''Asteroma coryli'' is a species of
fungus
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from t ...
in the family
plant pathogen that causes
leaf spot
A leaf spot is a limited, discoloured, diseased area of a leaf that is caused by fungal, bacterial or viral plant diseases, or by injuries from nematodes, insects, environmental factors, toxicity or herbicides. These discoloured spots or lesions ...
on
hazelnut.
References
Diaporthales
Fungal tree pathogens and diseases
Fungi described in 1870
Nut tree diseases
{{fungus-tree-disease-stub