Where it is invasive, C. nutans is a problem on farmland because it competes with native forage plants, crops, and hinders the movement of livestock because livestock do not want to walk through it. Native plants are outcompeted by C. nutans because it is a prolific seed producer. It spreads seeds for an extended period of time, dispersing them close to the plant creating dense stands that crowd native plants. It reduces animal production in grazed pastures by reducing the amount of pasture available. The spiny vegetation catches in the wool of sheep, reducing the value of the wool. The presence of the seed in pasture and crop seed generally prevents certification of the seed.
Location Specific Impacts:
United States (USA)
Agricultural: Competes with crops, forage for livestock, and impedes the movement of livestock because they avoid entering the dense stands.
Competition: Affects ecosystems by competing with native plants, including rare and endangered species.
Economic/Livelihoods: Costs farmers in the United States and Canada millions of dollars each year in lost crop yields and management expenses.
New Mexico (United States (USA))
Competition: In New Mexico, C. nutans is also encroaching on the habitat of rare and endangered species, such as Mescalero thistle (Cirsium vinaceum ), which grows in springs, seeps, and marshy valley bottoms in east of this state. C. vinaceum is closely related to C. nutans , making control techniques, such as herbicides, difficult to use without killing both species.