LAUSR

Abstract Soil-borne wheat mosaic virus (SBWMV), the causal agent of Wheat soil-borne mosaic (WSBM) was discovered for the first time in the dryland wheat production zone of the US Pacific Northwest (PNW) in 2008. Current WSBM distribution in the Walla Walla Valley that spans the Oregon/Washington border was documented during 2017 and 2018. Yield loss estimates of rainfed winter wheat were also determined for this growing region. WSBM is more widely distributed in the Walla Walla Valley than was previously estimated. Significant reductions of grain yield (40%), biomass (37%), and heads per area (34%) were documented in association with SBWMV infection in commercial winter wheat fields each year. Test weight was reduced by 2.3% (P = 0.08). No significant difference in the number of spikelets per head was observed in association with WSBM. This work is part of an ongoing effort to provide management solutions to WSBM.