Polizzi G, Vitale A
Dipartimento di Scienze e Tecnologie Fitosanitarie, University of Catania, Via S. Sofia 100, 95123 Catania, Italy.
Plant Dis. 2006 Jan;90(1):114. doi: 10.1094/PD-90-0114B.
Sandpaper sotol (Dasylirion serratifolium Zucc.), native to Mexico, has green leaves with margins highlighted by whitish yellow prickles like a fine sandpaper. During the spring of 2004 and 2005, necrotic lesions were observed in the middle of leaf blades and near prickles on 2- to 5-year-old, container-grown sandpaper sotol plants from two nurseries in eastern Sicily (Italy). Symptoms were detected on 20 to 30% of plants and consisted of reddish lesions that developed a reddish brown stripe surrounded by a yellow halo. As lesions enlarged, the center turned yellow and expanded rapidly causing blight of young leaves. Occasionally, symptomatic tissues had masses of gray fungal conidia and/or sclerotia. Botrytis cinerea was isolated consistently from infected tissues disinfected for 1 min in 1% NaOCl and rinsed in sterile distilled water and grown on potato dextrose agar (PDA). Hyaline, ovoid conidia (average 6.4 × 9.7 μm) and conidiophores were similar to those described of B. cinerea, and 5- to 8-day-old cultures developed black sclerotia that were round or irregular in shape (average 1.55 × 1.02 mm) that is typical of gray mold (1). Koch's postulates were performed by spraying 6-week-old sandpaper sotol plants grown in 12-cm pots with a spore suspension (1 × 10 CFU per ml) obtained from 12-day-old cultures grown on PDA. Eight plants were naturally wounded by scratching leaf blades among themselves and were subsequently inoculated, while eight plants were inoculated without wounding. An equal number of noninoculated plants sprayed with sterile water served as controls. All plants were maintained in high humidity conditions (90 to 95% relative humidity) at 20 ± 2°C. Leaf spots similar to the ones observed in nurseries were evident on all naturally wounded and nonwounded plants within 2 to 3 weeks after inoculation. Noninoculated control plants were symptomless. B. cinerea was reisolated from affected tissues. The pathogen has reduced commercial value of sandpaper sotol plants and may represent a limiting factor for the cultivation of this plant in eastern Sicily. To our knowledge, this is the first report in the world of leaf spot and blight caused by B. cinerea on D. serratifolium. Reference: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CAB International Mycological Institute, Kew, Surrey, England, 1971.
砂纸龙舌兰（Dasylirion serratifolium Zucc.）原产于墨西哥，其绿色叶片边缘有类似细砂纸的淡黄白色刺。2004年和2005年春季，在意大利西西里岛东部两个苗圃中2至5年生、盆栽的砂纸龙舌兰植株上，观察到叶片中部和刺附近出现坏死斑。在20%至30%的植株上检测到症状，表现为红色病斑，病斑上形成一条红棕色条纹，周围有黄色晕圈。随着病斑扩大，中心变黄并迅速扩展，导致幼叶枯萎。偶尔，有症状的组织上有大量灰色真菌分生孢子和/或菌核。从在1%次氯酸钠中消毒1分钟、无菌蒸馏水冲洗后并在马铃薯葡萄糖琼脂（PDA）上培养的感染组织中，持续分离到灰葡萄孢。透明、卵形的分生孢子（平均6.4×9.7μm）和分生孢子梗与已描述的灰葡萄孢相似，5至8日龄培养物形成圆形或不规则形状的黑色菌核（平均1.55×1.02mm），这是灰霉病的典型特征（1）。通过用从在PDA上培养12日龄的培养物中获得的孢子悬浮液（每毫升1×10CFU）喷洒在12厘米盆中生长的6周龄砂纸龙舌兰植株上，进行柯赫氏法则验证。八株植株相互划伤叶片造成自然伤口后接种，另外八株植株未划伤直接接种。数量相等的喷洒无菌水的未接种植株作为对照。所有植株在20±2°C、高湿度条件（相对湿度90%至95%）下培养。接种后2至3周内，所有自然受伤和未受伤的植株上都出现了与苗圃中观察到的类似的叶斑。未接种的对照植株无症状。从受影响的组织中再次分离到灰葡萄孢。该病原菌降低了砂纸龙舌兰植株的商业价值，可能是西西里岛东部这种植物种植的一个限制因素。据我们所知，这是世界上关于灰葡萄孢引起的锯齿叶龙舌兰叶斑病和叶枯病的首次报道。参考文献：（1）M. B. Ellis. Dematiaceous Hyphomycetes. CAB International Mycological Institute, Kew, Surrey, England, 1971.
