I planted Snowsweet and Honeycrisp trees last fall and pruned the main trunk early this April. Over the summer, the upper end of the pruned trunk has turned black and the bark is flaky. My other little apple trees that I did not prune do not have this discoloration problem. Is this normal after pruning the main trunk? If not, how to remedy for overall tree health?
It appears to be Sun scald, more information at http://extension.usu.edu/files/publications/factsheet/NR_FF_021pr.pdf