Predicting Overwintering of Wheat Stripe Rust in Central and Northwestern China

Stripe rust, caused by Puccinia striiformis Westend. f. sp. tritici Erikss. (Pst), is an important disease of wheat. In China, Pst management has focused on the Gansu region where the pathogen can complete its annual cycle, including oversummering and overwintering. From this region, Pst inoculum is dispersed to the southern Yangtze River region in the late autumn/early winter and then to the main wheat production regions in the following spring. We used historical weather data (1995 to 2016) and field stripe rust assessment data (8 years) in the spring to evaluate the performance of a published model for predicting the potential of Pst overwintering in the Gansu region. Both predicted and observed values of rust overwintering in the Gansu region varied greatly between years and between sites within a single year, indicating the value of predicting rust overwintering for disease management. The model predictions fitted with observed values satisfactorily. All high incidences of rust in the spring were observed in the fields of the monitoring sites where the high potential of overwintering was predicted. Conversely, the predicted rust overwintering potential was also close to zero in the fields where rust was not observed in the spring. There were many false-positive predictions, which may be attributable to the absence of rust in autumn seedlings. This model can be used to target rust management in the spring and its effectiveness will be further improved if autumn rust assessment can be carried out.