is there any hope for my rhododendron?
I've had a rhododendron in the front of my house for 5 or 6 years. After the first few, it started looking really sparse, and chunks of it began dying off. This spring, I moved the sick plant to the back yard shade, where it's doing a little better, and put a new capistrano rhody in the same place in the front. It's dying quickly. Leaves are curling up, the ones underneath are turning brown branch by branch, and even the upper branches are looking yellow and spotted.
When I bought the new plant, it had some yellowish branches underneath, and a few spots on the leaves. The nursery said it was from watering the plants when they were packed in tight on display, but that it would go away. I was careful to water it faithfully for the first several weeks, and tried to water the base of the plant, rather than from the top.
When it started to look worse, I was told that I may be over watering, so I mostly stopped. We haven't had much rain, and it has still not improved.
I have very sandy soil, and it's pretty hot out there for several hours in the afternoon. I have trouble keeping anything else watered enough. It's hard to believe this could have root rot... but watering did not seem to help.
How can I tell if this is root rot, drought, or something else?