Can you help diagnose the problem with my beautiful, old rhododendron? It...
Check the trunk for signs of boring holes and frass, which is a sawdust like sign of borers. Is the area wet? There could be a problem within the roots as well, such as a rot.
Unfortunately the outlook does not look good for this plant as there are not good control options for any of these possibilities.
There are no signs of borers or rot. I spoke with someone on the phone who said it might be botryosphaeria and I looked at the pictures. I am wondering if that is what it is. That lady said there is no cure. Should I prune off the dead branches? Should I wait until fall? I am hoping that it will come back next year, since there is so much new growth inside, closer to the trunk. Thanks.
Is impossible to tell for sure what exactly is going on from photos, but it surely could be a disease.
You can prune out wood you are sure is dead any time, and then wait and see if it is able to recover.