I have a fig tree cut down to just above the ground and want to know how to stop it from
growing, i.e. putting up suckers. I plan to pave over that area and am afraid, because of its vigorous growth, that it will find a way up and out.
I recommend renting a stump grinder, or hiring a tree service to grind
the stump and the larger roots. You can water the area well to soften the
soil, and try digging up the remaining roots. You could try applying
full-strength vinegar to kill any shoots, or you can wait and continue to
cut them off as soon as they emerge. Over time, this should weaken any
part of the tree that remains in the ground, and it will eventually die.
You could also cover the area with black plastic once the stump and major
roots have been removed. This should suppress any growth coming up from
what is left of the roots. There are also chemical treatments which
should only be used with extreme caution, and exactly according to
directions on the product.
If you look at page 4 of this document on controlling invasive species from the Hawaiian Ecosystems at Risk project, you will see the different approaches used to remove fig trees and their roots from a natural area (in Central California), including physical and chemical methods.