Wonder if any of you could cast some light on to this.

I have some Golcrest conifers which were doing fine until I noticed that
the middle of the conifer is turning like a soot black.
The result is that it is stopping the conifers from growing and some are
dying.
Any ideas as to what it may be?


Sorry I cannot help, I have just checked my Goldcrest and they are all fine.
Does it wash off or is it a bug of some sort ?