Bila J, Mondjana A M, Wulff E G, Mortensen C N
Universidade Eduardo Mondlane, Faculdade de Agronomia e Engenharia Florestal, Departamento de Produção e Protecção Vegetal, Maputo, Moçambique.
Danish Seed Health Centre for Developing Countries, Department of Plant Biology and Biotechnology, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg, Copenhagen, Denmark. Supported by the Danish International Development Agency.
Plant Dis. 2009 Nov;93(11):1218. doi: 10.1094/PDIS-93-11-1218A.
In August and September of 2007, black rot symptoms were observed on seedbed and field plants of Brassica spp. grown in the southern districts of Boane, Mahotas, and Chòkwé in Mozambique. One hundred eighty-two cabbage-growing households were evaluated for the incidence of Xanthomonas campestris pv. campestris. Five Brassica cultivars, Glory F1, Glory of Enkhuizen, Copenhagen Market, Starke (Brassica oleracea pv. capitata L.), and Tronchuda (B. oleracea L. var. costata DC) were grown in the areas for several years. The hybrid Glory F1 was the most popular grown cultivar in the surveyed areas. In the Boane district, the highest incidence of black rot was recorded on Copenhagen Market (70%), Starke (67.9%), and Glory F1 (67.3%). In Chòkwé, Tronchuda (Portuguese kale) was the least affected Brassica crop. Water-soaked lesions starting at the edge of leaves with typical V-shaped necrotic lesions and vein discoloration were the most commonly observed symptoms. When examined with a microscope, cut edges of symptomatic stem and leaf tissues consistently exhibited bacterial streaming. The bacteria were isolated from commercial seed and field-grown plants on semiselective agar media (2). Forty-six X. campestris pv. campestris strains that were gram negative, aerobic, starch positive, nitrate negative, and oxidase negative or weakly positive (3) were further identified on the basis of ELISA (Agdia Inc., Elhart, IN), GN Biolog Microbial Identification System, version 4.2 (Biolog Inc., Hayward, CA), and PCR-specific primers (1). Pathogenicity tests were conducted by pin inoculating two upper leaves of cabbage (cv. Wirosa) in the 2- to 3-leaf stage with bacterial growth from 24-h-old agar cultures (2). Black rot symptoms developed on nearly all inoculated plants within 7 to 14 days. No symptoms were observed on control plants inoculated with a sterile pin without bacterial inoculum. The severity of black rot of Brassica spp. in three important farming districts caused significant losses in Mozambique. References: (1) T. Berg et al. Plant Pathol. 54:416, 2005. (2) S. J. Roberts and H. Koenraadt. Page 1 in: International Rules for Seed Testing: Annexe to Chapter 7 Seed Health Methods. ISTA, 2007. (3) N. W. Schaad et al. Laboratory Guide for Identification of Plant Pathogenic Bacteria. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2001.
2007年8月和9月，在莫桑比克博阿内、马霍塔斯和乔克韦南部地区种植的十字花科植物的苗床和田间植株上观察到黑腐病症状。对182个种植甘蓝的家庭进行了野油菜黄单胞菌野油菜致病变种发病率的评估。五个十字花科品种，即荣耀F1、恩克赫伊曾荣耀、哥本哈根市场、斯塔克（甘蓝变种甘蓝L.）和特伦库达（甘蓝L.变种肋状DC）在这些地区种植了数年。杂交种荣耀F1是调查地区种植最普遍的品种。在博阿内区，哥本哈根市场（70%）、斯塔克（67.9%）和荣耀F1（67.3%）的黑腐病发病率最高。在乔克韦，特伦库达（葡萄牙羽衣甘蓝）是受影响最小的十字花科作物。从叶边缘开始的水渍状病斑，伴有典型的V形坏死病斑和叶脉变色，是最常见的症状。在显微镜下检查时，有症状的茎和叶组织的切口边缘始终显示出细菌溢菌现象。从商业种子和田间种植的植株上，在半选择性琼脂培养基上分离出细菌（2）。根据酶联免疫吸附测定法（Agdia公司，埃尔哈特，印第安纳州）、GN Biolog微生物鉴定系统4.2版（Biolog公司，海沃德，加利福尼亚州）和PCR特异性引物（1），进一步鉴定了46株革兰氏阴性、需氧、淀粉阳性、硝酸盐阴性且氧化酶阴性或弱阳性的野油菜黄单胞菌野油菜致病变种菌株（3）。通过用来自24小时龄琼脂培养物的细菌生长物针刺接种处于2至3叶期的甘蓝（品种维罗萨）的两片上部叶片进行致病性测试（2）。几乎所有接种的植株在7至14天内出现黑腐病症状。用无菌针接种无细菌接种物的对照植株未观察到症状。莫桑比克三个重要农业区的十字花科植物黑腐病严重程度造成了重大损失。参考文献：（1）T. Berg等人，《植物病理学》54:416，2005年。（2）S. J. Roberts和H. Koenraadt，载于《国际种子检验规则：第7章种子健康方法附录》，ISTA，2007年。（3）N. W. Schaad等人，《植物病原细菌鉴定实验室指南》第3版，美国植物病理学会，圣保罗，明尼苏达州，2001年。
