canadian thistle control

Asked June 19, 2017, 3:39 PM EDT

The information I received said to cut the thistle just before blooming to 10 inch height, with fall herbicide application. I bought a rotary cutter and cut 3 acres at 10 inch setting. However, many thistles were pushed down by tractor and just sprang back up. What if I cut to 3 or 4 inches instead? Will that greatly diminish the effectiveness of the Fall herbicide (Stinger ) application? I believe cutting them to 10 inches is supposed to stress them more, but the mower doesn't seem to be effective at that height. Thanks

Meeker County Minnesota

1 Response

Canada thistle is a tough weed. I'm not sure where you are getting your information, but this publication from the USDA and Penn State recommends late spring mowing close to the ground:
https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_018027.pdf

Then go after the second stage growth with an herbicide in the fall. And I did not see Canada thistle listed on the Stinger label, so be sure you pick an appropriate herbicide in the fall:
http://www.herbiguide.com.au/Labels/AMINMETS_69370-100366.PDF

Expect to have to repeat treatments.