Where are you in the UK, and what position is the tree planted in? In good soil, in an open, windy exposed position, for instance, or tucked into a shady, dry corner?

And which particular Sorbus do you have?

Many thanks for your responses.

We live in Falmouth, Cornwall.

Unfortunately, I cannot recall the variety of our Sorbus. I can tell you that it has white berries. At a previous address we had another Sorbus (variety Joseph Rock) which was successful and thrived.

Possibly Sorbus cashmiriana, that has white berries. But I'd still like an answer to the rest of my question above re the planting environment.

If they are very large white berries likely, as Bamboo says to be cashmiriana. We do need the answer to the rest of Bamboo's question though.

Thank you.

Although planted in a corner (wall to one side and open fence the other) the roots are in shade but the soil there is mostly damp.

Hope this helps.

Could it be planted too close to the wall? Is the fencing such that wind whistles through it? Which way does the tree face? Finally is your soil neutral to acidic Japanese acers do not like an alkaline soil.

Thank you. Would just mention that it is a Sorbus not Japanese acer, although, coincidentally, we also have two of them, both currently showing good Autumn colour.

Oops sorry about that your Sorbus cashmiriana needs space to grow as it can get to 12 metres in height... Damp or not the soil near a wall is likely to be impoverished so lightly fork in some good organic matter taking care not to disturb the roots also make sure you do not raise the soil level around the trunk.

Is the area where its planted somewhere that has a good depth of soil, and how close to the wall is it? I know that in your part of the world, often there's bedrock not far beneath the soil.
The other thing is whether the tree itself is sick, or showing signs of disease - anything on that front? Actually, a photo would be an enormous help...