European plum (Prunus domestica) orchards in the Kashi region, Xinjiang, China, suffer from fruit brown spot disease. The disease typically appears as red spots on the fruit surface that expand into brown necrotic lesions; affected fruit flesh can shrink, and fruits can harden and drop. We isolate and identify pathogens associated with this disease in this plum from five Kashi counties. Of 210 fungal isolates obtained through standard tissue isolation, Alternaria accounted for 84.8%, with the remainder comprising species of Aspergillus (9.5%), Diplodia (3.3%), and Neoscytalidium (2.4%). Using PCR amplification and sequencing of five loci, pathogens were identified using multi-gene phylogenetic analyses, combined with observations of colony and spore morphology. Multi-locus sequences of Alternaria isolates were highly homologous to those of the Alternaria alternata type strain, and we refer them to an A. alternata species complex. Pathogenicity tests confirm that Alternaria isolates reproduce brown spot symptoms on European plum fruits. By demonstrating that Alternaria is the primary pathogen causing brown spot disease in European plum in Xinjiang, we clarify both the fungal species composition and taxonomic placement of the dominant pathogen associated with this disease.

Little is known about the fungal pathogens responsible for fig (Ficus carica L.) branch canker in the Kashi region of Xinjiang, China. Using a combination of morphological characterization and multilocus sequence analyses of ITS, TEF1-α, and RPB2, we identified fungal isolates obtained from cankered fig branches collected in commercial orchards in this region. The pathogenicity of representative isolates was evaluated by artificial inoculation of fig branches under natural field conditions. Two dominant fungal species, Fusarium proliferatum and Alternaria alternata, were consistently isolated from diseased tissues. In inoculation assays, both species induced typical branch canker lesions similar to those observed in the field. Lesions caused by F. proliferatum were generally larger than those induced by A. alternata. The original pathogens were successfully re-isolated from the inoculated branches, thereby fulfilling Koch’s postulates. This study represents the first report of F. proliferatum and A. alternata as causal agents of fig branch canker in Xinjiang and expands the known spectrum of pathogens associated with fig branch diseases. These findings provide a scientific basis for improved disease monitoring and the development of sustainable management strategies in local fig orchards.

European plum (Prunus domestica L.) is widely cultivated worldwide, with China producing 6.8 million t annually (55% of the global total output). However, the Kashgar region of Xinjiang, China’s primary production area, has experienced outbreaks of brown spot disease caused by Alternaria alternata (Fr.) Keissl. Outbreaks of this disease severely hinder both domestic and global development of the European plum industry. Because this pathogen has a strong latent infection capability during the early stages of disease development, its early detection is important. We develop two detection methods targeting the ITS sequence of A. alternata: LAMP-Cresol Red chromogenic visible endpoint detection and LAMP-SYBR Green I real-time fluorescent detection. Both methods demonstrate high specificity for A. alternata, enabling stable detection of the pathogen in various plant samples; detection limits reach the femtogram (fg) level, significantly surpassing conventional PCR detection capabilities. Development of these highly efficient and precise early detection methods provides a solid foundation for sustainable development of China as a global hub of the European plum industry, and contributes significantly to global disease prevention, control, and industrial stability for this crop.