Apple tree rot

I have a King apple tree ( or so I've been told ), that has been the victim of poor pruning.
Several old cuts seem to have gathered water over the years & now have some lovely compost pockets.
What should I do & is it possible to slam a branch into them as a "graft" ?

Thanks

 

Try searching "apple canker" for starters.

 

Short answer, no.

Can you graft branches to the main trunk or otherwhere, maybe.
If you want some guidance for the 'how' part, try here: http://www.extension.umn.edu/distribution/horticulture/DG0532.html