"...Could the dropped needles from the deodar be causing the soil to be alkaline?..."

No.

"...I always thought that evergreen needles would tend to have an acidifying effect..."

That is a myth.

Organic material like leaves, conifer needles, today's newspaper, tend to be pH neutral (for the most part). So if you add them (lots of it) to acid soil, it will raise the pH. If your soil is alkaline and you add that same material to it, it will lower the pH.

tj

Azaleas do like slightly acid soil, moist, but well-draining. It is possible that the soil on the one side of the path is different in some way - builders may have dumped "stuff" in one area rather than in another; the tree roots may be taking more of the available nutrients on the one side; the tree may be shading it too much. Not being there, I can't say for sure. A little poking around in the soil may answer some of the above. Applying a dose of an acid-loving-plant fertilizer (one for holies, rhodies, azaleas, etc.) would also possibly help.

And sometimes plants that were bought from the same nursery and given the same culture can have one thrive and one die for no observable reason. I would do what you can to correct matters, making sure that they both get plenty of water (without drowning them). In the interests of symmetry, you might want to replace the one that is doing badly - maybe even foregoing symmetry and putting something else over there, maybe something that would be happier with the alkilinity, slight though you say it is.

Thanks for your replies. Frankly, I'm mystified about what could be causing this. From the get-go, the soil was basically the same on both sides of the path. How do I know? Because when we built the house and landscaped it, we dug out and removed the soil around the house for the foundation plantings. Then, we backfilled it with amended top soil. We even had to rent a jackhammer to escavate the area because we ran into a large vein of shale. Oh how I remember that well. My husband still quotes me saying "I'm not doing this all day. I'll have organ damage." The tree roots do not extend to this area because they stop at a retaining wall up from this plant.

The kurumes have been in the ground for 14 years and both have done well on either side up until the last 3 years. I've been treating the sick one with Hollytone, which definitely helps. The severe drought last year sort of amplified this plant's problem, so I am giving it one more year or so to rehabilitate. I've thinned out the worst-looking branches and like I said, applied Hollytone to help with the chlorosis. If it doesn't perk up permanently, I may take your suggestion to replace it with something else. I just like that symmetry for paths.