Rice tungro

Rice tungro is a severe viral disease that poses a major threat to global rice production, particularly in tropical regions. It is characterized by a viral complex involving the Rice tungro bacilliform virus (RTBV) and the Rice tungro spherical virus (RTSV), which together cause devastating damage to the host plant.

The disease is transmitted by leafhoppers, most notably Nephotettix virescens. These insects acquire the virus by feeding on infected plants and subsequently transmit it to healthy ones. The transmission is semi-persistent, meaning the insect remains infectious for a relatively short duration but can cause significant outbreaks if vector populations are high.

Typical symptoms include stunting of the plant, reduced tiller number, and distinctive yellowing or orange-yellow discoloration of leaves starting from the tip. In advanced stages, the plants produce small, poorly filled panicles, which significantly impacts the yield quality and weight of the harvested rice.

The spread of Rice tungro is heavily influenced by agricultural practices and environmental conditions. Continuous cropping cycles and the presence of susceptible rice varieties throughout the year provide a stable habitat for leafhoppers, allowing the virus to persist and migrate easily across rice-growing landscapes.

Management and prevention focus on integrated pest management (IPM) strategies. These include:

• Planting resistant rice cultivars.
• Synchronous planting to break the insect life cycle.
• Removal of volunteer rice plants and weeds that harbor the virus.
• Judicious use of insecticides to manage leafhopper populations during critical growth stages.