Hi
We moved to a house with a lovely rose garden, however, that lovely rose garden is seriously ill! All the roses (David Austins) are covered in black spot. I began to remove the offending leaves before spraying but it is too prolific!
I am completely new to gardening and caring for roses and I as such, I have two questions that I hope someone can help me with...

I was wondering if I could just cut all the rose bushes right back (the steams look ill too).

Can black spot spread to other plants, as my clematis and some weeds, are now covered in spots that look very similar!

Thanks guys.
Krissy