Wright A F, Harmon P F
Department of Plant Pathology, University of Florida, Gainsville.
Plant Dis. 2009 Sep;93(9):962. doi: 10.1094/PDIS-93-9-0962C.
Stem blight of southern highbush blueberries has been attributed to Botryosphaeria dothidea (2). Symptoms include necrotic branches with attached leaves and brown discoloration of the vasculature extending the length of the affected branch. A 2007 field survey of stem blight in Florida resulted in isolates of the previously reported B. dothidea and Neofusicoccum ribis and isolates of unreported Lasiodiplodia theobromae (2). Isolates of L. theobromae were identified to species level by morphological characterization (3). Identity was confirmed by comparison of rDNA sequences of representative isolates (GenBank Accession No. FJ882072) to reference sequences (99% similarity to Accession No. EF622074) (1). Seven, fresh, pruning wounds on southern highbush blueberries cv. Misty were inoculated with a 10-mm V8 juice agar plug of isolate MixFC-6 taken from the margin of a 3-day-old colony. Seven wounds were inoculated with a sterile agar plug. All plugs were attached to the wounds with Parafilm. Mean lesion length 14 days after inoculation was 8.6 ± 2.4 cm. The pathogen was reisolated from the margin of lesions and identified by colony growth characteristics on potato dextrose agar. No lesions were observed on control plants. To our knowledge, this is the first report that stem blight of southern highbush blueberries in Florida can be caused by L. theobromae. References: (1) A. Alves et al. Fungal Divers. 28:1, 2008. (2) F. L. Caruso and D. C. Ramsdell. Compendium of Blueberry and Cranberry Diseases. The American Phytopathological Society, St. Paul, MN, 1995. (3) P. W. Crous et al. Stud. Mycol. 55:235, 2006.
南方高丛蓝莓的干腐病被认为是由葡萄座腔菌（Botryosphaeria dothidea）引起的（2）。症状包括带有附着叶片的坏死枝条以及受影响枝条全长范围内维管束的褐色变色。2007年在佛罗里达州对干腐病进行的田间调查，分离出了先前报道过的葡萄座腔菌和李新壳梭孢（Neofusicoccum ribis），以及未报道过的可可毛色二孢（Lasiodiplodia theobromae）（2）。通过形态学特征将可可毛色二孢的分离株鉴定到种的水平（3）。通过将代表性分离株的rDNA序列（GenBank登录号FJ882072）与参考序列进行比较（与登录号EF622074的相似度为99%）来确认其身份（1）。在南方高丛蓝莓品种“密斯提”（cv. Misty）上，用取自3日龄菌落边缘的10毫米V8汁琼脂块接种了7个新鲜的修剪伤口。用无菌琼脂块接种了7个伤口。所有琼脂块都用封口膜固定在伤口上。接种后14天的平均病斑长度为8.6±2.4厘米。从病斑边缘重新分离出病原菌，并通过在马铃薯葡萄糖琼脂上的菌落生长特征进行鉴定。对照植株上未观察到病斑。据我们所知，这是关于佛罗里达州南方高丛蓝莓干腐病可由可可毛色二孢引起的首次报道。参考文献：（1）A. Alves等人，《真菌多样性》（Fungal Divers.）28:1，2008年。（2）F. L. Caruso和D. C. Ramsdell，《蓝莓和蔓越莓病害简编》（Compendium of Blueberry and Cranberry Diseases）。美国植物病理学会，明尼苏达州圣保罗，1995年。（3）P. W. Crous等人，《真菌学研究》（Stud. Mycol.）55:235，2006年。
