Preceding Crop Straw Return Methods Influence the Disease Severity of Wheat Crown Rot

Straw return has potential benefits for soil fertility, environmental sustainability, and yield. However, its effects on pathogen carryover and disease in subsequent crop cycles remain unclear. Wheat is a crucial food source. This study examined the effects of straw return methods—deep plowing (DP), rotary tillage (RT), and deep loosening (DL)—on wheat crown rot. Trials were conducted in fields with maize straw return, and the wheat crown rot incidence and severity were compared after maize straw return. The wheat root microbial communities were assessed using absolute and relative quantification sequencing techniques (AS and RS), and the relationship between changes in the bacterial community and the abundance of crown rot pathogen Fusarium pseudograminearum was explored. DP reduced the crown rot incidence (22.0) and severity (6.8) in subsequent wheat crops, showing values significantly lower than those under RT (64.0 incidence, 24.0 severity) and DL (49.0 incidence, 18.8 severity). Variations in wheat root fungal diversity and composition were observed among methods and soil depths within the DP regime. The abundance of F. pseudograminearum was significantly lower under DP than under RT and DL (RS: less than 0.1% in DP and more than 0.5% in RT and DL; AS: less than 10,000 reads in DP and more than 50,000 in RT and DL). The reduced pathogen abundance may be associated with shifts in bacterial genera due to straw return practices. This study shows the importance of selecting appropriate straw return methods to manage wheat crown rot.