Hi guy's, I have a dilema; I have a friend who has a mature Ash tree (fraxinus excelsior) in his garden that is displaying possibly two different fungus brackets. Or the same but young and old? He wants to know if it would be safe to build a expensive tree house for his son in this tree? The tree in question has been pollarded in the past. The way i see it is either, dont build the tree house and leave the tree alone, re-pollard the tree and then build the tree house or worst case scenario fell the tree completly because the fungus brackets are rot causing and dangerous.The fungus fruiting bodies are at the base of the tree and half way up it in a cavity. Not sounding good is it? So my question is what are the fungus brackets? and what course of action would you suggest? This is an academic question only and there is no liability attached to the answer. I look forward to hearing some opinions, photo's are attached. Regards, Neil McGregor.