Pathogen Identification and Screening of Biocontrol Bacteria for Euonymus japonicus Anthracnose

ZHANG Zongxia; LÜ Juan; HAN Bo; FAN Susu; YAN Fanfeng

doi:10.15933/j.cnki.1004-3268.2026.05.010

Abstract：To clarify the pathogen species of anthracnose on Euonymus japonicus and screen green biocontrol resources in Ji'nan,Shandong Province,the tissue isolation method was used to isolate pathogens from diseased plants.The taxonomic status of the pathogens was identified via morphological observation,multi-gene sequence analysis,and pathogenicity test,and the biological characteristics were determined.Further,biocontrol bacteria with significant antagonistic effects against E.japonicus anthracnose were screened from the rhizosphere soil of healthy plants,and their antagonistic activity and control efficacy against the pathogens were evaluated via in vitro dual culture assay and leaf antibacterial test.The results showed that the pathogenic strain EJJN05,isolated from diseased plants,was identified as Colletotrichum siamense through morphological observation,pathogenicity test,and multi-gene sequence analysis.The optimal growth conditions for this strain were PDA medium,30℃and pH 7.A strain designated as EJSF04 with significant antagonistic effect against the pathogen was isolated from the rhizosphere soil of healthy E.japonicus plants.In dual culture assay,the inhibition rate reached 85.12％,and the in vitro leaf test showed that the fermentation broth of EJSF04 had a control efficacy of 78.32％for preventive treatment of anthracnose,which was significantly higher than that of curative treatment(63.18％).Combined with morphological observation and 16S rDNA and gyrB gene sequences analysis,strain EJSF04 was identified as Bacillus velezensis.This study provided a solid scientific basis for the effective implementation of green prevention and control measures against E.japonicus anthracnose.