Wick R L, Lerner J, Pair S D, Fletcher J, Mitchell F, Bruton B D
University of Massachusetts, Department of Plant Pathology, Amherst 01103.
USDA-ARS, Lane, OK 74555.
Plant Dis. 2001 Sep;85(9):1031. doi: 10.1094/PDIS.2001.85.9.1031C.
Commercial plantings of summer squash in Charlemont, Franklin County, MA, were decimated in 1999 by 100% incidence of a yellowing disease resembling cucurbit yellow vine disease (CYVD) (1). Both plantings were established in the same field during the third week of May, one with transplants and the second by direct-seeding. Each planting consisted of four 30-m rows each of yellow zucchini (Cucurbita pepo cv. Gold Rush), summer squash (C. pepo cv. Seneca Prolific), and zucchini (C. pepo cv. Condor). Crops were produced organically and pyrethrum was used to control a high infestation of squash bugs, Anasa tristis (De Geer) (Heteroptera:Coreidae), a putative vector of CYVD (3). Just prior to fruit set, during the first two weeks of June, plants began showing symptoms of foliar chlorosis, plant stunting, or both. All of the plants in the field eventually wilted and collapsed. Cross-sections of the below-ground stem and primary root revealed a honey-brown phloem discoloration and healthy appearing xylem, symptoms characteristic of CYVD. Plants yielded marketable fruit for only about 1 week. When plant samples were tested by polymerase chain reaction (PCR) with CYVD bacterium specific primers (2), a band of the expected size for the CYVD bacterium, identified as Serratia marcescens based on 16s rDNA and groE sequence analyses (4), was amplified in every case. Since all plant samples collected were symptomatic and PCR positive for S. marcescens, asymptomatic greenhouse plants were run simultaneously as a control. All control plants tested negative. A third planting, similar to the two disease-affected plantings and containing the same three squash cultivars from the same seed lot, was established at about the same time approximately 3 km away. No symptoms of CYVD occurred at this site, further evidence that the pathogen is not seed-borne (1). Furthermore, squash bugs were not observed in this field. In 2000, the disease was observed in a planting of 'Atlantic Giant' pumpkin in Erving, Franklin County, MA, and confirmed by PCR. Until now, CYVD has been reported only in the states of Oklahoma, Texas, and Tennessee. Confirmation of the disease in Massachusetts significantly increases the known geographical range of CYVD to include the New England area. References: (1) B. D. Bruton et al. Plant Dis. 82:512-520, 1998. (2) U. Melcher et al. Phytopathology 89:S95, 1999. (3) S. D. Pair et al. Pages 145-148 in: Proc. 19th Ann. Hort. Conf., Okla. State Univ. (4) J. Rascoe et al. Phytopathology 90:S63, 2000.
1999年，马萨诸塞州富兰克林县查勒蒙的西葫芦夏季商业种植遭受重创，一种类似葫芦科黄化藤病（CYVD）的黄化病发病率达100%（1）。两次种植均于5月的第三周在同一块田地进行，一次是移栽，另一次是直播。每次种植都包括四排30米长的黄色西葫芦（西葫芦品种“金 Rush”）、夏季南瓜（西葫芦品种“塞内卡多产”）和西葫芦（西葫芦品种“神鹰”）。作物采用有机种植方式，除虫菊用于控制南瓜缘蝽（Anasa tristis (De Geer)，半翅目：缘蝽科）的大量侵害，南瓜缘蝽被认为是CYVD的一种传播媒介（3）。就在坐果前，6月的前两周，植株开始出现叶片黄化、植株生长受阻或两者皆有的症状。田地里所有的植株最终都枯萎倒下。地下茎和主根的横切面显示韧皮部呈蜜褐色变色，木质部外观正常，这是CYVD的典型症状。植株仅在大约1周的时间里产出了可上市的果实。当用CYVD细菌特异性引物通过聚合酶链反应（PCR）对植物样本进行检测时（2），在每种情况下都扩增出了CYVD细菌预期大小的条带，根据16s rDNA和groE序列分析（4），该细菌被鉴定为粘质沙雷氏菌。由于采集的所有植物样本都有症状且对粘质沙雷氏菌PCR检测呈阳性，同时种植了无症状的温室植株作为对照。所有对照植株检测均为阴性。大约在同一时间，在约3公里外建立了第三次种植，与两次受病害影响的种植类似，包含来自同一批种子的相同三个南瓜品种。该地块未出现CYVD症状，进一步证明该病原体不是种子传播的（1）。此外，在这块地里未观察到南瓜缘蝽。2000年，在马萨诸塞州富兰克林县欧文的“大西洋巨人”南瓜种植中观察到了这种病害，并通过PCR得到证实。到目前为止，CYVD仅在俄克拉荷马州、得克萨斯州和田纳西州有报道。在马萨诸塞州对该病害的确认显著扩大了已知的CYVD地理范围，使其包括新英格兰地区。参考文献：（1）B. D. Bruton等人，《植物病害》82:512 - 520，1998年。（2）U. Melcher等人，《植物病理学》89:S95，1999年。（3）S. D. Pair等人，载于《第19届年度园艺会议论文集》，俄克拉荷马州立大学，第145 - 148页。（4）J. Rascoe等人，《植物病理学》90:S63，2000年。
