Dunno, can't say without more info - how long have you had the plant? Is it in a pot or in the ground? Is it just the lower leaves? Are the leaves turning completely yellow, or patchily yellow? A photograph would be useful too.

And is your soil acidic or not? Rhododendrons don't do well in alkaline soil.

Just FEW LEAVES . LARGE PLANT IN A LARGE WOODEN BARREL. was fantastic when in bloom this year so I dont want to loose it.It is in Ericaesus soil.

A few leaves - are they at the bottom? How long's it been in the same container?

What Bamboo asked plus have you fed it at all?