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Do you recognize spotted knapweed? It is all around us and is spreading. This plant is in roadsides and non-cropland across many areas in Minnesota cattle country and is spread mostly by human activities. Why should you care? Because spotted knapweed is like a skunk in an outhouse.once it is there nobody else stays.

Spotted Knapweed excretes a compound from its roots called catechin that acts like a herbicide to neighboring plants and soon the native vegetation is gone and only spotted knapweed is left. The leaves contain a compound call cinicin that is very bitter and cattle, deer, rabbits and most other grazing animals except goats will not willingly eat this plant. Try some yourself, chew a leaf and you will soon discover what a vile plant this is.

Spotted knapweed is a short lived perennial plant that only reproduces by seed and some of the seed that is produced can stay dormant for five or more years. This plant is not difficult to control with herbicides and some may even call it a wimp. But don't underestimate this plant because it takes a sustained effort to control it on a site because of the seed dormancy.

Spotted knapweed does not have a very effective seed dispersal method. Seed is 'flicked' from heads as wind blows stems back and forth. Most seed is dispersed within a few feet of the mother plant which results in areas with very high plant densities. Unfortunately, humans are very effective in moving knapweed seed and this invasive plant has been dispersed across this region on various types of machinery and recreational vehicles, in hay movement, and in gravel used in road maintenance from infested gravel pits. We think that gravel pits serve as a primary source of spotted knapweed seed for infesting roadsides.

In Clearwater County, a weed task force has been formed to develop strategies for managing this plant. A pilot project will be initiated in 2006 to work with gravel pit owners to eliminate the plant from these locations. A roadside treatment program will be started that will evaluate the best strategies for controlling this plant and approximately 77 miles of county roadways will be treated. Non-herbicidal approaches to spotted knapweed control will be evaluated on the Conservation Farm and at Itasca State Park.

What can you do?

1. Learn to recognize this plant and use practices so you don't accidentally spread the seed. Call or stop by your local Extension, NRCS, SWCD or Environmental Services offices and ask for a spotted knapweed bulletin.


2. If you own a 4-wheeler or snowmobile be careful about dragging spotted knapweed plants from one location to another


3. If you harvest roadside hay, avoid spotted knapweed patches and take precautions if moving infested hay.


4. If you own land with spotted knapweed patches treat it with a herbicide this spring before the plants begin to bolt (send up a seed head). This plant is not difficult to control with herbicides if the applications are made at the correct time.

For more information, contact Dr. Holen at 218-281-8691 or Jim Stordahl at the Polk County office in McIntosh at 800-450-2465, or at the Clearwater County office on Wednesdays at 800- 866-3125.