内蒙古黄瓜靶斑病菌的鉴定及药剂敏感性测定

Identification of Corynespora cassiicola on cucumber and determination of fungicedes sensitivity to it in Inner Mongolia

对来自内蒙古自治区赤峰市宁城县五化镇山头村的黄瓜叶斑病标本进行组织分离,纯化得到20株分离物,经柯氏验证均为致病菌。结合病菌形态学特征和分子生物学相关序列分析,确定该病原菌为多主棒孢菌[Corynespora cassiicola(Berk&Curt)Wei]。采用菌丝生长速率法和孢子萌发法测定C.cassiicola对26种药剂的敏感性。结果表明,代表菌株HGBB-Ⅲ菌丝生长对25%咪鲜胺EC、40%肟菌·咪鲜胺EW、40%苯醚甲环唑SC和10%苯醚甲环唑WG的敏感性较高,EC_(50)<1 mg·L^(-1);对430 g·L^(-1)戊唑醇SC、50%腐霉利WP、50%福美双WP、50%异菌脲WP、75%肟菌·戊唑醇WG、40%唑醚·戊唑醇SC、32.5%苯甲·嘧菌酯SC、30%肟菌·戊唑醇SC的敏感性略低,1 mg·L^(-1)<EC_(50)<10 mg·L^(-1)。HGBB-III的孢子萌发对50%福美双WP的敏感性最高,EC_(50)<1 mg·L^(-1),对42.4%唑醚·氟酰胺SC、200 g·L^(-1)氟酰羟·苯甲唑SC、40%唑醚·戊唑醇SC、12%苯甲·氟酰胺SC的敏感性较低,10 mg·L^(-1)<EC_(50)<100 mg·L^(-1)。上述药剂中,50%福美双WP对病原菌菌丝生长和孢子萌发的抑制效果均较好,可以作为防治过程中的首选药剂。

In this study,twenty isolates were purified from cucumber leaves showing spots from Chifeng City of Inner Mongolia,then verified by Koch's postulate.Combined with morphological characteristics and molecular biology-related sequence analysis,the pathogen was identified as Corynespora cassiicola.The sensitivity of C.cassiicola to 26 fungicides was determined by mycelium growth rate and spore germination methods.The results showed that the mycelial growth of the representative strain HGBB-III was more sensitive to 25%prochloraz EC,40%trifloxystrobin prochloraz EW,40%difenoconazole SC and 10%difenoconazole WG(EC_(50)<1 mg·L^(-1));followed by 430 g·L^(-1)tebuconazole SC,50%procymidone WP,50%thiram WP,50%iprodione WP,75%trifloxystrobin tebuconazole WG,40%pyraclostrobin tebuconazole SC,32.5%difenoconazole azoxystrobin SC,30%trifloxystrobin tebuconazole SC(1 mg·L^(-1)<EC_(50)<10 mg·L^(-1)).The spore germination of C.cassiicola was the most sensitive to 50%thiram WP(EC_(50)<1 mg·L^(-1)),low sensitive to 42.4%pyraclostrobin fluxapyroxad SC,200 g·L^(-1)pydiflumetofen difenoconazole SC,40%pyraclostrobin tebuconazole SC,12%difenoconazole fluxapyroxad SC(10 mg·L^(-1)<EC_(50)<100 mg·L^(-1)).Of those,50%thiram WP had good inhibitory effects on mycelial growth and spore germination of pathogenic fungus,which could be used as the preferred fungicide in the control programme.