Kasson Matthew T, Livingston William H
Pennsylvania State University, Department of Plant Pathology, 401 Buckhout Laboratory, University Park, Pennsylvania 16802, USA.
Mycologia. 2009 Mar-Apr;101(2):190-5. doi: 10.3852/08-165.
Beech bark disease (BBD) requires prior infestation of bark by an exotic scale insect, Cryptococcus fagisuga, to permit infection by one or more fungi, primarily Neonectria ditissima and Neonectria faginata. Previous studies in North America report a progression in which N. faginata replaces N. ditissima as the dominant pathogen in the BBD complex. To examine the status of the Neonectria populations in forests that have developed for decades with and without BBD a survey was conducted 2005-2006 in northern Maine. Ascospore measurements from 201 beech bark disks containing mature perithecia support reports that, once established, N. faginata dominates the BBD complex. However stands did contain more N. ditissima when other highly susceptible hardwood tree species were present (R2 = 0.775), regardless of disease severity. Abundance of N. ditissima in areas long affected by BBD suggests that N. ditissima, by continually supplying inocula from nonbeech hosts, continues to affect BBD.
山毛榉树皮病（BBD）需要一种外来的介壳虫—— Cryptococcus fagisuga先侵染树皮，才能使一种或多种真菌（主要是 Neonectria ditissima和 Neonectria faginata）感染。北美此前的研究报告了一种进展情况，即 N. faginata取代 N. ditissima成为BBD复合体中的主要病原体。为了研究在有和没有BBD的情况下已经发展了几十年的森林中Neonectria种群的状况，2005年至2006年在缅因州北部进行了一项调查。对201个含有成熟子囊壳的山毛榉树皮圆盘进行的子囊孢子测量结果支持了以下报告，即一旦定殖，N. faginata在BBD复合体中占主导地位。然而，当存在其他高度易感的硬木树种时，林分中确实含有更多的 N. ditissima（R2 = 0.775），无论疾病严重程度如何。在长期受BBD影响的地区，N. ditissima的数量较多，这表明 N. ditissima通过不断从非山毛榉寄主提供接种体，继续影响BBD。
