Phytophthora nicotianae diseases worldwide: new knowledge of a long-recognised pathogen

Phytophthora nicotianae was first isolated from tobacco at the end of the 19th century. This organism isnow considered as one of the most devastating oomycete plant pathogens, with a recognized host range of morethan 255 species over five continents and a wide diversity of climates. The economic losses caused by P. nicotianaeare difficult to estimate, because of the diversity of its hosts and ecological niches. For these reasons, this pathogenrepresents a continuous challenge to plant disease management programmes, which frequently rely solely on theuse of chemicals. Phytophthora nicotianae is better adapted than its competitors to abiotic stresses, especially toclimate warming. As a result, its importance is increasing. This review illustrates, with some examples, how P. nicotianaecurrently impacts plant economies worldwide, and how it may constitute more severe threats to agricultureand natural ecosystems in the context of global climate change.9