the Mecinus weevils in the toadflax population and eventually grow enough of the beetles so they could be collected and sent to other toadflax populations in the state.  The original weevils came from the Palisade Insectary, with an additional supply from Washington and Montana provided by the Animal and Plant Health Inspection Service.

CDA's Insectary program, in Palisade, is among only a handful of programs in the U.S. that offers farmers, ranchers and resource managers access to dozens of species of beneficial insects and mites as tools for use in Integrated Pest Management programs. The insectary produces and releases about 30 different species of biological control agents to combat noxious weeds and insect pests throughout Colorado.

According to the CDA and the Palisade Insectary, some sites being monitored have seen as much as a 95% control of toadflax using this insect-based defense.

Other partners included the City of Greeley, City of Fort Collins, State Land Board, CDOT, USDA-Forest Service, USDA-APHIS, and two private landowners.

Source: Colorado Department of Agriculture