The U.S. Fish and Wildlife Service is hoping to add an innovative weapon to its arsenal used to battle Canada thistle, an invasive weed and long-time thorn in the side of federal land managers. The Service’s Midwest Region has joined forces with the U.S.
Geological Survey’s Northern Prairie Wildlife Research Center to study seed planting techniques that could minimize the noxious weed in tallgrass prairie restoration projects on National Wildlife Refuge System lands.
The National Wildlife Refuge System has an active habitat restoration program and annually seeds thousands of acres in the upper Midwest to native plant species. In Fiscal Year 2003, the Service’s Midwest Region restored 26,690 wetland acres and 7,394 upland acres, primarily on refuges and wetland management districts in Minnesota, Iowa and Wisconsin. Over the next year, the Service will be testing various prairie seed mixtures on three sites in Minnesota and one in Iowa to determine if certain mixtures can reduce or eliminate Canada thistle from restored areas.
“ The goal of the research is to compare the ability of differing seed mixes and application techniques to suppress Canada thistle establishment in new restorations,” said Tim Yager, ecosystem biologist for the National Wildlife Refuge System at Ft. Snelling, Minn. “We hypothesize that by increasing competition and decreasing the disturbance inherent in seeding, we can produce more weed-resistant restorations.”
Canada thistle, (Cirsium arvense) plagues prairie restorations, forcing the Service to control the weed by applying pesticides or mowing, control measures that are detrimental to the restoration effort and expensive. Prairie grass seedlings are disturbed during early growing stages, weakening the native seedlings as much or more than it does Canada thistle. “Continued control of Canada thistle may perpetuate the repeated disturbances that favor infestation by a variety of exotic plants, thistle included,” Yager said.
The study will be conducted at Neal Smith National Wildlife Refuge in central Iowa, Fergus Falls Wetland Management District in western Minnesota, Morris Wetland Management District in western Minnesota and Litchfield Wetland Management District in central Minnesota.
Canada thistle is a native of southeastern Eurasia. It was introduced to Canada as a contaminant of crop seed as early as the late 18th century and has since spread across the United States. It is a rooted perennial that grows to three to four feet tall with spiny dark green leaves. The weed’s flower top ranges in color from rose-purple to pink to white.
For more information on this study, contact Tim Yager, U.S. Fish and Wildlife Service, by phone (612-713-5365) or by e-mail at timothy_yager@fws.gov.
The U.S. Fish and Wildlife Service is the principal federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. The Service manages the 95-million-acre National Wildlife Refuge System, which encompasses 545 national wildlife refuges, thousands of small wetlands and other special management areas. It also operates 69 national fish hatcheries, 63 Fish and Wildlife Management offices and 81 ecological services field stations. The agency enforces federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, and helps foreign governments with their conservation efforts. It also oversees the Federal Assistance program, which distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state fish and wildlife agencies.
