Sorghum mosaic virus

Sorghum mosaic virus (Potyvirus halapensis) is a significant viral pathogen of the Potyviridae family that affects various cereal crops. This virus acts as a systemic pathogen, colonizing the host plant's vascular tissues and redirecting nutrients, which leads to metabolic stress and a severe reduction in biomass and grain production.

The host range is primarily limited to the Poaceae family, with sorghum, maize, and sudangrass being the most economically affected species. Perennial weeds, particularly Johnsongrass (Sorghum halepense), serve as critical primary hosts. The virus overwinters in the rhizomes of these weeds, allowing for rapid spread to new seasonal plantings as growth begins.

Symptoms of the infection typically manifest as foliar mosaic patterns, featuring alternating patches of light green, yellow, and deep green tissue. Advanced stages of the disease may cause stunted plant height, chlorotic streaks, leaf distortion, and poor head exertion. These physiological changes significantly impede the plant's ability to fill grain and maximize yield potential.

Transmission occurs through non-persistent vectors, specifically various species of aphids. When an aphid probes or feeds on an infected plant, it acquires the virus on its stylet and can transmit it to a healthy host within seconds. Because this mode of transmission is rapid, chemical control of aphid populations often serves only as a partial mitigation strategy.

Integrated disease management is essential for long-term protection. Strategies include planting certified virus-free seeds, selecting resistant or tolerant sorghum cultivars, and maintaining rigorous weed control, especially the elimination of Johnsongrass near field perimeters. Crop rotation and proper site selection can also help disrupt the infection cycle by reducing the initial inoculum pressure in the environment.