My advice would be firstly cut this stuff down to within an inch or so of the ground, clean up all arisings, allow to resprout but only by a couple of inches, spray with brushwood killer. Repeat the process as many times as you need to in order to irradicate the stuff. Hope that helps.. Make sure you use brushwood killer not ordinary herbicide or you will just be wasting money..
No Deborah, Roundup is just for broadleaf weeds grass and brambles, you need a brushwood killer. Like SBK Not sure where you are but that's a British product, if elsewhere will be sold under a different name, just ask your local garden store for brushwood killer, follow instructions carefully don't get on your skin..
Thanks for the information Robert. I'll have to go back and tell the sales assistant in the garden centre who recommended it. I've used Roundup in the past but was talked out of it for use on bracken. Perhaps I should have followed my own thoughts in the first place.