This is a Fuji apple tree. This one branch had wilted leaves and the unripe apples had gone soft/wrinkly.

I cut the branch off and you can see the cross section above. I have a pear close by that had fireblight, but that was much different looking than this (there was no blackening or wilting of branch, just the leaves/apples)

You can see the leaves are all good below it, but I'm concerned this disease will be moving down. How far into the healthy branch should I cut?