I was thinking about just having them scalp it with a Weedwhacker, then apply the thick mulch, then come back with the round up to hit whatever grass makes it through.
But if we can use the round up safely, the first time, that would be ideal. Some turf can be pretty relentless.
My town uses me as a consultant and for years I have recommended putting large mulch rings around the trees at the town Square. They just told me this morning, They are planning to do just that. When I asked how they plan to remove the sod they said with an excavator. I put the kibosh on that...
I’ve only seen a few of them around. A municipal Forester in a city just south of me says they make a great small/medium street tree. But they are not native and I worry about planting potential future invasive.