It’s the sap oozing from cankers or wounds on trees. What Causes Gummosis On Peach Trees? The biotic cause of peach fungus gummosis (PFG) is Botryosphaeria dothidea, which infests the tree through its ...

Caused by a fungus called Ceratocystis platani, canker stain will lead to discoloration in the tree's sapwood, yellow, ...