陇西县黄芪白粉病病原鉴定及其生物学特性测定

Pathogen identification and biological characteristics determination of Astragalus powdery mildew in Longxi County

【目的】为了明确陇西县黄芪白粉病的发生情况.【方法】采用五点取样法,对陇西县6个乡镇黄芪白粉病的发生进行调查,根据形态学和分子生物学特征鉴定病原,并对黄芪白粉菌分生孢子在不同温度、pH值、光照及碳源条件下的萌发率等生物学特性进行了研究.【结果】2018年陇西县黄芪平均发病率为31.17%,平均病情指数为18.08.经形态特征观测和rDNA-ITS序列对比,将陇西县黄芪白粉病病原菌鉴定为子囊菌门黄芪白粉菌(Erysiphe astragali);病原菌分生孢子萌发最适温度为25℃,最适pH范围为6~8.不同碳源对分生孢子萌发效果影响不明显.光照条件下分生孢子萌发较好,黑暗条件下萌发率较差.【结论】通过对陇西县黄芪白粉病病原鉴定及生物学特性测定,在7月~9月上旬,当地气温有利于分生孢子萌发,易导致白粉病大面积发生和蔓延.在防治白粉病时,应选择白粉病始发期开始防治.

【Objective】In order to clarify the occurrence of powdery mildew in Astragalus membranaceus in Longxi County.【Method】The investigation was conducted by using five-point sampling method in 6 townships of Longxi County.The pathogen was identified based on morphological and molecular biology characteristics.The biological characteristics of germination rate of conidia under different conditions of temperature,pH value,light and carbon source were studied.【Result】The results showed that the average incidence of Astragalus was 31.17%in 2018,and the average disease index was 18.08.Through morphological observation and rDNA-ITS sequence comparison,the pathogen of Astragalus powdery mildew in Longxi County was identified as Erysiphe astragali in ascomycete.The optimal temperature for conidia germination of the pathogen was 25℃,and the optimal pH ranged from 6 to 8.Different carbon sources showed little effect on the germination of conidia.The conidia germinated well under light condition,and the germination rate was poor under dark condition.【Conclusion】The local temperature was conducive to the germination of conidia from July to early September,which easily caused the occurrence and spread of powdery mildew.In terms of prevention and control of powdery mildew,the control work should be started in the initiation period of powdery mildew occurrence.