ISOLATION OF PYTHIUM-OLIGANDRUM FROM EGYPTIAN SOIL AND ITS MYCOPARASITIC EFFECT ON PYTHIUM-ULTIMUM VAR. ULTIMUM THE DAMPING-OFF ORGANISM OFWHEAT

Pythium oligandrum Drechsler bearing spherical sporangia with complex subglobose elements was isolated for the first time in Egypt from agri cultural field soil cultivated with alfalfa (Trifolium alexandrinum) i n El-Minia, Egypt. This fungus was found to be an active bio-control a gent against P. ultimum var. ultimum, the damping-off organism of whea t. In agar plates, P. oligandrum parasitized P. ultimum var. ultimum h yphae with the aid of thin haustorial branches or infection pegs, even tually leading to host destruction. Incorporation of P. oligandrum int o carboxymethylcellulose seed coating successfully eliminated pre-emer gence damping-off of wheat caused by P. ultimum var. ultimum, whereas Post-emergence damping-off was prevented by adding inocula of P. oliga ndrum to the soil.