This rose has very bad black spot, should I cut it right back or just keep treating it and wait for it to recover?
Hmm, if it's as badly affected as that I'd swap it for another, tougher, variety.
Ooooh. That's upsetting looking. Unless you are deeply attached to that plant for sentimental reasons, get rid of it and buy something with more resistance to the disease.
They are two rose trees in pots, matching pair so I would like to save it if possible
I'm treating them with something recommended in another post so hopefully that will help!
I can only glimpse the pot. It looks fairly small. Plants are more like to become " ill " if they're stressed . I'd suggest a bigger pot and nice fresh compost and it should grow away happier.
The pot is quite tall, are the roots shallow and wide, should I change the pot to a shorter wider pot?
regular feeding with liquid tomato food will help.