Polyhedral particles about 70 nm in diameter were detected in a dipped preparation under the electron microscope from rice plants with symptoms including stunting of the plants and appearance of white chlorotic specks on foliage in Nepal. Similar particles were also observed in ultra-thin sections of infected leaves. In agar gel diffusion test using antiserum to rice dwarf virus, a precipitin line was formed with sap from infected tissues. However, no such a line was observed with the sap from healthy tissues. These results together with the symptomatology confirm that the disease was caused by rice dwarf virus.
Nephotettix nigropictus the only known vector of rice dwarf virus in Nepal, occurred prevalently on weeds and paddy fields in the late growing season of rice in the hill area of Nepal such as Kathmandu.
Latex agglutination method was applied to detect virus antigen of rice dwarf disease in both plants and insect vectors.