Lethal bole rot

Lethal bole rot is a severe fungal disease caused by the basidiomycete Marasmiellus cocophilus. It primarily affects coconut palms (Cocos nucifera), causing progressive decay of the trunk tissue. This disease is highly destructive and can lead to the death of entire plantations if left unmanaged, presenting a significant threat to global coconut production.

The pathogen typically invades the palm through wounds on the stem or near the root collar. Once established, the mycelium spreads throughout the internal tissues, disrupting the flow of water and nutrients. The fungus produces enzymes that degrade the structural integrity of the wood, eventually leading to a failure of the terminal bud and the inevitable death of the tree.

Visible symptoms often begin with the yellowing and drooping of the lower leaves. As the infection advances, the leaves eventually collapse and die. A key diagnostic feature is the appearance of small, white to tan-colored fruiting bodies of the fungus at the base of the trunk or on decaying stem tissues during periods of high humidity.

The development of Marasmiellus cocophilus is strongly correlated with high environmental moisture and heavy rainfall. The disease spreads through spores transported by wind, water splashes, or even by insects that interact with infected palms. The soil can act as a long-term reservoir for the pathogen, allowing it to persist between planting cycles.

Effective management strategies focus on containment and sanitation:

• Immediate roguing (removal) and burning of symptomatic trees to limit spore spread.
• Maintaining proper spacing between palms to ensure adequate airflow and humidity regulation.
• Sterilizing all agricultural equipment used for harvesting or pruning to prevent cross-contamination.
• Improving soil drainage to minimize the conditions favorable for fungal growth.