Rice black-streaked dwarf disease

The causative agent of the disease is Fijivirus boryzae, a member of the Fijivirus genus within the Reoviridae family. This virus is a major constraint in cereal production, causing systemic infection that disrupts plant metabolism. The virus contains a segmented double-stranded RNA genome, facilitating its stability and persistence in host tissues.

The primary host for this pathogen is rice (Oryza sativa), although it also affects various other graminaceous crops and wild grasses. The disease has significant economic impact in rice-growing regions across East Asia. The virus's ability to persist in perennial grasses makes it difficult to eradicate from agricultural landscapes.

Symptoms typically manifest as dark-colored enations or galls on the veins of leaves and sheaths, caused by abnormal tissue cell proliferation. Infected plants exhibit severe stunting, dark green coloration, and excessive tillering. In many cases, the panicles fail to emerge, resulting in significant yield loss or total crop failure.

Transmission occurs through insect vectors, primarily small planthoppers such as Laodelphax striatellus. The transmission mode is persistent-propagative, meaning the virus multiplies within the insect vector. Once acquired, the vector remains infectious for its entire lifespan, and the virus can also be passed vertically to the insect's offspring.

Control strategies focus on minimizing vector populations and reducing the initial inoculum. Effective integrated pest management (IPM) practices include:

• Selection and planting of resistant or tolerant rice varieties.
• Systematic monitoring and control of planthopper populations during critical growth stages.
• Removal of infected plants and control of weeds serving as viral reservoirs.
• Optimizing planting dates to avoid the peak activity periods of the insect vectors.