Bark damage on an avocado

After about fourteen years of waiting, one of my seedling-grown avocado
trees started flowering in earnest, but only on one high branch. Close
inspection revealed that leader had been completely girdled a couple
feet lower. Photos are at
http://www.zefox.net/~bp/avocado/

This looks quite different from the rat damage seen on the lemon tree last
spring and maybe older. Once again, the astonishment lay in the completeness
of the girdling and the apparent flourishing of the isolated top growth.
Most of the tree is unharmed, unlike the lemon, which is making a good
recovery nonetheless.

Only the girdled branch bloomed with enthusiasm, though there are a few
flowers further down the tree that might (if I'm very lucky) offer a hint
of the fruit quality. If it's poor I'll topwork the tree with good scion
wood, so it's no huge loss either way.

Thanks for reading, and any thoughts.

bob prohaska