Just grab them as low to the ground as you can and pull them out, taking as much root with it as you can. The plant will focus its nutrients and efforts on the sections not being torn out. Any time you see another escapee, grab it and pull. They will become less frequent as the main body fleshes out and grows.
Nature doesn't like bare empty spaces so consider filling in that large empty barked area with some more crops and raspberry escapees will have some competition and become less likely as well.