Causes mosaic symptoms in rice (Oryza sativa) characterized by spindle shaped yellow flecks and streaks (Fig.1) visible on the lower leaves but usually not on the newly growing leaves. Causes necrotic fleck lesions on the basal portions of stems and sheaths in some plants (Fig.2). Infected plants are moderately stunted; the tillers are decreased in number, and somewhat prostrate.
Occurs in rice that is transplanted from upland nurseries to paddy fields or direct-seeded in upland fields; rare in rice transplanted from lowland nurseries to paddy fields or direct-seeded in paddy fields (Fujii, 1975). Paddy rice with necrosis mosaic disease often suffers also from rice blast (Pyricularia oryzae) especially on panicles and nodes, resulting in a great reduction of yield (Fujii, 1975).