I took this off pigeonchat site
,,,ASPERGILLOSIS,,,green deposits on tongue , check feed for mould , loft vetilation , 1 or 2 drop's of iodine on tongue , also 4 or 5 drop's in the drinker , untill it clear's up , if not caught early enough can become a lung infection , then your into doxy & tylan , if your on deep litter get it out , spray the loft with vikron's or a strong mix of iodine , also check nesting material tobac stalk's / straw , this is a fungas / mould it will go through the loft like wild fire .
I don't know if it would be the same as this refers to a green tongue in a young bird