Deceased Japanese Acer

Earlier in the week when the gales came through my lovely Acer was downed. It was large and about 30 years old. When I looked at the broken trunk I realised it was diseased and partly callused over. A small section was left behind. It looked as if it severed where it had been grafted onto a root stock.

Monty was planting an Apricot? on GW last night and said to take care of the graft point. That's where I think I went wrong. I had a small glade of Acers and had logs leaves etc piled around for wildlife. I think that's how the graft perhaps got covered and disease set in. 

Just posting this as a caution to others.