Posted: 30/09/2012 at 18:30
Roundup will only be effective on growing greenery, so not at this time of year. In what state are the tree stumps, and what size? And what kind of tree?
If they are small digging out is the most effective remedy. Or at the very least dig around the base of the tree and sever the main roots. If they are very large get someone in with a stump-grinder. If you saw down a small tree, leave a good length of trunk so you can use it as a lever to break off the roots as you dig around. It will make the job much easier.
If you dig out the brambles - by far the best method - you will not get rid of them in one season. A hoe will be totally useless. You need a strong fork. They will spring again if you leave the largest roots. The growth will be weak, but you must get rid of everything before you put down the weed-supressing fabric or you will get in an awful mess. It is not the panacea you might imagine.