What is eating my rhododendrons
This damage is unusual looking. How far off the ground does the damage appear, and is it on more than one type of plant or only on the rhododendron? It rather looks like some sort of animal damage. If it were bird, sapsucker damage, it would appear as a series of holes in the bark in lines. The bark would still be on, though. This damage looks like some feeding damage, with the bark stripped off. I suspect it could be caused by moles, voles, squirrels, or most likely a groundhog caused this damage. Animals will do this in the winter.
If the damage is at the base of the trunk, make sure mulch or ground cover such as ivy is not piled to close to the trunk of the plant. That allows for hiding places.
With this amount of damage all the way around the trunk, I am not sure the plant will survive the long term. Do not wrap or paint, but try to allow the plant to produce some wound healing by itself. It may heal over.
Thanks you for contacting Cooperative Extension.
The damage is always between 4 1/2 feet and 5 1/2 feet off the ground. It is on several branches now. I have only seen it on the rhododendrons so far. Thank you for your help.
Very unusual to have damage like that so far up on the shrub. I still believe it may be some sort of bird, although it's possible it is an animal such as a deer. Are the any insects that you can see? Either way, it is not disease. You could try shaking some ground red pepper on the area. It will deter animals, but not birds.