Cappelli C, Buonaurio R, Torricelli R
Istituto di Patologia Vegetale, Borgo XX Giugno 74, 06121 Perugia, Italy.
Istituto di Miglioramento Genetico Vegetale, Borgo XX Giugno, 74, 06121 Perugia, Italy.
Plant Dis. 1999 Jan;83(1):77. doi: 10.1094/PDIS.1999.83.1.77C.
In May 1997, ascochyta blight incited by Ascochyta lentis Vassiljevsky was observed at an incidence of less than 5% in lentil (Lens culinaris Medik.) fields in Umbria (Central Italy). Symptoms appeared on leaves and stems as tan spots surrounded by a dark margin. Small black pycnidia that produced a pink exudate containing hyaline, 1 septate, 14.2 to 15.8 × 3.5 μm conidia under high humidity were visible in the center of the spots. The fungus was consistently isolated on potato dextrose agar from diseased leaves or stems. To satisfy Koch's postulates, a conidial suspension (10 conidia per ml) of the fungus was sprayed on leaves of 20-day-old lentil plants (landrace Castelluccio) that were maintained in a humidity chamber for 96 h after inoculation. Lesions resembling symptoms that occurred in the field were observed on plants 3 weeks after inoculation. Symptoms were not observed on control plants sprayed with water. The fungus reisolated from the diseased plants was identical to the original isolates. Based on morphological characteristics of pycnidia and conidia as well as pathogenicity, the fungus was identified as A. lentis. A deep-freeze blotter method (2) was used to detect A. lentis in lentil seeds of 20 local landraces used by Umbrian farmers and two accessions from Canada and Turkey, as well as in seed collected from infected fields. The fungus was present only in the two lentil accessions with an incidence of about 5%. Although the fungus had been isolated from Italian seed germplasm in 1986 (1), this is the first report of ascochyta blight occurring in lentil crops in Italy. The heavy rainfalls that characterize the first stage of lentil cultivation in Umbria are favorable for disease development while hot and dry conditions that usually occur during flowering and maturation prevent the dissemination of inoculum and the infection of the seeds. For these reasons, some Umbrian areas could be more suitable for production of ascochyta-free lentil seeds. References: (1) W. J. Kaiser and R. M. Hannan. Phytopathology 76:355, 1986. (2) T. Limonard. Proc. Int. Seed Test. Assoc. 33:343, 1968.
1997年5月，在翁布里亚（意大利中部）的小扁豆（Lens culinaris Medik.）田中观察到由扁豆壳二孢菌（Ascochyta lentis Vassiljevsky）引起的壳二孢叶枯病，发病率低于5%。叶片和茎上出现症状，表现为黄褐色斑点，周围有深色边缘。在斑点中心可见小黑点（分生孢子器），在高湿度条件下，这些小黑点产生含有透明、具1个隔膜、14.2至15.8×3.5μm分生孢子的粉红色渗出物。该真菌始终能从患病叶片或茎上在马铃薯葡萄糖琼脂培养基上分离得到。为了满足科赫法则，将该真菌的分生孢子悬浮液（每毫升10个分生孢子）喷洒在20日龄小扁豆植株（地方品种卡斯泰卢乔）的叶片上，接种后在湿度箱中放置96小时。接种3周后，在植株上观察到与田间出现的症状相似的病斑。喷水处理的对照植株上未观察到症状。从患病植株上重新分离得到的真菌与原始分离株相同。根据分生孢子器和分生孢子的形态特征以及致病性，该真菌被鉴定为扁豆壳二孢菌。采用深度冷冻吸墨纸法（2）检测翁布里亚农民使用的20个当地地方品种以及来自加拿大和土耳其的两个种质的小扁豆种子中的扁豆壳二孢菌，同时也检测了从感染田采集的种子中的该菌。该真菌仅存在于两个种质中，发病率约为5%。尽管1986年曾从意大利种子种质中分离出该真菌（1），但这是意大利小扁豆作物中发生壳二孢叶枯病的首次报道。翁布里亚小扁豆种植第一阶段的暴雨有利于病害发展，而开花和成熟期间通常出现的炎热干燥条件则可防止接种体传播和种子感染。由于这些原因，翁布里亚的一些地区可能更适合生产无壳二孢菌的小扁豆种子。参考文献：（1）W. J. 凯泽和R. M. 汉南。《植物病理学》76:355，1986年。（2）T. 利莫纳德。《国际种子检验协会会刊》33:343，1968年。
