As you know, millions of CRP acres could be available immediately to alleviate the tragic consequences our farmers are facing now in the Upper Midwest and Great Plains. As acres expire in the coming months, the Secretary will have the authority to enroll additional acres affected by multiple year disasters into the program, thereby meeting the needs of hundreds of farmers in the Northern Great Plains. Banvel, Roundup, Tordon, 2,4-D, Curtail, and Stinger are herbicides that have the greatest activity on Canada thistle. Highest rates should be used without interfering with next years cropping pattern. Situations may occur where spot treatment with herbicides at high rates may be viewed as the best Canada thistle management program even if the carryover may injure next year's crop.
Timing is a critical factor.
Herbicide application after a frost at 32 degrees F may enhance control but application in late October when leaf tissue was destroyed by frost may result in less control due to lack of herbicide uptake. Tillage can be a critical factor. If lower herbicide rates or less effective herbicides are used, tillage is very important. If tillage is not planned then use the most effective herbicide or tank-mix at higher rates. Spray rosettes of actively growing plants.