I agree. It has been very wet. There is something called stem canker which is more serious, but it doesn't look like that to me. Canker looks a bit like a wart and is wrinkly and can spread to encircle the stem.
Black spot can appear on the stems as well as the leaves. Apart from the commercial sprays, you can make a spray with 2 tbsps of bicarbonate of soda, a gallon of water and a splash of washing up liquid, which will help the bicarb stick to the leaves. You spray the stems and both sides of the leaves weekly.Obviously, observe good garden hygiene and get rid of any affected leaves, because they will fall anyway and if left, will enable the virus to affect other plants and survive until next year. Any affected stems should be pruned off, too, and disposed of or burnt. It is said that roses planted in too much shade or without adequate air circulation are most vulnerable, but here in wet Wales, they are all vulnerable except the few resistant varieties