Silver Maple Trunk Cracks and Oozing: Phytophthora Canker Diagnosis

A Sacramento silver maple had multiple trunk gashes and dark oozing sap. Two arborists disagreed: one blamed beetles, the other a disease ("tar"). The canopy was full and well-watered.

Expert Conclusion: Phytophthora Bleeding Canker

Jen rules out beetles (no holes or frass). The symptoms—cracks, dark sap—match Phytophthora canker, a fungal disease that girdles trunks over time. No cure exists; management focuses on tree vigor.

Key Points

• Native Phytophthora species are most common; exotic P. ramorum (sudden oak death) is unlikely in Sacramento.
• Monitor for canopy thinning, dieback, or hazard potential.
• Consult local county extension for confirmation: UC ANR County Offices.
• Plan for eventual removal if structural integrity declines.

Resources: Nevada Dept. of Agriculture PDF | UMass Extension Fact Sheet