Ganoderma root rot

The disease is caused by the fungus Ganoderma zonatum, a basidiomycete responsible for white rot of the roots and the lower trunk. This pathogen systemically degrades wood components, primarily lignin, which leads to the structural collapse of the tree's base.

This pathogen has a broad host range, including economic crops like avocado and landscape trees such as plane trees. The fungus typically invades the plant through wounds in the root system, base of the trunk, or through root-to-root contact with infected material in the soil.

Diagnostic symptoms often involve severe canopy thinning, leaf yellowing, and gradual branch dieback. The presence of shelf-like, woody fruiting bodies (conks) at the base of the trunk is the diagnostic indicator, often showing distinct concentric zones of growth on the upper surface.

Favorable conditions for infection include excessive soil moisture, poor drainage, and physical damage to the root collar. The fungus can persist in the soil for several years, making the site unsuitable for replanting without proper sanitation or soil treatment protocols.

Effective management strategies include:

• Immediate removal of infected trees including the root ball.
• Improving soil drainage to prevent moisture buildup at the base.
• Preventing mechanical injuries during cultivation.
• Regular inspections to detect early symptoms of fruiting body formation.