Tree invasions and biosecurity: eco-evolutionary dynamics of hitchhiking fungi

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Phytophthora cactorum and Colletotrichum acutatum: Survival and Detection

Phytophthora cactorum and Colletotrichum acutatum are pathogens which are transported with plant material as latent infections and can also survive in soil and plant debris. Since the beginning of 1990’s P. cactorum caused losses in strawberries in Finland and increased culling of silver birch seedlings in forest nurseries because of stem lesions. In this study primers specific for the pathogen were designed, and in a simple PCR they gave an amplification product from pure cultures only when P. cactorum was used as a template. No cross reactions were found with other Phytophthoras in group I or other microbes. Inoculated strawberry plants gave also a clear band in PCR-analyses when the template concentration was diluted. However, amplification was not always reproducible with birch seedlings. With soil samples the best result was gained by a combination of baiting and isolation. C. acutatum is a quarantine pathogen on strawberry in the European Union and thus the infected plants are destroyed in Finland to avoid further spread of the pathogen. The pathogen has earlier been found to survive over one winter in infected plant debris and soil. In the survival test (2003-2005) done in this study, specific amplification products were obtained from test plants inoculated with artificially infected plant residues after 20 months of storage outdoors on soil surface. More positive results were achieved from bait plants grown in soil collected from the field where infected plants had been destroyed two years before, than from samples collected a year after the plant destruction

FORESTS AND SOCIETY – RESPONDING TO GLOBAL DRIVERS OF CHANGERegional Examples of Forest Related Challenges and Opportunities 14 Sustainability of Boreal Forests and Forestry in a Changing Environment

Abstract: The circumpolar boreal forest is the fourth largest terrestrial biome on the planet. It is entering a period of relatively rapid transition, propelled by climate change and economic development. Warming conditions threaten to alter processes as diverse as permafrost retention, insect outbreaks, and transportation. Thawing permafrost and increased levels of natural and anthropogenic disturbance may result in net releases of carbon dioxide and methane, while forest cover with greater biomass can be expected to expand onto the arctic tundra. Human use in some parts of northern forests is becoming more centralised and industrialised, with cumulative impacts from hydroelectric development, the oil and gas sector, mining, timber harvesting, and transportation. Communities tend to be widely spaced, and are either highly dependent on resource-based commodity exports or on subsistence-based lifestyles supported by local biodiversity. Efforts are underway in many jurisdictions to curtail illegal logging and environmentally damaging industrial development, to account for non-timber forest values in the course of forest management, and to promote the economic diversification of communities. In order to preserve the integrity of ecosystem processes, effort

Viruses accumulate in aging infection centers of a fungal forest pathogen

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