Control effect of tobacco bacterial wilt by Beauveria bassiana and Cordyceps javanica

Abstract:

[Background] Tobacco bacterial wilt is a soil-borne disease caused by Ralstonia solanacearum, causing huge losses to tobacco production. [Objective] To investigate the inhibitory effect and control efficiency of two biocontrol strains of Beauveria bassiana HZXJ and Cordyceps javanica Bd01 on R.solanacearum. [Methods] The inhibitory effects of the two biocontrol strains and their fermentation broths on the growth of R.solanacearum were measured by plate confrontation test, agar diffusion method, and growth curve method. The effect of strain HZXJ and Bd01 1×10⁸ conidia/mL suspension on tobacco bacterial wilt was determined by indoor pot experiment and field experiment. [Results] The plate confrontation test showed that the inhibition rates of strain HZXJ and strain Bd01 on the fermentation broth at 10 days were 51.28% and 47.59%, respectively. The inhibition rates of the pasteurized fermentation broths of B.bassiana HZXJ and C.javanica Bd01 on R.solanacearum cultured at 10 days were 62.54% and 35.49%, respectively. The growth curves drawn by biocontrol bacteria and R.solanacearum OD₆₀₀ also showed that the aseptic fermentation supernatants of HZXJ and Bd01 both had inhibitory effects on R. solanacearum. The results the control efficiency of strain HZXJ and strain Bd01 on tobacco bacterial wilt after treatment with 1×10⁸ conidia/mL suspension for 15 days was 43.33% and 19.99%, respectively, and the control efficiency of 52% copper chloride sulfate soluble powder 800 times solution was 39.99%. The control effect of HZXJ and Bd01 on tobacco bacterial wilt at 30 days was 43.75% and 21.87% respectively, and the control effect of 52% copper chloride sulfate soluble powder 800 times solution was 46.90%. The results of field test showed that the control efficiency of strain HZXJ and Bd01 1×10⁸ conidia/mL suspension for 15 days was 80.00% and 35.00%, respectively, and the control efficiency of 52% copper chloride sulfate soluble powder 800 times solution was 40.00%. The control effect of strain HZXJ and Bd01 on tobacco bacterial wilt at 30 days was 52.63% and 63.16%, respectively, and the control effect of 52% copper chloride sulfate soluble powder 800 times solution was 53.98%. [Conclusion] B.bassiana HZXJ and C.javanica Bd01 showed significant inhibitory effects on R.solanacearum. Both strains had the potential of serving the biocontrol of tobacco bacterial wilt.