Yellow Blue Fungus around bark might be killing tree?

[Ballinlawn]

Hi all, need some help with my tree's, a yellow, bluish type fungus has grown around the bark and seems to be killing new growth. I am from Ireland, please help

[Lindsaylew82]

Without a picture, it's pretty difficult to imagine what you're talking about.

Sounds like maybe lichen?

If so, they're not bad for the tree, but they can in abundance, indicate poor health of the host tree.