Antagonistic Bacteria Screening Of Xanthomonas Citri Subsp.Citri And Chemical Control Experiment Of Citrus Canker Disease

Citrus canker disease is a bacterial quarantine disease caused by Xanthomonas citri subsp.citri(Xcc),which is one of the main citrus diseases.At present,citrus canker disease has occurred in some citrus growing areas in Guangxi.Biological control is the research direction of plant disease control,and the chemical application to control plant diseases is also indispensable in the field.Therefore,antagonistic bacteria screening and chemical control experiments were carried out in this research,in order to provide theoretical basis for the effective control of citrus canker.In this study,it was found that four antagonistic bacteria strains J1、KC、T1 and T2 had good inhibitory effect to Xcc through plate confrontation test,the strain J1 and KC were Bacillus subtilis preserved in the laboratory,the antibacterial circle were 14.2mm,21.0mm,14.3mm and 16.2mm respectively.In vitro test,the disease control effect of four antagonistic bacteria strains to citrus canker disease were 88.89%,83.33%,66.67%and 61.11%respectively.T1 strain was identified as Bacillus amyloliquefaciens and T2 strain was Bacillus pumilus by the results of analyzing the sequences of 16Sr RNA,gyrA,gyrB,purH genes and testing the physiological and biochemical characteristics.Both strain T1 and strain T2 could use glucose,arabinose,xylose,mannitol,mannose,lactose,sorbita,raffinose,maltose,melibiose,and rhamnose as carbon sources.The results of toxicity test showed that 10%IDHA-Cu SG had no toxic effect to Xcc.the EC50 value of 27.12%Copper sulfate SC,37.5%Cupic Hydroxide SC,30%Cuaminosulfate AS and 0.3%Tetramycin AS to Xcc are 572.33μg/mL,819.16μg/mL,1442.55μg/mL,0.47μg/mL,respectively.According to the analysis of EC50value,the strongest toxic effect to Xcc was 0.3%Tetramycin AS.In vitro test,the disease control effect of 10%IDHA-Cu SG,27.12%Copper sulfate SC,37.5%Cupic Hydroxide SC,30%Cuaminosulfate AS and 0.3%Tetramycin AS to citrus canker disease were 100%,94.44%,72.22%,88.89%and 88.89%respectively.In the field experiment,the disease control effect of five fungicides to citrus canker disease were between 20%and 40%.