Maybe four years ago, the huge locust tree next door "died"...its large limbs fell one by one, so by the end, it was just a massive, barren trunk, sitting just outside our property line. It looked not unlike the tree at the end of Tim Burton's Sleepy Hollow.

After a year+ of it just sitting there (resting? scheming?), it started sending out runners. I did not quite catch what was going on at first, so I cut the thorny bastards as I found them. Last spring, it redoubled its demonic efforts and there are now clusters of shoots working their way across my yard.

For good and bad, the house next door was foreclosed on, so there is no neighbor to talk with. Most of the things I have read seem to start with herbicide on a newly cut stump. Since it is not on my yard (and is not a newly cut stump...yet), is there any way to manage just the runners?