Trapero A, Romero M A, Varo R, Sánchez M E
Departamento de Agronomía, ETSIAM, Universidad de Córdoba, Apdo. 3048, 14080 Córdoba, Spain.
Plant Dis. 2003 Oct;87(10):1263. doi: 10.1094/PDIS.2003.87.10.1263A.
Forestation of agricultural lands has led to a great increase in the production of plants in forest nurseries in southern Spain. During a disease survey of several nurseries, performed in 1998 and 1999, a necrotic leaf spot was found causing defoliation in seedlings of two mediterranean forest species, the ericaceous shrub Arbutus unedo and the leguminous tree Ceratonia siliqua. The affected plants were 9 to 24 months old and growing in fertilized peat in containers. Symptoms on both species consisted of large necrotic lesions (up to 20 mm in diameter) that were located mainly, but not exclusively, along the leaf margin. On A. unedo, necrotic spots were bordered by a red halo, while on C. siliqua the halo was dark. The fungus consistently isolated from both hosts was identified as Pestalotiopsis maculans (Corda) Nag Raj (=Pestalotiopsis guepinii), based on morphological characters (1). Acervular conidiomata (up to 200 μm in diameter) developed on the necrotic lesions of leaves incubated at 100% relative humidity and 20 to 24°C, and in cultures on potato dextrose agar (PDA) at 20 to 24°C over the course of 7 days. All isolates had 5-celled smooth conidia. Apical and basal cells were hyaline, while the three median cells were brown; the upper two were darker than the lower one. Conidia were 22 to 30 μm (mean length) and 5 to 9 μm (mean width). There were typically three (range 1 to 4) apical appendages averaging 17 μm long. The average basal appendage was 6 μm long. One-year-old seedlings and detached leaves from healthy field trees of A. unedo and C. siliqua were sprayed to runoff with an aqueous conidial suspension (10 conidia ml) of two isolates of the fungus. All inoculated and control plants sprayed with water only were incubated in a growth chamber at 100% relative humidity and 20 to 24°C for 48 h and then in the same growth chamber at 50 to 80% relative humidity or in the greenhouse (10 to 30°C and 40 to 80% relative humidity) until symptoms developed. Detached leaves were incubated to prevent desiccation in a humid chamber at 100% relative humidity and 20 to 24°C for 2 months. After a period of 2 to 4 months, lesions developed on all inoculated leaves but not on noninoculated controls. Lesion morphology on both hosts was similar to that observed in naturally infected plants in the nurseries. P. maculans was reisolated from lesions of all infected leaves but not from control leaves. Although other species of Pestalotiopsis have been reported infecting leaves of C. siliqua (1), to our knowledge, this is the first report of a Pestalotiopsis sp. on A. unedo and of P. maculans on C. siliqua. Reference: (1) T. R. Nag Raj. Coelomycetous Anamorphs with Appendage-Bearing Conidia. Mycologue Publications, Waterloo, Ontario, Canada, 1993.
农田造林使得西班牙南部森林苗圃的植物产量大幅增加。在1998年和1999年对多个苗圃进行的病害调查中，发现一种坏死叶斑病导致两种地中海森林树种的幼苗落叶，这两种树种分别是杜鹃花科灌木草莓树（Arbutus unedo）和豆科树木角豆树（Ceratonia siliqua）。受影响的植株年龄为9至24个月，生长在装有施肥泥炭的容器中。两种树种的症状均为大型坏死斑（直径可达20毫米），主要但并非仅沿着叶缘分布。在草莓树上，坏死斑周围有红色晕圈，而在角豆树上，晕圈为深色。根据形态特征，从两种寄主上持续分离出的真菌被鉴定为黄斑拟盘多毛孢（Pestalotiopsis maculans (Corda) Nag Raj = Pestalotiopsis guepinii）（1）。在相对湿度100%、温度20至24°C的条件下，于坏死叶斑上培养，以及在20至24°C的马铃薯葡萄糖琼脂（PDA）培养基上培养7天后，可形成直径达200微米的分生孢子盘。所有分离菌株都有5个细胞的光滑分生孢子。顶端和基部细胞无色透明，中间三个细胞为棕色；上部两个细胞比下部一个细胞颜色更深。分生孢子长22至30微米（平均长度），宽5至9微米（平均宽度）。通常有三个（范围为1至4个）顶端附属丝，平均长度为17微米。基部附属丝平均长度为6微米。用该真菌的两个分离菌株的分生孢子水悬液（10个分生孢子/毫升）将草莓树和角豆树一岁的幼苗及健康田间树木的离体叶片喷洒至径流状态。所有接种的植株和仅喷水的对照植株先在相对湿度100%、温度20至24°C的生长室中培养48小时，然后在相对湿度50至80%的同一生长室或温室（温度10至30°C、相对湿度40至80%）中培养，直至症状出现。将离体叶片在相对湿度100%、温度20至24°C的湿润培养箱中培养2个月以防止干燥。2至4个月后，所有接种叶片上出现病斑，而未接种的对照叶片上未出现。两种寄主上病斑的形态与苗圃中自然感染植株上观察到的相似。从所有感染叶片的病斑上重新分离出黄斑拟盘多毛孢，但对照叶片上未分离出。尽管已有报道称其他拟盘多毛孢属物种感染角豆树的叶片（1），但据我们所知，这是关于拟盘多毛孢属物种感染草莓树以及黄斑拟盘多毛孢感染角豆树叶的首次报道。参考文献：（1）T. R. Nag Raj. Coelomycetous Anamorphs with Appendage - Bearing Conidia. Mycologue Publications, Waterloo, Ontario, Canada, 1993.
