Differential response of winter wheat and barley cultivars to yellow dwarf virus strains and aphid vectors.
Yellow dwarf viruses (YDV), comprising strains of barley yellow dwarf virus (BYDV) and cereal yellow dwarf virus (CYDV), constrain cereal production in the United States by causing yellow dwarf disease (YDD). Five principal B/CYDV strains occur in cereals: BYDV-PAV, -MAV, -RMV, -SGV, and CYDV-RPV. Although YDV has been reported in Nebraska, cultivar-specific responses and field-level strain composition remain poorly characterized. We conducted a two-year (2024-2025), multi-location field study at Mead, Fairbury, and Concord, Nebraska to evaluate 10 widely grown wheat and barley cultivars for YDD incidence, virus strain diversity, and aphid infestation. Across years and locations, YDV infection was higher in wheat (29.73%) than in barley (12.53%). In wheat, cv. SY Monument exhibited the highest YDV incidence (36-92%) and the greatest aphid abundance, whereas cv. Ruth consistently showed the lowest incidence (4-20%) and minimal aphid infestation. In barley, cv. Fortress had the highest infection levels (8-48%) and aphid abundance, while cvs. NB19420 and NB21427 were generally the least infected (0-20% and 4-12%, respectively) and supported the lowest aphid populations. Strain composition differed by crop: wheat infections were dominated by PAV-associated single and mixed infections, whereas barley shifted toward MAV-dominated infections with reduced strain diversity. Aphid abundance was positively associated with YDV infection in wheat and barley. Collectively, these results highlight the interacting roles of host susceptibility, strain diversity, and vector dynamics in shaping YDD epidemiology and support integrated cultivar- and vector-based management strategies.