Pythium oligandrum has received much attention in terms of physiology, ecology, mode of parasitism and potential for the biocontrol of plant pathogens. A recent biological molecular investigation using amplified PCR products and PCR-RFLP patterns enabled easy differentiation of Pythium oligandrum from other Pythium species. Pythium oligandrum is also a strong colonizer of the rhizosphere in hydroponic systems when microflora is nearly absent.