Today 
Apple sooty blotch is caused by an overwintering fungus, which is typically found on trees or branches growing in shade and damp. It creates a splatter of dark, sooty spots all over the skin of the fruit, although the flesh isn't affected at all and the taste doesn't suffer. The spots can be easily scraped off.
Solution
Organic
Good garden hygiene eases many fungal problems, so ensure you clear away all fallen, affected fruits and leaves by late-autumn. Dispose of them but not on your compost heap, as this could redistribute the fungus around the garden.
Chemical
There's no specific control, but spraying for apple scab using mancozeb or myclobutanil fungicide at regular intervals during the growing season invariably eliminates the problem.
