@Weedygarden I went back and looked at the first page of posts. Your plant is next to a fence, right?
I mentioned birds in part of a sentence in my reply...
Birds are the most common method by which poke sallet is spread. They swallow the berries. The seeds don't digest. The bird sits on a fence... and poop! A new poke plant is born.
If you have poke in your neighborhood and a fence birds like to sit on... the odds are your battle with poke will be unending. I find it on fence lines everywhere here on the farm. It doesn't have to be a fence, it could be a tree limb or a power line birds like to perch on.
So, don't be surprised if you kill a poke root and the next year there is another poke plant. Just so you know...