Rice transitory yellowing virus

Rice transitory yellowing virus (RTYV) is a destructive plant pathogen belonging to the Nucleorhabdovirus genus within the Rhabdoviridae family. This virus is a significant concern for rice producers globally, as it disrupts essential physiological functions of the host plant, leading to stunted growth and reduced yields. As an obligate parasite, it relies exclusively on specific insect vectors for survival and spread.

The disease caused by this virus is characterized by a distinctive yellowing of the foliage, typically starting from the older leaves and progressing upwards. Infected plants exhibit significantly reduced height, reduced tiller production, and failure of the panicles to develop properly. This results in poor grain filling and, in severe cases, complete crop failure.

The biological cycle of the virus is intricately linked to its primary vector, the rice leafhopper Nephotettix apicalis. When the insect feeds on infected plant tissue, it acquires the virus. After a latent period within the leafhopper, the virus becomes transmissible, and the insect can infect healthy plants for the remainder of its lifespan. This persistent transmission mode ensures the virus remains a constant threat within the field.

Environmental conditions that favor the proliferation of the leafhopper vector directly influence the incidence of the disease. High humidity and warm temperatures create an ideal climate for the vector to multiply rapidly. The virus spreads most effectively in areas where rice is grown continuously, providing a stable habitat for the vectors and a consistent source of inoculum.

Effective management and protection of rice crops involve integrated pest management (IPM) practices:

• Selection and cultivation of rice varieties known for their resistance or tolerance to RTYV.
• Implementation of regular monitoring programs to track the population density of leafhopper vectors.
• Targeted use of insecticides to reduce vector populations during critical growth stages.
• Sanitation practices, including the eradication of alternative weed hosts that harbor the virus during fallow periods.