Attached is a photo of a 60 yr. old species rhododendron that is part of a planting of 12. This plant has been ill for a couple of years and I'm not sure why. Is this the result of disease or poisoning of some kind? Will it spread to the rest of them? My camera wasn't doing a very good job of picking up the wood on the higher branches but it's cracked and grayish. Even wood that still supports some growth. It's been declining for some time and is especially bad this year. The leaves shrivel at the ends as in the photo and become worse and worse until eventually the branch dies.