Identification of the Pathogen of Tobacco Leaf Blight and Screening for Control Agents

In order to identify the pathogen of bacterial leaf blight in Liupanshui City, Guizhou Province and screen for control agents, in this study pathogenic bacteria were isolated by tissue separation. In combination with morphological identification, Koch's rule and molecular biology approaches, physiological and biochemical characteristics of the bacteria were preliminarily studied. The toxicity of 15 fungicides to the pathogen was determined by the bacteriostasis method. The results showed that the pathogen has 100% homologous with Pantoea agglomerans, a gram-negative bacterium, which can use carbon and nitrogen sources such as D- arabinose, propanol and peptone. The screening test of indoor control agents showed that 1.6% Thiamphenone EW, 3% Zhongshengmycin WP and 80% Ethylicin EC had good antibacterial effects on the bacteria. The EC₅₀ values were 0.004 mg/mL, 0.0135 mg/mL and 0.1176 mg/mL respectively. The tests showed that the bacterial leaf blight pathogen of tobacco was Pantoea agglomerans. 1.6% thiamethoxone EW can be used as an effective agent to control the disease.