Short-Term Effects of Cover Crop Rotation on Soilborne Pathogens of Winter Wheat in Traditional Crop–Fallow Systems

Management of soilborne diseases is challenging in the winter wheat production system of the inland Pacific Northwest due to the lack of effective management options and increased adoption of no-till practices. To determine whether cover crops (CCs) could be a viable management tool for winter wheat soilborne disease in no-till dryland winter wheat systems, a 4-site-year study was conducted in northeastern Oregon under low and intermediate annual precipitation regimes. The treatments included three fall-planted CCs (winter lentil, winter pea, and fall mix), six spring-planted CCs (common vetch, phacelia, spring barley, tillage radish, yellow mustard, and spring mix), and a fallow control. The abundance of soilborne pathogens was quantified during the winter wheat phase following a single-year CC rotation. The abundance of soilborne pathogens varied between study sites. The CCs influenced the abundance of Fusarium pseudograminearum and Pythium clade F in crop year 2022/2023, but none significantly reduced the pathogen abundance compared with fallow. Most CCs increased Pythium clade F abundance in crop year 2022/2023 compared with fallow. There was no effect of CC on any pathogen in crop year 2021/2022. Overall, the results suggest that short-term, single-year CC rotations do not reduce the abundance of soilborne pathogens of winter wheat compared with fallow. This study highlights the need for longer-term CC studies to better understand their impacts on soilborne diseases of wheat. [Formula: see text] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .