just got the pic up, that aint to bad roundup will deffiently kill it mate, but i would wait untill the weather warmed up abit before you spray it on, make sure
when you do it even when the leaves have started going brown carry on spraying it, or even better when the fellas alseep jump over cut the bottom with a
pair of loppers and pour the roundup on were you have cut all the main roots, no need to touch the top then it will all just die off....