Ornamental Lemon Trunk Gummosis: Borer Injury Response

Donna: ornamental lemon, 4 inches above soil line, orange goo oozes, hardens dry.

Expert Assessment

Steve: plant-origin substance, defense response to injury—likely borer insect tunneling in stem. Hole may be nearly invisible. If insect: limited options. Prevention via protective trunk sprays more effective. Try flicking hard material to check for hole beneath.

Key Insight

Gummosis (sap oozing) is the tree's attempt to seal borer entry. Once borers are inside, control is difficult. Preventive trunk sprays during borer flight periods are the standard management.