Combine harvesters facilitate the spread of <i>Fusarium</i> crown rot across wheat-growing regions in Xiangyang

Wheat crown rot is a destructive soil-borne disease affecting major wheat-growing regions worldwide. Mechanical transmission represents an important pathway for the spread of wheat diseases and combine harvesters, essential for large-scale farming operations, potentially facilitate long-distance pathogen dispersal through infected residue. However, the precise role of combine harvesters in the epidemiology of wheat crown rot remains unclear. The study revealed that the residue in the grain tank was significantly higher than that in other components, accounting for 44%-69% of the total residue. Pathogen isolation, identification, and PCR-based rapid detection confirmed the consistent presence of Fusarium pseudograminearum and F. graminearum in harvester residues following cross-regional operations from infected fields. Additionally, field trials demonstrated that after operating in disease-free fields, combine harvesters carrying pathogens led to disease incidence of 12% and 17% over two consecutive years. The application of physical and chemical treatments to harvesters prior to cross-regional operations significantly reduced field disease incidence. This study provides the first systematic evidence that combine harvesters serve as efficient vectors for long-distance dissemination of wheat crown rot pathogens, establishing a critical foundation for developing targeted biosecurity measures in wheat production systems.