What's doing this to this Hawthorn?

[Daniël Bos]

Hello, a Hawthorn hedge I'm in the process of laying has a weird patch of death.

Trees are dying back from the twigs down, there's some reaction growth (retrenchment type twiglets?) lower down on some but not all.

There are weird patches on the bark, rougher looking than usual.

There's blackness in the cut surface of affected but still alive branches.

I've not found any fruiting bodies of any sort.

 

So... What is causing this, and can it be halted? Is it likely to spread along the hedge?

 

Thanks, Daniel.

[Daniël Bos]

Thanks Ed!

 

Another detail I forgot to mention: the worst affected area is where there are a series of bird feeding stations, so there's heaps and heaps of songbirds on that bit especially.