Can anyone identify this fungus please?

[Coletti]

This fungus is present on a leylandii and so far no one seems to know what it is and what problems it may cause so just wondered if anyone on here could shed some light on it? It covers a large portion of the main stem on several trees although there is no sign that the trees are in decline however, there are several sub 1" branches that are dead with a large amount of it at the branch union

 

Thanks in advance

 

George

[jaime bray]

Checking on phone, hard to see, but are there bore holes amongst the white mildew?

 

The trees I've seen it on, it's often the case that the trunk in which the fungus present had become dysfunctional.

[Betula]

I've seen it before, I don't know if it is directly related but the trees I have seen it on have seiridium canker that affects leylandii, Monterey cypress etc.

 

Look to see if there is any dieback in the canopy.