Abstract
Pythium iwayamai, P. okanoganense and P. paddicum, the main causal organisms of Pythium snow rot, were isolated from rotted leaves of wheat and barley grown in 122 paddy fields and 7 upland fields between 1982 and 1986. P. paddium was the dominant pathogen in ill-drained paddy fields in the previous season. From well-drained paddy fields, all three pathogens were isolated independently or simultaneously. On the other hand, P. iwayamai was the dominant pathogen in upland fields. The results indicate that distribution of the pathogens may vary with the degree of drainage in the fields.
