apple tree diseases

Question

I grafted two apple cuttings onto a wild pear several years ago. It was successful and fruited. But this year the grafts snapped, revealing the cause: a brown/red rot in the heart of the wood. What is it?

Answer 1

It sounds like it is a wood rot of some kind.
Could be a bacterial disease or fungus.

A canker may have occurred at the graft site from an injury or even winter damage.

Here is a link with more information.

https://www.gardeningknowhow.com/edible/fruits/apples/apple-tree-diseases.htm