Hi Romain,

according to Saracchi et al. (2008) and Rocchi et al. (2010) there are two genera/species causing these resin like clusters on Carpinus betulus. One is the genus Endothiella and the other one is Cytospora decipiens (teleomorph: Anthostoma decipiens). The latter is described and illustrated in Rocchi et al. but I don't know how to distinguish this species from Endothiella species. I hope this still helps you.

Best wishes,
Gernot

Saracchi M., Rocchi F., Quaroni S. 2008. Further studies on the etiological agents of Carpinus betulus decline. Journal of Plant Pathology 90: S2: 453. (http://sipav.org/main/jpp/index.php/jpp/article/view/706/493)
Rocchi F., Quaroni S., Sardi P., Saracchi M. 2010. Studies on Anthostoma decipiens involved in Carpinus betulus decline. Journal of Plant Pathology 92(3): 637–644. (http://www.sipav.org/main/jpp/index.php/jpp/article/view/308)

Hi Gernot,

Thanks a lot for you answer and the articles references. According to the succinct description of the differences between the two species in Rocchi et al. (2010) ("Preliminary studies related the fungus producing yellowish cirri to the genus Endothiella, and the other pathogen generating red resin masses on the cortical surfaces"), I would say the fungus on the pictures above is Cytospora decipiens. 

But, if anybody has more information about Endothiella species on Carpinus betulus, I'm still interested.

Regards,

Romain

Hello all,
Oh my! After the problems with Fagus, then Hymenoscyphus pseudoalbidus on Fraxinus, now here's Carpinus decline! Where will it stop?
Cheers - LUC.

yes, it is Anthostoma decipiens... asexual form

Dr. Federico Rocchi (the original)