Rigidiporus microporus

Taxonomic position and pathogen type: Rigidiporus microporus is a basidiomycete fungus belonging to the Meripilaceae family. It is a notorious necrotrophic pathogen known for causing wood decay. As a specialized phytopathogen, it primarily targets the root systems of perennial woody species, functioning as an aggressive decomposer of lignocellulosic material.

Diseases and host plants: The fungus is best known for causing White Root Disease. This condition is the most destructive disease affecting Hevea brasiliensis (rubber trees) globally. It typically infects the root system, causing the woody tissue to break down into a soft, white fibrous mass, eventually leading to the death of the host plant.

Biology and life cycle: The pathogen spreads via mycelial contact between infected roots and healthy ones in the soil. It also produces fruiting bodies on the base of infected stumps, releasing basidiospores that can colonize new wounds. Its ability to persist in dead woody debris for many years makes it an extremely persistent threat in agricultural environments.

Development conditions and damage: The fungus thrives in warm, humid climates with well-distributed rainfall, which are typical for tropical rubber plantations. The damage is significant: the loss of functional roots prevents water and nutrient uptake, causing yellowing of leaves, premature defoliation, and ultimately, tree collapse, leading to substantial economic loss.

Protection and control measures: Effective management relies on an integrated approach to mitigate the risk:

• Pre-planting sanitation: thorough removal of stumps and buried woody debris.
• Chemical treatment: application of fungicides around the root zone of early-stage infected trees.
• Isolation: digging deep trenches around infected patches to contain mycelial spread.
• Monitoring: routine field inspections to identify and remove diseased trees before the pathogen spreads further.