This question has already been answered for you yesterday?
But I am going to stick my neck out and disagree. I know this plant as an Aralia Fatsia Japonica. I have 2 -12 year old large plants and this happened in the draught earlier this year. I gave them a fine spray of water and then left a slow hose under them for several hours and they recovered. I think that what you should try it to.

Drc may well be right, and his solution is well worth trying. In fact, I hope he is right, it simplifies things greatly!
If a good soaking doesn't work, though, you may still need the fungicide.
I just had a thought...do vine weevils attack Aralia roots, Drc?

Not that I know of Tugb. I have never encountered VW but I always add grit when planting in my clay soil and I understand that this deters them from laying eggs?

We don't have VW here, but I have seen this kind of effect with green fruit beetle grubs eating the roots.

We have it here and I hope I never encounter it Tugb. I was hoping for an up date on this?