I suspect Rose Rosette Virus, which once discovered/confirmed means immediate removal of the bushes to prevent any spreading. It is not only fatal to a bush, but there is no treatment/cure, just removal and placed in a large plastic bag, then put into household trash, never composted or tossed 'out back.' The virus is spread by an airborne mite. The mites are so tiny and travel great distances, for a mite, that infected bushes shedding mites could be next door or blocks away.

I would watch the roses intently, look at photos of Rose Rosette Virus/Disease on the internet, and as soon as you reach the conclusion that they are virused, act quickly. It won't take long to find out one way or another.

Otherwise it could be nutritional, which should clear up quickly under the fertilization program you have underway. I really think it is RRV.

Rose Rosette Virus has hit so many rose gardens I would venture to say that it is a plague in many places in the USA. I've, had it, and my garden is very isolated from outside roses...no others in my immediate neighborhood.

Hope I'm wrong.

Moses

It looks like a nutritional problem. When the pH (I've done this...eeek!) gets out of whack the rose can't absorb the nutrients that are there.

I found this:

Abiotic problems and disorders of roses

• FEW OR NO FLOWERS
• PALE YELLOW LEAVES
• LEAF MARGINS (EDGES) BROWNING
• LEAVES: GREEN BETWEEN VEINS,
• HERBICIDE INJURY
• PROBLEMS DUE TO POOR CARE AFTER PLANTING
• LEAVES: YELLOW BETWEEN VEINS, VEINS REMAIN GREEN

Chlorosis symptoms, caused by a deficiency of iron, appear as yellow leaves with prominent green veins. These symptoms are usually caused by high soil pH.

So maybe you could lower the pH? I would ask other people here first before you do what I suggest as I've been wrong many times. I hope this gets better for you.

Start by repruning them. I see a lot of dead looking canes. Knock Outs are very prone to canker, and it is possible that the problem is simply canes that should have been pruned and weren't.

Thank you!