We have a fatsia japonica in our front yard (Raleigh, NC) which faces North and is partly shady. It gets some morning and mostly mid-afternoon sun. The plant has grown well since we planted it 5 years ago, but every spring and sometimes in the fall, the leaves yellow and brown and then drop. When they drop they are black. In the past, I've sprayed in with a fungicide following the application directions, and I think that has been somewhat effective. I also fertilize it in the spring. Still it seems to happen every year which suggests to me another problem. I went to my local nursery, and they suggested there was an iron deficiency and gave me an additive to correct that. This did nothing. In fact it seemed to speed up dropping the leaves, but this might be my imagination. It is situated near the hose. So my questions are, is it getting too much water, perhaps from hose sputtering and leaking? Is this plant prone to fungus (I haven't read anything that suggests this)? Does this look like a fungus--one that might reoccur constantly? What else could it be?
Fatsia Japonica Dropping Leaves
Whenever Fatsia has a flush of new growth and leaves, it sheds the oldest leaves. I think your plant is fine and doing what it naturally does.
Ditto to Growin - it's normal. No need to add any fungicides, fertiliser, etc., etc.