甜瓜黑点根腐病菌Monosporascus cannonballus在中国大陆的首次报道

2005年夏季,在甘肃省中部的半干旱种植区的一块甜瓜品种试验田中,一些甜瓜植株在收获前2周突然凋萎,从病根上分离得到3株生长速度快的高温型子囊菌,对其中2个菌株进行了形态特征、生物学特性及致病性研究,根据其独特的、每个子囊内仅产生一个黑色子囊孢子的主要形态特征和对甜瓜及西瓜的致病性,将其鉴定为Monosporascus cannonballus PollackUecker。这是该菌在我国大陆的首次报道。

First report on Monosporascus cannonballus on melon in China Mainland

In summer 2005, some melon (Cucumis melo L.) plants showing vine decline two weeks before harvest were observed in a variety test fields in semiarid melon growing areas of Gansu Province (Northwestern China). The disease incidence was up to 50% in melon cv. ‘Tainong No.2’. Three isolates were obtained from the roots with necrosis and brownish lesions. 30-60 days after incubation on PDA at 25 ℃ under the darkness, the isolates formed mature perithecia with a diameter of 316-594 μm. These perithecia released numerous asci, with each asci containing a single spherical ascospore (black in maturity) of 28.6-44.8 μm in diameter. This fungus was identified by ascospore morphology as Monosporascus cannonballus Pollack and Uecker. The optimum temperature for mycelial growth of the two isolates of M. cannonballus was 30 ℃. Pathogenicity of the two isolates was confirmed by inoculating embryo roots of melon cv. ‘86-1’ and watermelon cv. ‘Jinfeng’ with mycelia of the fungus grown on PDA. M. cannonballus was reported on melon in Taiwan of China in 1994, but this is the first report of the fungus on melon in China Mainland.