Italian to English Science Agriculture Fruit and vegetable pests and diseases

I am revising a text about lemons which was translated into English from Italian ( which is not one of my working languages). This must refer to some kind of disease, probably a common name for it, but I can't work out which it is.

It appears in this sentence:
"...on the positive side the quality this season was much better compared to last year, when Sicily suffered a very serious attack of Cottonello, staining the peel of the fruit."·

I managed to find a text online which refers to " malattia detta «cotonella»", which I think may refer to mildew, but need to confirm.