My Fatsia japonica is ill ;(

I have had this plant in my garden, (I bought when still very small), for about 15 years. It has been doing very well all these years, grew to a size of over 2.50m, but this year it looks sad, the leaves are yellowing but even more concerning are the black spots that affected some leaves, these grow in size and eventually the whole leaf dies off..
Could it be a fungal, virus or bacterial disease? I didn't notice any critters on the leaves.
Any help or advise is greatly appreciated!

Some pictures of the affected leaves..

detail of the damage..

another sick leaf..

on the underside close-up of a black spot..

It is first visible on the underside, this is how it starts..

I have asked it in the Pest and Diseases Forum some time ago but no one seems to know as I get no reply! :(
Hopefully someone over here can help ?

To me it looks like the signs of root damage. Either root rot or the roots were cut or crushed or something like that.

Thanks Growin for the response! :)
I'm sure the roots have never been disturbed, so the other option could possibly been root rot. Now I'll have to find out what could be the cause of that... I know that the drainage is very good as it has been very healthy all these long years and there has not been made any changes in its immidiate proximity..perhaps I should carefully dig a little and have a check on its roots ?

This one is a real stumper!

Could this plant have gone through a dry phase? I've seen this before on Fatsia and I'm trying to remember what caused it.

Yes Leftwood it looks like that!

No Growin, I don't think it has gone through a dry phase, the rainfall has been normal, not too much, not too little..I have given it some organic fast working fertilizer about three weeks ago in the hope its condition is going to improve.
I wonder if there could be a connection with my Acer japonicum that is in the terminal stage of haven fallen prone to the dreaded verticillium welt disease, that one is planted about 3,5 m distance from the Fatsia.

It's definitely not any kind of wilt disease, as the symptoms would be very similar, if not exactly the same, on the fatsia.

Thanks Leftwood, at least that gives some hope that it might not be a fatal disease!

If your plant is 15 years old, it may just be getting ready to send out new shoots. I have one that is about 10 years old and it does what yours is doing periodically. The foliage on mine looks like yours when new stems are getting ready to develop, or are starting to.

The old main stems seems to peter out after X amount of years, so I cut them out and new ones appear very quickly.

If yours is a multi-trunk plant, with several old trunks, I suspect that's what's going on.

Thanks Jasper Dale! That sounds interesting! Mine is a one stemmed one that branches out higher up on the main stem. It has a couple of new shoots that appeared I think last year.
But these show the same symptoms and look anemic with a couple of there leaves dying of like on the main stem. I checked the soil and it feels nicely damp and crumbly.

I have another tall Fatsia, also one stemmed but without new shoots, in another place of the garden that started getting ill last year.
Despite me giving it organic fertilizer the new leaves that grew this year turned out very small and yellowish. The strange thing is that the surrounding plants of both Fatsias don't show any signs of lack of nutrients.

On this picture of the one that got ill this year you can see the new growth at the bottom with tired looking leaves;

and this is the one that got ill last year with the abnormal small leaves..

I think I found out what's wrong with my Fatsia; perhaps an alternaria leaf blight disease caused by Alternaria panax..
I thought it could be interesting for others too!

http://www.cababstractsplus.org/abstracts/Abstract.aspx?AcNo=20043062371
and;
http://www.ppis.moag.gov.il/ppis/plant_disease_gallery/D_S_W_S_May2009/LIT/LEVY.pdf

Typical with alternaria species is the yellow hallow and concentric circles forming the spots. I was going to say that wasn't what you had, bonitin, until I re examined your photos. I am not completely convinced either way, but A. panax a possibility.

Yes, I was also not so sure about the alternaria Leftwood! But some of its symptoms look like that. Perhaps its a combination of nasty things. I noticed today that the stem of a sick leaf already half brown had completely dried up so it must have something to do with the vascular system that gets blocked in one way or another.

It doesn't look good, booohoooo ;(
I've cut through a stem of a new shoot at the feet of the Fatsia and it looks like the vessels are infected with something dreadful, don't know if this could be caused by A.panax?