Purpose Summer strawberry plays a key role in the global food market, but its production is seriously threatened by anthracnose. This study aimed to clarify the pathogen species of strawberry anthracnose and screen effective antagonistic bacteria.
Methods The diseased fruits of strawberry anthracnose were collected from Daibu Town, Huize County, Yunnan Province. The pathogenic fungi were isolated, purified, and identified by tissue isolation method, and their biological characteristics were studied. In addition, endophytic bacteria from strawberry roots, stems, leaves, and fruits were isolated by plate confrontation method.
Results The isolated pathogens were members of the Colletotrichum acutatum species complex, specifically C. nymphaeae. The optimum pH of the strain was 6, and it grew best on 2% strawberry decoction. The carbon source more favorable for its growth was starch, and the nitrogen source was peptone, indicating that C. nymphaeae was more likely to use organic nitrogen. Different light conditions had no significant effect on its growth. Among the 26 bacterial strains isolated from strawberry, nine showed significant antagonistic activity against the target pathogens. Among them, strain Y3, which was molecularly identified as Bacillus siamensis, exhibited the strongest antagonistic effect.
Conclusion This study isolated the summer strawberry anthracnose pathogen C. nymphaeae, characterized its biological properties, and screened an endophytic bacterium (B. siamensis) with significant antagonistic activity against this pathogen. The findings provide important microbial resources for the biological control of summer strawberry anthracnose in Yunnan.
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