[Objective] We isolated and identified walnut blight pathogen from diseased walnut growing in Jiange county,Guangyuan city,Sichuan province,to control the disease.[Methods] A total of 30 infested branch samples at different developing stages were randomly collected.Pathogen isolation and purification were conducted from walnut twigs tissue by normal tissue isolation method.To fulfill Koch's postulates,pathogenicity test was done with the isolates.In addition,the pathogen was identified based on morphological characteristics and molecular biotechnology,and biological characteristics were determined using colony growth methods.[Results] In total 180 isolates were obtained.The pathogenicity test showed that the pathogens of walnut twig blight were mainly caused by Phompsis capsici.On PDA plate,the mycelium of the pathogen was white.The spore-bearing structures could generate oval and linear conidiums.PDA medium was the most appropriate for mycelium growth.The mycelium could effectively use a variety of carbon and nitrogen sources.Among the 9 carbon and nitrogen sources tested,the appropriate carbon sources were sucrose and fructose and the optimum nitrogen sources were molybdenum acid and phenylalanine.The best mycelium growth was obtained at 25 ℃ and pH between 6.0 and 7.0.The mycelium grew fastest under dark conditions.[Conclusion] Phompsis capsici can easily invade from wounds to cause disease.%[目的]鉴定四川省广元市剑阁县核桃枯枝病的病原,为该病害的防治奠定基础.[方法]随机采集不同发病阶段的枝干样品30份,采用常规组织分离法分离纯化核桃枯枝病病原菌,用柯赫氏法则对菌株进行致病性验证,结合形态学特征和分子生物学方法对病原菌进行鉴定,采用菌落生长法进行生物学特性研究.[结果]共分离得到180个菌株.致病性测定结果表明核桃枯枝病的病原菌为拟茎点霉Phompsis capsici,这是首次关于Phompsis capsici导致核桃枯枝病在我国发生和研究的报道.在PDA平板上该病原菌菌丝为白色,能产生椭圆形和线形两种分生孢子.病菌菌丝生长以PDA培养基为最适.菌丝能有效利用多种碳、氮源,在供试的9种碳、氮源中,适宜生长的碳源为蔗糖和果糖,氮源为钼氨酸和苯丙氨酸.最适生长温度为25℃,最适pH为6.0-7.0.黑暗条件下菌丝生长最快. [结论]Phompsis capsici最易从伤口侵入致病.
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