I've recently removed a tree that was damaging a retaining wall. I can't
name the tree but it had the uncanny ability to grow through a small gap in
the wall ( at this point the trunk was around 20cm wide by 1/2 cm thick) and
then once it found a big gap grow normally. It's fast growing, around from
around 1m to 4m in less than 5 years, and had fairly small green leaves.
Anyway, my question is: do I need to treat the roots to stop it growing
back? And if I do what do I use.

Regards

Paul