Close attention should be placed on any feed or seed materials imported from the northern and northwestern states. Quick identification and eradication of Canada thistle plants is essential to prevent its spread. First plants to appear should be destroyed by pulling or hoeing before becoming securely rooted. Canada thistles usually appear above ground in early spring. The decline in total food reserves in underground parts proceeds rapidly, then is slower until early summer when the plants bloom and are in their weakest stage.
Cultivation begun then is usually most effective.
Persistent cultivation, which destroys roots and rootstocks and exhausts food reserves, is effective in eradication. Avoid continuous small grain or row crops. Combination of cultivation, crops and chemicals - One season of intensive cultivation followed by winter wheat or winter rye will eradicate a high percentage of Canada thistle. The following herbicides may be used for cost-share with landowners. Other products labeled and registered for use on this noxious weed in Kansas may be used in accordance with label directions but are not available for cost-share.