Melzer M S, Boland G J, Celetti M J
University of Guelph, Guelph, Ontario N1G 2W1.
Ontario Ministry of Agriculture, Food and Rural Affairs and Environmental Biology, University of Guelph, Guelph, Ontario N1G 2W1.
Plant Dis. 2001 Aug;85(8):919. doi: 10.1094/PDIS.2001.85.8.919D.
During the summer of 2000, brown, angular-shaped leaf spots, frequently surrounded by a chlorotic halo, were observed in commercial fields of green bean (Phaseolus vulgaris L.) in Ontario, Canada. Brown synematta (30 to 60 μm × 160 to 330 μm) and brown conidia (2 to 5 septate, usually curved, 5 to 7.3 μm × 35 to 66 μm) from the underside of diseased leaves were plated onto V8 agar. Within 3 to 4 days, dark olive green colonies formed, and after 10 to 14 days, white mycelial growth occurred on the upper surface of colonies, and colonies appeared gray. The causal agent was tentatively identified as Phaeoisariopsis griseola (Sacc.) Ferraris, the cause of angular leaf spot of bean, and this identification was later confirmed by the Centraalbureau voor Schimmelcultures, The Netherlands. New colonies of the fungus were started by streaking conidia across plates of V8 agar and new conidia were produced within 36 h. Conidial suspensions of 1 × 10 conidia/ml were sprayed onto leaves of green bean varieties Goldrush, Strike, Bronco, and Gold Mine. Plants were placed in a mist chamber at 20 ± 2°C for 11 days and then kept at high humidity for four more days. Lesions were observed 8 to 10 days after treatment and synematta developed 12 to 14 days after treatment. Disease symptoms and synematta were observed on all bean varieties tested. P. griseola was reisolated from inoculated plants, fulfilling Koch's postulates. To our knowledge, this is the first report of angular leaf spot occurring on P. vulgaris in Ontario.
2000年夏季，在加拿大安大略省的菜豆（Phaseolus vulgaris L.）商业种植田中，发现了褐色、角状的叶斑，这些叶斑周围常常有褪绿晕圈。从患病叶片下表面采集褐色分生孢子盘（30至60微米×160至330微米）和褐色分生孢子（2至5个隔膜，通常弯曲，5至7.3微米×35至66微米），接种到V8琼脂培养基上。3至4天内形成深橄榄绿色菌落，10至14天后，菌落在菌落上表面出现白色菌丝生长，菌落呈现灰色。病原菌初步鉴定为菜豆生尾孢（Phaeoisariopsis griseola (Sacc.) Ferraris），即菜豆角斑病的病原菌，该鉴定后来得到荷兰中央真菌培养中心的确认。通过将分生孢子划线接种到V8琼脂平板上，获得了该真菌的新菌落，36小时内产生了新的分生孢子。将浓度为1×10个分生孢子/毫升的分生孢子悬浮液喷洒到菜豆品种Goldrush、Strike、Bronco和Gold Mine的叶片上。将植株置于温度为20±2°C的喷雾室中11天，然后再保持高湿度4天。处理后8至10天观察到病斑，处理后12至14天观察到分生孢子盘。在所测试的所有菜豆品种上均观察到了病害症状和分生孢子盘。从接种的植株上重新分离出菜豆生尾孢，满足了柯赫氏法则。据我们所知，这是安大略省菜豆上发生角斑病的首次报道。
