Question: What is this strange growth on my Beech tree? It starts out white and then turns a sooty black color.

Answer: The sponge-like growth on this branch and leaf collected from a beech tree is an unusual type of sooty mold. Sooty molds are entirely superficial saprophytes that get their nourishment from honeydew-like secretions from insects such as aphids, soft scale, and mealy bugs. The beech tree was infested with a woolly aphid species and thus this specific sooty mold fungus, known as Scorias spongiosa, is feeding on the honey dew excrement
from the woolly aphid.

Additional information on sooty mold may be found at Sooty Mold-- Is it pollution or is it ALIVE???

--Gail Ruhl, Senior Plant Disease Diagnostician, Interim P&PDL Director, Purdue University

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