Black Spot on Roses - New Gardener
I've just moved into a flat with my first garden (very excited!), which has lots of rose bushes. The garden was obviously loved at some point, but has been neglected recently and some of the rose bushes have black spot. I've researched a few treatments (although I'd love recommendations), but my big question is how to deal with a rose which has nearly all leaves infected? I know I'm supposed to prune all the infected leaves, but there won't be much left.
Should I go ahead and prune it now? Just cut off the worst cases, treat and cut it back hard when the leaves start dying back in autumn? Or is this a lost cause and should I ask the landlord if I can dig it up and replace it with a black spot resistant strain?
Thanks in advance for the advice.