Archivio Journal of Plant Pathology

Abstract:

During April 2012, in Alar area of Xinjiang, diseased ‘Jun jujube’ was affected by stem rot with about 10% incidence. The diseased bark turned red and orange cirrus of conidia arised. Infected trees eventually withered and died. Seven fungi were isolated from symptomatic stems and transferred to potato dextrose agar at 25°C in the dark. The colonies of seven isolates were originally white, then turned yellow brown and formed dark globose pycnidia after 14 days. Conidia were allantoid, aseptate, hyaline, with the size of 5.15-8.69 × 0.76-1.23 μm. Pycnidia formed in culture measured 485 to 1225 μm in diameter. The internal transcribed spacer (ITS) region of ribosomal DNA was amplified from genomic DNA with primers ITS1 and ITS4. ITS sequences of the seven isolates had 100% homology and one of the sequences was submitted to GenBank (Accession No. KP261087). BLAST analysis of the fungal sequence showed 100% nucleotide similarity with Cytospora sp. 26 HQ21 isolate (KC342501). So, based on morphological and molecular characteristics, these seven isolates were identified as Cytospora sp. Symptoms of the disease were reproduced on the healthy stems of Cytospora sp. artificially inoculated following the method described by TalgØ and Stensvand (2013). Controls remained symptomless and Cytospora sp. was constantly reisolated from inoculated stems. Members of Cytospora are associated with cankers and dieback on a wide range of trees and shrubs (Spielman, 1985). To our knowledge, this is the first report of Cytospora sp. causing stem rot on ‘Jun jujube’ in Xinjiang.