Maize mosaic

Maize mosaic is a devastating viral disease caused by the Maize mosaic virus (MMV), which belongs to the genus Nucleorhabdovirus. The virus is known to affect maize (corn), as well as a range of other important grass species like sorghum and pearl millet. It is particularly prevalent in tropical and subtropical regions worldwide, causing significant agronomic challenges.

The virus is transmitted in a persistent manner by the planthopper Peregrinus maidis. Once a planthopper feeds on an infected plant, it remains a vector for the duration of its lifespan, facilitating the spread of the virus throughout the field. MMV is not known to be seed-borne, meaning the primary pathway for disease outbreak is the migration and feeding activity of these specific insect vectors.

The biology and development of the disease are heavily dependent on the ecology of the planthopper population. Warm, humid environments promote high vector activity, which is essential for rapid viral transmission. The virus is able to survive in alternate host plants or perennial grasses, which serve as a reservoir for the virus during periods when maize is not actively being grown.

The impact of the disease on crop yield can be severe. Symptoms typically appear as chlorotic stripes on the leaves, followed by plant stunting and the development of poorly filled ears. By disrupting the photosynthetic capacity of the plant, the virus limits the overall growth and grain development. In susceptible cultivars, infestations can lead to substantial losses in both the quantity and quality of the harvest.

Effective management of Maize mosaic relies on integrated pest and disease control strategies:

• Planting resistant or tolerant maize hybrids to mitigate the effects of infection.
• Applying insecticides to manage the populations of the planthopper vector.
• Implementing strict weed control to eliminate reservoir hosts of the virus and the vector.
• Practicing appropriate planting dates to minimize overlap with peak vector activity periods.