Department of Plant Pathology and Microbiology, Iowa State University, Ames 50011.
Plant Dis. 2018 Oct;102(10):1928-1937. doi: 10.1094/PDIS-03-17-0380-RE. Epub 2018 Aug 2.
Fusarium oxysporum is frequently associated with soybean root rot in the United States. Information about pathogenicity and other phenotypic characteristics of F. oxysporum populations is limited. The objective of the research described herein was to assess phenotypic characteristics of F. oxysporum isolates from soybean, including the interaction between isolates and soybean cultivars, fungal growth characteristics in culture, and sensitivity to fungicides commonly used as seed treatment products. The pathogenicity of 14 isolates was evaluated in rolled-towel and Petri-dish assays using 11 soybean cultivars. In the rolled-towel assay, seed were inoculated with a conidial suspension and disease severity was observed. In the Petri-dish assay, F. oxysporum isolates were grown on 2% water agar and seed were placed on the F. oxysporum colony to observe the symptoms that developed. Cultivars differed in susceptibility to F. oxysporum, and significant (P = 0.0140) isolate-cultivar interactions were observed. F. oxysporum isolates differed in radial growth on potato dextrose agar at 25°C. Pyraclostrobin and trifloxystrobin reduced conidial germination with average 50% effective concentration (EC) of 0.15 and 0.20 µg active ingredient (a.i.)/ml, respectively. Ipconazole reduced fungal growth with average EC of 0.23 µg a.i./ml, whereas fludioxonil was ineffective. Our results illustrate soybean F. oxysporum isolate variability and the potential for their management through cultivar selection or seed treatment.
尖孢镰刀菌（Fusarium oxysporum）在美国常与大豆根腐病有关。关于尖孢镰刀菌种群的致病性和其他表型特征的信息有限。本文所述研究的目的是评估来自大豆的尖孢镰刀菌分离株的表型特征，包括分离株与大豆品种之间的相互作用、培养物中真菌生长特性以及对常用作种子处理产品的杀菌剂的敏感性。使用 11 个大豆品种，通过滚毛巾和培养皿试验评估了 14 个分离株的致病性。在滚毛巾试验中，用分生孢子悬浮液接种种子，并观察疾病严重程度。在培养皿试验中，将尖孢镰刀菌分离物在 2%水琼脂上生长，并将种子放在尖孢镰刀菌菌落上，观察出现的症状。品种对尖孢镰刀菌的敏感性不同，并且观察到显著的（P = 0.0140）分离株-品种相互作用。在 25°C 下，马铃薯葡萄糖琼脂上尖孢镰刀菌分离株的径向生长存在差异。吡唑醚菌酯和三氟苯唑菌胺分别以平均 50%有效浓度（EC）0.15 和 0.20 µg 有效成分（a.i.）/ml 抑制分生孢子萌发。抑霉唑以平均 EC 0.23 µg a.i./ml 抑制真菌生长，而氟啶胺无效。我们的结果说明了大豆尖孢镰刀菌分离株的变异性，以及通过品种选择或种子处理来管理它们的潜力。
