Sorghum mosaic

Sorghum mosaic virus (SrMV) is a significant plant pathogen belonging to the genus Potyvirus within the Potyviridae family. As a positive-sense single-stranded RNA virus, it causes systemic infection in many economically important graminaceous crops. The virus is recognized globally as a major limiting factor in the cultivation of sorghum and related grasses.

The primary hosts for this virus include cultivated sorghum, maize, sugarcane, and several wild grass species. Infection is typically characterized by mosaic patterns, chlorotic stripes, and mottled discoloration on the leaves. Depending on the specific strain of the virus and the host's susceptibility, symptoms may also include severe leaf deformation, stunted plant growth, and a marked reduction in overall yield.

The biological cycle of the virus is heavily dependent on insect vectors, primarily various species of aphids. Transmission is non-persistent; the aphid acquires the virus particles during brief probes of infected plant tissues and can transmit them to healthy plants almost immediately. The virus remains associated with the aphid's stylet, allowing for rapid spread within the field as aphids move between plants to feed.

Development and spread of the disease are dictated by weather patterns that influence aphid populations. Warm conditions and adequate moisture support the rapid multiplication and migration of vectors. Furthermore, the presence of alternative hosts, such as perennial grassy weeds around fields, provides a continuous reservoir for the virus, ensuring it remains present in the environment even between cropping seasons.

The economic impact of Sorghum mosaic is significant, as it interferes with plant metabolism and reduces photosynthetic efficiency. Control strategies are primarily focused on prevention and management of the vector populations, as curative treatments for infected plants are not available. Essential control measures include:

• Utilization of resistant or tolerant sorghum hybrids.
• Active management and removal of weed hosts to reduce infection sources.
• Strategic application of insecticides to control aphid vectors during the critical stages of growth.
• Adhering to recommended planting dates to avoid peaks in vector migration.
• Maintaining spatial isolation from sugarcane fields which may act as a permanent virus reservoir.