6 Pathogens Identification Of Atractylodes Macrocephala?Dendrobium Officinale And Chrysanthemum Morifolium And Prevention Research

Chinese herbal is one of the ten major agricultural industries in Zhejiang Province.Basically,the traditional medicinal herbs advantageous areas such as Atractylodes,Chrysanthemum,and other valuable Chinese herbal medicine areas including Dendrobium officinale have been formed,which are important economic sources for farmers to increase their incomes.However,the basic research of the diseases were weak,the registration of pesticide products were less in the production and the quality and safety system became lags behind,resulting in pesticide residue and food safety issues becoming one of the key factors restricting the development of the industry.Therefore,to clarify the occurrence of diseases,hazards and laws,have become particularly important in the production of Chinese herbal medicines.In this study,the disease samples were collected from the main producing areas of A.macrocephala,C.morifolium and D.officinale in Zhejiang Province.The pathogenic fungus were isolated,identified and pathogenicity testing.Pathogenic fungus were identified through comprehensive morphological and molecular phylogenetic analysis,and then this stduy initially explored the prevention and treatment of these diseases.It was confirmed that Atractylodes sheath blight was caused by Rhizoctonia solani,it has the highest sensitivity to thifluzamide and fludioxonil with EC₅₀ of 0.06?g·mL^-1;Sclerotium rolfsii was caused by souther blight,its sensitivity to pyraclostrobin was the highest with EC₅₀ value of 0.02?g·mL^-1;Atractylodes spot blight disease was caused by Phoma exigua var.linicola and its spore had the highest sensitivity to pyraclostrobin with EC₅₀ of 0.10?g·mL^-1.In this study,the biological characteristics of the spot blight showed that the optimum conditions for mycelia growth of this pathogen:temperature,25?;pH value,8;carbon sources,starch and nitrogen sources,peptone.The optimum conditions for the germination of conidia of P.exigua were temperature,24?and RH,100%.The lethal temperature of mycelia and conidia was 47?and 54?.In vitro,the more active fungicides were screened,the results showed that the control effect of leaf spot reached 100%in vitro when pyraclostrobin concentration was 8.5?g·mL^-1.Dendrobium candidum black spot was caused by Alternaria tenuissima,which had the highest sensitivity to fludioxonil with EC₅₀ of 0.10?g·mL^-1.Anthrax was caused by Colletotrichum fructicola,which had the highest sensitivity to prochloraz with EC50 of0.02?g·mL^-1.The results of fungicide screening showed that the control effect could achieve 49.28%,when difenoconazole was 2.8?g·mL^-1 in vitro;thecontrol effect of difenoconazole 4.8?g·mL^-1 to anthracnose reached 42.0%in vitro.The pathogen of Chrysanthemum morifolium leaf blight was Colletotrichum truncatum.The resistance of 34 strains of C.truncatum to carbendazim was tested by the distinguishing dosage method.The?-tublin gene of C.truncatum was analyzed and compared.The results showed that the resistance rate of laef blight to carbendazim was as high as 93.94%,and the molecular mechanism was mutation at the position 198 of?-tublin gene?E198A?.Based on the fungicides screening and control effection in vitro,the mycelial growth rate was used to determine the sensitivity of the leaf blight to pyraclostrobin.The results showed that:among them,the EC₅₀ value of 33 isolates was continuously distributed in the range of 0.060-0.370?g·mL^-1 with the average EC₅₀ of0.177?g mL^-1,which was sensitive baseline of oxazolium ester.