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RUSSIAN KNAPWEED
Russian knapweed is a perennial that reproduces from seed as well as root. In Idaho, it can grow in a wide range of soils and environmental conditions. It is aggressive and difficult to control. Seeds can remain viable for up to five years. This weed forms dense colonies that compete with and replace native and desirable vegetation. Due to its bitter taste, livestock will not graze it. This noxious weed is known to cause chewing disease.
Control
To eradicate Russian knapweed, it is important to place continual stress on it. Biological: Stem/leaf gall nematodes have been used in some instances, but long-term success has not been determined. It is known that the nematode does not move readily from plant to plant.
Mechanical: Cultivators are unable to reach the deep rootstock, which is known to reach depths of 23 feet. This makes it extremely difficult to control in cultivated fields. Root fragments can be easily spread from one end of a field to the next.
Cultural: Planting desirable vegetation is effective once the weed is weakened with herbicide. Cultural control along with herbicide use provides the best management.
Herbicide: This department has seen good results in rangeland, pastures, and other non-crop areas by applying products containing picloram or clopyralid at bud to bloom stage or early in the fall. 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. |