You may have also heard of spotted knapweed. Spotted knapweed is a perennial plant that spreads by seed. One plant produces up to 1000 or more seeds that can remain viable in the soil for at least five years, and likely longer. These pretty but destructive plants spread quickly and can drive out native plants from grasslands and degrade the value of rangelands.
In BC, a study was done to assess the economic impacts of seven invasive plant species, including knapweed. In this study, in the absence of any management, the total expected damages were estimated to be a minimum of $65 million in 2008, rising to $139 million by 2020. Knapweed can also cause increased erosion and run off and reduced forage for wildlife or livestock. It can even increase fire risk.
Knapweed has spread throughout much of the interior of BC, but we still have opportunities to prevent its spread into new areas and to limit its impact.