Hi, the attached are photos of a fungus growing from an old apple tree that had been heavily pruned last year. Advice?
Fungus on old apple tree
This site may be helpful.
Because it is in the trunk of the tree may be better to leave it be and if it is still given you fruits then after you gather all this year fruits may be best to cut all the area where the fungus is and use it as firewood to avoid the spores that the fungus is producing and spreading into the environment.