Black spot is caused by fungus and can be serious on roses. You can get specific fungicide sprays for roses with or without insecticides, it is best to spray in dry weather usually about every six weeks. Also clear away any affected leaves as left on the ground they continue to cause problems.

The secret is to spray before the roses get black spot. Roseclear will do the job. Another tip if you grow climbing roses on a trellis, don't forget to spray the woodwork also as spores will live on it.