Lachnocladium brasiliense

Lachnocladium brasiliense is a fungal pathogen responsible for the condition commonly referred to as "white thread blight." As a basidiomycete fungus, it colonizes the surface of host plants, creating a web of white mycelial strands that systematically extract nutrients and disrupt the physiological functions of the affected tissue.

The primary hosts of this pathogen are tropical woody plants, with cocoa trees being particularly susceptible. The fungus typically attacks young shoots, petioles, and developing fruit pods. Its presence hinders the plant's ability to transport water and nutrients, which often results in severe dieback and significant losses in agricultural productivity.

Visual symptoms are distinct, characterized by the appearance of thin, white, thread-like mycelia that branch out over the surface of the plant stems and leaves. As the infection progresses, the leaves may turn brown and wither while still attached to the plant, eventually falling off. Under favorable conditions, the white threads may cover almost the entire branch, leading to tissue death.

The development of Lachnocladium brasiliense is heavily dependent on microclimatic conditions, specifically high humidity levels and shaded, poorly ventilated areas. High planting density significantly increases the risk of infection, as the environment remains consistently damp, facilitating the growth of the fungal mycelium and the spread of spores throughout the canopy.

Effective disease management requires a combination of cultural and chemical strategies. Sanitation is paramount: growers must prune and remove infected twigs and debris from the orchard floor to reduce the inoculum reservoir. Additionally, managing tree canopy density to allow sunlight penetration and improved airflow is an essential practice for preventing the establishment and spread of the fungus.