Freeze Damage on young Tulare Walnut tree

The cold dry December we had in 2011 caused freezing damage on some young walnuts.  This is a walnut entering its' second leaf.  The lowest buds are OK but the upper part of the tree will need to be removed.  If left behind, the tree would grow around the dead wood and create a weak trunk.  The roots are unaffected and the tree will regrow vigorously. The interesting thing is that the freeze damage happened seemingly at random to only 11 trees on 30 acres.  Good soil moisture during the cold winter months, and not pruning too early are freeze-prevention measures for young walnuts.