Yeah, burdock… what a disaster. I guess like all plants it has a limit in climate zone tolerance, but I know it is totally happy here. Here it will grow 6 feet or a bit more. As mentioned the large clusters of burs will cling to anything, spreading the small sunflower like seeds far and wide. I have observed the seeds continuing to germinate nearly 25 years after the last contamination, not sure how much longer they may persist, but it’s not looking good at all.
About 5 - 6 years ago they arrived on my land. They will grow in fairly significant shade, so tend to crowd out natural growth with their huge leaves and breadth. The only somewhat effective solution is spot spraying with Killex (2-4D, mecoprop, dicamba. A few walks per year with a backpack sprayer, for life, just to limit infestation in a local area.
The roots are edible, best dug from first year plants in the fall. Peeled and boiled they are good eating.
The garden seed trade offers Japanese burdock as a root vegetable, called gobo. Considering the above, this seems like a very negligent thing, as I don’t want to see wild burdock with even greater genetic diversity.
I imagine in time some sort of insect pest or disease will instate a natural order, but it will likely be decades if not centuries.