Occurrence and Spread of Rice Tungro Spherical Virus in the Philippines. N. B. Bajet, International Rice Research Institute, P.O. Box 933, Manila, Philippines. V. M. Aguiero, R. D. Daquioag, G. B. Jonson, R. C. Cabunagan, E. M. Mesina, and H. Hibino, International Rice Research Institute, P.O. Box 933, Manila, Philippines. Plant Dis. 70:971-973. Accepted for publication 2 April 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-971.

Rice virus diseases were surveyed in the Philippines from November 1983 to March 1985. Rice tungro was the most prevalent disease. Leaf samples collected in the field were tested for rice viruses by enzyme-linked immunosorbent assay (ELISA). Rice grassy stunt and rice ragged stunt viruses were not observed in the visual survey but were detected by ELISA in some leaf samples collected at Camarines Sur, Iloilo, Laguna, and Antique. In most locations, many plants showing tungrolike leaf yellowing contained rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV). In some locations, however, many leaf samples with similar symptoms contained neither virus. Many plants without the symptoms in the same fields contained RTSV alone. RTSV also occurred in the fields where tungrolike symptoms were not observed. A high proportion of vector leafhoppers collected in the fields transmitted RTSV alone. These results indicate that aside from tungro (a disease complex associated with RTBV and RTSV), RTSV also occurs and spreads as an independent disease in the Philippines.

Keyword(s): epidemiology, Nephotettix virescens, N. nigropictus, Recilia dorsalis, rice tungro virus, rice waika virus.