Hi everyone, I'm fairly new to fruit trees so I think I'm still making plenty of mistakes. The photos here are of an espaliered pear and double grafted plum and the dead branches I dissected. Recently I cut back some dead wood from these trees. Unfortunately it appears as though the brown stuff has invaded living tissue which I don't want to chop off if I can help it. What is wrong with these trees? Is it contagious? Do I need to chop down further to get rid of the brown stuff and if so how much further down?