| Abstract: | Objective] The objective of this experiment is to identify pathogens causing cotton leaf spot in Xinjiang. Method] Two hundred and six leaf samples displaying typical leaf spot symptoms were collected from 30 loci in 7 different regions of Xinjiang in 2016 and 2017. The fungal isolates were purified using conventional methods. Ten representative fungal strains were selected for further tests based on different sampling times, locations, and colony characteristics. The strains were identified based on their morphological characteristics and the sequence analysis of both rDNA internal transcribed spacer and histone 3 gene. Result] In north of Xinjiang, Alternaria alternata and A. tenuissima were the dominant pathogens at the seedling stage (from May to June), whereas in August and September, A. tenuissima was the main pathogen and few were A. alternata and A. macrospora. In south of Xinjiang, A. tenuissima was the main pathogen at the seedling stage, whereas in August and September, A. tenuissima and A. macrospora dominated. Further, Gossypium hirsutum and G. barbadense was mainly infected with A. tenuissima and A. macrospora, respectively. Conclusion] The main pathogens causing cotton leaf spot in Xinjiang are A. alternata, A. tenuissima and A. macrospora. |
