Winter wheat producers must remember that the key to controlling the wheat streak mosaic virus disease is to break the green bridge through effective use of herbicides and appropriate planting date. Insecticides are not effective in managing this disease. The following paragraph, provided by Jan Knodel, discusses the difference between the wheat curl mite, which transmits the wheat streak mosaic virus, and the two spotted spider mites that have been reported in soybean and corn:
Some questions have come in about controlling wheat curl mites with foliar insecticides to prevent transmission of wheat streak mosaic virus in winter wheat. The wheat curl mite, Aceria tosichella, belongs to the Acari: Eriophyidae family, and should not be confused with the two-spotted spider mite, Tetranychus urticae, in the Acari: Tetranychidae family. The drought of 2012 has been a bad year for two-spotted spider mite infestations in soybeans, dry beans and field corn. Producers know that the two-spotted spider mite can be effectively controlled with selected insecticides and/or acaricides. However, it is important to understand that these insecticides or acaricides have been tested and they will NOT control the wheat curl mite. Cultural practices (breaking the green bridge) are the best IPM tool that will disrupt the mite and disease cycle. (from Jan Knodel)
The strategies used to break the green bridge (see figure) and manage wheat streak mosaic (WSMV) are:
1) Plant winter wheat during the recommended planting windows: ie. Sept. 1-15 for the northern half of ND, and September 15-30 for the southern half of the state. Earlier planting will result in winter wheat emerging when mites are still very active and when grassy weeds, volunteers in the field or adjacent fields, and corn are still green, all of which may harbor the mites.
2) Control volunteer wheat and grassy weeds in a field two weeks prior to planting the next susceptible crop. A two-week window of not having a host present assures that the mite has gone through its life cycle and not found a subsequent host to feed on and transmit the virus.