Isolation and Identification of Stem Blight Pathogen on Amomum villosum

To ascertain the taxonomic status of the pathogen of stem blight on A.villosum,the pathogen was isolated and its pathogenicity,morphology and rDNA-ITS sequence were analyzed in this study.The results showed that stem blight mainly damaged the stem.Water soaked lesions initially appeared at the stem,and then extended to spindle or irregular,with brown and clear edge.Lesions with conidia on the surface late got brittle,grey-brown to pale and caused stem broken and plant wilt.Conidia mission looked like cream and produced sclerotium when cultivated for 6~7days.Acervulus was rounded with the diameter of 60~150μm.The conidia with brown base and septate were arranged like barrier.It is a single cell,fusiform,and measured 10~18μm× 4.5~5μm.In molecular identification,the rDNAITS sequence of the pathogen showed 99% homology with several sequences of Colletotrichum crassipes.According to the morphological and molecular characteristics,the pathogen was identified as C.crassipes.