The rhizome rot of Hindu lotus has been reported from different parts of Japan, such as Osaka, Tokushima, Aichi and Kagawa prefectures. Several species of Pythium and Fusarium were isolated from diseased lotus rhizome and considered as the causal organisms.
Pythium species were isolated selectivery by using corn-meal agar containing 50ppm streptomycin.
Pythium nelumbium n. sp. was identified as a new species besides P. spinosum Sawada, and P. ostracodes Drech. Sporangia of P. nelumbium are filamentous or composed of inflated elements and produce both zoospores and conidia. Oogonia are smooth, spherical and 20.7-31.1μ in diameter. Oospores filling the oogonium. Numerous antheridia, 8-15, are attached to an oogonium and either diclinous or androgynous.
The fungus was isolated from diseased lotus rhizome collected from Kadoma City, Osaka.