There isn't one. Either spray with a systemic fungicide biweekly to control it, or buy sulphur soil or sulphur chips to mulch beneath the roses, and wettable sulphur to spray with.

thanks i will try mulching with sulphur chips

My mum swears by spraying diluted washing-up liquid onto leaves to get rid of blackspot. Haven't tried it yet myself, so not too sure if it does work.

hi thanks for your answer i will try it and report back to you

Lijemc, the washing up spray is used for blackfly (aphid infestation) not black spot, which is a fungal infection. Although, even for aphids, washing up liquid is no more environmentally friendly than a pesticide, and slightly more injurious to plants, and I wouldn't recommend it as being better than a pesticide.