积雪草漆斑病病原鉴定及室内药剂筛选

Identification of the pathogen causing black spot disease of Centella asiatica and screening of effective fungicides

关键词:  积雪草, 泛生漆斑菌, 病原菌, 药剂筛选

Key words:  Centella asiatica, Myrothecium inundatum, pathogen, screening of fungicides

摘要:

近年来,在广西各地积雪草种植基地,出现一种为害极重的病害,该病害病原菌主要为害积雪草叶片、叶柄,可致使叶片大面积枯死,该病害发生普遍、侵染期长,严重影响积雪草药材的品质和产量。该研究采用常规组织分离法从积雪草病叶上分离病原菌并根据柯赫氏法则验证其致病性; 通过菌落特征、菌株形态及ITS序列分析鉴定病原菌; 在室内利用生长速率法测定10种杀菌剂对该菌的抑制活性。结果表明:为害积雪草叶片的病原菌为泛生漆斑菌(Myrothecium inundatum); 该菌侵染性强,接种至健康积雪草叶片后24 h即可发病,并迅速扩展引起叶片萎蔫; 杀菌剂 60%唑醚·代森联水分散粒剂、45%恶霉灵·甲霜可湿性粉剂、1.8%辛菌胺醋酸盐水剂、80%代森锰锌可湿性粉剂室内对积雪草漆斑病病原菌的抑菌率均在98%以上,抑菌效果极强,建议在生产中轮换应用防治积雪草漆斑病。15%咪鲜胺微乳剂、70%甲基硫菌灵可湿性粉剂和10%苯醚菌酯悬浮剂对该病原菌的抑菌率也均在92%以上,抑菌效果良好,在生产中可酌情考虑使用。

Abstract:

In recent years, a new disease of Centella asiatica occurred seriously in producing area of Guangxi, this pathogen usually damages the leaves and petioles, and it can lead a large area of C. asiatica to wither. It occured very common and had a long infection period on C. asiatica, so the yield and quality of C. asiatica declined seriously. We used general tissue separation to isolate from infected plants, and corroborated the pathogenicity according to Koch's Rule.; and identified the pathogen mainly based on the morphological characters and molecular analysis of internal transcribed spacer(ITS)sequences, using growth rate method, antimicrobial activity of ten fungicides assayed against the pathogen. The result showed that the pathogen Myrothecium inundatum was discovered, which resulted in black spot disease of Centella asiatica. It had strong infectiousness and occurred on healthy leaves in 24 h, and expanded rapidly to bring about the leaves wilting. The indoor antibacterial rate of the four fungicides 60% Pyraclostrobin-metiram WG, 45% Hymexazol-metalaxyl WP, 1.8% Xinjunan acetate AS and 80% Mancozeb WP were above 98%, they had strong antimicrobial effects. The relevant references indicated that Myrothecium inundatum the four fungicides could take turns to control this disease in field. The indoor antibacterial rate of these three fungicides 15% Prochloraz ME, 70%Thiophanatemethyl WP and 10%Kresoxim-methyl SC were above 92%, the antimicrobial effects of them were also satisfied. Therefore, we can consider to use these three fungicides in production properly.