Posted: 13/05/2015 at 09:28
A photo would help. Missing bark is important whatever it looks like underneath, that's the growing part of the tree.
If you want a wildlife garden forget the sprays. You need to achieve a balance of life forms and wiping some out won't take you there, it has effects right up the food chain
Tree diseases are mostly specific to species and are unlikely to spread to the others you mention.
Is it possible this tree is one of the variegated ones, some of which are very suceptible to frost/wind and anything else that comes their way, and that the plain green part has reverted?