Field Screen for Identification of Resistance to Mite-Transmitted Viruses in Winter Wheat.

A complex of three viruses (Wheat streak mosaic virus, Triticum mosaic virus, and High Plains wheat mosaic virus) causes significant yield loss in winter wheat in the Great Plains. All three of these viruses are transmitted by the wheat curl mite (Aceria tosichella Keifer). A wheat screen has been developed to screen developing and advanced lines of hard red and white winter wheat varieties for greater resistance to wheat streak mosaic virus and the other mite-vectored viruses. This screening process was done under field conditions by using natural infestations of mites and virus. An artificial green bridge was established to enable mite survival from the previous winter wheat crop through the summer to provide mites to infest the fall planted screen. The screen included varieties that are commercially available to Nebraska wheat producers and breeder lines that will eventually develop into released varieties. After the winter wheat screen was planted in September, mites moved into the screen and infected the newly planted wheat with viruses. Mite populations were monitored on mite-resistant lines and virus impact was determined through visual ratings and relative chlorophyll estimates. Several developing lines were identified with high levels of resistance to the viruses, and limitations in resistance of commercial lines were identified. The development of varieties with effective resistance to these viruses will enable growers to better manage this important risk to yield and quality.