Sugarcane mosaic

Systematic position and pathogen type: The causal agent of the disease is the Sugarcane mosaic virus (SCMV). It is classified within the genus Potyvirus, family Potyviridae. This pathogen is a positive-sense single-stranded RNA virus that primarily infects species within the Poaceae (grass) family.

Host crops and symptoms: The virus has a wide host range, including sugarcane, maize, sorghum, and various wild grasses. The characteristic symptoms manifest as a mosaic pattern of light and dark green leaf patches, stunted growth, chlorosis, and sometimes leaf twisting. In severe infections, plants exhibit significant developmental delays and reduced yield potential.

Biology and lifecycle: The virus does not persist in the soil for extended periods. It overwinters primarily in perennial grass weeds or infected crop residues. Transmission is mediated non-persistently by aphid vectors. When an aphid feeds on an infected plant, it acquires the virus and can transmit it to healthy plants almost immediately upon moving to a new host.

Conditions for spread and economic impact: Warm weather and the presence of vectors are the primary drivers of disease spread. The economic damage is attributed to the reduced photosynthetic capacity of the plants, which leads to poor grain filling and reduced biomass production. In susceptible hybrids, infection can lead to substantial losses in both forage and grain yields.

Protection and control measures: Controlling SCMV requires an integrated pest management approach:

• Selecting and planting resistant or tolerant cultivars.
• Implementing weed control programs to remove virus reservoirs.
• Monitoring and managing aphid populations using targeted insecticide applications.
• Maintaining proper field sanitation and avoiding early planting of highly susceptible crops near known infection sources.