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Abstract Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a common airborne wheat disease. The frequent occurrence at a large scale in China has caused significant yield losses and poses a considerable threat to food security. To effectively manage and forecast the disease, a comprehensive understanding of the long-distance migration patterns of Pst is essential. Shaanxi province, situated in close proximity to the northwestern epidemic areas in China, plays a crucial role as a key overwintering region for Pst. However, it remains uncertain whether Pst, after winter reproduction in Shaanxi province, can extend its spread to the primary wheat regions in the North China Plain. In this study, during February and June 2022, a total of 302 Pst samples were collected from Shaanxi province and the North China Plain. Thirteen pairs of simple sequence repeat (SSR) markers were adopted to analyze the population genetic structure. It was observed that both genetic and genotypic diversities exhibited a discernible decline from the Shaanxi to the North China Plain. Moreover, Shaanxi displayed a close genetic relationship with Henan and Shandong, whereas Henan exhibited the most substantial population exchange with Shaanxi. Further analysis revealed that Shaanxi served as the primary inoculum of Pst in the investigated region, and the spread of Pst to Henan and Shandong originated from Shaanxi. As a result, the epidemics in Shandong further led to the prevailing of the disease in Hebei. Our study enhances the understanding of the epidemiological patterns of wheat stripe rust in the springtime prevalent regions of China, and it provides insights for future disease management.

Abstract Grapevine downy mildew (GDM) caused by Plasmopara viticola is a recurrent disease of wine grapes in the Ningxia Hui Autonomous Region (Ningxia) of northwestern China. However, the primary infectious pathogen in this region has not been thoroughly investigated. In this study, a multiplex real-time PCR assay was utilized to quantify P. viticola in soil, leaf residues, and asymptomatic leaf samples from ten commercial vineyards in two consecutive years to better understand the epidemiological significance of overwintering primary inoculum and its inoculum potential before the appearance of the first visual GDM symptoms. The DNA primers and multiplex real-time PCR assays that had been established exhibited specificity towards P. viticola within the test samples. The majority of the asymptomatic leaves (60%), leaf residues (80%), and soil samples (100%) tested positive for P. viticola. In addition, the amount of primary inoculum of P. viticola was found to be lower in soil than in leaf residues. The area under the disease progress curve in terms of the molecular disease index (AUDPC-MDI) was used to evaluate the overall latent P. viticola infection in asymptomatic leaves. Asymptomatic leaves were found to have different levels of P. viticola infection, and high AUDPC-MDIs correlated with a high AUDPC in terms of disease index (AUDPC-DI), with a significant correlation relationship between them (P

Abstract Southern corn rust (SCR) caused by Puccinia polysor a Underw is one of the most devastating maize diseases, resulting in substantial yield losses worldwide. The pathogen is an obligate biotrophic parasite that is difficult to culture on artificial media. In recent years, the disease has become prevalent—both globally and in China—and increasing difficult to control because of its wide distribution, long-distance migration, multiple physiological races and fast evolution, all of which have contributed to a considerable increase in the risks of associated epidemics. In this review, we summarize the current knowledge of P. polysora, with emphasis on its global distribution (particularly in China), life and disease cycle, population genetics, migration, physiological races, resistance genes in maize and management. Understanding the underlying factors and processes in SCR epidemics should facilitate management of the disease and breeding for resistant maize varieties.