Isolation,identification and biological characteristics of the pathogen causing black rot disease in 'Zanhuangdazao' jujube of Shanxi province

【Objective】To clarify the pathogen causing‘Zanhuangdazao'jujube black rot disease andtheir biological characteristics.【Methods】Samples with typical symptoms of the black rot were collectedfrom Shilou County,Shanxi Province from 2011 to 2013. Pathogen was isolated from diseased fruit seg-ments and pathogenicity was tested following Koch's postulate. Identification of the pathogens was madeby morphological study and r DNA molecular identification. Biological characteristics of the pathogen weredetermined by measuring the diameter of the colony and counting the number of conidia using Hemocy-tometer Measurement.【Results】The black rot disease was mainly caused by Alternaria tenuissima. Theoptimum growth conditions for A. tenuissima were as follows: temperature,28 ℃;p H value,8;carbonsource,glucose;nitrogen source,sodium nitrate;medium,PDA. Light had no obvious effect on myceli-al growth. The optimum conditions for the germination of conidia of A. tenuissima were: temperature,28 ℃;p H value,10;without carbon source;nitrogen source,sodium nitrate. The alternation of lightand darkness was helpful to conidium germination.【Conclusion】A. tenuissima is pathogen causing‘Zan-huangdazao'jujube black rot disease in Shanxi Province and the determination of its primary biologicalproperty lays a foundation for further studies in pathogen infection and disease control.