This disease can attack leaves, stems and fruit of plants. Black spot is caused by a fungus .It starts with circular, feathery black spots, which first develop on the upper surface of leaves and continues with all infected leaves turning yellow and falling prematurely. When the new leaves are produced they can also be infected. This is a common problem on roses especially during warm conditions and can have devastative consequences so be sure to check your rose bushes daily for any signs of black spot.
For preventive action on roses, use a good Richgro Garden Compost in Autumn which will help reduce the incidence of fungal diseases in next seasons. For immediate control, use Mancozeb Plus Sulphur Fungicide (see label for situations).