Wheat streak mosaic

Wheat streak mosaic (WSM) is a destructive viral disease caused by the Wheat streak mosaic virus (WSMV), which belongs to the genus Tritimovirus within the family Potyviridae. This phytopathogen infects a wide range of cereal crops, including wheat, barley, corn, and millets, often leading to severe yield reductions in affected fields.

The virus is exclusively transmitted by the wheat curl mite, Aceria tosichella. This microscopic vector picks up the virus while feeding on infected plants and transmits it to healthy tissues during subsequent feeding events. Transmission is mechanical and does not occur through the soil, water, or seeds themselves.

The epidemiology of the disease relies heavily on the presence of the mite vector and host plants throughout the growing season. Warm temperatures and mild autumn conditions promote rapid mite reproduction and migration. Mites typically move from maturing wheat crops or volunteer wheat into newly emerged winter wheat seedlings in the autumn.

Symptoms of WSMV infection typically appear as discontinuous yellow or light green streaks that follow the veins of the leaf blades. In severe cases, the entire leaf becomes chlorotic, and the plant exhibits stunted growth, reduced tillering, and poor kernel development. This leads to lighter test weights and significant grain yield loss.

Managing Wheat streak mosaic requires a multifaceted approach focused on preventing the survival of the vector:

• controlling volunteer wheat before planting new crops;
• delaying winter wheat planting to avoid peak mite activity;
• removing grassy weeds that serve as alternate hosts;
• planting varieties that demonstrate resistance or tolerance to the virus.