My parrotia persica is having problems. It has a few branches with bark that is splitting and approximatley half the branches only have a few leaves on them. I suspect a bad pruning cut last year may have allowed an infection of some sort to enter. The other half of the tree is well leafed and looks quite healthy. My question is: what is the cause of the defoliation and bark splitting, and how do I treat it. This tree is about 1o years old and is mult-branched. Would it be too risky to prune off the ailing branches, which would mean about 50% of the tree? Also if this is recommended, is their an optimum time of year to prune it? Many thanks!