Use something with dicamba, repeatedly--Three Way for instance. For tough weeds mix that with T-Zone--both at full strength and add spreader sticker. Repeat as needed. Mow or trim as often as needed to keep it cut off short--you don't want green leaves to send food to the roots (which are wide ranging and deep).
Remember Canada thistle creeps with long underground stems. You have to kill it all--or it will come back. Kill it wait for roots to sprout--kill it again--three times at least.
Last edited by RigglePLC; 09-25-2009 at 08:22 PM.