I have two 12-15 year old peach trees that have an issue with their bark. There is a scaly black appearance to them (almost as if they were charred in a forest fire) starting from the bottom of the trunk extending upwardly to the main branches. It hasn't hit any of the outer portions of the branches. Both leafed out a little scraggly this year (not sure if that was due to the harsh winter). Treat with copper fungicide each year, fertilizer, Ironite. My younger peach trees don't seem to be affected (knock on wood). Any ideas what I'm dealing with?