Increase of Bacterial Leaf Streak in Hard Red Spring Wheat in North Dakota and Yield Loss Considerations.

Bacterial leaf streak (BLS), caused by Xanthomonas translucens pv. undulosa, has increased in both prevalence and severity in the major hard red spring wheat (HRSW) producing state North Dakota (ND). The disease is readily observed after flag leaf emergence and can quickly lead to defoliation and severe yield loss. The objectives of this research is to document prevalence and incidence of BLS in ND and provide estimations of yield and economic losses. Trained field scouts determined the incidence and prevalence of BLS in ND on HRSW plants between Feekes Growth Stage (FGS) 8 to FGS 11.2 from 2015 to 2021, and data were used to determine BLS affected hectares. Yield data in combination with BLS ratings were obtained from HRSW performance trials to estimate impact of BLS on yield. The combination of variety identity, hectarage data, BLS affected hectarage estimates, and yield loss estimates were used to estimate economic losses from BLS in 2019 and 2020. Our data suggest that BLS affected hectares ranged from 747 to 141,680 between 2015 and 2021. Yield loss was observed at multiple HRSW performance trial locations with estimated yield losses as high as 60% on susceptible varieties. The amount of BLS affected hectares was the highest in 2019 and 2020 and direct economic losses for ND HRSW producers were estimated as high as $4.7 and $8.0 million dollars, respectively. These data highlight the importance of BLS in HRSW and the need to procure resources for breeding efforts and grower education on management of BLS.