Pathogen Identification and Biological Characteristics of Rose Leaf Blotch in Tianjin

Taking one disease on leaf of Rosa chinersis that found in Tianjin flower nursery as test material,the pathogen was identified through morphological characteristics,pathogenicity and rDNA-ITS sequence analysis,simple biological characteristics research of this pathogen was conducted also.The results showed that fungal colony that developed on PDA was 34.6-37.2mm in diameter,with concentric rings in white in four days.The conidia was fusiform and 4.83-9.11μm in diameter,formed by five cells with four transverses;the apical appendage of conidia was 2-3,5.93-36.23μm in length;the basal appendage of conidia was 1,2.85-16.05μm in length.The homology of rDNA-ITS sequence between this pathogen and Pestalotiopsis clavispora was 99%.Based on the morphological characteristics and rDNA-ITS sequence analysis,the pathogen was finally identified as P.clavispora.This was the first report that Pestalotiopsis clavisporacould cause leaf blotch disease of Rosa chinensis Jacq in China.Biological characteristics studies demonstrated that the optimum temperature for growth was 25℃,no significant difference existed in the range of 20-30℃;the suitable pH value was around 5.0;the suitable carbon source was lactose.