I like to use Baldo Villegas' website on rose diseases and pests. It's really helpful.

Here is a link that might be useful: Baldo Villegas

Compendium of Rose Diseases. There are two editions, one is only two years out of date.

You should be able to get it through Interlibrary Loan and it's rather expensive and doesn't have a lot of pictures of some diseases.

The Consulting Rosarian manual from the ARS is mostly text, but has some photos. You don't have to be a CR to buy the manual.

Baldo Villegas' website is the best there is, IMO, but there is also a pamphlet with photos written by Rich Baer and Ann Hooper called "Chompers, Suckers, Raspers, and Borers: Everything You May (or May Not) Want to Know About the Insects that Attack Roses."
I see she also has one about rose diseases called "Common Rose Diseases Identification, Causes, and Cures" but I've not read that one.
You can get them through Primary Products' (Ann Hooper's) website. (And no, I am in no way affiliated with Primary Products.) :-)

I'm not sure what part of the country you are in, but I live in Sacramento, California, and I have a wonderful booklet that I got from the University of California ANR (Agriculture and Natural Resources). "The experts at the University of California IPM Program (Integrated Pest Management) have written this beautiful guide especially for the home rose enthusiast." It tells about rose pests and their natural predators, diseases, and deficiencies, all with excellent photos. It seems to be meant for California rose growers, so if you live elsewhere it might not be of much use to you. However, you could contact your nearest university or Master Gardener program to see if they could recommend something similar. I know that this booklet has been a huge help to me! I was able to identify two insects on my roses that looked like Baddies but who turned out to be the ones that live off aphids and consume tons of them - and my roses were practically being destroyed by aphids. This year these two heroes have arrived again, in the nick of time! Hint: I try to leave the aphids alone, because I figure a Ladybug or Syrphid Fly is most likely to plant a batch of eggs where there is an ample food supply...

Laura