Since 2015, Araucaria araucana, an ecologically and economically important conifer native to Argentina and Chile, has suffered an unusual partial death of the crown throughout almost all of the distribution range in Argentina. No primary pathogen or pest was evident, associated with the phenomenon. Isolates of Mortierella, a poorly studied fungal genus in Patagonia, were obtained from the margins of necrotic phloem tissue of symptomatic trees. Five species of Mortierella were isolated from affected tissues. In inoculation tests, Mortierella alpina and M. aff. basiparvispora were pathogenic to A. araucana. These species caused necrosis of phloem, leading to chlorosis, foliar desiccation and eventually death, demonstrating that Mortierellales may play a role in the decline of the tree.

中文翻译：

---

阿根廷巴塔哥尼亚正在下降的南洋杉树中的被孢霉属物种

自 2015 年以来，南洋杉是一种原产于阿根廷和智利的在生态和经济上具有重要意义的针叶树，在阿根廷的几乎所有分布范围内都发生了异常的树冠部分死亡。没有明显的主要病原体或害虫与该现象相关。从有症状的树木坏死韧皮部组织的边缘获得被孢霉属的分离株，这是一种在巴塔哥尼亚研究不足的真菌属。从受影响的组织中分离出五种被孢霉属。在接种试验中，Mortierella alpina 和 M. aff。basiparvispora 对 A. araucana 具有致病性。这些物种导致韧皮部坏死，导致萎黄、叶片干燥并最终死亡，这表明被孢霉属可能在树木的衰退中起作用。