(1900) Rigidoporus microporus is a plant pathogen, known to cause white root rot disease on various tropical crops, such as cacao, cassava, tea, with economical importance on the para rubber tree (Hevea brasiliensis).

Rigidoporus lignosus (klotzsch) Imazeki, the causal agent of white root rot, was first reported on rubber in 1904 from Botanical Gardens, Singapore.

[2] Its above ground symptoms indicates that the trees are mostly beyond treatment and recovery, as rapid progress of infection makes death imminent.

International Rubber Research and Development Board survey indicates that this disease is described as "severe" in Côte d'Ivoire, Nigeria and Sri Lanka, and as a significant, endemic problem in Gabon, Indonesia, Malaysia and Thailand.

The causative agent (Rigidoporus lignosus) persists on dead or live root debris for a long time, while causing new infections on healthy plants.

This fungus has a wide host range (more than 100 woody species in the Ivory Coast have been recorded as being susceptible) and causes the greatest losses in plantations of H. brasiliensis and, to a lesser extent, of teak (Tectona grandis L.).

[8] The fungus forms many white, somewhat flattened mycelia strands 1–2 mm thick that grow on and adhere strongly to the surface of the root bark.

These rhizomorphs grow rapidly and may extend several meters through the soil in the absence of any woody substrate.

First, however, the rhizomorphs must change morphogenetically into infectious hyphae, characterized by degrading extracellular enzymes able to decay the wood.

[9] This mechanism is strictly regulated by conditions of partial anoxia in the soil, at a depth determined by whether the texture is sandy or clayey.

Wood colonization inside the taproot spreads up to the collar and to other portions of the root system.

A controlled and effective method for artificially infecting young Hevea plants has been developed by reproducing the conditions of soil anoxia in the greenhouse.

This coloration fades along a gradient from the progression front of the parasite toward the tissues colonized earlier, where the wood is particularly friable.

R. lignosus causes a white rot of the wood characterized by degradation of lignin in the cell walls.

The orange-yellow sporophores form mainly during the rainy season at the base of trees heavily attacked by the fungus.

These sporophores produce a large number of basidiospores, even during the dry season, but seem to have a limited role in disseminating the disease.

[13] In Hevea plantations established immediately after a forest is cleared, mycelia filaments of R. lignosus cause infection (Pichel, 1956).