Woodward J E, Batla M A, Dotray P A, Wheeler T A, Baughman T A
Texas A&M University System, Lubbock, TX 79403.
Texas A&M University System, Vernon, TX 76385.
Plant Dis. 2008 Mar;92(3):482. doi: 10.1094/PDIS-92-3-0482C.
Sclerotinia blight, caused by the soilborne fungus Sclerotinia minor Jagger, is a major disease of peanut (Arachis hypogaea L.) in parts of west Texas. Previous reports have indicated that annual weed species may serve as collateral hosts for S. minor (2). Several Ipomoea spp. are commonly found in peanut fields throughout the region. In September of 2007, Ipomoea hederacea and I. coccinea plants with bleached, shredded stems, and signs of black sclerotia were collected from a field known to be infested with S. minor. Symptomatic stem sections were rinsed in tap water, surface disinfested in 0.5% sodium hypochlorite for 1 min, air dried, and plated on potato dextrose agar (PDA). Pure cultures of S. minor consisting of white, fluffy mycelia and small (<2 mm), black, irregular sclerotia were consistently recovered. Pathogenicity tests were conducted by wound-inoculating healthy I. hederacea and I. coccinea transplants (n = 3) with agar plugs obtained from the edges of actively growing S. minor cultures. Plants were incubated in a dew chamber at 20°C and 95% relative humidity for 5 days. Plants inoculated with sterile PDA plugs served as controls (n = 3). A similar test was conducted using the susceptible peanut cultivar Flavorunner 458. Characteristic symptoms of Sclerotinia blight (3) were observed on all inoculated weed and peanut plants; whereas, the controls remained healthy. Pathogenicity tests were repeated with similar results. Cultures of S. minor were obtained from all symptomatic tissues, fulfilling Koch's postulates. These results indicate that I. hederacea and I. coccinea are additional hosts of S. minor and that sclerotia produced on infected plants can significantly augment soil inoculum. S. minor has been observed to infect I. batatas seedlings in New Jersey (1); however, this to our knowledge is the first report of S. minor infecting Ipomoea spp. in Texas. Therefore, weed management should inevitability be a part of disease management strategies for the control of Sclerotinia blight in peanut. References: (1) Anonymous. Index of Plant Diseases in the United States. USDA Handb. No. 165, 1960. (2) J. E. Hollowell et al. Plant Dis. 87:197, 2003. (3) D. M. Porter and H. A. Melouk. Sclerotinia blight. Page 34 in: Compendium of Peanut Diseases. 2nd ed. N. Kokalis-Burelle et al., eds. The American Phytopathologicial Society, St. Paul, MN, 1997.
由土壤传播真菌小核盘菌（Sclerotinia minor Jagger）引起的菌核病，是德克萨斯州西部部分地区花生（Arachis hypogaea L.）的一种主要病害。先前的报告表明，一年生杂草物种可能是小核盘菌的 collateral 寄主（2）。该地区的花生田中常见几种甘薯属（Ipomoea spp.）植物。2007年9月，从一块已知受小核盘菌侵染的田地中采集了茎部漂白、撕裂且有黑色菌核迹象的圆叶牵牛（Ipomoea hederacea）和南美旋花（I. coccinea）植株。有症状的茎段用自来水冲洗，在0.5%次氯酸钠中进行表面消毒1分钟，风干后接种到马铃薯葡萄糖琼脂（PDA）上。始终能分离出由白色、蓬松菌丝体和小（<2毫米）、黑色、不规则菌核组成的小核盘菌纯培养物。通过用从活跃生长的小核盘菌培养物边缘获取的琼脂块对健康的圆叶牵牛和南美旋花移栽苗（n = 3）进行伤口接种来进行致病性测试。将植株在20°C和95%相对湿度的保湿箱中培养5天。接种无菌PDA琼脂块的植株作为对照（n = 3）。使用易感花生品种弗拉沃勒纳458进行了类似测试。在所有接种的杂草和花生植株上均观察到菌核病的特征症状（3）；而对照植株保持健康。致病性测试重复进行，结果相似。从所有有症状的组织中都获得了小核盘菌培养物，满足柯赫氏法则。这些结果表明，圆叶牵牛和南美旋花是小核盘菌的额外寄主，并且受感染植株上产生的菌核可显著增加土壤接种体。在新泽西已观察到小核盘菌感染甘薯（Ipomoea batatas）幼苗（1）；然而，据我们所知，这是小核盘菌在德克萨斯州感染甘薯属植物的首次报道。因此，杂草管理必然应成为花生菌核病防治病害管理策略的一部分。参考文献：（1）匿名。美国植物病害索引。美国农业部手册第165号，1960年。（2）J. E. 霍洛韦尔等人。植物病害。87:197，2003年。（3）D. M. 波特和H. A. 梅洛乌克。菌核病。载于：花生病害简编。第2版。N. 科卡利斯 - 布雷勒等人编。美国植物病理学会，明尼苏达州圣保罗，1997年，第34页。
