New apple tree or not?

[OlafsTwig]

There's an apple tree in my neighbour's garden, close to the boundary (the branches hang over). I think it was quite old - it was certainly not a baby tree twelve years ago. A few years ago it had loads of apples, then it had a major prune. Last year it seemed fine I think (maybe one dead branch? didn't pay much attention). This year it flowered and came into leaf, but then all the leaves dropped off branch by branch and it's looking like an ex-tree .

Is this likely to be a disease of some sort? And if so, should I avoid planting a new apple? For how long? Or is that how old apple trees die? Is it worth asking my neighbours if they know anything? (We're neighbourly but not friends, iyswim).

Hi there I have a four year old apple tree it's always been fine and this year I put it in a bigger pot. It then checked out leaves went black and apparently it has fire blight. I pruned it right back and disinfected the secateurs afterwards. Apparently a lot of t are disease prone. New green shoots have appeared but no apples this year!