Apple canker has decreased yields of the economically important apple (Malus domestica) crop in China in recent years. Pathogen identity is highly challenging and the disease is poorly understood. Specimens of 339 fungi were isolated from apple trees in the primary apple-producing region in the Tarim Basin during the current study. In total, nine species of Cytospora and five species of the family Botryosphaeriaceae were identified by morphological observation and multilocus phylogenetic analyses: internal transcribed spacer (ITS), actin, translation elongation factor (TEF), and β-tubulin (TUB) gene regions for Cytospora and ITS, TEF, and TUB for Botryosphaeriaceae. Cytospora pyri from the Cytospora genus was the dominant species causing apple canker in the Tarim Basin. C. melnikii, C. tritici, C. euonymina, Diplodia seriata, and Botryosphaeria dothidea have been described as the cause of apple canker in China. Apple (Red Fuji) branches were utilized to assess the pathogenicity of 24 representative fungal isolates from the 14 species, and branches from seven distinct woody plants (Korla pear, walnut, Chinese date, Xinjiang poplar, sand jujube, Populus euphratica, and willow) were utilized to analyze the host range. The main pathogenic fungal species of apple canker around the Tarim Basin were identified and biological characteristics explored. Pathogen diversity and regional source diversity were assessed with host range and pathogenicity. The aim was to provide a theoretical foundation for the prevention and treatment of apple canker.

Apple (Malus pumila Mill.) is an important fruit crop in Xinjiang, China. In September 2021, apple tree canker was observed in a 21-year-old commercial apple orchard cv. Fuji in Xinjiang (38°17'51....

Cotton Verticillium wilt is a disease that significantly impacts the cotton industry, severely affecting cotton quality and the economic well-being of farmers. Bacillus atrophaeus YL84 is a biocontrol bacterium with broad-spectrum antagonistic and growth-promoting characteristics, previously isolated by our laboratory. This study aimed to elucidate the antagonistic effects of sterilized fermentation filtrate from Bacillus atrophaeus YL84 on cotton Verticillium wilt pathogen Verticillium dahliae and its growth-promoting effects on cotton. The experiments were conducted in vitro and in vivo to assess these effects comprehensively. Using the dual culture method, it was found that Bacillus atrophaeus YL84 exhibited a high inhibition rate on mycelial growth of V. dahliae, with an inhibition rate of 84.11%. The undiluted YL84 sterilized fermentation filtrate and its 10% volume fraction dilution (fermentation filtrate diluted to 10%) exhibited inhibition rates of 80.25% and 72.16% for conidial germination and mycelial growth of V. dahliae, respectively. Scanning electron microscopy showed increased branching, swelling, and shortened internodes in the antagonized mycelia. Conductivity measurements revealed a significant enhancement caused by the YL84 filtrate, with conductivity increasing by 8.94 times compared to the control at a 250 μg/mL concentration. Similarly, protein leakage peaked at 9.47 times the control level at 250 μg/mL, demonstrating the filtrate’s potent impact on mycelial cell membrane permeability. The enzymatic activities of polygalacturonase (PG), cellulase (CL), and β-glucosidase (β-GC) were significantly reduced following treatment with YL84 sterilized fermentation filtrate, with reductions from control levels of 15.78, 10.11, and 5.01 U/mL to treatment levels of 11.81, 6.96, and 1.44 U/mL, respectively. Indoor pot experiments demonstrated that different concentrations of YL84 sterilized fermentation filtrate significantly suppressed the occurrence of cotton Verticillium wilt while promoting plant growth. Compared to the control group, application of 250 μg/mL YL84 sterilized fermentation filtrate resulted in a control efficacy of 66.69% for cotton Verticillium wilt, with increases in plant height, root length, fresh weight, and dry weight of 9.36–33.85%, 17.33–29.49%, 16.79–28.24%, and 25–58.33%, respectively. These findings underscore the potential of the YL84 filtrate as both a biocontrol agent and a promoter of cotton plant growth in agricultural settings. These results indicate that Bacillus atrophaeus YL84 sterilized fermentation filtrate possesses both disease-suppressing and growth-promoting activities, making it a promising candidate for development and use as a biocontrol agent and plant growth promoter.

Pear Valsa cankers were found in various Korla fragrant pear orchards in Alaer, Xinjiang. Disease samples underwent tissue isolation, resulting in six isolates. Pathogenicity tests revealed that the XLFL-6 isolate was the most virulent, demonstrating typical Valsa canker symptoms. Research on its biological characteristics indicated that the optimal growth conditions for XLFL-6 were a temperature of 28 °C and a pH of five. Under these conditions, the colonies of XLFL-6 exhibited the largest growth diameter, and adding glucose and peptone separately to the Czapek medium was most conducive to the growth of its mycelium. Based on morphological observations and multigene sequence analyses (ITS+TEF+TUB), the pathogenic fungus was identified as C. pyri. The infection process of C. pyri was elucidated through tissue observations using both light and electron microscopy. The conidia displayed a similar germination pattern on both wounded and intact twigs. However, the infection process was delayed in the case of intact bark. By 8 h post-inoculation, the conidia achieved a germination rate of 15%. Although germination had occurred, the infection process had not yet commenced. In contrast, for wounded bark tissue, it was observed that 24 h post-inoculation, the fungal hyphae from the conidia directly invaded the wounded tissue. These hyphae penetrate the cell walls, proliferate within the host tissue, and spread throughout the phloem and xylem. After 20 d, numerous pycnidia had breached the bark surface, and yellow waxy gums filled with conidia flowed abundantly from the pycnidia ostioles, with the host tissue being nearly totally disintegrated. Regarding enzyme activity, the polygalacturonase (PG) activity, the primary cell wall-degrading enzyme in the treatment group, was seven times greater than that of the control group. The carboxymethyl cellulose (Cx) activity within the treatment group continued to increase. Xylanase activity rose swiftly to its peak between days 1 and 4, then decreased from days 5 to 10, although it remained higher than that of the control group. Overall, this study is the first to provide a detailed report on the characteristics and proliferation of C. pyri and further elucidates its modes and pathways of invasion.

Korla pear (Pyrus sinkiangensis Yü) is an important commercial fruit tree that originated in China (Zhou et al. 2020). In April 2020, a survey was conducted in Aksu region, Xinjiang (40°55'37"N, 80...

Walnut (Juglans regia L.) has become an important economic fruit tree in China. In April 2022, branch dieback was observed in 15-year-old walnut trees (cv Wen 185) in a commercial orchard in Aksu, ...