Abstract
Rhizoctonia oryzae RYKER et GOOCH, Sclerotium fumigatum NAKATA, S. hydrophilum SACC. and S. oryzae-stativae SAW. causing rice sclerotial diseases were used for investigation of their viability under natural and artificial conditions.
1) Under natural conditions, reisolation of hyphae from plant residues infected by those fungi after 90 days, resulted in generally higher frequency than that from scierotia exposed on the soil surface.
2) When sclerotia were sheathed in plant residues under natural conditions, they overwintered better than those exposed on the soil surface.
3) Regardless of the wide moisture range (0%-10-97%-100%), sclerotia of S. oryzae-sativae survived for 240 days under artificial conditions (25-28C), although sclerotia of R. oryzae and S. fumigatum were less tolerant to such moisture conditions.
