Abstract: Fusarium solani is a pathogen that could cause collar canker and dieback of Camellia sinensis. To obtain strains with strong antagonistic activity against F. solani, a total of 56 endophytic strains were isolated and purified from healthy leaves of tea trees collected from a tea garden in Xinxian, Xinyang, Henan province by dilution plate method and were screened in dual cultures with F. solani. The strain was identified based on morphological characteristics, physiological, biochemical and molecular tests. Biocontrol and growth-promoting traits and antibacterial spectrum test were also detected. The effects on the mycelial growth of F. solani were evaluated by ferment product and volatile test by buckle culture. The results show that strain YB-1476 exhibited the strongest antagonistic activity against F. solani with growth inhibition rate of 63.31% and was identified as Bacillus velezensis. Strain YB-1476 could produce siderophore, indoleacetic acid, and be able to secrete β-1,3-glucanase, cellulase and solubilize phosphorus. Furthermore, strain YB-1476 displayed strong antagonistic activity against Bipolaris sorokinana, Fusarium graminearum PH-1, Fusarium moniliforme, Fusarium oxysporum f. sp. niveum and Alternaria solani and growth inhibition rates were 65.03%, 42.32%, 51.67%, 52.33% and 63.22%, respectively. In addition, ferment products show that the growth inhibition rates of the original fermentation broth, 10-fold, and 100-fold dilutions were 66.67%, 51.85%, 18.52%, respectively and the volatile test shows that growth inhibition rate against F. solani was 53.37%. The above results demonstrate that B. velezensis YB-1476 is a strain with great application potential to control collar canker and dieback of tea trees.

Key words: Fusarium solani, Camellia sinensis, collar canker and dieback, biocontrol