Question
There are several dying maple trees in my neighborhood. The bark has turned a uniform flat black color. It does not appear to be powdery. It looks almost like the trees were painted with a flat black paint. What is causing this? Thanks, Tom

Answer
Hi Tom,

This is most likely a fungal infestation.  There are many types of fungi that specialize in metabolizing the carbohydrates of dead or diseased trees.  Many of these fungi do not have a fuzzy-like appearance; in fact many of them appear to be black films as you describe.

The first step in identifying a fungus is being able to culture it on laboratory media.  In many cases, the fungi are quite particular about their "food", and cannot be cultured successfully in laboratories.  

Many of the indications that you describe are clues that the black color is due to a fungal infestation-the black coloration, the poor health of the trees, etc.  Usually the fungus is not the cause of the trees' poor health, and there is little that can be done except to consult a professional arborist.

Good Luck,