Dear Chris,

I'd like to ask, what's the difference between Macrophoma fraxini and Diplodia fraxini (or rather D. mutila, without brown conidia)? 
Thank you in advance.

Viktorie

https://www.researchgate.net/publication/260591572_The_complex_of_Diplodia_species_associated_with_Fraxinus_and_some_other_woody_hosts_in_Italy_and_Portugal

They may represent the same thing as far as I know. "Coelomycetes" can be a taxonomic minefield, crying out for more molecular work.

Yes, there's also a paper "Relationship of Macrophoma and Diplodia" (1904) by J.T.Emerson who obtained both types of conidia from a single pycnidium. That's why I was asking, to see if there's a molecular work on them. 

By the way, my collections identified as Diplodia (fraxini or mutila, I'm still not sure how to distinguish them without dark brown conidia abundantly present) released a pigment into water or KOH mount, hyaline in visible light, but bluegreen in UV 365 nm. (The dark blue background is an artifact, I probably forgot to use UV filter.)

Correction: the UV+ water-soluble pigment it's actually not from the fungus, but from upper layer of Fraxinus bark. :-/ Sorry for not checking that before.