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SPOTTED KNAPWEED
Spotted knapweed is a biennial or short-lived perennial. Mature plants can grow 3 feet tall. This plant will produce an average of 1,000 seeds that can remain viable in the soil for up to seven years. Spotted knapweed is an aggressive weed that rapidly invades pasture; rangeland, and fallow land, causing a serious decline in forage and crop production.
Control
Mechanical: The most effective control is early detection and removal. Digging or pulling can remove small populations. It is best to remove the entire root. Mowing is generally not successful unless it is conducted often. Plants tend to re-flower at a lower height.
Once established in a non-crop situation, hot prescribed burns will assist in reducing knapweed stands. Following a burn, reseeding with native species is recommended. The potential affects of intense burning on native species should be taken into consideration. Biological: There are several biological control agents available. The most promising are the two seed-head attacking flies Urophora affinis and U. quadrifasciata. Congruently, these two flies have reduced seed production 95% in experimental populations. This weed is not desirable forage for livestock, due to its bitter taste.
Herbicide: In rangeland, pastures, roadsides, and other non-crop areas, products containing picloram or clopyralid have proven effective. Treatment is suggested from the rosette to bolt stage. Picloram is a "restricted use" product and can only be applied by a licensed applicator.
When choosing any kind of control method, assure that your choice is suited for your particular situation. Always read and follow the entire product label before applying any herbicide. |