Abstract:In this study, the fresh flower apparatus, new branches, leaves and fruits of healthy ‘Kuerlexiangli’ pear trees were used as experimental materials, we obtained endophytic bacteria strains and culture colonies with the method of endophytic bacteria isolation in plant tissues. The bacteria with bacteriostatic effect on Erwinia amylovora, Pseudomonas syringae pv. syringae and Valsa mali var. pyri were screened by plate confrontation culture and rescreening of fermentation broth. We tested the control effect of antagonistic strains against pear fire blight by spraying ‘Kuerlexiangli’ pear inflorescences in vitro and potted birch pear seedlings, in order to explore the biocontrol resources of endophytic bacteria and lay a foundation for exploring the biological control ways of pear diseases. The results showed the following: (1) a total of 337 endophytic bacterial strains were isolated from branches, leaves, flowers and fruit tissues of ‘Kuerlexiangli’ pear, of which 14 strains had obvious bacteriostatic activity. 8, 9 and 4 strains of bacteria with bacteriostatic effect on E. amylovora, P. syringae pv. syringae and V. mali var. pyri were further screened. Among them, ZN5, SN19 and HN9 strains had antagonistic effect on P. syringae pv. syringae and V. mali var. pyri pathogen, while HN89 strain showed potent bacteriostatic effect on three kinds of pathogens. A total of 7 strains (SN37, HN89, HN98, HN143, HN126, TN68 and TN16) with bacteriostatic effect against E. amylovora and competitive strains TN50 were screened. (2) The pretreatment (spraying) of endophytic strain TN50 had a significant effect on preventing flower rot of ‘Kuerlexiangli’ pear, and its control effect (52.36%) was similar in agricultural streptomycin (60.67%); followed by HN89(39.66%). The pretreatment (spraying) of endophytic strains TN50, HN89 and SN37 could significantly reduce the branch withering rate and disease index of potted birch pear seedlings (P < 0.05). The average protective control effect of 7~15 d was 67.20%, 54.32% and 45.91%, respectively, and the therapeutic control effect was 63.88%, 52.10% and 36.17%, respectively. (3) Based on the morphological characteristics and 16S DNA sequence, TN50, HN89 and SN37 were identified as Klebsiella sp., Paenibacillus sp. and Pseudomonas sp., respectively.