Hi , 

Its difficult to tell what the exact problem may be at this time of year. It could be that they are all suffering from Rose Rosette disease or the branches have a canker disease building up. 

Roses, especially the knock out variety, benefit from a hard renewal pruning annually. It looks like the close proximity to the fence and possibly the clay soil that may be poor draining, could be stressing them as well. The bed they are in could be a little bigger so the roots aren't being effected by the turf grass area. If you use any turf treatment with Dicamba herbicide that can negatively effect the health of the roses as well. Do you know if there was a treatment recently or last year?

You could try to do a hard prune on all of them. If you can sanitize your pruners between each shrub that may help - you can just wipe the pruner blades with some rubbing alcohol (don't use bleach because it will corrode the metal). Then you can add a thin layer of compost around the base, avoiding burying the root crown or branches/stems at the base, then apply some organic mulch like shredded hard wood taking care not to pack it at the base either. This will help add nutrients back into the soil and improve the clay soil conditions as they decompose. If you can bring the bed out a little as you do this, that will help.

As the roses re-grow this spring, monitor for any issues, rose rosette symptoms, insect problems, etc. You can review rose problems on the link below for rose care guide. 

Guide to Pruning Roses

Rose Care Guide

Mulching Trees and Shrubs

Let us know if you have additional questions or when they regrow if you notice any problems, feel free to send in photos. 

Emily