A disease of rice plants similar to tungro disease in symtoms occurred in Okinawa, Japan, in 1977. A virus belonging to rhabdovirus group was observed in both ultratnin sections and dip preparations from diseased plants. The virus was transmitted in a persistent manner by the green rice leafhopper, and was identified as rice transitory yellowing virus.
To investigate the water permeability of the brown-discolored marginal zone, artificial lesions were prepared by means of inoculation at heat-injured spots. These lesions formed sharp brown-discolored zone which seemed to barricade the parasite. Water content of these lesions decreased rapidly even under sufficient water supply, suggesting that the brown-discolored tissue inhibits the supply of water and water soluble nutrients to the fungus enclosed in the lesion.