Posted: 03/08/2014 at 16:31
I've used Roundup, and found it most effective by cutting the plant back to a couple of ft, then painting the leaves and stem rather than spraying. The problem with spraying would be that some of the spray may go onto plants you don't want to kill for instance the lawn.
Roundup is effective if the ration of plant covered with the stuff is sufficient to weaken the plant and migrate into the roots.So don't cut the bramble back to an inch of the soil.
Alternatively if it is only one bramble it's easily dug up, you just need to ensure you dig the crown up, if roots are left they don't grow back as strong and can easily be pulled up whilst small or dug out again. If a small bramble you can usually dig out most the roots with the crown.
Hope this is helpful...