These fungi grow mostly on insect honeydew. Therefore, they grow on any plant where enough honeydew accumulates. Often, more than one fungus may intermingle on the same leaf.   

Symptoms

Sooty mold fungi have black mycelium and grow on insect honeydew. The honeydew is excreted by certain types of scales and aphids. The thickness and black intensity can vary with the individual fungus as well as multiple fungi growing together.  

Life Cycle

As long as there is a sufficient amount of honey dew on the plant material, sooty mold fungi have the ability to grow.  

Management

Control most sooty molds by controlling the insects which produce the honeydew.