White J F, Johnston S A, Wang C-L, Chin C-K
Department of Plant Pathology.
Department of Plant Science, Rutgers University, New Brunswick, NJ 08903.
Plant Dis. 1997 Feb;81(2):227. doi: 10.1094/PDIS.1997.81.2.227B.
Powdery mildew of tomatoes caused by an Erysiphe sp. has been reported to occur in greenhouses in New York (2). In March and April of 1996, outbreaks of this disease were found in greenhouse-grown tomato plants of cv. PSR55809 at the Cook College campus in New Brunswick, NJ, and in cv. Match in commercial greenhouses in Burlington County, NJ. Identification of an Erysiphe sp. was made by comparative morphology of the conidial state since the perfect stage was not observed. Symptoms included development of patches of white mycelium predominantly on upper surfaces of older leaves followed by chlorosis of tissues colonized by the fungus. Microscopic examination of mycelium revealed the presence of typical Oidium conidiogenous cells and conidia. Conidiogenous cells were short and cylindrical and produce conidia in chains apically. Conidia were hyaline, cylindrical to ellipsoidal, and measured 36 + 4.9 × 16.7 + 2.2 μm (n = 20). Both conidia and symptoms of this powdery mildew are comparable to those previously given for the Erysiphe sp. described in New York (2). Another powdery mildew of tomato, caused by Oidiopsis sicula Scalia, occurs in the western U.S., Mediterranean Basin, Africa, and Asia. However, the conidia of O. sicula are of two types, pyriform and cylindrical, and they are larger than those of an Erysiphe sp. (1). To verify pathogenicity of this Erysiphe sp. to tomatoes, conidia washed from leaves were misted onto uninfected leaves of young tomato plants. After 1 week in a growth chamber (25°C; 80% relative humidity; 12 h of light), typical powdery mildew symptoms were evident on inoculated plants, while unmisted plants remained free of symptoms. Microscopic examination of the fungus on surfaces of leaves confirmed it to be an Erysiphe sp. References: (1) R. N. Campbell and R. W. Scheuerman. Plant Dis. Rep. 63:1087, 1979. (2) D. M. Karasevicz and T. A. Zitter. Plant Dis. 80:709, 1996.
据报道，一种白粉菌属（Erysiphe sp.）引起的番茄白粉病在纽约的温室中出现（2）。1996年3月和4月，在新泽西州新不伦瑞克市库克学院校园内种植的cv. PSR55809番茄植株以及新泽西州伯灵顿县商业温室中种植的cv. Match番茄植株上发现了这种病害的爆发。由于未观察到其有性阶段，通过分生孢子状态的比较形态学鉴定出一种白粉菌属。症状包括主要在老叶上表面形成白色菌丝体斑块，随后被真菌侵染的组织出现黄化。对菌丝体的显微镜检查发现存在典型的粉孢分生孢子梗细胞和分生孢子。分生孢子梗细胞短且呈圆柱形，顶端成链状产生分生孢子。分生孢子无色，圆柱形至椭圆形，大小为36 ± 4.9 × 16.7 ± 2.2 μm（n = 20）。这种白粉病的分生孢子和症状与先前在纽约描述的白粉菌属的情况相当（2）。另一种由西氏拟粉孢（Oidiopsis sicula Scalia）引起的番茄白粉病发生在美国西部、地中海盆地、非洲和亚洲。然而，西氏拟粉孢的分生孢子有两种类型，梨形和圆柱形，且比白粉菌属的分生孢子大（1）。为了验证这种白粉菌属对番茄的致病性，将从叶片上冲洗下来的分生孢子喷雾到未感染的幼嫩番茄植株叶片上。在生长室（25°C；相对湿度80%；光照12小时）中放置1周后，接种的植株上出现了典型的白粉病症状，而未喷雾的植株没有症状。对叶片表面真菌的显微镜检查证实其为白粉菌属。参考文献：（1）R. N. 坎贝尔和R. W. 舍尔曼。植物病害报告63:1087，1979。（2）D. M. 卡拉塞维茨和T. A. 齐特。植物病害80:709，1996。
