油茶叶斑病病原菌的分离、鉴定与室内毒力测定

Isolation and Identification of Pathogen of Camellia oleifera Leaf Spot and Laboratory Test of Virulence

为了明确湖南丘陵地区油茶叶斑病的病原菌种类,从双峰县油茶基地采集了7份油茶叶斑病病叶样本,采用组织分离法从中分离纯化获得3株病原菌,通过形态学观察、分子生物学鉴定及致病性检测,证实该地区油茶叶斑病的病原菌为交链格孢Alternaria alternata。通过带毒介质菌丝生长速率法测定该病原真菌对6种药剂的敏感性,结果表明,6种化学药剂的EC_(50)值由大到小排列依次为70%甲基硫菌灵可湿性粉剂>75%百菌清可湿性粉剂>5%己唑醇悬浮剂>43%戊唑醇悬浮剂>10%苯醚甲环唑水分散粒剂>45%咪鲜胺水乳剂,后面4种化学药剂对油茶叶斑病病原菌均具有较好的抑菌效果;油茶叶斑病病原菌对45%咪鲜胺水乳剂最为敏感,其EC_(50)值为0.5215 mg/L;对70%甲基硫菌灵可湿性粉剂最不敏感,其EC_(50)值为9021.94 mg/L。

To identify the pathogen causing leaf spot of Camellia oleifera in Hunan hilly regions,seven infected leaves samples were collected from the prodution base in Shuangfeng County,Hunan Province.Through the tissue isolation and further puri?cation,three pathogenic strains were obtained.According to morphological characteristics,and multilocus sequence analyses of rDNA-ITS and EF-1α,they were identi?ed as Alternaria alternata.The sensitivity of the fungus to six kinds of chemical agents was determined by mycelial growth rate method;the results found that in the order of EC_(50)from high to low,it was thiophanate-methyl 70%WP>chlorothalonil 75%WP>hexaconazole 5%SC>tebuconazole 43%SC>difenoconazole 10%WG>prochloraz 45%EW,of which the later four chemical agents had good antimicrobial ef?cacy on the pathogen of Camellia oleifera leaf spot;the pathogen was most sensitive to prochloraz 45%EW(EC_(50)=0.5215 mg/L),and most insensitive to thiophanate-methyl 70%WP(EC_(50)=9021.94 mg/L).