Hello all

I have a potted 4 seasons lemon whichlives on my balcony.

We live in central Italy where it gets cold at night in winter so I've wrapped it in fleece to protect it. I opened the fleece this morning (it's a warm day and there are some buds opening in the hope so I was hoping they'd be pollinated) and noticed that lots of the leaves are covered in what I assume is some kind of dusty black mould - see photos attached.

I'm assuming I should remove the affected leaves, but what else - some kind of mould spray? Should I be opening the fleece more often to 'air' the plant? Any advice much appreciated!