Woodward J E, Brenneman T B, Kemerait R C, Culbreath A K, Clark J R
Department of Plant Pathology, University of Georgia, Coastal Plain Experiment Station, Tifton 31793.
University of Georgia Cooperative Extension Service, Baxley 31513.
Plant Dis. 2005 Aug;89(8):910. doi: 10.1094/PD-89-0910C.
Because of the importance of spotted wilt caused by Tomato spotted wilt virus (TSWV), most peanut (Arachis hypogaea L.) breeding programs in the southeastern United States are focusing on developing resistance to TSWV. Many of the cultivars with improved resistance to TSWV are late maturing, requiring 150 days to reach optimum maturity. This factor could greatly impact disease problems at harvest. During November of 2004, an unknown disease was observed on peanut cvs. Georgia 02-C and Hull in a commercial field in Appling County. Symptoms included wilting stems with water-soaked lesions and a dense, gray mold growing on infected tissues. Final disease incidence was less than 5%. For isolation, diseased tissue was surface sterilized by soaking in 0.5% sodium hypochlorite for 1 min, air dried, plated on potato dextrose agar (PDA), and incubated at 20°C. Botrytis cinerea Pers.:Fr., causal agent of Botrytis blight, was isolated from the margins of infected tissue. Mycelia were initially white but became gray after 72 h at which time tall, branched, septate conidiophores formed. Mature, unicellular, ellipsoid, hyaline conidia (8.9 × 10.4 μm) formed in botryose heads (1). Hard, black, irregular-shaped sclerotia formed after 2 weeks. Stems of greenhouse-grown peanut plants (cv. Georgia Green) were inoculated with PDA plugs colonized with either B. cinerea or B. allii Munn. Inoculations were made 3 cm below the last fully expanded leaf on wounded and nonwounded tissue. Noncolonized PDA plugs served as controls (n = 9). Plants were arranged in a dew chamber at 20°C in a randomized complete block design. Lesions and spore masses identical to those observed in the field appeared 3 to 5 days after being inoculated with B. cinerea. The B. allii inoculations caused only superficial lesions. After 5 days, mean lesion lengths for B. cinerea were 59 and 37 mm for wounded and nonwounded inoculations, respectively. B. cinerea was recovered from 100% of the symptomatic tissues. Botrytis blight is considered a late-season disease that occurs in cool, wet weather (3). Symptoms similar to those of Botrytis blight were observed on mature and over-mature peanut in Georgia and have been cited as "unpublished observations" (2); however, to our knowledge, this is the first report of the disease in Georgia. Although Botrytis blight is not considered a major peanut disease, it may become more prevalent at harvest as producers utilize late-maturing cultivars to manage spotted wilt. References: (1) H. L. Barnett and B. B. Hunter. Illustrated Guide of Imperfect Fungi. 4th ed. The American Phytopathological Society, St. Paul, MN, 1998. (2) K. H. Garren and C. Wilson. Peanut Diseases. Pages 262-333 in: The Peanut, the Unpredictable Legume. The National Fertilizer Assoc. Washington D.C. 1951. (3) D. M. Porter. Botrytis blight. Pages 10-11 in: Compendium of Peanut Diseases. 2nd ed. N. Kokalis-Burelle et al., eds. The American Phytopathological Society, St. Paul, MN. 1997.
由于番茄斑萎病毒（TSWV）引起的花生斑萎病的重要性，美国东南部的大多数花生（Arachis hypogaea L.）育种项目都专注于培育对TSWV的抗性。许多对TSWV抗性增强的品种成熟较晚，需要150天才能达到最佳成熟度。这一因素可能会在收获时极大地影响病害问题。2004年11月，在阿普林县的一个商业田地里，在花生品种Georgia 02-C和赫尔上观察到一种不明病害。症状包括茎部萎蔫，有水浸状病斑，在受感染组织上生长着浓密的灰色霉层。最终病害发生率低于5%。为了分离病原菌，将患病组织在0.5%次氯酸钠中浸泡1分钟进行表面消毒，空气干燥后，接种到马铃薯葡萄糖琼脂（PDA）上，并在20°C下培养。从受感染组织边缘分离出了灰葡萄孢菌（Botrytis cinerea Pers.:Fr.），它是灰霉病的病原菌。菌丝体最初是白色的，但在72小时后变成灰色，此时形成高大、分枝、有隔膜的分生孢子梗。成熟的、单细胞、椭圆形、透明的分生孢子（8.9×10.4μm）在葡萄状头状体中形成（1）。2周后形成坚硬、黑色、形状不规则的菌核。用接种了灰葡萄孢菌或葱腐葡萄孢菌（B. allii Munn.）的PDA菌块接种温室种植的花生植株（品种Georgia Green）的茎。在最后一片完全展开叶下方3厘米处，在受伤和未受伤的组织上进行接种。未接种的PDA菌块作为对照（n = 9）。将植株以随机完全区组设计排列在20°C的露室中。接种灰葡萄孢菌后3至5天，出现了与在田间观察到的相同的病斑和孢子团。接种葱腐葡萄孢菌仅引起表面病斑。5天后，接种灰葡萄孢菌的受伤和未受伤组织的平均病斑长度分别为59毫米和37毫米。从100%的有症状组织中重新分离出了灰葡萄孢菌。灰霉病被认为是一种在凉爽、潮湿天气发生的后期病害（3）。在佐治亚州，在成熟和过熟的花生上观察到了与灰霉病相似的症状，并被引述为“未发表的观察结果”（2）；然而，据我们所知，这是佐治亚州关于该病的首次报道。尽管灰霉病不被认为是花生的主要病害，但随着生产者利用晚熟品种来防治斑萎病，它在收获时可能会变得更加普遍。参考文献：（1）H. L. Barnett和B. B. Hunter。《不完全真菌图解指南》。第4版。美国植物病理学会，明尼苏达州圣保罗，1998年。（2）K. H. Garren和C. Wilson。《花生病害》。载于《花生，不可预测的豆科植物》第262 - 333页。国家肥料协会。华盛顿特区，1951年。（3）D. M. Porter。《灰霉病》。载于《花生病害简编》第2版。N. Kokalis - Burelle等人编。美国植物病理学会，明尼苏达州圣保罗，1997年。
