Leggy bush rose - advice appreciated
I have what I believe to be a Korresia rose bush in my garden. It always produces an abundance of lovely yellow flowers and I prune it each spring by at least a third.
Now though it's reached about 6' or more and is very leggy with all the flowers concentrated at or near the top of the plant. This year it's also covered with blackspot. So, my question is would it be better to cut it back now while it's still in flower, wait until it's finished flowering, or prune as usual in the Spring.
Also, how radical should I be with my pruning, down to about a foot or two, or reduce it to half it's current height, for example.