Shamoun S F, Zhao S
Canadian Forest Service, Pacific Forestry Centre, 506 West Burnside Road, Victoria, BC V8Z 1M5, Canada.
Plant Dis. 2005 Jun;89(6):685. doi: 10.1094/PD-89-0685B.
Salal (Gaultheria shallon Pursh.) is an ericaceous, evergreen, and rhizomatous shrub that competes for nutrients and moisture with young conifers in low elevation, coastal British Columbia (BC). A survey was conducted on southern Vancouver Island, BC during the summer of 1999 to find fungal pathogens of salal that might serve as biocontrol organisms (3). Phoma exigua Desmaz. (isolate PFC2705) near Parksville, BC proved to be pathogenic on salal. Identification of PFC2705 at the Centraalbureau voor Schimmelcultures was based on morphology and ITS sequences (GenBank Accession No. AY927784). Pathogenicity was determined with 24 salal seedlings (3-month-old) by inoculating with mycelial suspensions (20% v/v) or conidial suspensions (1 × 10 conidia per ml in 0.5% potato dextrose broth). Inoculated seedlings were placed in plastic bags and incubated in a greenhouse (16 to 23°C with natural light). Plastic bags were removed after 2 days. Initial disease symptoms were observed 2 days after inoculation. Brown, sunken lesions appeared on the surface of young leaves and stems and extended quickly. All seedlings were killed within 14 days. Twelve control plants showed no disease symptoms. With diseased salal leaves incubated at 23°C with 12-h fluorescent light/dark and 100% relative humidity, pycnidia appeared on leaf surfaces within 5 days. Conidia were hyaline, ellipsoid, one-celled, sometimes two- to three-celled, 2.5 to 3.8 × 5 to 12.5 μm, with a rounded base; the colony was gray or dark gray on potato dextrose agar after 5 to 7 days. Reisolation from the inoculated diseased leaves produced a mycelial colony that shared the same growth and morphological characteristics as the initial isolate. Phyllosticta gaultheriae Ellis & Everh., a widely reported foliar pathogen of salal, is distinct morphologically from P. exigua (1). To our knowledge, this is the first report of P. exigua as a pathogen of salal in Canada (2). A voucher specimen has been deposited at the Pacific Forestry Center Herbarium (DAVFP No. 28735). References: (1) J. Bissett and S. J. Darbyshire. No. 275 in: Fungi Canadenses, 1984. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society. St. Paul. MN, 1989. (3) S. F. Shamoun et al. Can. J. Plant Pathol. 22:192, 2000.
沙巴越橘（Gaultheria shallon Pursh.）是一种杜鹃花科的常绿根茎灌木，在不列颠哥伦比亚省（BC）沿海的低海拔地区会与幼年针叶树争夺养分和水分。1999年夏天，在BC省温哥华岛南部进行了一项调查，以寻找可能用作生物防治剂的沙巴越橘真菌病原体（3）。位于BC省帕克斯维尔附近的微小茎点霉（Phoma exigua Desmaz.，分离株PFC2705）被证明对沙巴越橘具有致病性。在荷兰真菌生物多样性中心对PFC2705的鉴定基于形态学和ITS序列（GenBank登录号AY927784）。通过用菌丝体悬浮液（20% v/v）或分生孢子悬浮液（在0.5%马铃薯葡萄糖肉汤中每毫升含1×10个分生孢子）接种24株3个月大的沙巴越橘幼苗来测定致病性。接种后的幼苗被放入塑料袋中，在温室（16至23°C，自然光）中培养。2天后取出塑料袋。接种后2天观察到初始病害症状。幼叶和茎表面出现褐色、凹陷的病斑，并迅速扩展。所有幼苗在14天内死亡。12株对照植物未表现出病害症状。将患病的沙巴越橘叶片在23°C、12小时荧光光照/黑暗和100%相对湿度下培养，5天内在叶片表面出现分生孢子器。分生孢子无色透明，椭圆形，单细胞，有时双细胞至三细胞，2.5至3.8×5至12.5μm，基部圆形；在马铃薯葡萄糖琼脂上培养5至7天后菌落为灰色或深灰色。从接种的患病叶片上重新分离得到的菌丝体菌落与初始分离株具有相同的生长和形态特征。广泛报道的沙巴越橘叶部病原体高氏叶点霉（Phyllosticta gaultheriae Ellis & Everh.）在形态上与微小茎点霉不同（1）。据我们所知，这是微小茎点霉作为加拿大沙巴越橘病原体的首次报道（2）。一份凭证标本已存放在太平洋林业中心植物标本馆（DAVFP编号28735）。参考文献：（1）J. Bissett和S. J. Darbyshire。载于《加拿大真菌》，1984年，第275号。（2）D. F. Farr等人。《美国植物和植物产品上的真菌》。美国植物病理学会。明尼苏达州圣保罗。1989年。（3）S. F. Shamoun等人。《加拿大植物病理学杂志》22:192，2000年。
