Symptoms of wheat streak mosaic typically start at the edge of the field, with severe yellowing, and decrease in severity with distance into the field (Workneh et al., 2009a). This is due to the movement of the mite vector over time and subsequent disease spread. Infection by WSMV is not considered to be a latent infection and is characterized by stunting, reduction in tiller number, and chlorosis or the breakdown of chlorophyll within the plant leaves progressing to a mosaic pattern and streaking appearance, which eventually leads to necrosis and plant death (Wiese, 1987). More severe symptoms are found when wheat becomes infected in the autumn compared to wheat infected in the spring or summer, which could be due to plant age at the time of infection (Hunger et al., 1992). During severe infections, the wheat heads are not able to produce grain or contain small, shrivelled seeds.