Pernezny K, Sonoda R M
University of Florida, Everglades Research and Education Center, P.O. Box 8003, Belle Glade 33430.
University of Florida, Indian River Research and Education Center, Ft. Pierce 34945. Florida Agric. Exp. Sta. Journal Series R-06021.
Plant Dis. 1998 Feb;82(2):262. doi: 10.1094/PDIS.1998.82.2.262D.
Powdery mildew was observed affecting mature, field-grown, fresh-market tomatoes in southeastern Florida (St. Lucie, Martin, Palm Beach, and Broward counties). Outbreaks were noted in May of 1996 and throughout the spring of 1997. Affected leaves were generally yellow and, in some cases, developed a purplish cast. Whitish areas of fungal growth were often seen in the middle of lesions, but were less prominent than that reported for powdery mildew of field tomato in Hungary (2). Microscopic examination revealed that conidia were produced in chains, contained no fibrosin bodies, and were not dimorphic. Conidial measurements were 33.2 × 15.6 μm, based on 21 samples of five conidia taken from five different fields. These measurements were similar to those for an Erysiphe sp. causing powdery mildew of greenhouse tomato in New York (1). Greenhouse-grown tomato plants, cv. Sunny, in the fourth-true-leaf stage were inoculated with conidia scraped from lesions gathered in commercial fields. A single-edged razor blade was used to transfer the fungus to the adaxial surface of the test plants. Powdery mildew symptoms were observed within 10 days of inoculation. Morphology and size of conidia taken from greenhouse plants were similar to those for original field samples. This is the first report of powdery mildew of field-grown tomato in Florida. References: (1) D. M. Karasevicz and T. A. Zitter. Plant Dis. 80:709, 1996. (2) L. Kiss. Plant Dis. 80:224, 1996.
在佛罗里达州东南部（圣卢西县、马丁县、棕榈滩县和布劳沃德县），发现白粉病影响了田间种植的成熟鲜食番茄。1996年5月以及1997年整个春季都出现了疫情。受影响的叶片通常发黄，在某些情况下还会呈现出紫色。在病斑中部经常可见真菌生长的白色区域，但不如匈牙利报道的田间番茄白粉病那样明显（2）。显微镜检查显示，分生孢子呈链状产生，不含纤维质体，且没有二型性。基于从五个不同田间采集的五个分生孢子的21个样本，分生孢子的测量尺寸为33.2×15.6μm。这些测量结果与在纽约引起温室番茄白粉病的白粉菌属（Erysiphe sp.）的测量结果相似（1）。对处于第四片真叶期的温室种植番茄品种“阳光”（cv. Sunny）接种从商业田间采集的病斑上刮下的分生孢子。使用单刃剃须刀片将真菌转移到试验植株的正面。接种后10天内观察到了白粉病症状。从温室植株上采集的分生孢子的形态和大小与原始田间样本相似。这是佛罗里达州田间种植番茄白粉病的首次报道。参考文献：（1）D. M. Karasevicz和T. A. Zitter。《植物病害》80:709，1996年。（2）L. Kiss。《植物病害》80:224，1996年。
