Ecology of larch black leaf rust in Russian Far East

落叶松黑叶锈病在东北及邻近地区的落叶松种中普遍存在。这种锈病是1994年在俄罗斯滨海地区的lgmelini上发现的。病害发生严重，表明只要环境条件有利于病原菌的传播和感染，病原菌就有可能破坏针叶林植被的主要组成部分落叶松林。然而，它的生命周期、宿主特异性和初次接种量在自然界中几乎一无所知，所有这些对于制定基于生态学的疾病有效控制措施是必不可少的。在这方面，1995年在符拉迪沃斯托克、乌苏里斯基和锡霍特-阿林自然保护区以及滨海边疆区和雅库茨克的利瓦迪斯卡亚山进行了实地观察。这种锈病只在锡霍特-阿林自然保护区的lgmelini上发现，那里的锈病似乎持续存在。在病原菌的生命周期中，首次在自然界中发现了其尿路期，表明真菌通过无性繁殖的尿路孢子进行繁殖和广泛传播。接种实验证明了这一假设；在L.gmelini上形成的脲嘧啶孢子成功地感染了L.gmelini和l.k empferi，先产生脲嘧啶，然后在这两个物种上产生结核菌。为了了解落叶松黑叶锈菌的整个生命周期，目前正在进行进一步的接种试验。

Larch black leaf rust was known to occur on Larix species in northeast China and adjacent areas. The rust was found on L.gmelini in the Primorski District, Russia in 1994. The disease incidence was sever and indicated that the causal fungus has potential to devastate larch stands, which are the major component of the Taiga vegetation, whenever environmental conditions favor the fungus to spread and infect. Nevertheless, virtually nothing is known as to its life cycle, host specificity and primary inoculum in nature, all of which are indispensable in order to develop the ecology-based effective control measures of the disease. In this context, field observations were carried out in Vladivostok, Ussuriski and Sikhote-Alin Nature Reserves, and Mt. Livadiskaya in the Primorski District and Yakutsk in 1995. The rust was only found on L.gmelini in the Sikhote-Alin Nature Reserve where the rust seemed to persist steadily. As to life cycle of the causal fungus, its uredinial stage was found for the first time in nature, indicating that the fungus multiplies and widely disperses by the vegetatively reproducing urediniospores. Inoculation experiments proved this presumption ; the urediniospores formed on L.gmelini was successfully infected L.gmelini and L.kaempferi reproducing uredinia first and then telia on both species. Further inoculation experiments are now being made to find out entire life cycle of the larch black leaf rust fungus.