Have five rhodys about 40 years old. We have let them grow together and to the ground to block out a back fence neighbor, who's yard is a mess. They are not looking good and look to have a lot of dead branches in the middle. One on the end has been sprouting odd looking growth for several years. I have pruned that out but it just keeps coming back. One of the reds didn't have hardly any blooms this spring and looks to have a lot of dead stuff in the middle. Whole area gets sprinkled daily but water might not be getting where it needs to go because of the growth. We've had several days in the upper 90s this summer, but this is a common occurrence around here. What should be my first step in tackling the problem? I would bring in an arborist but I want someone who knows rhodys. Thanks.
Rhododendrons can suffer from watering issues; too much or too little.
Their root system is shallow and they do not have a tap root to draw water from.
During the hot summer they will need regular watering to thrive.
They can also suffer from pest infestations and some diseases that can cause leaf drop and die back.
A soil test would be a good idea to also determine if the plants are receiving enough nutrients.
These links will refresh you on the care requirements.