The characteristic symptoms of P. oryzae are general chlorosis, pronounced stunting and profuse tillering. The chlorotic leaves are uniformly pale green or pale yellow. Discoloration first appears on the emerging young leaves and then chlorosis on all the succeeding leaves. Plants infected early may die prematurely. Those which survive until maturity produce only a few defective heads or no heads at all. Plants infected in the late growing stage may show chlorotic branches arising from upper nodes or small chlorotic tillers in the stubble, or no other symptom except distortion of panicles, or characteristic chlorosis tillering on the ratoon grown on the cut stubbles (Chen, 1977).

Plants can be infected at all growth stages. They are most vulnerable to infection at the tillering stage. Rice grassy stunt virus symptoms develop 10−12 days after infection. Infected stubble and volunteer rice are sources of rice grassy stunt virus. It cannot be transmitted via brown planthopper eggs.

Causal organism is Phytoplasma oryzae The disease is transmitted by leaf hopper Nephotettix cincticeps, Napicalis etc.