Black coating

[Treeaddict]

What is this black coating? I’ve only seen it on Norway maples, I believe. Some had it and were apparently healthy, some were not.

 

[Treeaddict]

It’s called: Gloomy Scale, Melanaspis tenebricosa(Comstock), Hemiptera: Diaspididae​

It affects mostly maples but other species as well occasionally. Horticultural soaps may work as well as insecticide.

 

[Treeaddict]

Or it may be:

Steganosporium Ovatum​

This is a fungus that attacks already weak trees. My research indicates that removal is the best option if the tree is experiencing this infection.

 

[Nutball]

I've seen it on healthy trees. Maybe certain maples have a high sugar content on the surface of their bark somehow.