To screen antagonistic bacteria strains against
Valsa pyri from agricultural plant Jiaosu and evaluate their biocontrol potential on pear canker, bacteria strains isolated from agricultural plant Jiaosu were screened by confrontation culture and oxford cup method. The inhibitory activities of bacteria strains against the conidia germination and mycelia growth of
V. pyri and their biocontrol effects on pear canker were evaluated. The results showed that 15 strains of 68 bacterial strains isolated from agricultural plant Jiaosu had antagonistic effects on V. pyri growth with the inhibitive rate from 41.25% to 74.14%, which accounted for 22.1% of isolated strains. Four strains (gjfn2, gjfn4, PFN41 and PGY-FX67) were obtained after the second run screening, and the inhibition rates of their fermentation and filtered fermentation both were over 70% and 60%, respectively, which were significantly higher than those of the other strains. Based on morphological, physiological and biochemical characteristics, 16S rRNA and gyrA gene sequence analysis, gjfn2, gjfn4 and PGY-FX67 were identified as
Bacillus velezensis and PFN41 was as
Bacillus amyloliquefaciens. The fermentation and filtered fermentation broth of the four antagonistic bacteria strains had obviously inhibitive effects on
V. pyri conidia germination. And the inhibitive rate of the fermentation and filtered fermentation broth of gjfn4 and PFN41 strains reached 100% after 36 h incubation, and it also could cause the morphological abnormality, bent and terminal enlargement of the
V. pyri mycelia. In detached twigs assay, the control effects of fermentation broths of the four strains were over 79% and filtered fermentation broths were over 73%. Among them, gjfn4 had the best control effect on pear canker, which the control effects of fermentation broth, filtered fermentation broth and 50 dilution of filtered fermentation broth were 84.79%, 81.57% and 67.27% respectively. The results indicated that the antagonistic bacteria strains screened from agricultural plant Jiaosu exhibited significant biocontrol potential to control pear canker, which provided a novel biological agent for control the disease.