Sooty Mould

Sooty Mould

Observation - Sooty Mould - UK and Ireland. Description: A black substance covering the leaves of a Goat Willow (Salix caprea) in a rather dark, damp corner. It is a surface coating and rubs off easily so I'm guessing that it's a smut. Can anyone put a name to it, please? Edit: Title changed to match Alan's co

A black substance covering the leaves of a Goat Willow (Salix caprea) in a rather dark, damp corner. It is a surface coating and rubs off easily so I'm guessing that it's a smut. Can anyone put a name to it, please?
Edit: Title changed to match Alan's comments. Still looking for an ID. What details should I look for if I can get hold of a sample?