Abstract: o screen actinomycetes strains against diverse Colletotrichum species that cause soybean anthracnose, the soil dilution spread plate method and the plate confrontation method were used to isolate and screen actinomycete strains with inhibitory effects on C. truncatum and C. gloeosporioides. The selected actinomycetes were classified and identified by phenotypic classification and molecular classification. Simultaneously, the antifungal spectrum of the candidate strains and their control efficacy in indoor potted plants were determined. The results indicated that 15 actinomycete strains with distinct inhibitory effects on soybean anthracnose pathogens were initially isolated. Among these, strain FJ-10 demonstrated the strongest inhibitory activity, with the in-vivo inhibition rates of 86.25% and 87.09% against C. truncatum and C. gloeosporioides, respectively, while those of its sterile fermentation broth were 82.93% and 77.89%, respectively. The apparent characteristics of the strain were similar to those of Streptomyces gancidicus. The similarities (homology) between the 16S rRNA and rpoB gene sequences of strain FJ-10 and those of S. gancidicus were 99.93% and 99.76%, respectively. On the phylogenetic tree, strain FJ-10 was grouped within the same branch as S. gancidicus. Consequently, FJ-10 was identified as S. gancidicus. In potted plant experiments, FJ-10 exhibited a 70.32% control efficacy against soybean anthracnose. FJ-10 possessed a broad antifungal spectrum, which had significant inhibitory effects on a wide range of plant pathogens. Given these findings, FJ-10 holds great promise for development and application in the field.

Key words: Streptomyces gancidicus, Colletotrichum truncatum, Colletotrichum gloeosporioides, biocontrol, control efficacy