Help, something's chewing on the stalks!

[SmokinAce 03]

I went away for the weekend and come back to find one down and many others attacked. Is it gophers? I live by beavers but I think they would have taken them down easily. What is the best method to prevent this? I was thinking of putting some 3-4 in. pvc around them, hoping for an easier solution though. All suggestions welcome.

 

[Haggardass]

Maybe just wrap some metal wire around the stalk, maybe some chicken coupe its what I did.