Abstract: Peach branch blight， a serious new fungal disease， burst out in Fengqiao town， Jiaxing city and Zhangqi town， Cixi city in Zhejiang in recent years. The symptom firstly appeared on the base of shoot twig with tan to black pit scab causing the leaves above withering sharply. The disease cause death of branch even the whole peach tree， and reduced seed setting rate about 20%-50% per year. To understand and control the disease， Kochs postulate was used and a species of fungus was found to be the pathogenic agent. The fungus yielded white to light olivesheen colony on potato saccharose agar （PSA） medium with short tiny cotton\|shaped hypha， and produced black spherical pycnidium with ostiole. There were two kinds of condium generated by pathogen，α\|type， fusiform， hyaline， unicellular， (5.2-8.7)μm×(1.3-2.7)μm；β\|type， linear， hyaline， unicellular， 1-3 oil globule，(11.5-26.2)μm×(0.9-2.1)μm. The ribosomal ITS 1\|58S\|ITS2 region was PCR amplified from genomic DNA from mycelium and obtained a sequence of 611 bp. A blast search from the GenBank revealed highest similarity （100%） to Phomopsis amygdali sequences in Europe. The pathogen was identified as Phomopsis amygdali Delacr. J.J. Tuset & M.T. Portilla （Fusicoccum amygdali Delacr.） associated with culture characters．

Key words: peach branch blight, identification of the pathogen, Phomopsis amygdali Delacr. J.J. Tuset &, M.T. Portilla