Epidemic dynamics of wheat stripe rust under climate change and lagging human-led disease management

Wheat stripe rust poses substantial challenges to food security in China, and elucidating its epidemic patterns provides a scientific basis for disease management. To investigate the factors underlying its widespread 2020 outbreak and the associated inoculum transmission dynamics, 645 Puccinia striiformis f. sp. tritici samples were collected from 15 provinces across China in this study. By integrating population genetic structure analyses with airflow trajectory simulations, we elucidate for the first time the inoculum transmission dynamics among central Shanxi, north-central Hebei, and south-central Inner Mongolia. Our findings demonstrate that inoculum originated in central Shanxi can traverse the Taihang Mountains to reach central Hebei, while both central Shanxi and northern Hebei serve as primary inoculum sources for south-central Inner Mongolia. Furthermore, inoculum from northwestern and southwestern China can disperse to the Huang-Huai-Hai wheat-growing region via distinct pathways, with northwestern inoculum being predominant. Analysis of meteorological data revealed that ample rainfall and optimal temperatures in the Pst oversummering and overwintering regions during the summer and winter of 2019 resulted in a significant accumulation of inoculum in the subsequent autumn and winter. This accumulation served as the main catalyst for the extensive wheat stripe rust epidemic in 2020. This study further clarifies the epidemic patterns of wheat stripe rust in China and is of great significance for disease forecasting and management.