Elmhirst J F, Verma N
Elmhirst Diagnostics and Research, 5727 Riverside Street, Abbotsford, British Columbia, V4X 1T6, Canada.
13989 29 Avenue, Surrey, British Columbia, V4P 2N1, Canada.
Plant Dis. 2008 Jan;92(1):175. doi: 10.1094/PDIS-92-1-0175B.
Gaultheria shallon Pursh (salal) is a native, Pacific Northwest forest understory plant produced by numerous commercial nurseries as a garden and landscape ground cover. Seed is sown in soilless media in greenhouse plug flats, and seedlings are transplanted into larger pots at 24 to 36 weeks. In October 2005, approximately 30% of 16-week-old G. shallon Pursh (salal) seedlings in a commercial greenhouse in coastal British Columbia, Canada were observed to be dying back. Black, water-soaked, cankers girdled the stems and petioles resulting in seedling necrosis. Cankers extended into the base of affected leaves, and irregular, black leaf spots with concentric rings were observed. A Colletotrichum sp. was isolated on potato dextrose agar (PDA) + 0.005% streptomycin. In May 2006, 160 20-week-old salal seedlings (two- to five-leaf stage) in four plug cell flats of 40 seedlings each were inoculated with a hand atomizer with a mycelial and spore suspension of approximately 1 × 10 CFU/ml (dilution plating) in 100 mL sterile dHO; 120 seedlings (four flats of 30 seedlings each) were sprayed with water alone. Flats were covered with black plastic for 48 h and then placed randomly in a shaded greenhouse at 14 to 22°C with overhead watering. The percentage of necrotic seedlings with black, water-soaked cankers and leaf spots in the inoculated flats at 1 to 8 weeks was 3.8, 7.6, 8.2, 16.4, 44.9, 62.0, 79.7, and 81.6, consecutively; versus 2.5% at 8 weeks in the noninoculated flats. Infection of the noninoculated seedlings was presumably due to spore splash from irrigation. Both the original isolate used as inoculum and colonies reisolated on PDA from inoculated, surface-sterilized, symptomatic tissues were identified as Colletotrichum acutatum J.H. Simmonds based on morphology (2) and PCR using a species-specific primer (1). Hyaline, aseptate, fusiform conidia, measuring 8 to 16 × 2.5 to 4 μm, were produced in acervuli without setae on plants and in culture. The teleomorph (Glomerella) stage was not observed. To our knowledge, this is the first report of an anthracnose disease of salal. References: (1) S. Freeman et al. Plant Dis. 82:596, 1998. (2) J. E. M. Mordue. No. 315 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1971.
沙巴越橘（Gaultheria shallon Pursh）是一种原产于太平洋西北部森林下层的植物，众多商业苗圃将其培育作为花园和景观地被植物。种子播于温室穴盘中的无土基质里，幼苗在24至36周时被移植到更大的花盆中。2005年10月，在加拿大不列颠哥伦比亚省沿海的一个商业温室里，约30%的16周龄沙巴越橘幼苗出现枯萎现象。黑色、水渍状的溃疡环绕着茎和叶柄，导致幼苗坏死。溃疡延伸至受影响叶片的基部，观察到有不规则的、带有同心环的黑色叶斑。在马铃薯葡萄糖琼脂（PDA）+0.005%链霉素培养基上分离到一种炭疽菌属（Colletotrichum sp.）真菌。2006年5月，用手持喷雾器将约1×10 CFU/ml（稀释平板计数法）的菌丝体和孢子悬浮液（100 mL无菌去离子水配制）接种到4个穴盘（每个穴盘40株幼苗）中的160株20周龄沙巴越橘幼苗（二至五叶期）上；120株幼苗（4个穴盘，每个穴盘30株）仅喷水。穴盘用黑色塑料覆盖48小时，然后随机放置在温度为14至22°C的遮荫温室中，进行顶部浇水。接种穴盘在1至8周时出现黑色、水渍状溃疡和叶斑的坏死幼苗百分比依次为3.8%、7.6%、8.2%、16.4%、44.9%、62.0%、79.7%和81.6%；未接种穴盘在8周时为2.5%。未接种幼苗的感染可能是由于灌溉时孢子飞溅所致。根据形态学（2）和使用种特异性引物的PCR（1），用作接种物的原始分离物以及从接种、表面消毒、有症状组织在PDA上重新分离的菌落均被鉴定为尖孢炭疽菌（Colletotrichum acutatum J.H. Simmonds）。在植物和培养物中的分生孢子盘里产生透明、无隔、梭形分生孢子，大小为8至16×2.5至4μm，未观察到有性阶段（小球壳菌属）。据我们所知，这是关于沙巴越橘炭疽病的首次报道。参考文献：（1）S. Freeman等人，《植物病害》82:596，1998年。（2）J.E.M. Mordue，载于《致病真菌和细菌描述》第315号，英联邦真菌研究所，英国萨里郡邱园，1971年。
