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Common hazel, Turkish hazel, powdery mildew The powdery mildew consisted of white mycelium covering areas between c. 2 cm in diameter and almost entire leaf surfaces. Keywords: common hazel; Turkish hazel; powdery mildew EN common hazel Turkish hazel powdery mildew 1 2 2 03/29/23 20230101 NES 230101 An unusual powdery mildew was observed in three intensive I Corylus avellana i (common hazel) plantations in the Drava region of Slovenia in September 2020 and subsequently in numerous other plantations across Slovenia (e.g., Upper Carniola and Gorizia regions). [Extracted from the article]

European ash, common ash, powdery mildew, manna ash REFERENCES 1 Beenken, L. & Brodtbeck, T. (2020) First record of Erysiphe salmonii causing powdery mildew on Fraxinus ornus in Switzerland. Keywords: common ash; European ash; manna ash; powdery mildew EN common ash European ash manna ash powdery mildew 1 2 2 03/29/23 20230101 NES 230101 In October 2022, powdery mildew symptoms were observed on young I Fraxinus ornus i and I F. excelsior i trees in multiple locations in central and western Slovenia. [Extracted from the article]

The presumed resistance of individual ash trees to ash dieback caused by invasive pathogen Hymenoscyphus fraxineus is an important issue for the maintenance of ash in European forests. All known studies regarding the resistance of ash trees to ash dieback were conducted in plantations and stands of F. excelsior; however, no such data exist for F. angustifolia. Crown damage assessments were performed over four consecutive years between 2009 and 2012 at a F. angustifolia clonal plantation in Hraščica, Slovenia. Inoculation of H. fraxineus into the branches of the most and least damaged clones of F. angustifolia and leaf phenology assessments was performed to verify the presence of defence mechanisms that limit fungal growth or promote disease escape. Additionally, root collars of selected clones were inspected for fungal infections. The crown damage assessments showed considerable differences among F. angustifolia clones, indicating genetic variability in susceptibility to ash dieback. Crown dieback progressed significantly over the 4-year time period; the mean crown damage of individual clones in 2012 varied between 16.7% and 83.8%. Significant differences among F. angustifolia clones were found in the inoculation trials and leaf phenology assessments. However, defence mechanisms such as early leaf flushing, early leaf shedding and the ability to inhibit pathogen growth in host tissues were not confirmed. High frequency of Armillaria spp. and H. fraxineus root collar infection demonstrated the need for whole tree inspection to determine causal agent of damages on individual ash trees. Armillaria spp. may be highly associated with ash decline epidemiology. [ABSTRACT FROM AUTHOR]

Ash dieback is an emerging disease caused by the fungus Chalara fraxinea that severely affects Fraxinus excelsior and F. angustifolia stands in Europe. Previous studies have shown that this pathogen prefers temperatures around 20°C, while its growth in pure cultures at 30°C proved to be very limited. The purpose of this study was to determine the effects of temperature on the development and growth of C. fraxinea in pure cultures and in plant tissues, as well as to test the heat tolerance of F. excelsior saplings. The sensitivity of fungus to heat in ash tissues was higher than in pure cultures. Low isolation success rate from diseased ash tissue after a five-hour hot water treatment at 36°C and the relatively high survival rate of ash saplings after hot water treatments at 36°C and 40°C indicate possibilities for the development of a C. fraxinea eradication method in ash saplings. Field monitoring showed that in hot weather periods, thermal conditions inside the ash tissues can be extreme enough to markedly decrease the viability of C. fraxinea in infected plant tissues. [ABSTRACT FROM AUTHOR]

Eutypella canker of maple, caused by the pathogen Eutypella parasitica, has recently been reported for the first time in Europe. A rule-based model of Eutypella parasitica spread risk in Europe is presented. This model incorporates the effects of spatial and temporal variability of multiple variables on pathogen spread and establishment. Model predictions are based on current knowledge of host susceptibility, pathogen reproduction and pathogen transmission, with particular regard to the host species’ distribution and climate suitability. Maps of host species’ distributions and monthly weather conditions were spatially analyzed in a Geographic Information System using the magnitude and direction of each variable's effect on disease spread. Spread risk predictions were computed for each month and averaged to generate a cumulative risk map. The model was calibrated using data on the natural distribution of Eutypella canker in North America. Extensive areas covering the natural distribution of maples in Europe are at considerable risk from the Eutypella parasitica infection. The most endangered regions are broad areas of the Balkans, the Apennines, France, Central and Eastern Europe and the Caucasus. [ABSTRACT FROM AUTHOR]

An abstract of the article "Chalara fraxinea causing common ash dieback newly reported in Slovenia," by N. Ogris, T. Hauptman and D. Jurc is presented.

The article focuses on the reported cankers on Acer campestre, commonly known as field maples, caused by Eutypella parasitica in Croatia. An overview of how the disease among the maples was detected is presented. It mentions that the morphological identification of E. parasitica was confirmed by using E. parasitica specific primers. After searching for possible treatments on the disease in Slovenia, the control wounds of the field maples healed, but E. parasitica-inoculated wounds showed lesions and wood discoloration and the fungus was successfully re-isolated from the infected part of the tree.

The article presents an abstract of the plant pathology research “First report of eutypella canker of Acer pseudoplatanus in Europe.”

The article discusses the first reported outbreak of charcoal disease caused by Biscogniauxia mediterranea on Turkey oak in Slovenia. In June 2004, the bark of Turkey oaks started to crack and fall off. By August 2004, the first perithecial stromata of Biscogniauxia mediterranea were seen in bark cracks on tree trunks and branches. Measurements suggest that the fungus could be categorized as B. mediterranea variety microspora. Symptoms come out after severe drought and hot weather. The emergence of this disease in the country suggests that climate change could result in outbreaks of this disease further north.

The article discusses the first report of Botryosphaeria dothidea causing dieback of the tree Ostrya carpinifolia , European hop hornbeam, in epiphytotic dimensions in Slovenia. The disease is characterized by bark necrosis, which can develop in healing cancers or expand to include the entire trunk or branches of the tree. Inoculations of two isolates from the necrotic bark of hop hornbeam and isolated on malt extract agar were done in nature with six replications on hop hornbeam coppice shoots. B. dothidea's host range consists mostly of trees and shrubs.