I had planted a nice Sterling Rhizome around March and it took off in the 3 gallon pot. It grew to around 14' tall and had about 10 little cones. Then about a week ago I noticed that it started turning brown and looked as though it was dying. It had been getting plenty of water and fertilizer but what could be the problem? Well, I took a good look at the bine at the soil line and noticed that it looked like it was about to break. As I looked a little further and scraped some soil away from the bine I saw what the problem was. Termites! Yep! I doused those little bastards with some Indoor/Outdoor pest control liquid and so far it has done the trick. Who would've thought that those little pests would eat my babies. I have 5 other varieties all planted the same way and haven't noticed any problems. I did spray some pest control liquid underneath all of the pots. Beware of Termites!
Anyway, hopefully you don't have the same problem that I have had. Maybe this response won't be considered off topic either.