after reading on several sites that running bamboo was easily controlled by trenching around it and pruning rhizomes that grew into the trench, i dug a 24"deep trench in a square 10' per side and planted a p. nigra. in the middle. after a year the nigra had only spread a couple feet, or so i thought. needing dirt for another project i decided to dig the trench down to 36".
at just over 30" i found rhizomes. eight feet from the nearest culm and still angling downward. they never so much as poked a hair into the trench.
