Isolation,identification and fungicide screening of Cycas leaf blight pathogen
[Objective]The purpose of the study was to identify the cause of leaf blight in Cycas in the Qingxiu Mountain Cycas Garden of Nanning Botanical Garden,explore methods for prevention and control,and provide a theoretical basis for the effective protection of Cycas germplasm resources.[Method]113 samples of blight leaves were collected from different diseased Cycas plants.The pathogenic fungi were isolated and purified using the dilution plating and single spore isolation method.Pathogenicity of the isolated strains was determined using Koch's postulates.Species identification of the isolates was carried out based on morphological and molecular biology methods.Seven fungi-cides,Mancozeb,Picoxystrobin,Propiconazole,Azoxystrobin,Fluopicolide Trifloxystrobin,Chlorfenapyr Pyriproxyfen,Chlorothalonil,were selected for in vitro efficacy tests against the pathogenic fungus.[Result]In the study,a total of 72 isolates were obtained through the isolation and purification of microorganisms from blight tissues,belonging to 13 different genera:Colletotrichum,Fusarium,Alternaria,Pestalotiopsis,Phyllosticta,Nigrospora,Cladosporium,Chaetomium,Hypoxylon,Xylaria,Botryosphaeria,Aspergilus,Neofusicoccum.Pathogenicity testing revealed that the Fusarium isolate GX2210 could induce lesions when inoculated into Cycas fronds.Further sequence a-nalysis of the CaM,bTUB,RPB2 and TEF1a genes was performed and confirmed the identity of this strain as Fusarium incarnatun.Effica-cy tests showed that Mancozeb was the most effective fungicide,with an inhibition concentration(ID50)of 0.3577 mg/L against the patho-gen.[Conclusion]F.incarnatum is the pathogen causing the leaf blight of Cycas in Nanning Botanical Garden.Mancozeb has a good inhibi-tory effect on F.incarnatum,and can be considered for the prevention and control of cycad leaf blight.
CycasLeaf blightPathogen isolationStrain identificationFungicide sensitivity test
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