The East Asian ambrosia beetle (Xylosandrus germanus - Blandford 1894) is an invasive species that has become successfully established in Europe and North America. In Slovenia, X. germanus was first recorded in 2000 in the western part of the country, and since 2008 the species has also been identified in other parts of Slovenia. The first economic damage was recorded in 2016 after a massive attack on recently felled logs of different tree species, spurring research into this non-native invasive species. To examine the distribution and abundance of X. germanus compared to other ambrosia beetles and to determine voltinism and the flight period of the species in our climatic conditions, we deployed 19 ethanol-baited traps from March to November 2017 in oak-, beech- and fir-dominated forest stands in central Slovenia. To verify the vertical distribution of X. germanus, traps were installed at altitudes ranging from 303 m to 941 m a.s.l. Furthermore, the impact of the ice storm that hit Slovenia in 2014 on the abundance of X. germanus was also studied. Non-native X. germanus represented 71.8% of the total catch and was significantly more abundant than the other five most common species: Xyleborinus saxesenii (20.0%), Xyleborus monographus (3.6%), Anisandrus dispar (2.5%), Trypodendron domesticum (1.2%) and Trypodendron signatum (0.6%). X. germanus was most abundant in beech-dominated stands, but the differences between forest types were not significant. The species was found along the entire altitudinal gradient. Our results indicate that the swarming of X. germanus in lowland forests may already occur by the middle of March. Maximum flying activity was observed in May and early June in forests below 600 m a.s.l. and at the end of May and in June in forests above 700 m a.s.l. Only one generation per year was observed. The ice storm positively affected the abundance of X. germanus, especially in areas where sanitary logging was delayed. Xyleborinus attenuatus was detected for the first time in Slovenia.

Dothistroma septosporum, the primary causal agent of Dothistroma needle blight, is one of the most significant foliar pathogens of pine worldwide. Its wide host and environmental ranges have led to its global success as a pathogen and severe economic damage to pine forests in many regions. This comprehensive global population study elucidated the historical migration pathways of the pathogen to reveal the Eurasian origin of the fungus. When over 3800 isolates were examined, three major population clusters were revealed: North America, Western Europe, and Eastern Europe, with distinct subclusters in the highly diverse Eastern European cluster. Modeling of historical scenarios using approximate Bayesian computation revealed the North American cluster was derived from an ancestral population in Eurasia. The Northeastern European subcluster was shown to be ancestral to all other European clusters and subclusters. The Turkish subcluster diverged first, followed by the Central European subcluster, then the Western European cluster, which has subsequently spread to much of the Southern Hemisphere. All clusters and subclusters contained both mating-types of the fungus, indicating the potential for sexual reproduction, although asexual reproduction remained the primary mode of reproduction. The study strongly suggests the native range of D. septosporum to be in Eastern Europe (i.e., the Baltic and Western Russia) and Western Asia.

Ash dieback is caused by a highly pathogenic fungus Hymenoscyphus pseudoalbidus (anamorph Chalara fraxinea). Possibilities for disease control are limited, and treatment of fallen leaf debris to prevent sporulation of the pathogen is one of the possible options to control the disease. In some cases chemical treatments could be used, but data on effective chemical agents for control of the ash dieback are lacking. The purpose of this study was to examine the effect of different chemical fungicides and urea on the pathogen. Out of eight tested fungicides, mycelial growth in Petri plates as well as development of H. pseudoalbidus apothecia on ash leaf petioles were most efficiently inhibited by carbendazim. Urea also proved to be effective in prevention of apothecial formation. In addition to inhibition of the pathogen, urea accelerates the degradation of treated leaf debris. Therefore, the use of urea for treatment of infected ash leaf debris could be more effective than the use of fungicides and also more environmentally acceptable.

The introduction of non-native organisms into new areas may pose major threats to natural ecosystems. Therefore, continuous and careful national surveys for the interception of invasive non-native species are necessary. During the national survey of quarantine species in 2023, two new non-native ambrosia beetles, Anisandrus maiche (Kurentzov) and Xylosandrus compactus (Eichhoff), were recorded in Slovenia. Anisandrus maiche was recorded in three locations in the eastern part of Slovenia, with a total of 386 individuals. Three individuals of Xylosandrus compactus were collected in one location near the port of Koper. We discuss the possible pathways of introduction and dispersal.