This sucker planted own-root gallicas years ago. Has time come up with any answer in how to deal with the ever-increasing perimeters. I can think of at least three gallicas that I surrounded with a buried ring of black plastic membrane vapour barrier, but all three have escaped and are on the run.
My only thoughts are a kettle of boiling water. (We have a slow combustion stove and I inherited my Mum's and Mother-in-Law's big kettles.)