To me that indicates an incompatible graft union. It could be a bad combination of scion and rootstock but is more likely due to a virus infection or similar. Something made the rootstock reject the scion. I've had it happen once.

After hurricane Sandy (ok, the winds were a bit stronger, 50mph) but I lost a Harglow apricot at the graft union. The cut was totally clean the graft must have been weak, but not brown like yours. You must have missed a small sign.

There were no strong winds here, despite forecasts. No branches were broken off on other trees. It's like the graft union just gave up and let go.

I didn't graft this tree, btw, I paid money for it from Raintree.

This post was edited by ltilton on Wed, Jun 26, 13 at 21:57