Target Investigations Xylella fastidiosa and hemipteran vector species. The harmful Gram-negative bacteria Xf is involved in a new and severe olive disease (Olive Quick Decline Syndrome – OQDS) firstly reported in 2013 in southern Italy (Apulia region, Salento peninsula). Xf isolated in Italy has been identified as a novel and distinct genotype (hereafter denoted as “CoDiRO Xf strain”), showing phylogenetic relationship with isolates of Xf subsp. pauca infecting oleander in Costa Rica. Although Xfis widely distributed in the Americas due to diseases caused in grapevine, citrus, fruit trees, and landscape plants, the first confirmed presence of Xf in the EU constitutes a novel and emerging threat for European agriculture. ‘Candidatus Liberibacter solanacearum’ and psyllid vector species. CaLsol is a recently described phloem-limited, Gram-negative, not culturable bacterium that has emerged as one of the most important pathogens affecting potato and other solanaceous crops (i.e. tomato and pepper) in the Americas and New Zealand. Recently EPPO has recommended member countries to regulate solanaceous haplotypes of CaLsol and its psyllid vector Bactericera cockerelli as quarantine pests, since non-solanaceous CaLsol haplotypes have now been found in Europe associated with diseased carrots and celery. The emergence of these CaLsol haplotypes in carrots and celery has raised serious concerns about the risk that they pose to potato and other solanaceous crops across the whole EU. Hymenoscyphus pseudoalbidus (anamorph. Chalara fraxinea) and new and exotic Phytophthora species. Hp is a pathogen introduced, for the first time in Poland in 2006, via plant trade, mainly affecting common ash (Fraxinus excelsior) and the narrow-leafed ash (F. angustifolia). The disease is usually fatal and has now been reported in most continental European countries as a very serious threat to ash populations. In addition, an increasing number of new emerging diseases affecting forest trees caused by several Phytophthora spp. is leading to significant economic losses and pose considerable risks to natural ecosystems. The knowledge of the genus Phytophthora is still limited and some hybrid species are still evolving, potentially increasing the risk of colonization of new forest hosts.