I don't recall anyone saying Robinia suckers before. I know Rhus Typhina does this if disturbed or chopped at. The guy next door had suckers sprouting over his lawn...not robinia. He followed them along and got them out and put the lawn back in place. I watched him do some of it. Hard work and very effective. I did say to him to poison the stump when he sawed it down, but he took no notice....hey ho. You must have a rogue robinia!.

Think any tree that is cut down goes into 'panick' mode and sprouts where ever the main roots have grown. This happened to our Rhus (damn thing) and we had to dig our lawn up and get the main root out, what a job that was. i have also noticed that the cherry tree outside our house which has been cut down (and caused subsidence to our house) it re-sprouting in our garden all over the place!!! So is our old plum tree, cut down a few years ago and still shooting up fifteen feet away. :(

Yes, Robinias are terrible for suckers, especially the pink-flowering hybrids. About all that you can do is locate the roots that the suckers are coming from, drill holes partway into them, fill the holes with SBK, , and cover the holes with duct tape, before you re-bury the roots.