Thomidis T, Michailides T J
Pomology Institute Naoussa (NAGREF), R. S. Naoussas 38, P.O. Box 122, P.C. 59200, Imathia, Greece.
Department of Plant Pathology, University of California Davis, Kearney Agriculture Center, 9240 South Riverbend Ave., Parlier 93648.
Plant Dis. 2008 Apr;92(4):650. doi: 10.1094/PDIS-92-4-0650B.
In Greece, kiwi (Actinidia deliciosa) is mostly found in the northern part of the country where approximately 440,000 ha are grown. In the summer of 2006, a Stemphylium sp. was frequently isolated from leaves of kiwi (cv. Hayward) grown in the province of Imathia. Symptomatic leaves were covered with irregular, necrotic, brown areas. Lesions had a distinct margin that, in some cases, covered a wide part of the diseased leaves. Intense symptoms were frequently observed and associated with defoliation. This Stemphylium sp. was consistently isolated from diseased leaves onto potato dextrose agar (PDA) after surface sterilization with 0.1% chlorine solution. On the basis of morphological characteristics of mycelia, dimensions (length 20 to 29 μm and width 14 to 21 μm) and mean length/width ratio (1.42 μm) of conidia, and width and apical cell width of condiophores, the fungus was identified as Stemphylium botryosum (Wallr.) (2,3) Koch's postulates were completed in the laboratory by inoculating leaves of kiwi (cv. Hayward) with an isolate of S. botryosum originated from a symptomatic leaf of a Hayward kiwi. Twenty leaves were surface sterilized by dipping them into 0.1% chlorine solution for 2 to 3 min, washing in sterile distilled water, and allowing them to dry in a laminar flow hood. A leaf was then placed into a petri plate containing a wet, sterilized paper towel. Inoculation was made by transferring a 5-mm-diameter mycelial disc from the margins of a 7-day-old culture onto the center of each leaf surface. Petri plates were closed and incubated at 25°C with 12 h of light for 6 days. Koch's postulates were satisfied when the same S. botryosum was reisolated from 100% of inoculated leaves that developed symptoms similar to those observed in the vineyards. Leaves inoculated with a PDA plug alone (with no S. botryosum) did not develop any symptoms. Previously, Alternaria alternata was reported as the causal agent of a leaf spot pathogen of kiwi (1,4). To our knowledge, this is the first report of the occurrence of S. botryosum causing leaf blight of kiwi in Greece and worldwide. This pathogen can cause a high level of defoliation in diseased plants. References: (1) L. Corazza et al. Plant Dis. 83:487, 1999. (2) M. B. Ellis. Dematiaceous Hyphomycetes. Mycology Institute. London, England, 1971. (3) E. G. Simmons. Mycologia 61:1, 1969. (4) C. Tsahouridou and C. C. Thanassoulopoulos. Plant Dis. 84:371, 2000.
在希腊，奇异果（中华猕猴桃）主要种植于该国北部，种植面积约44万公顷。2006年夏季，在伊马夏省种植的奇异果（品种海沃德）叶片上频繁分离出一种匍柄霉属真菌。有症状的叶片上布满不规则的坏死褐色区域。病斑边缘清晰，在某些情况下，覆盖了患病叶片的很大一部分。经常观察到严重症状并伴有落叶现象。在用0.1%氯溶液进行表面消毒后，这种匍柄霉属真菌始终能从患病叶片上分离到马铃薯葡萄糖琼脂（PDA）培养基上。根据菌丝体的形态特征、分生孢子的尺寸（长度20至29微米，宽度14至21微米）和平均长宽比（1.42微米）以及分生孢子梗的宽度和顶端细胞宽度，该真菌被鉴定为葡萄匍柄霉（Wallr.）（2,3）通过用源自海沃德奇异果有症状叶片的葡萄匍柄霉分离株接种奇异果（品种海沃德）叶片，在实验室完成了柯赫氏法则验证。将20片叶子浸入0.1%氯溶液中2至3分钟进行表面消毒，用无菌蒸馏水冲洗，然后在层流罩中晾干。然后将一片叶子放入装有湿润无菌纸巾的培养皿中。通过从7日龄培养物边缘转移一个直径5毫米的菌丝圆盘到每片叶表面的中心进行接种。培养皿盖上盖子，在25°C下光照12小时培养6天。当从100%出现与葡萄园观察到的症状相似症状的接种叶片中重新分离出相同的葡萄匍柄霉时，柯赫氏法则得到满足。仅接种PDA菌块（无葡萄匍柄霉）的叶片未出现任何症状。此前，链格孢被报道为奇异果叶斑病的病原菌（1,4）。据我们所知，这是葡萄匍柄霉在希腊和全球范围内导致奇异果叶枯病的首次报道。这种病原菌可使患病植株大量落叶。参考文献：（1）L. Corazza等人，《植物病害》83:487，1999年。（2）M. B. Ellis，《暗色丝孢菌》，真菌研究所，英国伦敦，1971年。（3）E. G. Simmons，《真菌学》61:1，1969年。（4）C. Tsahouridou和C. C. Thanassoulopoulos，《植物病害》84:371，2000年。
