Garibaldi A, Minuto A, Gullino M L
Centre of Competence for the Innovation in the Agro-environmental Sector (AGROINNOVA) and DIVAPRA, University of Torino, Via Leonardo da Vinci 44, 10095 Grugliasco, Italy.
Plant Dis. 2004 Dec;88(12):1381. doi: 10.1094/PDIS.2004.88.12.1381C.
Several species of Diplotaxis (D. tenuifolia, D. erucoides, and D. muralis), known as wild rocket, are now widely cultivated in Italy. Wild rocket is used in Mediterranean cuisine as salad, a component of packaged salad products, and as a garnish for food. During the fall of 2002, a foliar disease of D. tenuifolia was observed in the field or greenhouse on several commercial farms in the Liguria Region of northern Italy. Symptoms appeared as small, irregular, dark brown-to-black speckling on the adaxial surfaces of leaves. The speckled areas sometimes expanded into larger spots. These symptoms were followed by leaf yellowing and the appearance of sporangiophores and sporangia on the lower and upper leaf surfaces. Sporangiophores were dichotomously branched with slender curved tips. Sporangia were ovoid, measuring 20 to 28 (average 22) μm long and 15 to 25 (average 19) μm wide. The causal agent of the disease was identified as Peronospora parasitica (3). Pathogenicity was established by inoculating 10 30-day-old plants of D. tenuifolia grown in pots in a peat/pumice/clay/composted bark mix (60:20:10:10), with a conidial suspension (10 conidia per ml). Ten noninoculated plants maintained under the same conditions served as the control. Plants were maintained in a glasshouse at air temperatures ranging between 10 and 26°C (average 16°C) and relative humidity at 85%. The pathogenicity test was done twice. Downy mildew symptoms developed within 12 days, and the same fungus was observed on inoculated plants. Noninoculated plants did not develop symptoms. To our knowledge, this is the first report of P. parasitica on D. tenuifolia in Italy. P. parasitca has been reported as the causal agent of downy mildew on D. muralis in England (1) and on cultivated rocket (Eruca sativa) in California (2). References: (1) J. Fraymouth. Trans. Br. Mycol. Soc. 39:79, 1956. (2) S. T. Koike. Plant Dis. 82:1063, 1998. (3) D. M. Spencer. The Downy Mildews. Academic Press. New York, 1981.
几种双行芥属植物（细叶双行芥、岩生双行芥和墙生双行芥），即人们所知的野生芝麻菜，目前在意大利广泛种植。野生芝麻菜在地中海烹饪中用作沙拉、包装沙拉产品的一种成分以及食物的装饰。2002年秋季，在意大利北部利古里亚地区的几个商业农场的田间或温室里，观察到细叶双行芥出现了一种叶部病害。症状表现为叶片正面出现小的、不规则的、深褐色至黑色的斑点。有斑点的区域有时会扩大成更大的斑块。这些症状之后是叶片发黄，并且在叶片的上、下表面出现孢囊梗和孢子囊。孢囊梗二叉状分枝，顶端细长弯曲。孢子囊呈卵形，长20至28（平均22）μm，宽15至25（平均19）μm。该病害的病原被鉴定为寄生霜霉（3）。通过用分生孢子悬浮液（每毫升10个分生孢子）接种10株在泥炭/浮石/黏土/堆肥树皮混合物（60:20:10:10）中盆栽生长30天的细叶双行芥植株来确定致病性。10株在相同条件下未接种的植株作为对照。植株置于温室中，气温在10至26°C（平均16°C）之间，相对湿度为85%。致病性试验进行了两次。霜霉病症状在12天内出现，并且在接种的植株上观察到了相同的真菌。未接种的植株没有出现症状。据我们所知，这是寄生霜霉在意大利细叶双行芥上的首次报道。寄生霜霉已被报道为英国墙生双行芥（1）和加利福尼亚栽培芝麻菜（芝麻菜）霜霉病的病原（2）。参考文献：（1）J. Fraymouth。《英国真菌学会会刊》39:79，1956年。（2）S. T. Koike。《植物病害》82:1063，1998年。（3）D. M. Spencer。《霜霉病》。学术出版社。纽约，1981年。
