What could be wrong with my Fatsia?

Where the pine roots have broken through is about 4 m from its trunk.

I imagine it is quite a tangle underground, what with the oak, cherry, pine, fatsia, robinia, a large holly, a large honeysuckle, and sundry smaller plants all within an area covering about 5 Sainsbury's-sized parking bays.

Revised plan - watering now, pruning next yr! Should I take off the most damaged leaves?

 

Yes, remove the oldest and the most damaged leaves.
I've never owned a fatsia, but I'm sure @pete can advise on what further pruning may be needed at this time.
Good luck!

 

I just take off anything that looks bad,if you find you are removing too many new leaves then consider taking that stem back to a suitable place.

I'd put a hose under it on trickle for an hour, maybe moving it around the root area from time to time.

 

Gotta ya! Just given it a good 5 mins hosing whilst it is still fully in shade.

 

You need to get water under the leaf canopy as well, just for good measure a few handfuls of chicken poo wouldn't hurt.

 

I watered all around, but especially concentrated on the area where the multiple stems come out of the ground. I have a gravel top-dressing, so spreading stuff is not so easy. I could give it some granules that fall between the gravel bits.

 

Applying diluted seaweed extract on the leaves and around the roots could help @ViewAhead. I use it as a tonic on anything that looks unwell (plantwise ). Also I'd consider raising the canopy to create more light below and improve access for watering and increased airflow to avoid fungal disease.

 

The canopy is mostly quite high. The stems are a bit congested, as happens with multi-stemmed shrubs, but leaf-wise, they do have room, especially lower down, because of its wide span

Not tried seaweed extract before. Sounds like a plan.