By Connie Strunk and Madalyn Shires et.al
Wheat streak mosaic virus (WSMV) is one of the most damaging viral diseases of winter wheat in the Great Plains. There are no in-season treatments that cure virus-infected wheat. WSMV is transmitted by the wheat curl mite, a microscopic pest that survives and spreads by moving among living grass hosts. Controlling volunteer wheat and grassy weeds is an important management step. In this article, we present information about pre-plant and post-planting management in winter wheat fields. It is important to understand that management of volunteer plants and grassy weeds should continue after plant due to the high disease pressure in 2025 and 2026 (Figure 1).
Breaking Down the Green Bridge
All plant viruses need a living host to survive. WSMV can only survive in living plant tissue, not in residue or soil. Wheat curl mites (vector) must feed on infected plants to acquire and transmit the virus. Volunteer wheat emerging after grain harvest is often the main source of inoculum (Figure 2), but numerous grassy weed species and volunteer corn as well as sorghum can harbor mites and virus. Hail events, harvest losses, or moisture following harvest can lead to abundant volunteer wheat growth. If this volunteer wheat becomes infected and remains alive until winter wheat emerges, mites can move directly into the new crop and transmit WSMV.
Why Weed Control Matters
Grassy weeds act as reservoirs for wheat curl mites. Fields, field borders, roadside ditches, and non-crop areas containing volunteer cereals or grassy weeds can increase the risk of fall infection.
Effective weed control accomplishes two important goals:
- Eliminates host plants that support wheat curl mite populations.
- Removes living tissue needed for virus survival between crops.
When volunteer wheat and grassy weeds are allowed to persist, they provide a continuous pathway for virus and mite survival from one wheat crop to the next.
Source : sdstate.edu