During investigations of colonization of healthy emerged sugar beet roots by microorganisms, the fungus Pythium oligandrum Drechsler was found on the root surface of sugar beet seedlings which already had true leaves, in Semčice (Central Bohemia) in 1972. Infection tests proved a low degree of pathogenicity of this fungus towards sugar beet seedlings. In laboratory conditions, Pythium oligandrum showed strong parasitism against Pythium ultimum Trow and Pythium debaryanum (Hesse) De By., which are significant root rot pathogens of sugar beet. In dual cultures with these fungi, P. oligandrum usually dominated the substrate within 24 hours after inoculation and completely destroyed or strongly suppressed the other fungus growing with it on agar medium. Because Pythium oligandrum exhibits only very weak pathogenicity towards sugar beet but is a strong parasite of P. ultimum and P. debaryanum, which it shares the rhizosphere with, its potential use for biological control of sugar beet root rot is discussed, using biopreparations applied to sugar beet seed.
Veselý D. (1977): Das Vorkommen von Pythium oligandrum Drechsler auf der Wurzeloberfläche auflaufender Zuckerrüben in Böhmen und einige Erkenntnisse zur Biologie des Pilzes. – Česká Mykologie 31(1): 41–51.
