Thank you for your question. 

I need a little bit more background information. When did you start noticing the yellowing of the leaves? And what does your fertilizer and watering regime look like?

The yellowing started about two weeks ago.  I haven't fertilized them since late May.  I'm concerned I have over-watered them.  Our sprinkler system waters that flower bed for about ten minutes five days per week with the cycle coming on about 4:00 AM

The yellowing leaves are a good indicator of too much water/ and or droopy leaves. Ideally you want to water when the soil is relatively dry but not too dry. I would avoid supplemental water for a while until the soil has time to dry out, I know that will prove difficult from the rain we are about to receive. Also, you don't need to worry about fertilizing unless you notice any nutrient deficiency symptoms in your plant and until we have more regular rain.

Thank you.  My concern is root rot.  How possible is it that I have induced root rot?

In infected plants, the tissue under the bark at ground level is darkly discolored if it has root rot. I would Peel back some of the bark at the base of the plant. If the plant is infected, a distinct boundary between healthy, white tissue and diseased, brown tissue will exist.

Have you noticed any additional symptoms like wilting and/or leaf rolling of the azalea leaves?