I have just noticed my double knockout roses seem to be dying. The leaves have brown spots and some leaves and branches are completely brown and drying up. What can I do?
Provided that the roses have been well watered and fed, it sounds like you may have a mix of insect and fungus problems. I would recommend buying some Bayer Tree and Shrub granules. Give all of the rosebushes a treatment of this product per the label instructions. Work into the soils a bit and water in well. Prune out all dead canes prior to doing the treatment.