Etiological agents of Fusarium crown rot in Illinois wheat.

Abstract

The world is experiencing major changes in both climate and agronomic practices, which are intensifying the need to monitor plant diseases as they expand into new growing regions. Fusarium crown or foot rot is one disease of wheat and other cereals that has previously been the subject of economic concern and research primarily in arid to semi-arid regions of the world. Many of the etiological agents involved in Fusarium crown rot (FCR) are cross-pathogenic in head tissues, causing the disease Fusarium head blight and increasing the risk for mycotoxin contamination of foods. During a survey of Fusarium head blight in the midwestern US state of Illinois in 2022, four soft red winter wheat fields displayed a high incidence of severe crown rot symptoms. The etiological agents of the observed symptoms were identified by translation elongation factor 1α sequencing, which revealed Fusarium graminearum, F. parabolicum, and F. acuminatum as the primary agents of FCR in Illinois wheat. The dominant Fusarium species varied across fields, with recovered isolates spanning five Fusarium species complexes, and a high diversity of likely secondary colonizers was also noted across fields. Lastly, no mycotoxins were detected in the screened wheat heads. Our results highlight the impact of local conditions in driving FCR and pathogen dynamics, even with relatively limited distances between fields. The identification of FCR agents in Illinois will serve as a resource for crop managers and breeders targeting effective control strategies in a changing agroecosystem.