Knapweed Management: Spotted Knapweed Control
Spotted and Russian knapweed are two members of the Southwest's “Dirty Dozen ”invasive weed species. Spotted knapweed
(Centauria maculosa Lam.) is a short-lived, noncreeping perennial that reproduces from seed and forms a new shoot each
year from a taproot.
Spotted Knapweed Control
Spotted knapweed can be controlled with herbicides; however, the weeds will reinvade if cultural techniques are not
integrated into the management plan.
- Herbicides that have proven effective for spotted knapweed control include picloram, clopyralid,
clopyralid + 2,4-D, or dicamba.
- Judicious herbicide application that does not injure grasses may allow them to compete effectively
with spotted knapweed. However, in severely infested rangeland, re-seeding with suitable perennial grasses
is necessary to prevent weed reinvasion.
- Insects, such as seedhead flies (Urophora affinis and U.quadrifasciata), root beetles ((Sphenoptera jugoslavica),
yellow-winged knapweed moth (Agapeta zoegana) and knapweed root weevil (Cyphocleonus achates) are being evaluated as
bio-control agents.
- Livestock (sheep, goats, cattle) will eat diffuse and spotted knapweed. Research by Colorado State
University scientists shows that cattle grazing knapweed twice in the spring decreased seed set by 50% and
tumbling off-site over winter by 15%.
Read the label. You must follow the label directions for all pesticides to get the best results.
Failure to follow labeled instructions may result in poor control, environmental damage, and wasted time, money and resources.
If you have questions, contact a crop consultant, Extension specialist or County Extension Agent.
For more information, contact an Extension Specialist or your County Extension Agent.
Southwestern Noxious/Invasive Weed Spotted & Russian Knapweed Excerpt:
Based on information from George Beck, Extension Weed Specialist, Colorado State University,
gbeck@lamar.colostate.edu
Click the following link for the audio file on knapweeds:
Spotted & Russian Knapweed
Click for problems with the audio file..
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Richard Lee: It's been reported that spotted knapweed species are responsible for a 42 million dollar economic loss in Montana.
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Narrator: The best strategy for controlling knapweed is to suppress infestations by chemical or mechanical means, then re-seed with desirable grasses. |
| Narrator: For more information, contact a state Extension specialist or your local County Extension Agent. |
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