Fusarium is the main causal agent of maize ear rot.The population structure of Fusarium species causing maize ear rot in 5 counties of Nanyang City was investigated.The pathogens were isolated from diseased corn samples using conventional tissue isolation method.The pathogenicity of the single spore derived isolates on corn leaves and ears was tested based on Koch＇s postulates.The pathogenic isolates were identified based on morphological characteristics and rDNA-ITS（internal transcribed spacer） sequences.Totally 105 Fusarium isolates were obtained from 80 maize ear rot samples collected from the investigation areas.The inoculation tests showed that all the Fusarium isolates obtained were virulent on corn leaves and ears.At least 4 fungal species were identified as causal agents of maize ear rot based on their morphological characteristics and rDNA-ITS sequences.They were Fusarium proliferatum,Gibberella monoliformis,F.equiseti and G.zeae.F.proliferatum and G.moniliformis were found to be the predominant and subdominant species,respectively,among the Fusarium spp.and Gibberella spp.associated with maize ear rot in Nanyang City.%镰刀菌是玉米穗腐病的主要病原菌.本研究对南阳市5县2009年夏玉米穗腐病致病镰刀菌的种群结构进行调查分析.从病样中按常规组织分离法进行病原菌分离,对分离物经单孢分离纯化后根据柯赫法则进行致病性检测,并根据形态特征和核糖体基因内转录间隔区（rDNA-ITS）序列对病原菌进行鉴定.从采集的80份穗腐病样品中分离获得105株镰刀菌,接种结果表明,所有菌株对玉米均有致病性.形态和分子鉴定结果表明,引起南阳市玉米穗腐病的镰刀菌至少有4种：层出镰刀菌Fusarium proliferatum、串珠赤霉菌Gibberella monoliformis、木贼镰刀菌F.equiseti及玉蜀黍赤霉菌G.zeae.南阳市玉米穗腐病致病镰刀菌以层出镰刀菌为优势种,串珠赤霉菌为次优势种.
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