Q.Bamboo spreading
We have bamboo growing on our side of our fence and have for 15 years. It does not appear to spread anywhere outside of the growing area. My neighbor just showed me about 15 5 foot ish, thick spears of asparagus type plants on their side of the fence! I was stunned as I have never seen those types of bamboo starts on our side of the fence. They looked otherworldly. But assuming they came from our bamboo, what type of barrier can we put in to stop that spread over in their yard?
Yes, the Bamboo has escaped your side of the fence.
This is no easy task, the article below has more information.
https://www.gardeningknowhow.com/ornamental/foliage/bamboo/kill-bamboo.htm