I'm a young aspiring landscaper and I am being brought in to do a job for someone.

They have a gorgeous European Plum tree but starting from the base out is a thick (bout quarter inch and size increases as you dig downward) vining/rooting system that has taken over about eight feet outwards from the tree's base.

We need to kill the vining system and till it out. But without hurting the plum tree. any suggestions would be very helpful.