PDF(Pubmed)
Abstract：
Nothophaeocryptopus gaeumannii is a common native, endophytic fungus of Douglas-fir foliage, which causes Swiss needle cast, an important foliage disease that is considered a threat to Douglas-fir plantations in Oregon. Disease expression is influenced by fungal fruiting bodies (pseudothecia), which plug the stomata and inhibit gas exchange. Trees are impacted when pseudothecia plug stomates on 1-year-old and older needles resulting in early needle abscission. Mature (100 years+) trees appear to be less impacted from disease, and we hypothesize this is due to the greater emergence of pseudothecia on older than younger needles, which allows for more needle retention. We measured the density of pseudothecia occluding stomates across 2- to 5-year-old needles from upper, middle, and lower canopy positions of mature trees at three sites in the Oregon Coast Range and two sites in the western Oregon Cascade Mountains. Binomial generalized linear mixed model (GLMM) was used to test for the effects of canopy position (upper, middle, and lower), sites, needle age (2-5 years old), and years (2016 and 2017), and their interactions on the pseudothecia density. Pseudothecia density varied annually depending on sites, needle age and canopy positions. Pseudothecia density peaked on 3-, and 4-year-old needles, however, needles emerging from the same year, like 2-year-old needles in 2016 and 3-year-old needles in 2017 both emerged in 2014, had consistently similar patterns of pseudothecia density for both years, across site and canopy positions. Canopy position was important for 3-, and 4-year-old needles, showing less pseudothecia in the lower canopy. This research confirms that N. gaeumannii pseudothecia density is greatest in 3- and 4-year old needles in mature trees in contrast to plantations where pseudothecia density usually peaks on 2-year-old needles, and that pseudothecia density (disease severity) is generally lower in mature trees. Something about mature forest canopies and foliage appears to increase the time it takes for pseudothecia to emerge from the needles, in contrast to younger plantations, thus allowing the mature trees to have greater needle retention.
摘要：
Nothophaeocryptopusgaeumannii是一个普通的本地人，道格拉斯冷杉叶的内生真菌，这导致瑞士针铸造，一种重要的叶子疾病，被认为是对俄勒冈州道格拉斯冷杉种植园的威胁。疾病表达受真菌子实体（假）的影响，堵塞气孔并抑制气体交换。当1岁和较旧的针头上的假性塞子造口导致早期针头脱落时，树木会受到影响。成熟（100年以上）的树木似乎受到疾病的影响较小，我们假设这是由于年龄较大的针头比年轻的针头出现更多的假性，这允许更多的针头保留。我们从上部测量了2至5岁的针头上的假阻塞口的密度，中间,在俄勒冈海岸山脉的三个地点和俄勒冈喀斯喀特山脉西部的两个地点，成熟树木的冠层位置较低。二项广义线性混合模型(GLMM)用于测试冠层位置的影响(上，中间,andlower),网站,针龄（2-5岁），和年份（2016年和2017年），以及它们对伪质密度的相互作用。假性密度每年因地点而异，针龄和冠层位置。伪质密度在3-上达到峰值，和4岁的针头，然而,同一年出现的针头，就像2016年的2岁针头和2017年的3岁针头都是在2014年出现的，这两年的假性针头密度一直相似，跨站点和顶篷位置。树冠的位置对3-很重要，和4岁的针头，在较低的树冠中显示出较少的假性。这项研究证实，与人工林相比，成熟树木中3岁和4岁的针叶中的假草密度最大，而2岁的针叶中的假草密度通常达到峰值。在成熟的树木中，假性密度（疾病严重程度）通常较低。关于成熟的森林树冠和树叶的一些东西似乎增加了假针出现的时间，与年轻的种植园相比，从而使成熟的树木有更大的针保留。
