Johnsongrass mosaic

Johnsongrass mosaic virus (JGMV) is a significant plant pathogen belonging to the genus Potyvirus within the family Potyviridae. As an RNA-based virus, it primarily affects members of the Poaceae family, causing systemic infections that impact growth and yield.

The host range is broad, but the virus is most economically damaging to maize and sorghum crops. The disease manifests as chlorotic mottling, mosaic patterns, and streaking on leaf blades. In severe cases, the infected plants exhibit stunted growth, reduced leaf size, and lower biomass production compared to healthy specimens.

The biology of JGMV is characterized by non-persistent transmission via aphids. The virus particles are acquired by aphids through probing and feeding on infected tissue and are transmitted almost immediately to healthy plants. This mechanism makes the virus highly efficient at spreading throughout a field during periods of high aphid activity.

Development and spread are facilitated by the presence of perennial host plants, specifically Sorghum halepense (Johnsongrass). The virus survives the winter in the rhizomes of these perennial weeds. As Johnsongrass regrows in the spring, the virus is transmitted to emerging crops by migrating aphids, establishing the primary infection points in the field.

Management of Johnsongrass mosaic requires a strategic approach focusing on the elimination of the viral source and vectors. Key strategies include:

• eradicating Johnsongrass populations in and around production areas;
• implementing early-season aphid management programs;
• selecting resistant or tolerant crop cultivars;
• optimizing planting times to avoid peak aphid flight periods;
• maintaining clean field borders to prevent initial entry of the pathogen.