Forest pathologists worldwide share a deep concern over the threat caused by alien invasive pathogens and pests appearing at an increasing frequency in Europe, as well as other forested continents.
In May 2011 seventy forest pathologists gathered in the Montesclaros Monastry, Spain, for a meeting in order to discuss recent research results. The discussions lead to a declaration urging strict constrictions to the international trade of especially rooted plants for planting. The declaration has been published on net pages of the International Union of Forest Research Organisations (IUFRO) and was named as Montesclaros Declaration. It has been signed by over 140 scientists from more than 30 countries.
During collection and edition of the supporting material (published together with the declaration) I realized how limited the availability of pictures is on large scale forest damages caused by alien, invasive forest pathogens and pests.
The threat caused by alien invasive forest pathogens could be largely eliminated simply by a ban of international trade of plants for planting, without the need of expensive protective measures. As an alternative to a trade ban, a licence mechanism could be established in which the costs caused by alien invasive pathogens and pests would be incorporated into the trade expenses. This idea has been proposed in a recent publication (Hantula, Müller & Uusivuori 2014).
The major tree species in Finnish forests (pine, spruce, birch and aspen) have so far not been challenged by serious alien forest pathogens but since 2007 ash stands in South Finland have been attacked by a new pathogen of Asian origin, Hymenoscyphus fraxineus. Luckily, this pathogen has not yet been as damaging here in Finland as elsewhere in Central Europe where it has often destroyed 90 % of the living mature trees. I have made a video (in Finnish language) on this disease in Finland with an interview of professor Jarkko Hantula and you find it on these net pages under Videos.