百日草炭疽病病原菌的分离鉴定及防治药剂筛选

为明确百日草炭疽病的病原菌，依据柯赫氏法则，对采集的病叶进行病原物分离并进行分离菌株致病性试验。确定菌株的致病性后，结合菌落形态，初步判断其为炭疽菌。运用分子生物学方法，扩增获得肌动蛋白基因 (actin gene, ACT)、几丁质合酶基因 (chitin synthase A gene, CHS)、磷酸甘油醛脱氢酶基因 (glyceraldehyde-3-phosphate dehydrogenase, GAPDH)、核糖体内部转录间隔区 (ribosomal internal transcribed spacer, ITS)、锰超氧化物歧化酶 (manganese-superoxide dismutase, SOD2)、谷氨酰胺合酶 (glutamine synthatase, GS)、微管蛋白 (beta-tubulin-TUB2) 以及钙调蛋白 (calmodulin, CaM ) 8个基因序列，进行联合系统发育分析，确定该菌为暹罗刺盘孢菌Colletotrichum siamense。离体抑菌活性测定结果表明，9种杀菌剂制剂75%肟菌 ? 戊唑醇水分散粒剂、35%氟菌 ? 戊唑醇悬浮剂、75%百菌清可湿性粉剂、250 g/L嘧菌酯悬浮剂、50%咪鲜胺可湿性粉剂、10%苯醚甲环唑水分散粒剂、10%丙硫菌唑悬浮剂、500 g/L氟啶胺悬浮剂和25%溴菌晴可湿性粉剂对供试病原菌的EC₅₀值分别为0.152、0.407、2.48、252、0.0342、0.556、317、0.00291和27.4 mg/L，其中500 g/L氟啶胺悬浮剂和50%咪鲜胺可湿性粉剂抑菌活性最强。

Isolation and identification of pathogen causing anthracnose on Zinnia elegans Jacq. and fungicides screening

To clarify the pathogen of anthracnose on Zinnia elegans Jacq., according to Koch's law, the diseased leaves were collected for the pathogen isolation and pathogenicity testing. After the pathogenicity test, based on their morphologic characteristics, the isolates were proved to be closely related to Colletotrichum species. To further investigated the pathogen, molecular identification based on the phylogenetic analysis of ACT (actin gene), CHS (chitin synthase A gene), GAPDH (glyceraldehyde-3-phosphate dehydrogenase), ITS (ribosomal internal transcribed spacer), SOD2 (manganese-superoxide dismutase), GS (glutamine synthatase), CaM (calmodulin) and TUB2 (beta-tubulin) was conducted and the pathogen was identified to be C. siamense. Furthermore, the antibiotic activity of nine fungicides to this pathogen was tested in vitro and it was found that the EC₅₀ values of trifloxystrobin + tebuconazole 75% water dispersible granule (WG), triflumizole + tebuconazole 35% suspension concentrate (SC), chlorothalonil 75% wettable powder (WP), azoxystrobin 250 g/L SC, prochloraz 50% WP, difenoconazole 10% WG, prothioconazole 10% SC, fluazinam 500 g/L SC and bromothalonil 25% WP were 0.152, 0.407, 2.48, 252, 0.0342, 0.556, 317, 0.00291 and 27.4 mg/L, respectively. Among them, fluazinam 500 g/L SC and prochloraz 50% WP showed the strongest fungicidal activities.