Leaf spot - are there any 'organic' treatments which actually work?

[PositivelyGlowing]

I have an ongoing 'infestation' of leaf spot on my Escallonia plants, I see that there are a number of harsh chemical treatments which aren't exactly wildlife friendly. Can anyone recommend any 'organic' treatments please which will actually cure a major leaf spot outbreak?

Any organic fungicide treatment for roses should help.

Thanks.