Rejuvinating a sulky tree

I shall leave more knowledgeable grapes to help answer as I am also trying to deal with some old neglected trees. If you can, try and get some pics on here - as many as possible of overview, truck etc. I recently started a thread and one very kind grape picked up on it being diseased, but as sad as that was it has started a whole new world of fruit trees for me.

I'll try and get some pictures tomorrow, weather permitting. It's been vile here the last few days.

It already sounds very weak and/or sick so it might only have a low chance of recovering from whatever is troubling it (disease, poor pruning in the past, out-competing plants nearby or too-weak rootstock).

Some pictures would be helpful - to start with, a whole-tree picture plus a picture of each side of the trunk showing the bark from soil level to the lowest branches.

Too many other plants could be the main problem actually as the poor tree is surrounded in a forest of bamboo, honeysuckle and jasmine.

I'll get some pictures tomorrow and hopefully you guys can help me try and save the thing.

1st image: Left-side view of the entire trunk.
2nd image: Left-side view of entire tree (roughly 10-12ft in height)
3rd image: Front view of the trunk and lower branches.
4th image: Front view of lower>middle branches.
5th image: Back view of upper trunk and lower branches.

I know the tree has canker and everyone will probably say to remove the entire tree but I'm not prepared to part with it yet. It had canker even when it was producing a lot of apples. I've been wanting to try and cut them out but I'm afraid to do it incase I end up hurting the tree more by doing that.

The forest of bamboo and ivy will be removed over the course of the winter which I hope will help add some more circulations to the tree.

The pictures look dark - I'm guessing lack of light isn't helping.
Fruit trees prefer sunny sites - the amount of direct sun they get determines how many blossom buds they produce for the following season. I experimented with a Golden Delicious in semi-shade and it stopped flowering for several years until I moved it to a sunny spot where it started to blossom and fruit again.
Root competition might also be stifling the tree.

Which variety is it? Or was it a family tree? If you can answer that question a lot of pieces of the puzzle might fall into place - including the 'canker' which I am wondering isn't all the result of canker but something else completely different and unexpected.............

Actually the pictures were taken facing direct evening sun instead of with the sun behind me which is why they're dark. The tree gets a lot of sun all day as it's up on a ridge with no obstructions other than the bamboo which will soon be removed anyway, but even now it doesn't cause a problem as the bamboo is no where near as high as even the middle of the tree canopy.

It did produce a lot of leaf bud and did flowers beautifully early in the year (around april-may) but after if flowered it didn't have the strength to produce apples and then the leaves began to stop growing.

I have no idea on the variety of the tree as it was planted by the people who lived here before us. All I know is that it produced medium sized green apples that are sharp and bitter in taste, and that the tree is roughly 8-10 years old.

I'm pretty sure root competition could be a problem as one side of the site is blocked by a solid brick wall fourcing the roots to be re-directed toward the bamboo or honeysuckle bushes. The honeysuckle and jasmine bushes are about three feet away from the tree but the baamboo is right on top of it.

The tree itself is hardy. The winters and grey rainy summers have never bothered it even a little. I've never found winter damage or water damage on the tree at all either.

Will giving is a hard prune help? I was thinking that if it is trying to compete for nutrients and space that if I prune the tree it will have less to feed. Is that right? I will remove the bamboo this winter but it will probablt take some time before that has any effect on the tree..

Probably the roots of the other plants are stronger than the roots of the apple.

If the apples are sharp/bitter, what do you use them for?

My best guess is that you are nurturing a rootstock - probably MM106 - which was never grafted, or the grafted bit died, or the grafted bit was accidentally pruned off, or it was a 'family tree' and it's been pruned so hard at some point that the grafted bits were accidentally removed.
The 'canker'-like lumps on the trunk and stems may well be burrknots (partially formed roots), although it is fairly common for canker (and crown rot) to attack burrknots because of the splits and cracks in the bark allowing easier access to diseases. Woolly aphids also love to hide in cracks and tend to spread canker. Fortunately MM106 has some resistance to woolly aphids and they avoid it unless there's nothing else around to feed on.
The high production of burrknots is why nurseries love the popular rootstocks because they root quickly and easily in the nursery.

Pruning might give a short-term boost to the tree but it doesn't deal with the underlying problem that the tree cannot compete with the other plants. You might find that the apple tree is so weak that it is unable to regrow what you prune off.
Whatever plant roots are crowding out the apple tree roots will need to be permanently removed. Chopping down the stems of the bamboo won't stop the roots underground from continuing to grow into the apple tree root zone and smother its roots. You'll need to carefully remove the roots of the other plants while trying to minimise the damage to the apple tree roots.

We used to use them for cooking most of the time since they are way too bitter too eat straight off the tree.

The bamboo will be completely removed - roots and all so that's not a problem. I'll only lightly prune it then. Just removing the crossing, rubbing and weak angle branches.

Thanks so much for the help!!

I'm going to be brutal. You don't like the fruit, it wasn't your choice of tree, its unhealthy and struggling to survive.
If it was a diseased rose of a sickly colour you wouldn't think twice about its future, the spade would be in your hand.

Right now there are more varieties of lovely fruit trees available to order as bare root plants than ever before so why don't you look through the nursery website lists and imagine planting a healthy tree with delicious fruit instead, though maybe not an apple in the same spot. The sooner you replant, the sooner you'll be enjoying your tree.

Agreed.
If it was mine it would be promptly removed and replaced by something useful - a better variety, a more disease-resistant variety, a more vigorous variety and a more vigorous rootstocks.
I could even be persuaded to concede that it might be worth planting a random variety like Peasgood's Nonsuch.

But as the owner insisted on not giving up on it.......

I've used MM106 apples for cooking too. Although they're a bit small for easy peeling/chopping they're good cookers, with good flavour. MM106 apples seem a bit prone to surface insect nibblings too, but in the kitchen the damaged bits can be peeled/cut off. After a few weeks off the tree mine usually get quite greasy skins and scented.
Being an offspring of an old rootstock crossed with an American fruiting variety (Rootstock M1 x Northern Spy = MM106) it's not a surprise that the apples are too sharp-tasting to eat yet still reasonable for cooking.