Abstract: To accurately prevent and control Louisiana iris leaf diseases，investigations on the occurrence of Louisiana iris leaf diseases，pathogen identification，and screening of control agents were conducted.The susceptible plants of Louisiana iris were investigated，infected leaves were used as pathogen identification materials and 11 fungicides were used as antibacterial agents.The disease resistance of different varieties was evaluated using mechanical sampling method. The pathogen species were identified using tissue separation method，Koch’s rule，morphological observation analysis，and molecular biology identification. The antibacterial agents were screened using diffusion method.The results showed that Louisiana iris variety Noble Moment had the strongest disease resistance，and varieties Colorific and Sea knight were more resistant to diseases，Heather Stream，Kristi G，News Brief，Pegaletta had poor disease resistance.The pathogens causing Iris leaf diseases were Fusarium fujikuroi，Cladosporium asperatum，Cladosporium cladosporioides，and Penicillium solidum.The indoor antibacterial toxicity test showed that the 11 fungicides tested had varying degrees of antibacterial toxicity against four pathogenic fungi.Among them，47% Colloidox（WP）had the best comprehensive antibacterial effect，followed by 43% Tebuconazole（SC），with average EC₅₀ values of 0.999 μg/mL，2.395 μg/mL，respectively.

Key words: Louisiana iris, Leaf disease, Pathogen identification, Control agent, Virulence assay

摘要： 为精准防控路易斯安那鸢尾叶部病害，开展了路易斯安那鸢尾叶部病害发生情况调查、病原鉴定和防治药剂筛选研究。以路易斯安那鸢尾的感病植株为调查对象，感病叶片为病原鉴定试材，11种杀菌剂为抑菌药剂，采用机械抽样法进行不同品种抗病性评价，采用组织分离法、柯赫氏法则、形态学观察分析和分子生物学鉴定进行病原种类鉴定，扩散法进行抑菌药剂筛选。结果表明，路易斯安那鸢尾品种Noble Moment 抗病能力最强，品种Colorific、Sea knight 较为抗病，Heather Stream、Kristi G、News Brief、Pegaletta抗病性较差。造成鸢尾叶部病害的病原为藤仓镰刀菌（Fusarium fujikuroi）、粗糙枝孢菌（Cladosporium asperulatum）、枝状枝孢菌（Cladosporium cladosporioides）、皮落青霉菌（Penicillium solitum）。室内抑菌试验测定结果表明，供试11种杀菌剂对4种病原菌均有不同程度的抑菌毒力，其中综合抑菌效果较好的是47%王铜（WP），其次是43%戊唑醇（SC），平均半数效应质量浓度（EC₅₀）分别为0.999、2.395 μg/mL。

关键词: 路易斯安那鸢尾, 叶部病害, 病原鉴定, 防治药剂, 毒力测定