裸仁美洲南瓜叶枯病病原菌鉴定及其寄主范围和侵染条件

Identification of pathogen causing Cucurbita pepo leaf blight in hull-less pumpkin and its host range and infection condition

近年来,在甘肃省武威地区裸仁美洲南瓜发生了一种叶枯病,采用常规组织分离法对罹病组织进行了病原菌分离培养,以及病原菌的形态、分离培养性状观察和致病性测定。结果表明,引起裸仁美洲南瓜叶枯病的致病菌为瓜链格孢Alternaria cucumerina(E11.et Ev.)E11 iott。寄主范围测定表明,该病原菌可侵染所有供试葫芦科植物,其中南瓜、西葫芦和甜瓜发病最严重;丝瓜和苦瓜发病较轻;该病原菌还可引起白菜和菜豆发病。温度和保湿时间对病原菌的侵染影响较大,25～30℃温度范围内最易侵染,病害潜育期仅为2～3天;当保湿时间60h时,病叶率达到88%,而保湿时间为6h时,病叶率仅为8%。南瓜不同品种对叶枯病的抗性差异较大,其中二星、天然、光板1号、无壳(李建民)和金无壳为高抗品种;四星、粒赛金、金大地、郑峰光板、日本南瓜为高感品种。

A disease causing hull-less pumpkin leaf blight was observed in Wuwei District of Gansu Province in recent years. The pathogen was isolated from the diseased plants using conventional isolating methods and identified as Alternaria cucumerina through their morphology, isolation culture characteristic, test of pathogenicity, etc. The host range test showed that the pathogen could infect all tested Cucurbitaceae plants. The most susceptible gourds crops were Cucurbita moschata, Cucurbita pepo and Cucurbita melo; while Luffa cylindrical and Momordica charantia were light infected; this pathogen could also attack Brassica pekinensis and Phaseolus vulgaris. Temperature and moisture time effected the infection of pathogen greatly. The optimum temperature for the pathogen infection was 25 -30 ℃ with the incubation period of only 2 - 3 d. When the moisture time was 60 h, the percentage of infected leaves was 88% ; while when the moisture time was 6 h, the percentage of infected leaves was only 8%. The different pumpkin varieties showed different resistance to the pathogen. The high resistance varieties were Erxing Tianran, Guangban No. 1, Wuke （Lijianming） and Jinwuke; while the most susceptible varieties were Sixing, Lisaijin, Jindadi, Zhengfengguangban and Ribennangua.