In 1978, a new disease of rice broke out in Hokkaido, the northern part of Japan, and the causal fungus was identified as Helminthosporium sativum P.K. & B. (=Bipolaris sorokiniana). Most of the diseased plants were observed in the paddy fields adjacent to spring wheat fields. Brown blotch appeared on leaves and glumes. Temperature at 28C was optimum for infection and disease development. The fungus was pathogenic to wheat and barley in addition to rice.
