Newcombe G, Callan B E
Washington State University, Puyallup 98371-4998.
Pacific Forestry Centre, Victoria, BC Canada, V8Z 1M5.
Plant Dis. 1997 Feb;81(2):231. doi: 10.1094/PDIS.1997.81.2.231B.
Marssonina brunnea (Ellis and Everh.) Magnus f. sp. brunnea Spiers is the most damaging Marssonina sp. affecting Populus spp. in the world (1). First described from eastern North America at the turn of the century, it subsequently became a serious disease of hybrid poplar in Europe in the 1960s and in New Zealand in 1976 (1). It causes punctiform black spots on both leaf surfaces and lesions on petioles and young stems. Symptoms are typically most severe in the lower portion of the crown of trees. Not observed in the Pacific Northwest on hybrid poplar until recently, it is still only present in a few locations. Voucher specimens from near Ilwaco, WA, at the mouth of the Columbia River, and from near Har-rison Mills, British Columbia, were deposited in the Herbarium at the Pacific Forestry Centre (DAVFP 25202 and 24958, respectively). The fungus was identified as M. brunnea by its conidial morphology. Conidia were hyaline, uniseptate, mostly straight, and narrowly obovoid, and, when measured in lactoglycerol, averaged 16.1 μm × 5.0 μm (WA collection) and 15.7 μm × 5.6 μm (BC collection). The septum is located about 30% of the total conidium length from the conidium base. Inoculations of leaf disks (1) proved that the species was pathogenic to hybrids but not to local P. tremuloides Michx., and thus the fungus was identified as M. brunnea f. sp. brunnea. Variation in resistance, from light spotting to severe, was noted both among 12 P. trichocarpa Torr. & A. Gray × P. deltoides J. Bartram ex. Marsh. hybrid clones in the Ilwaco plantation and among 56 hybrid clones in the inoculation study. Reference: (1) A. G. Spiers. Eur. J. For. Pathol. 18:140, 1988.
杨树炭疽病菌（Ellis和Everh.）Magnus f. sp. brunnea Spiers是世界上对杨树危害最大的炭疽菌（1）。该病菌于世纪之交首次在北美东部被描述，随后在20世纪60年代成为欧洲杂交杨树的一种严重病害，并于1976年在新西兰出现（1）。它会在叶片两面形成点状黑点，在叶柄和幼茎上造成病斑。症状通常在树冠下部最为严重。直到最近，在太平洋西北部的杂交杨树上才发现这种病菌，且目前仅在少数地点存在。来自华盛顿州伊尔瓦科附近（哥伦比亚河口）以及不列颠哥伦比亚省哈里森米尔斯附近的凭证标本分别保存在太平洋林业中心植物标本馆（分别为DAVFP 25202和24958）。通过分生孢子形态将该真菌鉴定为杨树炭疽病菌。分生孢子透明，具单隔膜，大多直形，狭倒卵形，在乳酸甘油中测量时，华盛顿州采集的平均为16.1μm×5.0μm，不列颠哥伦比亚省采集的平均为15.7μm×5.6μm。隔膜位于分生孢子基部至分生孢子总长度的约30%处。叶片接种试验（1）证明该菌种对杂交杨树致病，但对当地的颤杨（P. tremuloides Michx.）不致病，因此该真菌被鉴定为杨树炭疽病菌f. sp. brunnea。在伊尔瓦科种植园的12个毛果杨（P. trichocarpa Torr. & A. Gray）×美洲黑杨（P. deltoides J. Bartram ex. Marsh.）杂交克隆以及接种研究中的56个杂交克隆中，均观察到了从轻度斑点到严重症状的抗性差异。参考文献：（1）A. G. Spiers。《欧洲林业病理学杂志》18:140，1988年。
