Keep hitting them with Gly 4 or roundup, Wet the plant and the ground under it good and keep after them. They do have a large deep root system and will keep coming back for a while from the root. Seems to me when you are using chemicals that bushhogging them oscasionally just makes them worse--especially for the next year.
Edited by Paul Burns (06/27/13 11:16 PM)
Paul Westport-Yuma Tn
On the banks of the Big Sandy River and Maple Creek