Re: green ash lower trunk fungus?
it may be a Hypoxylon type fungi but at the least I would suggest that if this tree has the potential to strike any targets of value (making it a hazard tree), get a qualified arborist to assess the issue and potential decay. Fungal fruiting bodies of decay fungi are usually a late indicator of the decay process rather than an early indicator.
Paul Buikema, CHT, I.S.A. Certified Arborist. Certified Tree Risk Assessor, 2010 BCLNA Member of the Year