| Curcuma wenyujin Y.H.Chen et C.Ling,Curcuma L.,Zingiberaceae,is a herbaceous plant which has a long history of medicinal use in China.It originated in Ruian,Zhejiang Province.In 1997,Hainan Province started to introduce and cultivate C.wenyujin.However,the output and quality of C.wenyujin had decreased due to southern blight and anthracnose in recent years.Currently,the research of C.wenyujin mainly focused on chemical components and pharmacological effects at home and abroad but rare about diseases.This article first carried out preliminary studies on the two diseases above,including pathogen identification,biological characteristics and fungicides screening in laboratory,the main results are as follows:C.wenyujin southern blight mainly damaged lower stem and leaf sheath,symptomatic plants initially had dark brown,water-soaked,irregular lesions on lower stem at the ground level,then the lesions gradually expanded upward before covered with a mass of white silk-like mycelium and tan sclerotia,finally followed by a complete collapse of the plant.Isolation and purification of pathogenic fungi,pathogenicity test,morphological characteristics and ITS gene phylogenetic analysis identified the pathogen of C.wenyujin southern blight as Sclerotium rolfsii Sacc.The results of biological characteristics test showed the optimum temperature range of mycelia growth and sclerotia formation was 30?32?,the lethal temperature of mycelia and sclerotia were 51 ? and 53 ?,the optimum pH range of mycelia growth was 5.0?6.0,the optimum pH of sclerotia formation was 7.0,the best carbon source and nitrogen source of mycelia growth and sclerotia formation were sucrose and sodium nitrate,respectively.Oat medium and corn medium were more suitable for pathogen growth,dark condition was conducive to mycelia growth,while 12 h light and dark alternate condition was conducive to sclerotia formation.10 kinds of fungicides toxicity to pathogen was determined by toxic medium method in the laboratory.The results showed that diniconazole,pyraclostrobin,difenoconazole and flusilazole which belonging to triazole fungicides had stronger antibacterial effects,with EC50 were all less than 1 ?g/mL.C.wenyujin anthracnose mainly damaged leaves,while occasionally damaged leaf sheathes.Initially diseased leaves appeared light yellow,water-soaked,oval lesions that further expanded soon afterwards.The center of spot was offwhite to grayish brown and the edge was dark brown surronded by a obvious yellow halo.There were many black dots on the obverse side of lesions,seriously making leaves curliness and withering.Through the pathogen isolation and purification,pathogenicity test,morphological characteristics and multi-gene(ITS?ACT?TUB2?CHS-1?GAPDH and HIS3)phylogeny analyses,the pathogen was finally identified as Colletotrichum curcumae(Syd.)E.J.Butler&Bisby.The results of biological characteristics test showed the culture conditions requirements of mycelia growth and spores generation were basically the same.The optimum temperature was 27 ?,the optimum pH was 6.0,the best medium was PDA,the best carbon source and nitrogen source were maltose and potassium nitrate,respectively.Dark conditions was conducive to macelia growth,while 12 h light and dark alternate condition was favorable for spores generation.10 kinds of fungicides toxicity to pathogen was determined by toxic medium method in the laboratory.The results showed that diniconazole,flusilazole,propiconazole and difenoconazole which belonging to triazole fungicides had stronger antibacterial effects as well as prochloraz which belonging to imidazole fungicides,with ECso were all less than 1 ?g/mL.The research results above not only provide a theoretical basis for field control of C.wenyujin disease,but also has great significance to the sustainable development of C.wenyujin industry in Hainan Province. |
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