I have a number of 15 year old roses that have black spot on leaves I have sprayed & collected old leaves but condition remains, if I move roses to a new area and prune hard would this clear the black spot.
The soil for roses need to be changed for new about every four years as it becomes diseased, but do move them to a area where roses haven`t been for several years. Treat the old soil with Jeyes Fluid as directed on the tin.