Here's some information from the U of A.

Here is a link that might be useful: Troubleshooting Rose Problems

You're not spraying water on the foliage at all, right?

Some controls we rosarians use:

Listerine, original, start at 50% solution, spray weekly
Lysol, unscented, spray weekly (some folks use it, some don't)
1 tsp chlorine bleach to 32 oz water with 1-2 drops of dishwashing liquid and/or 1/2 tsp baking soda. The bleach is for the powdery mildew, the dishwashing liquid is for the aphids and the baking soda is supposed to act as a spreader/sticker but mostly gums up the sprayer before the bleach corrodes it.
Fungicidal soaps - several on the market, Safer is a common brand.
Fungicides - An effective fungicide will eradicate the powdery mildew in 1-2 weeks of spraying. Some roses, namely Mr Lincoln, Tropicana, Queen Elizabeth, Dolly Parton, Fragrant Cloud and a few others are 'mildew magnets'. Just to clarify that not all roses get mildew.

Most cases of powdery mildew can be controlled by:
Planting: Plan for the mature size of the bush to allow airflow between bushes.
Location: Roses do better in full morning sun rather than filtered or morning shade. Roses under trees and overhangs will show powdery mildew faster than ones receiving good sunlight.
Water: While watering in the morning is advised, evening watering isn't that much of an impact on PM. Powdery Mildew spores become active at 60F, thrive when days are warm and nights are cool, and must have dry leaves to form.

Fungicides do not kill bugs, only disease. A mix of fungicide and pesticide will kill both, including good bugs, but not cutter bees or spider mites. Cutter bees do not ingest the leaves they cut and spider mites require a spray that kills spiders. Ortho's Rose Pride, formerly Funginex, is very effective and not as dangerous as Immunox.
Wear a mask, goggles and gloves when applying. Do not spray on a windy day, near fish ponds or pets.

Hope this helped.....Jeannie Cochell, Consulting Rosarian

Jeannie, thanks so much! I'm saving your message and going for the simplest solutions first. I do notice that some plants are affected and others not. These roses are in full morning sun and spaced well, so that's not the problem. The aphids are starting to raise their nasty little heads, too. Is there a prayer that Listerine or Safer might do them in?

My thank-you post to aztreelvr didn't post! :( So, thank you for that link. I printed it out and will save it. I'm sure the doggone spider mites will be here sooner or later and I need to be prepared.

Nope, Listerine or Safer Fungicidal soup will have limited or no impact on the aphids. Might keep 'em healthy and fresh-breathed, though, lol. Garlic repels aphids. I plant society garlic amongst my roses and also keep the hummingbird feeders fresh and clean. There are so many natural predators for aphids that I don't want to kill off the good bugs and their food source. Hosing down the roses should take care of most of the aphids, anyway.

The spider mites come in on the monsoon winds. First dust storm of the season and you'll have spider mites. Healthy, well-hydrated roses, mature roses will fend off the mites better than one that's stressed by over-fertilization and under-watering. Also, don't use Seven (carbaryl) during the spring. It kills off the spider mite preditors and leaves your bushes more susceptible to heavy infestations. Again, hosing off the roses will also take care of the spider mites while washing off dust, disease and hydrating the leaves.

I don't use pesticides at all in the house or yard. If I can't control the little buggers without harsh chemicals, it will be up to ladybugs and birds to do the job. I'd love to attract a whole flock of verdins to the yard; they are wonderful aphid-pickers. I do try to blast the aphids off with a jet spray, but I think they just dry off and climb back up. ;o)