ABSTRACT
Most seedlings collapses before and after emergence may be due to pathogenic Pythium species. P. carolinianum and P. periplocum were two Pythium species associated with flowering cherry seeds in nature, which is interesting to note. Various mature plants, commonly associated with Pythium spp., were often shriveled and their roots discolored. Two Pythium species were found as flowering cherry seed associates, during the study on seed-borne pathogenic fungi of forest trees. Seed-associated Pythium may be noteworthy, but has not been previously reported in Japan and other countries, and may be related to the disappearance of young cherry seedlings under natural renewal. These fungi were also detected from forest soils together with seven other Pythium species. Pythium species, including P. aphanidermatum, P. myriotylum, P. splendens, and P. ultimum, have been found commonly on plants and soils worldwide. Pythium species have been found everywhere often together with Fusarium and Rhizoctonia species in Japan.
