油茶炭疽病复合病菌鉴定及室内药剂评价

Identification of the Compound Pathogens Causing Anthracnose of Camellia oleifera and Evaluation of Fungicides in Laboratory

【目的】探讨油茶炭疽病复合病菌种类,筛选油茶炭疽病复合病菌的高效杀菌剂,为科学防治油茶炭疽病提供依据。【方法】从湖南、广西、广东、江苏,海南等地油茶成林采集炭疽病叶样本,采用组织分离法分离纯化致病菌,结合形态学和多基因联合系统发育分析进行种类鉴定;通过复合侵染试验研究致病菌之间的关系;采用菌丝生长速率法测定杀菌剂咪鲜胺、苯醚甲环唑、嘧菌酯、啶氧菌酯,氟吡菌酰胺和啶酰菌胺对油茶致病菌的室内毒力。【结果】1)从106个油茶炭疽病病斑中分离获得186株致病菌,其中主要病原菌是炭疽属真菌130株,拟盘多毛孢属真菌18株,新拟盘多毛孢属真菌28株,假拟盘多毛孢属真菌4株,链格孢属真菌6株;分离出单一炭疽病菌的病斑55个,而能同时分离出炭疽病菌和其他致病菌的病斑有51个,其中同一个病斑能同时分离出同属不同种或不同属致病菌的病斑有51个,分离的不同病菌有7种组合方式:同属不同种炭疽菌、炭疽菌和拟盘多毛孢属真菌、炭疽菌和新拟盘多毛孢属真菌、炭疽菌和假拟盘多毛孢属真菌、炭疽菌和链格孢属真菌两两组合以及炭疽菌和拟盘多毛孢属和新拟盘多毛孢属、炭疽菌和拟盘多毛孢属和链格孢属真菌3种菌的组合。2)将炭疽菌属和拟盘多毛孢属,炭疽菌属和新拟盘多毛孢属,炭疽菌同属不同种这3种分离率最多的组合方式致病菌回接到油茶上,发现炭疽病菌和其他致病菌复合接种的病斑显著大于只接同种病菌的病斑,表明油茶炭疽病斑中存在炭疽病菌与其他病原菌复合侵染协同增效的现象。3)室内毒力测定结果显示,苯醚甲环唑和咪鲜胺对炭疽菌属,拟盘多毛孢和新拟盘多毛孢致病菌均具有较强的抑制作用,平均EC50在0.011~0.555μg·mL^(-1)之间;其次是嘧菌酯和啶氧菌酯,这2种药剂对拟盘多毛孢和新拟盘多毛孢的室内毒力最强,平均EC50在0.007~0.020μg·mL^(-1)之间,但对炭疽菌的抑制作用较差;而啶酰菌胺和氟吡菌酰胺对油茶炭疽菌和拟盘多毛孢属致病菌几乎没有抑制作用。【结论】油茶炭疽病斑中存在炭疽菌和其他病菌复合侵染现象,咪鲜胺和苯醚甲环唑可作为防治油茶炭疽病复合侵染的主选药剂。

【Objective】This study aims to identify the compound pathogens causing anthracnose of Camellia oleifera and to screen effective fungicides for compound pathogens on C.oleifera,in order to provide targeted strategy for controlling C.oleifera anthracnose.【Method】Leaf samples with anthracnose symptoms were collected from C.oleifera plantations in Hunan,Guangxi,Guangdong,Jiangsu and Hainan Provinces,China.Tissue separation method was used to isolate and purify the pathogenic fungi,and the morphological characteristics combined with and multi gene phylogenetic analysis were used to identify species.The composite infection experiments were used to study the relationship between pathogenic fungi and pathogenicity.The mycelial growth rate method was used to determine the indoor virulence of fungicides such as prochloraz,difenoconazole,azoxystrobin,picoxystrobin,fluopyram and boscalid to pathogens of C.oleifera.【Result】1)The result showed that a total of 186 isolates were obtained from 106 symptomatic lesions,among which 130 isolates of Colletotrichum genus were the main pathogens,followed by 18 isolates in Pestalotiopsis genus,28 isolates in Neopestalotiopsis genus,4 isolates in Pseudopestalotiopsis genus and 6 isolates in Alternaria genus.There were 55 lesions from which only species of Colletotrichum genus were isolated,and 51 lesions from which both Colletotrichum species and other pathogens were isolated.There were 51 lesions from which multiple pathogens with different species in the same genus or from the different genus were simultaneously isolated.There were 7 combinations of different strains isolated:different species of Colletotrichum genus,Colletotrichum sp.and Pestalotiopsis sp.or Neopestalotiopsis sp.or Pseudopestalotiopsis sp.or Alternaria sp.,Colletotrichum sp.,Pestalotiopsis sp.and Neopestalotiopsis sp.or Alternaria sp.2)Further co-infection experiment showed that the lesion size caused by inoculation with mixed strains was significantly larger than that caused by inoculation with single strain,indicating that there was synergistic effect of compound infection of Colletotrichum sp.and other pathogens in C.oleifera anthracnose lesions.3)The virulence test results showed that difenoconazole and prochloraz had the strongest inhibitory effects on Colletotrichum,Pestalotiopsis and Neopestalotiopsis pathogens of C.oleifera,with EC50 mean values of 0.011 to 0.555μg·mL^(−1).Azoxystrobin and picoxystrobin had the highest indoor toxicity to Pestalotiopsis and Neopestalotiopsis,with an average EC50 from 0.007 to 0.020μg·mL^(−1),but had weak inhibitory effect on Colletotrichum.Boscalid and fluopyram had almost no inhibitory effects.【Conclusion】The results indicate that there is compound infection of Colletotrichum sp.and other pathogens in anthracnose lesions of C.oleifera,and prochloraz and difenoconazole can be used as the main fungicides to control C.oleifera anthracnose caused by compound infection of pathogens.