Wet discoloration of the outer bark of coast live oak surrounding entry holes made by the polyphagous shothole borer, Euwallacea sp., is a symptom of fusarium dieback, caused by an unnamed species of Fusarium.

Damage to coast live oak showing borer holes surrounded by necrosis and exudate caused by the Fusarium fungus. Credit: Akif Eskalen
Credit: Akif Eskalen