(Centaurea maculosa)
Sheep and Goats: Grazing by sheep and goats will result in severe shedding of leaves, lessened crown, lessened root, and above ground growth of premature plants, if grazed properly. Limited and repeated grazing is recommended when grasses are dormant. This process reduces spotted knapweed seedlings, rosettes, and production. This requires careful management to prevent overuse of the desirable species. (1)
Tilling (Plowing): You must till 2-3 years in a row and combine it with annual cropping. This will lessen seed in the soil. You must also follow up with perennial vegetation seeding or planting. (1)
Hand Pulling: This method should only be used with small scale infestations and should only be done each spring before plants produce seeds. You must remove roots for a depth of 2-3 inches to kill roots. Removed plants should be bagged and disposed of off site. (1) *Wear gloves when pulling knapweed!
Controlled Burning: Burning is not effective in controlling spotted knapweed infestations. (1)
Seeding & Reseeding: Is an important step when the beneficial plant community makes up less than 30% of all the vegetation. (1)
Mowing: Is not practical on sites that are rocky or steep or where shrubs are present. Repeated mowing can cause prostrate (the plant stems grow flat along the ground) growth which may still flower. (1)
Watering: Over watering can be detrimental to spotted knapweed. This can benefit the plants surrounding it therefore, killing the knapweed. (1)
Fertilization: Fertilization can be beneficial to surrounding plant life. So, in turn the surrounding plant life will out compete with the knapweed eventually killing it. (1)
http://www.ext.nodak.edu/extpubs/plantsci/weeds/w842w.htm
http://www.efn.org/~ipmpa/Noxknapw.html
http://www.mslacountyweed.org/pages/IWMCEMA.html
http://www.dnr.state.wi.us/org/caer/ce/eek/veg/plants/spottedknapweed.htm
http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/Centaurea_maculosa.html
http://www.usask.ca/agriculture/plantsci/classes/range/centaurea.html
http://www.vnps.org/invasive/invcent.htm
http://www.ext.nodak.edu/extpubs/plantsci/weeds/w1146w.htm
http://www.ext.nodak.edu/extpubs/plantsci/weeds/w842w.htm
http://www.mtweed.org/Identification/Knapweed/knapweed.html
Photo by Mr. Breitenfeldt, WHS parking lot, 1990's.
Bibliography:
1) Missoula County Weed District Home Page. Spotted Knapweed-Centaurea maculosa. [Online] Available http://www.mslacountyweed.org/pages/IWMCEMA.html, February 18, 2006.
By: Terry Woodbury, 02/2006.
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