Earlier this year one of mine shot up and went about 2-3' past the top of the trellis... started hanging over and growing back down... I went up there and ran another line that it could grow horizontally on so it would be supported... in training it on that one, it broke! snapped right off, so I trimmed it back to about an inch above one of the lateral junctions. It survived and never grew taller but it did send out a ton of lateral side shoots like crazy and I think I ended up with more hops due to that. I ended up doing this will all 5 of my plants once they reached the top and they pretty much all did the same thing.