|Weisz, R -|
|Horton, J.R. -|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 10, 2009
Publication Date: January 27, 2010
Citation: Cowger, C., Weisz, R., Anderson, J.M., Horton, J. 2010. Maize Debris Increases Barley Yellow Dwarf Virus Severity in North Carolina Winter Wheat. Agronomy Journal. 102:688-696 Interpretive Summary: In two out of three years, we found greater severity of yellow dwarf virus (YDV) symptoms in wheat planted into no or minimum tillage of corn residue. In the third year of the study, wheat was planted very late, and avoided high infestations of the aphids that vector the YDV. Three different strains of the YDV were found. We hypothesize that corn residue attracts the aphids, which in turn, infect the early planted wheat with YDV.
Technical Abstract: In the eastern U.S., wheat is often planted with minimal or no tillage into maize residues. We conducted a field experiment in the North Carolina Piedmont to compare the effects of three maize residue treatments (unchopped, chopped, and removed) on Fusarium head blight (FHB) in two winter wheat cultivars. While FHB levels were too low for meaningful comparisons, severe epidemics of barley/cereal yellow dwarf virus (YDV) did develop in two years out of three. In those two years, YDV symptoms of discoloration and stunting were greater (P = 0.001), and yield was lower (P = 0.01), in plots with maize residue than in plots without maize residue. In the third year, when planting was late because of a severe fall drought, no YDV epidemic developed, and there were no differences in wheat yield due to maize residue treatment (P = 0.25). In the first two years, leaf samples from all plots were assayed for viruses using a multiplexed reverse transcription polymerase chain reaction (RT-PCR) method. The most common YDV serotypes were MAV, PAV, and RPV, which were each detected in at least 46% and 74% of samples in the two years, respectively. Our finding of greater YDV severity in association with surface residue is consistent with the reported aphid preference for high-intensity yellow colors, which we hypothesize attracted aphids preferentially to residue-covered plots in the fall. Our results support a recommendation of seed or seedling insecticide treatment when planting wheat into heavy unincorporated maize residue in the North Carolina Piedmont.