Study On Physiological And Biochemical Characteristics Of Xanthomonas Axonopodis Pv. Citri And Screening Pesticide For Protection In Hunan Province

Citrus bacterial canker disease is one of important quarantine disease in citrus industry of the world,Serious damages on the world's citrus production.The pathogen Xanthomonas axonopodis pv.citri is the chief pathogen infects Citrus,poncitrus,etc.It can cause leaf and fruit drop,As well as heavy losses of the citrus production and fruit quality.1.Isolated strains from Citrus bacterial canker disease samples originated from difference cultivars and different area in Hunan province.After inoculated C.sinensis. red-orange and Bingtang sweet orange in vitro with all isolates,Some of them could cause typical symptoms of citrus canker and were identified to be Xanthomonas axonopodis pv.citri.2.The utilization ability of 10â…©.axonopodis pv.citri strains to carbohy-drates, such as Acetate,D-fructose,Rhamnose,Surcrose,α-Galactose etc.were different according to 17 physiological characteristics test.The biochemical characteristics of 10â…©.axonopodis pv.citri strains to Reduction of nitrate,Cytochrome oxldase,Catalase, Prod uction of H₂S,Hydrolysis of starch were identification.The cluster analysis according to these physiological and biochemical characteristics indicated that there were some differentiations among strains of Xanthomonas axonopodis pv.citri in Hunan Province.3.The results of inoculation with Xanthomonas axonopodis pv.citri in vitro showed that Citrus.qiensis,Citrus.Bingtanggensis,Citrus.rfiuherensis were high susceptible,Ccit rus. limon,Citrus.aurantiumvat.amara,Citru.sinensi,were middle susceptible,Citrus.paaraa Disi were middle resistant.It indicated that inoculation with Xanthomonas axonopodis pv.citri in vitro was a potential method to value the resistant or susceptible varieties am ong citrus.4.In laboratory test 10%Zhibaosu,70%Copper-Hydroxide,20%Thiodiazole-Copper, 77%Droxide,The result indicate that each have certain inhibitory onâ…¹. axonopodis pv.Citri.The virulence of 20%Thiodiazole-Copper and 77%Droxide is higher(EC₅₀=190.54mg/L and 204.17mg/L respectively).Than 10%Zhibaosu and 70% Copper was(EC₅₀=331.97 mg/L and 504.54 mg/L respectively).20%Thiodiazole -Copper was the best inhibition to Xanthomonas anoxopodis pv.citris mycelium growth with an EC₅₀ of 190.54 mg/L.