Coming up in my garden right next to some forest (primarily oak mixed with beech, birch, maple) in southwest Sweden. Last year i dug the area out and removed (most) roots. Not much came up but this little sprout. I suppose it could be roots reaching in from the adjacent forest.
Bamboo. Gotta dig up the root, pour glyphosate on the cut root, or for short term, white vinegar.
Glyphosates have no place in nature. Id rather my whole farm overrun by bamboo before i poison it. Besides, there is no bamboo anywhere in my area and i haven’t brought in any organic materials from elsewhere.
Just relaying info as I encountered it recently. I'm no gardener or farmer. Obviously digging it up is best and most effective, but the option is there. I was eradicating around a patio in a overrun garden to keep mosquito population down.