Brenda Coutts from DAFWA discusses Wheat Streak Mosaic Virus from symptoms, through risk cycles and onto management options.
Wheat Streak Mosaic Virus (WSMV) infects all cereals and many annual grasses. It is spread by wheat curl mite and is seed-borne.
Infection at early growth stages (pre-flowering) can lead to high yield losses (up to 80%) whilst infection after grain set has little to no impact on yield. Infected plants produce small shrivelled grains.
This year, WSMV is widespread in Central and Northern Ag regions of WA. It has usually been found in crops adjacent to paddocks where extensive volunteer wheat has been maintained for stock feed.
For early infections: spray out to avoid infected seed developing and being left in the field for next season. Avoid retaining any infected seed for sowing in future years. Insecticides are not useful in killing mites so you will need to spray out the whole affected area to stop plant growth and seed setting in affected plants.
Next season: If maintaining volunteer wheat for stock feed next season then a 20m border spray can limit the spread of WSMV into nearby crops.