
As Celli said, stand on it before you use anything on it to 'bruise' it so the weed killer gets in to the tough exterior sheathe Buy Glysophate (round up) as thats the only thing that will kill the roots properly. As soon as you see it sprouting get weedkiller on it. Failing that, find a LICENCED sprayer in your area, where we can use stronger stuff than you can buy :) :)
Oh and it will take YEARS to eradicate, the same as ground elder :)
Lea :)