mad_gallica may be right. Although they seldom need pruning in the spring, it may be helpful to severely prune back one third of the canes each spring to keep them young. Older canes tend to slow down and sprawl with thinner laterals.
The older canes on mine tend to discolor as they age. When that happens I cut them back almost to the ground. All mine are own root so that's no big problem. William Baffin and John Cabot are slow to repeat and any repeat is sparse. George Vancouver, Champlain, and the climber Quadra repeat well.
I use slow release organic fertilizers, horse manure, and don't spray.

Valerie