Antonopoulos D F, Elena K, Tjamos E C
Benaki Phytopathological Institute, St. Delta 8, 145 61 Kifissia, Greece and Agricultural University of Athens, Iera Odos 75, 118 55 Votanikos, Athens, Greece.
Benaki Phytopathological Institute, St. Delta 8, 145 61 Kifissia, Greece.
Plant Dis. 2003 Jun;87(6):751. doi: 10.1094/PDIS.2003.87.6.751B.
In August 2000, samples of alfalfa (Medicago sativa L.) plants cv. Iliki showing wilt symptoms consistent with those reported for Fusarium wilt (1) were collected from an alfalfa field of the Agricultural University of Athens. Symptoms of the disease were chlorosis, yellowing, premature defoliation, wilting, vascular discoloration (dark brown), stunting, and death of plants. Fusarium oxysporum was isolated from the stems of diseased plants. Fresh cultures of the isolated fungus on potato dextrose agar (PDA) media developed whitish purple mycelium, short phialides, microconidia, and later, macroconidia and chlamydospores matching the description of F. oxysporum Schlechtend.:Fr. f. sp. medicaginis (Weimer) W.C. Snyder & H.N. Hans. (2). The fungus was maintained on PDA cultures at 4°C. Pathogenicity tests were conducted in a greenhouse (12-h photoperiod at 25 to 32°C) on alfalfa Greek cv. Iliki. An aqueous suspension of 10 microconidia per ml was prepared, and roots of 7-week-old seedlings were dipped for 20 min and then returned to pots. Within 15 days, all inoculated plants exhibited typical Fusarium wilt symptoms similar to those observed in the field. Four weeks after inoculation, almost all plants were dead. Control seedlings (root-dipped for 20 min in sterile distilled water) remained healthy. The fungus was reisolated from the symptomatic seedlings, fulfilling Koch's postulates. Weimer (3) first described Fusarium wilt of alfalfa and identified the causal organism as Fusarium oxysporum f. sp. medicaginis. Cross-artificial inoculation to cotton plants cv. Myrto, Christina, and Acala CJ2 was also performed, but none of the cultivars developed any macroscopic symptoms of the disease. To our knowledge, this is the first report of alfalfa Fusarium wilt in Greece. Although the pathogen was located in a rather isolated spot of alfalfa cultivation in Attica County, the occurrence of the pathogen and its importance in other alfalfa growing regions of Greece will be investigated. References: (1) D. C. Erwin. Fusarium wilt. Pages 33-34 in: Compendium of Alfalfa Diseases. 2nd ed. D. L. Stuteville and D. C. Erwin eds. The American Phytopathological Society, St. Paul, MN, 1990. (2) W. C. Snyder and H. N. Hansen. Am. J. Bot. 27:64, 1940. (3) J. L. Weimer. J. Agric. Res. 37:419, 1928.
2000年8月，从雅典农业大学的一块苜蓿田中采集了表现出与镰刀菌枯萎病报告症状一致的苜蓿（紫花苜蓿）植株样本，品种为Iliki。该病的症状包括萎黄病、发黄、过早落叶、枯萎、维管束变色（深褐色）、生长受阻以及植株死亡。从患病植株的茎中分离出尖孢镰刀菌。将分离出的真菌在马铃薯葡萄糖琼脂（PDA）培养基上进行新鲜培养，形成了白色紫色菌丝体、短瓶梗、小型分生孢子，随后还形成了大型分生孢子和厚垣孢子，与尖孢镰刀菌Schlechtend.:Fr. f. sp. medicaginis（Weimer）W.C. Snyder & H.N. Hans.的描述相符。该真菌保存在4°C的PDA培养基上。在温室（25至32°C，12小时光周期）中对希腊苜蓿品种Iliki进行了致病性测试。制备了每毫升含10个小型分生孢子的水悬浮液，将7周龄幼苗的根浸泡20分钟，然后放回花盆中。15天内，所有接种的植株都表现出典型的镰刀菌枯萎病症状，与在田间观察到的症状相似。接种四周后，几乎所有植株都死亡。对照幼苗（在无菌蒸馏水中浸泡根20分钟）保持健康。从有症状的幼苗中重新分离出该真菌，满足了柯赫氏法则。Weimer（3）首次描述了苜蓿镰刀菌枯萎病，并确定病原菌为尖孢镰刀菌苜蓿专化型。还对棉花品种Myrto、Christina和Acala CJ2进行了交叉人工接种，但没有一个品种出现该病的任何宏观症状。据我们所知，这是希腊苜蓿镰刀菌枯萎病的首次报告。尽管病原菌位于阿提卡县一个相当孤立的苜蓿种植点，但将对该病原菌在希腊其他苜蓿种植区的发生情况及其重要性进行调查。参考文献：（1）D.C. Erwin. 镰刀菌枯萎病。载于：《苜蓿病害简编》第2版，D.L. Stuteville和D.C. Erwin编。美国植物病理学会，明尼苏达州圣保罗，1990年，第33 - 34页。（2）W.C. Snyder和H.N. Hansen. 《美国植物学杂志》27:64，1940年。（3）J.L. Weimer. 《农业研究杂志》37:419，1928年。
