First Report of Diplodia fraxini and Diplodia subglobosa Causing Canker and Dieback of Fraxinus excelsior in Slovenia.

In recent decades the vitality and productivity of European ash trees in Slovenia have been reduced by the onset of canker and dieback disease symptoms on young and old trees, identified primarily as ash dieback caused by Hymenoscyphus fraxineus. Given the limited information available about the etiology of this emerging disease, a study was carried out to isolate, identify, and characterize the fungal species involved in the observed ash symptoms. Field surveys were conducted in five forest sites where 50 symptomatic branch samples were collected. All samples were inspected and used for fungal isolation. Based on morphology, colony appearance, and DNA sequence data of the internal transcribed spacer region, 125 fungal colonies belonging to five species were isolated and identified. Only a few symptomatic ash samples yielded colonies of H. fraxineus, whereas Botryosphaeriaceae species were isolated with a high frequency, with Diplodia fraxini as the dominant species. A pathogenicity test proved that all isolated species were pathogenic on European ash, causing bark lesions and wood discoloration. All Botryosphaeriaceae species isolated in this study are reported for the first time on European ash in Slovenia.

Biotic threats for 23 major non-native tree species in Europe.

For non-native tree species with an origin outside of Europe a detailed compilation of enemy species including the severity of their attack is lacking up to now. We collected information on native and non-native species attacking non-native trees, i.e. type, extent and time of first observation of damage for 23 important non-native trees in 27 European countries. Our database includes about 2300 synthesised attack records (synthesised per biotic threat, tree and country) from over 800 species. Insects (49%) and fungi (45%) are the main observed biotic threats, but also arachnids, bacteria including phytoplasmas, mammals, nematodes, plants and viruses have been recorded. This information will be valuable to identify patterns and drivers of attacks, and trees with a lower current health risk to be considered for planting. In addition, our database will provide a baseline to which future impacts on non-native tree species could be compared with and thus will allow to analyse temporal trends of impacts.

Calculation procedure for RITY-A phenology model of Ips typographus.

The RITY-2 phenology model was developed for the spatiotemporal simulation of the seasonal development of European spruce bark beetle, Ips typographus. RITY-2 is based on the PHENIPS model and was developed through improving PHENIPS with innovative approaches and calibrating and validating it for Slovenia. RITY-2 predictions are based on air temperatures from Integrated Nowcasting through a Comprehensive Analysis (INCA) system, which is used to calculate the effective bark temperature for beetle development. In this paper we describe the calculation procedure for RITY-2.•INCA enables high resolution spatial and temporal simulations and predictions.•An innovative procedure was introduced that finds the most appropriate spring date threshold from which the calculation of the phenological model is initiated.•Simplified and customized linear models for calculation of the air temperature in the forest and bark temperatures were developed.

Species-Specific Primers for Eutypella parasitica, the Causal Agent of Eutypella Canker of Maple.

Eutypella parasitica was recently reported in Europe for the first time, and this study reports the molecular evaluation of the internal transcribed spacer (ITS)1/5.8S/ITS2 regions of 68 isolates of the fungus obtained in pure culture with polymerase chain reaction restriction fragment length polymorphism (RFLP). The RFLP patterns of all isolates proved identical and the restriction profiles served to differentiate E. parasitica from Eutypa lata, another pathogenic member of the family Diatrypaceae. Low intraspecific variability was detected in the sequenced ITS1/5.8S/ITS2 regions of eight Eutypella parasitica isolates originating from different hosts and geographical locations. Based on this ITS region, EpR/F primers specific to E. parasitica were constructed and tested with a wide range of fungal isolates. The EpR/F primer pair successfully amplified the expected fragment size of 341 bp from isolates of E. parasitica and also directly from infected maple wood shavings. The RFLP patterns and species-specific primers represent a step toward routine, large-scale, and rapid molecular diagnostics and identification of E. parasitica.