, I am going to admit I don't know what a conk is or a pathogen. Is this bad?
look it up
Yes the hollow sound stops at the red line and also stops exactly at the graft line, there's is a piece at the bottom you can see that came off really easily. I will leave it alone, but I have observed two things lately. 1 is a white color in some areas, looks like spray paint and hard to get on camera tried.
if onbly on the outside of the bark then no problem; could be lichen
2 is white mushrooms growing at the corner of the sidewalk about 6 feet away from the trunk.
pic?