Incidence and impact of Swiss needle cast in forest plantations of Douglas-fir in coastal Oregon
Incidence and impact of Swiss needle cast in forest plantations of Douglas-fir in coastal Oregon
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DOI：
10.1094/pdis.2000.84.7.773
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发表时间：
2000-07-01
期刊：
影响因子：
4.5
通讯作者：
McWilliams, MG
中科院分区：
文献类型：
--
作者：
Hansen, EM;Stone, JK;McWilliams, MG
由子囊菌Phaeocryptopus gaeumannii引起的瑞士针管流行病正在导致俄勒冈州海岸沿线的花旗松人工林落叶和生长减少。自1996年以来，每年通过航空勘测对有症状的种植园面积进行监测； 1999年春季，119,500公顷受到影响。还在不同疾病严重程度的九个永久性地块上监测了病原体和症状的发展。靠近海岸的低海拔种植园的感染水平和症状严重程度最高。在病害严重的地区，树木只保留当年的针叶。落叶与真菌假囊泡闭塞的气孔数量成正比，无论针叶年龄如何，当大约 50% 的气孔被占据时，针叶就会脱落。真菌孢子形成和过早针叶脱落在树木的上部树枝上最为严重。每年使用杀菌剂可显着增加针头保留率。树木的高度和直径生长以及树木总体积因疾病而减少，并且树木体积与我们小区树木上的针保留显着相关。在早期以西特卡云杉和西部铁杉或红桤木为主的地区建立的花旗松种植园中，这种流行病仍然最为严重。
An epidemic of Swiss needle cast, caused by the ascomycete Phaeocryptopus gaeumannii, is causing defoliation and growth reductions in Douglas-fir forest plantations along the Oregon Coast. The area of symptomatic plantations has been monitored annually since 1996 by aerial survey; in spring 1999, 119,500 ha were affected. Pathogen and symptom development have also been monitored on nine permanent plots in stands of differing disease severity. Infection levels and symptom severity are greatest in low elevation plantations close to the coast. In areas of severe disease, trees retain only current year needles. Defoliation is proportional to the number of stomata occluded by pseudothecia of the fungus, with needles being shed when about 50% of stomata are occupied, regardless of needle age. Fungus sporulation and premature needle abscission are greatest on the upper branches of trees. Annual application of fungicides increases needle retention significantly. Tree height and diameter growth and total tree volume are reduced by disease, and tree volume is significantly correlated with needle retention on our plot trees. The epidemic continues to be most severe in Douglas-fir plantations established on sites where Sitka spruce and western hemlock or red alder predominated in earlier times.