old rhododendron is dying
We do have a very very old rhododendron and year after year it gave us an abundance of flowers. Since about 2 years it is declining and this year it looks almost as if it wants to die. It still has some flowers but no comparison to it's former glory. What can we do to save it?
Your rhododendron looks like it may have been subject to a fungal disease called botryosphaeria canker. All you can do is prune out dying branches back to healthy tissue during dry weather. Keep well watered during dry periods and mulch to conserve moisture. See the attached link for information http://extension.umd.edu/hgic/topics/botryosphaeria-canker-shrubs
Now we recommend pruning the rhododendron back by about one quarter for the next several years to help thicken it up. Mature rhododendron usually require little pruning beyond shaping, as well as, to remove dead or diseased wood.
Generally prune right after flowering. You can remove spent flower heads. Be careful not to damage the growth buds at the base of each flower stalk.
If you prune back to the main trunk, flowering will be delayed but if you prune back to a branch the plant should flower next season.