Posted: 16/07/2014 at 14:05
A local rose grower, who wins medals at RHS shows, told our local hortsoc that even disease resistant new roses only keep their resistance for say 12-15 years when mutations of the various diseases creep up on them. He would then advise replanting with even newer varieties.
I also think it pays to do your very first spray very early in the season when you have not much more than bare branches and bud bumps. Follow Dave's advice above , but start very early. depending on how mild the winter has been, you might be thinking of early March. Go out and have a look then.