MEADOW KNAPWEED




meadowknapweed_flowerstem.jpg Lesser%20knapweed.jpg

Scientific Name: Centaurea jacea x nigra
Common Name(s): Meadow Knapweed
Origin: Europe
Identification:
~ perennial plant.
~ grows up to 3.5 feet tall.
~ flowers bloom from midsummer through fall and are pink to reddish-purple.
~ Basal leaves can be entire, lobed or toothed and have a petiole.
~ stem leaves are smaller and don't have a petiole.
Characteristics:
~ invasive plant which competes strongly with native plants.
~ well adapted to multiple habitats such as pastures, parks, roadsides, lawns and railroads.
~ coarse, tough foliage makes it unpalatable for most livestock giving it an advantage over other weeds.
~ reproduces mainly by seeds but can resprout via root and crown fragments.
Habitat: Found from B.C. to northern California
Control/ eradication recommendations:
~ Cultivation can be an effective cultural control as well as mowing the plants periodically which may make them more palatable for livestock and more susceptable to herbicides.
~ Herbicides such as picloram, triclopyr or clopyralid are available to control knapweed.
~ In B.C Larinus minutus and Larinus obtusus (beetle) are used as biological controls. Metzneria paucipunctella (moth) and Urophora quadrifasciata (fly) are also control agents in B.C.
References:
http://cru.cahe.wsu.edu/CEPublications/pnw0566/PNW0566.pdf
http://www.kingcounty.gov/environment/animalsAndPlants/noxious-weeds/weed-identification/meadow-knapweed.aspx
http://cru.cahe.wsu.edu/CEPublications/pnw0566/PNW0566.pdf