What could be wrong with my Fatsia?

I have a Fatsia. It is about 4m x 4m and 25 yrs old. Normally, after flowering a proportion of leaves go yellow and drop off. Like this one ...



However, last yr and again now, some leaves have unhealthy brown patches. They don't drop off, just cling on looking sickly, although the stems holding them to the trunk are healthy and green and firm. The photos below show some I have cut off to demonstrate the problem. I estimate about a third of all the leaves are affected, growing both high up and lower down, and from all branches. What could be the problem? Is it just this is an old shrub that has had its day?

 

My guess would be it's dry,they cover their own root area with leaves at the best of times, so the roots have to go along way to get moisture.

 

@ViewAhead not sure if this will help. Ours went through a "bad" stage for some years and we just ignored it. Then last year we thought we need to do something or dig it out. So we cut it back quite a lot and this year it has sent up new growth without any signs of leaf damage.
Maybe not the same as what yours is going through but could cutting it back be possible?

 

I'd agree with @pete
If there's not enough water at the roots to support all the foliage, the plant will drop the oldest (and most inefficient) leaves first in an effort to survive.

Yours is old at around 25yrs - which is around their typical life expectancy, but with some tlc it could keep going for many more years.

 

Thank you all!

Re dryness, this started last summer when it was very wet indeed. It is in competition with a large oak and a water-sucking pine, neither on my property, but has been for yrs. The leaves don't fall off (I cut those to photograph the problem) and the stems are green and firm, suggesting moisture is present.

@On the Levels, I could cut back, but there is some new bushy growth at the base which is also showing the problem.

 

I've always given mine a good cutback about every other year, the main one is pretty old possibly going back to the mid 80s when I thought is was a houseplant and in my usual way had to try one outside.
They respond well to pruning even down to a stump if needs be.

 

I do prune off a stem or two every 2-3 yrs, just to keep it within my property. The damaged leaves are not only where pruning has occurred though, so I don't think the issue is caused by my maintenance.

 

I think it's not the maintenance that has caused the issue but perhaps not enough pruning
If you can open up the canopy so that the winter rains can get in plus perhaps some shallow hoeing around the root area it might help, just a suggestion.
It's probably compacted under it and very dry.

 

The roots have ivy on the ground, inhabited by slowworms, so I can't really disturb that. (The ivy layer is not congested and doesn't extend up the Fatsia at all.) I will try the watering suggestion and see if the damage stops spreading.

I will wait till early Sept to do any pruning, to avoid the hottest period.

 

A mature oak will suck up several hundred gallons of water a day during summer.
The conifer less so, but still a substantial amount, and the ivy will be using water nearer the surface.
So you fatsia is likely to be thirsty.

If you remove a substantial amount of foliage as @On the Levels done, the plant will need much less water, so is better able to withstand a lack of it, but will slow its growth,

I'm sure it'll be ok with some tlc

 

I usually prune after flowering if you're not going to do it now I'd wait until next spring, it's unlikely to have a water problem through the winter.

 

Yes, I usually do it after flowering, but as it needs some TLC, I will do some in Sept.

The pine in the next garden has grown almost as tall as the oak in just a few yrs. Everything down that end of my garden is struggling somewhat. It is a monster ... and an unfortunately attractive habitat for pigeons, magpies and squirrels. It is about 4 m from my Fatsia and their canopies touch. It is only a metre from my Cherry. Its roots have come up through my grass. These are very fat and orange, and very oily if you cut through them. Both my plants were there for about 12 yrs before my previous neighbour put it in. I will take a photo to give you an idea.

 

The pine ...

 

The roots and a view from upstairs, across my Robinia. The oak on the left is not the one near my Fatsia. There is one just to the right of it, outside my fence. It is LARGE, but was there before the Fatsia (obviously) and they have always coexisted happily together. The Cherry was there too, but was a tiny 2 m tall sapling with a trunk only a couple of inches in diameter. Now, it is bigger, but the Fatsia and it have grown up together and never had a problem. The pine was small (about 2 m) when it went in, but has shot up. The central stem was cut back about 3 yrs ago, which has caused it to bush out a lot.

 

It's your call of course, but doing some pruning after flowering as @pete suggests is a good idea.
By removing some leaves your plant will need less water and won't be struggling as it is now, so it may seem a harsh sort of tlc, but beneficial to your plant.
Of course if you regularly give it a good denching for the rest of the summer you'll provide enough water for all the foliage so pruning isn't needed at this time.

Tree roots appearing above the surface of the soil is not unusual for some tree varieties, but is often a sign that the soil is so congested with roots there's insufficient oxygen for them, so they break free of the surface to get more oxygen.