Need help identifying problem - Coconut palm Florida

[RevT]

 I recently found white fly and black sooty mold on many of the leaves of my coconut palms. I’ve since removed much of the effected fronds and treated with Neem oil. I noticed 2 of the effected palms have this mildew/mold on their lower trunk. Hoping it’s nothing, but if it’s something serious I’d like to try contain it if possible. Any ideas as to this  black around trunk? Maybe related to black sooty mold on the fronds? 
TIA 

Edited October 1, 2021 by RevT

[Merlyn]

Thielaviopsis frequently has a "bleeding trunk syndrome" that looks like dark stains below a weeping hole.  But yours doesn't look the same.  Do you have lawn sprinklers hitting the base of the trunk?  That would definitely cause fungal growth.

[RevT]

No sprinklers.