Forum Flora Germanica

Any comment to 'black belt', in the centre of twig ? It appears to be common thing on site.
http://agrozoo.net/jsp/Galery_one_image ... 4411369ece

Hi,
I don't see Diatrype disciformis here, but I don't know what it is.

http://ascofrance.fr/base-de-donnees?substrat=Fagus (lots of "black things" to see here ...)