Abstract:
In order to screen for highly effective microbial-chemical combinations for controlling tobacco target spot disease, the mycelial growth rate method combined with the leaf puncture method was employed to screen chemical agents with high efficacy against
Rhizoctonia solani DB-9. Antagonistic assays in Petri dishes and leaf puncture tests were used to screen active biocontrol bacteria from the rhizosphere soil of
Phragmites australis in Tarim Basin, Xinjiang. The antagonistic isolates were identified through morphological characterization and 16S rRNA gene sequencing. The compatibility of selected chemical agents and biocontrol strains was assessed by using the Oxford cup method, and the combinations were subsequently formulated. Finally, the leaf puncture method was used to evaluate the control efficacy of agent-chemical combinations against tobacco target spot disease. Results showed that pyraclostrobin, carbendazim, and tebuconazole effectively controlled tobacco target spot disease, with EC50 values below 0.5 mg/L against the mycelial growth of
R.
solani DB-9 and
in vivo control efficacy exceeding 60%. The inhibition rate of
Bacillus inaquosorum 127-2 on
R.
solani DB-9 was 87.5 %
in vitro and 53.51 %
in vivo, respectively, which could effectively reduce the expansion of the pathogen. Compatibility tests revealed that 127-2 was compatible with pyraclostrobin and carbendazim, and the control efficacy of pyraclostrobin and 127-2 at 1﹕1 against tobacco target spot disease reached up to 98%. Therefore, the combination of Strain 127-2 and pyraclostrobin can be applied for tobacco target spot disease control. This approach not only ensures effective disease control but also reduces the reliance on chemical agents, improving long-term efficacy and stability, indicating promising application potential.