[Objective] The paper was to study the occurrence rule of Pistacia vera leaf brown spot and the biological characteristics of its pathogen.[Method] The occurrence rule of P.vera leaf brown spot was investigated in field.A fungus was isolated and purified from the diseased tissue of P.vera,its cultural trait and morphological characteristics were observed in indoor experiment,and the classification status was identified according to its morphology.The effects of different temperatures on mycelial growth of the pathogen,as well as the effects of different temperatures and humidity on spore germination of the pathogen were also studied.[Result] P.vera leaf brown spot was a fungal disease,which mainly infected the leaves and fruits of P.vera,causing leaf spot and blight.The disease had serious incidence in introduction place of P.vera in China.The fungal disease was identified to be Alternaria alternaria,the appropriate temperature for mycelial growth was 20-25 ℃,the appropriate temperature for spore germination was 25-30 ℃,and the appropriate relative humidity was over 95%.[Conclusion] Late spring and early summer,as well as late summer and early autumn are two peak periods for incidence of the disease,continuous rain in summer is the decisive condition for the infection and outbreak of P.vera leaf brown spot.
