Hi,it certainly is, you need to remove all the leaves with signs of black spot (burn them) and spray with fungicide I used fungus clear ultra , it took me 12 months to clear them all , good luck

Rose Clear Ultra should sort it out but it's best to have a spray routine before you get black spot. Once there is a reasonable leaf system they need to be sprayed. Also if you have a climbing rose or one growing over a pergola, it doesn't hurt to spray the woodwork as well for over-wintering blackspot spores.

And remember to pick up all the dropped leaves under the bush as they will reinfect the plant if left over the winter.