Calling all American Holly experts - what is up with this patchy red bark?

[Bonsai Nut]

Was down by the coast over the last week (just north of Wilmington, NC), and ran into some interesting trees that I believe are American Holly (Ilex opaca). They were exhibiting a very interesting mottled bark pattern that was a bright red and caught my eye from across a parking lot. Though American Holly is native to the area, I'm not sure these were native/natural trees because of how they were planted along the edge of a gravel access road. There were about five trees interspersed along the road, in an otherwise heavily wooded area. Only the hollies had the red blotching pattern - other pines and deciduous did not. The red color did not look like fungus to me(?) but who knows? It had distinct margins, and there were areas were it looked like bark had flaked off, leaving a sharp edge between the red and other bark colors.

The trees seemed to be healthy, though they had chlorotic foliage. Any thoughts?

 

[BrianBay9]

It's not lichen?

 

[19Mateo83]

I believe that is called bark rash lichen. It makes for some very unique and interesting Holly trees.

Bark Rash Lichen | Loyola University Center for Environmental Communication

When I walk the forests, I'm drawn to a group of living organism of which I have little knowledge - lichens. I know their forms, that they are composed of a fungus and an alga, a bit about their reproduction, and that they are often encountered in surprising locations. I've seen them in our...

lucec.loyno.edu