Title: Plant imports, Phytophthoras, and forest degradation
Author: Brasier, Clive;
Source: In: Frankel, S.J.; Kliejunas, J.T.; Palmieri, K.M.; Alexander, J.M. tech. coords. 2013. Proceedings of the sudden oak death fifth science symposium. Gen. Tech. Rep. PSW-GTR-243. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 1-2
Publication Series: General Technical Report (GTR)
Numerous 'exotic' tree pathogens are arriving in Europe, North America, and elsewhere due to flaws in current international plant health sanitary and phytosanitary (SPS) protocols. These include lack of protection against the many organisms unknown to science, an emphasis on promoting trade rather than promoting environmental biosecurity, a steadily increasing globalization of the trade in rooted plants, and the failure of regulatory authorities to take meaningful and effective action (Brasier 2005, 2008; Liebhold et al. 2012,Webber 2010). The United Kingdom, for example, has experienced multiple major tree disease events involving introduced pathogens in commercial forests, woodlands, and urban trees over the past decade, from alders and horse chestnuts to pines and larches (Brasier 2012). The situation in the United Kingdom is effectively a full blown, though largely un-trumpeted, forest and amenity tree biosecurity emergency.
Phytophthora species are particularly well suited to spread on imported plants, being frequently soil inhabiting, favored by irrigation and other factors in intensive nurseries, and occurring as latent sporulating infections in symptomless host material (e.g., Denman et al. 2009, Vercauteren et al. 2013). About half of the current disease outbreaks in the United Kingdom are caused by introduced Phytophthora spp., among them two different evolutionary lineages of P. ramorum (EU1 and EU2). The possible scale of the Phytophthora threat is further indicated by an estimate that there may be 100 to 500 Phytophthora spp. unknown to science in underexplored ecosystems – the "invasives in waiting" (Brasier 2009). A significant proportion of these unknowns could be a threat to forest health in the future if they are introduced beyond their native range.
Keywords: PSW-GTR-243, Sudden oak death, Phytophthora ramorum, invasive species, tanoak, Notholithocarpus densiflorus, coast live oak, Quercus agrifolia, Japanese larch, Larix kaempferi
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Brasier, Clive. 2013. Plant imports, Phytophthoras, and forest degradation. In: Frankel, S.J.; Kliejunas, J.T.; Palmieri, K.M.; Alexander, J.M. tech. coords. Proceedings of the sudden oak death fifth science symposium. Gen. Tech. Rep. PSW-GTR-243. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 1-2.
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