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.

Populus × euramericana (Dode) Guinier clone (cl.) “I-214” is a fast-growing interspecific hybrid between Eastern cottonwood (P. deltoides Bartr. ex Marsh) and European black poplar (Populus nigra L.). Populus × euramericana was introduced into Serbia in the 1950s and has become one of the most widely grown poplar species. In September 2019, cankers were observed on stems and branches of P. × euramericana cl. “I-214” trees in a two-year-old poplar plantation in the province of Vojvodina, Serbia. The canker tissue was soft and watery, and a colorless fluid that smelled rotten flowed from the cracks in the bark, suggesting possible bacterial disease. After two weeks, diseased trees experienced crown die-back and oozing of foamy, odorous exudates and this study aimed to identify the causal agent of the disease. Canker margins and exudates were collected from 20 symptomatic trees. The associated bacterium was isolated and identified using biochemical characteristics, phylogenetic analyses based on 16S rRNA gene sequences, and multilocus sequence analyses (MLSA) based on partial sequencing of three housekeeping genes (gyrB, infB, and atpD). The pathogen was identified as Lonsdalea populi. Pathogenicity tests were conducted on rooted cuttings of P. × euramericana cl. “I-214” in an environmental test chamber and demonstrated that the isolated bacterial strain was able to reproduce symptoms of softened, water-soaked cankers and exudation. To the best of our knowledge, this is the first report of L. populi causing bacterial canker disease on P. × euramericana cl. “I-214” in Serbia and in southeastern Europe (SEE). It is also the first report of a bacterial disease on hybrid poplars, including P. × euramericana in this country and in SEE. If the disease spreads into new areas, selection for L. populi resistance may need to be integrated into future poplar breeding programs.

In this study, the growth and physiological performance of four newly bred black locust (Robinia pseudoacacia L.) clones (‘NK1’, ‘NK2’, ‘PL040’, ‘PL251’) together with one registered in Hungary (‘Üllői’) were monitored and compared in a field experiment located in the dry temperate climatic zone of Eastern Central Europe. Tree height and diameter at breast height were measured monthly during May–August 2022, an extremely dry period. Ecophysiological parameters such as leaf temperature, vapor pressure deficit, intercellular carbon dioxide level, transpiration and assimilation rates, and stomatal conductance to water and CO₂ were measured in situ. There was a high clonal effect on survival rate and growth of the trees and on the physiological parameters. ‘NK1’ performed best regarding height (1.88 m), while ‘PL040’ (23.76 mm) had the highest diameter increment (n = 16–26). The highest carboxylation efficiency was found in ‘NK2’ (0.077 µmol m⁻² s⁻¹), while the lowest was in ‘NK1’ (0.035 µmol m⁻² s⁻¹), not showing a significant difference from the ‘Üllői’. Water-use efficiency values were found to be the highest in ‘NK2’ and ‘Üllői’ (4.92 and 4.78 kg m⁻³, respectively). C_i was found to be maximum in ‘NK1’ and ‘PL040’ (286.15 and 287.37 µmol mol⁻¹, respectively), while it was minimum in ‘Üllői’ (248.30 µmol mol⁻¹). Physiological parameters were found to be significantly different in the clones due to their genetic differences. A strong positive correlation was found between the transpiration and the assimilation rates (r = 0.843–0.994). Within the growing period, the loss of leaves due to abiotic stress was 0 for ‘NK1’ and negligible for the others. ‘NK2’ stood out among the other clones in most of the parameters tested (height, thickness, assimilation, WUE). In addition to its high photosynthetic intensity, its water-use efficiency was also high.

Department of Forest Protection of the Hungarian Forest Research Institute started a long term monitoring project in 2002 in order to study the Alder Phytophthora disease, particularly to determine the importance of the disease, the extent of the damage and the severity of the infection at different regions of the country. According to the results of four years investigations, Phytophthora and its typical symptoms are present all over Hungary. The rate of the infected trees, the intensity and spreading of Phytophthora infection, together with the rate of mortality shows, that this disease currently do not poses a direct danger to the existence of alder stands. Phytophthora symptoms were found in 75% of the stands but in 50.9% of the plots with Phytophthora present the infection rate is lower than 1%.

Forest damage has been increasingly recorded over the past decade in both Europe and Hungary, primarily due to prolonged droughts, causing a decline in forest health. In the framework of ICP Forests, the forest damage has been monitored for decades; however, it is labour-intensive and time-consuming. Satellite-based remote sensing offers a rapid and efficient method for assessing large-scale damage events, combining the ground-based ICP Forests datasets. This study utilised cloud computing and Sentinel-2 satellite imagery to monitor forest health and detect anomalies. Standardised NDVI (Z NDVI) maps were produced for the period from 2017 to 2023 to identify disturbances in the forest. The research focused on seven active ICP Forests Level II and 78 Level I plots in Hungary. Z NDVI values were divided into five categories based on damage severity, and there was agreement between Level II field data and satellite imagery. In 2017, severe damage was caused by late frost and wind; however, the forest recovered by 2018. Another decline was observed in 2021 due to wind and in 2022 due to drought. Data from the ICP Forests Level I plots, which represent forest condition in Hungary, indicated that 80% of the monitored stands were damaged, with 30% suffering moderate damage and 15% experiencing severe damage. Z NDVI classifications aligned with the field data, showing widespread forest damage across the country.

Necrosis of needles and shoots caused by various damaging agents, have emerged about fifteen or twenty years ago in the Hungarian Austrian pine stands. Damages caused mainly Sphaeropsis sapinea Dyko & Sutton, Mycosphaerella pini E. Rostrup (its anamorph Dothistroma septospora /Dorog./ Morlet), and Sclerophoma pithyophila (Corda) Höhn, and Cenangium ferruginosum Fr. ex Fr. Appearance and rapid spread of the fungi may surely be attributable to the anomalies in weather conditions. Since, the prevailing conditions, according to the long term predictions, have a fair chance of becoming permanent, it seems to be rational to select resistant or less susceptible species in producing propagation material of Austrian pine in the future. This brought up the investigation on the susceptibility of those clones, which are considered as basis for the elite propagation material of Austrian pine, to individual damaging agents. The investigations were carried on clone bank of Kisunyom. The results showed the susceptibility to the damaging agents considerable differences prevailed among the clone-groups, so it has been confirmed that in the process of genetic improvement when individuals are selected for cultivation, their susceptibility to the damaging agents should also be considered.