Fusarium circinatum, the causal agent of pine pitch canker (PPC), is currently one of the most important threats of Pinus spp. globally. This pathogen is known in many pine-growing regions, including natural and planted forests, and can affect all life stages of trees, from emerging seedlings to mature trees. Despite the importance of PPC, the global distribution of F. circinatum is poorly documented, and this problem is also true of the hosts within countries that are affected. The aim of this study was to review the global distribution of F. circinatum, with a particular focus on Europe. We considered (1) the current and historical pathogen records, both positive and negative, based on confirmed reports from Europe and globally; (2) the genetic diversity and population structure of the pathogen; (3) the current distribution of PPC in Europe, comparing published models of predicted disease distribution; and (4) host susceptibility by reviewing literature and generating a comprehensive list of known hosts for the fungus. These data were collated from 41 countries and used to compile a specially constructed geo-database. A review of 6297 observation records showed that F. circinatum and the symptoms it causes on conifers occurred in 14 countries, including four in Europe, and is absent in 28 countries. Field observations and experimental data from 138 host species revealed 106 susceptible host species including 85 Pinus species, 6 non-pine tree species and 15 grass and herb species. Our data confirm that susceptibility to F. circinatum varies between different host species, tree ages and environmental characteristics. Knowledge on the geographic distribution, host range and the relative susceptibility of different hosts is essential for disease management, mitigation and containment strategies. The findings reported in this review will support countries that are currently free of F. circinatum in implementing effective procedures and restrictions and prevent further spread of the pathogen.

Ash dieback caused by the invasive alien fungal pathogen Hymenoscyphus fraxineus often has devastating consequences for the survival, growth and wood quality of Fraxinus excelsior. We analyse the silvicultural implications of ash dieback in forest stands in Europe and review the advice on how to modify management accordingly. We draw on literature as well as unpublished observations and personal experience. The relevant strategy depends on the management objective, the site type (moist or dry), the stand type (pure or mixed stands, even-aged or uneven-aged stands), the age and the degree of dieback. Generally, the strategy should be conservative and trees that are healthy or slightly damaged may be marked and retained. Where dieback is severe, the suggested approach is to harvest remaining commercial timber before value depreciation and to regenerate or replant the area with other tree species. In forests of high value for habitat conservation, it may be advisable to let natural succession proceed unhindered. In all situations, forestry practice plays a key role in implementing in situ and ex situ conservation strategies for ash by preserving trees with low damage levels in all phases of stand development. Wherever there are infected ash trees, risks for operational staff, forest visitors and infrastructure posed by damaged, destabilized ash trees must be minimized.

In recent years collar necroses and butt rot associated with the ash dieback disease occurred with alarming frequency in Fraxinus excelsior. We analysed tree ring structures to identify the year of necrosis initiation on a set of 507 necroses on 155 stem discs from nine severely diseased south-western German stands. The number of first-time infections of trees was highest from 2010 to 2012 and slightly decreased in 2013 and 2014, whereas the total number of newly emerging individual necroses remained high. Logistic modelling of disease progression suggests that collar rot infection has almost reached its maximum incidence and that a fraction of trees will remain healthy at the root collar. On average, Hymenoscyphus fraxineus was isolated more frequently from younger collar necroses, whereas older necroses were more often colonized by Armillaria spp. Advanced stages of rot that may pose a risk to forest workers, visitors and traffic were observed already in two years-old necroses infected by Armillaria spp.

• Lecanosticta spp.now recorded in 44 countries, mostly in the northern hemisphere. • L. acicola has increased its range, now found in 24 out of 26 European countries. • Climate change means L. acicola could affect 74% of Pinus forested area by 2100. • Lecanosticta species were recorded on 70 hosts, including Pinus, Cedrus and Picea. • We explore global BSNB management strategies using European Case studies.