The past two summers I have applied some preventive fungal inhibitors, and I also gave the plants some fertilizer. In addition, I have been much more meticulous in removing dead stems and keeping the soil around the base of the plants free from debris.
We were amazed at how much healthier, vigorous, and blossom-yielding several of the rose bushes were this year. Perhaps we might also add that this was a very wet spring, but the net result has been a veritable wave of magenta-hued flowers in the yard.
Moral of the story: when your wife suggests something, she is probably right.