Nenad Keča

Botryosphaeriaceae associated with the die-back of ornamental trees in the Western Balkans

Extensive die-back and mortality of various ornamental trees and shrubs has been observed in parts of the Western Balkans region during the past decade. The disease symptoms have been typical of those caused by pathogens residing in the Botryosphaeriaceae. The aims of this study were to isolate and characterize Botryosphaeriaceae species associated with diseased ornamental trees in Serbia, Montenegro, Bosnia and Herzegovina. Isolates were initially characterized based on the DNA sequence data for the internal transcribed spacer rDNA and six major clades were identified. Representative isolates from each clade were further characterized using DNA sequence data for the translation elongation factor 1-alpha, β-tubulin-2 and large subunit rRNA gene regions, as well as the morphology of the asexual morphs. Ten species of the Botryosphaeriaceae were identified of which eight, i.e., Dothiorella sarmentorum, Neofusicoccum parvum, Botryosphaeria dothidea, Phaeobotryon cupressi, Sphaeropsis visci, Diplodia seriata, D. sapinea and D. mutila were known taxa. The remaining two species could be identified only as Dothiorella spp. Dichomera syn-asexual morphs of D. sapinea, Dothiorella sp. 2 and B. dothidea, as well as unique morphological characters for a number of the known species are described. Based on host plants and geographic distribution, the majority of Botryosphaeriaceae species found represent new records. The results of this study contribute to our knowledge of the distribution, host associations and impacts of these fungi on trees in urban environments.

Insights into the phylogeny of Northern Hemisphere Armillaria: Neighbor-net and Bayesian analyses of translation elongation factor 1-α gene sequences

ABSTRACT Armillaria possesses several intriguing characteristics that have inspired wide interest in understanding phylogenetic relationships within and among species of this genus. Nuclear ribosomal DNA sequence–based analyses of Armillaria provide only limited information for phylogenetic studies among widely divergent taxa. More recent studies have shown that translation elongation factor 1-α (tef1) sequences are highly informative for phylogenetic analysis of Armillaria species within diverse global regions. This study used Neighbor-net and coalescence-based Bayesian analyses to examine phylogenetic relationships of newly determined and existing tef1 sequences derived from diverse Armillaria species from across the Northern Hemisphere, with Southern Hemisphere Armillaria species included for reference. Based on the Bayesian analysis of tef1 sequences, Armillaria species from the Northern Hemisphere are generally contained within the following four superclades, which are named according to the specific epithet of the most frequently cited species within the superclade: (i) Socialis/Tabescens (exannulate) superclade including Eurasian A. ectypa, North American A. socialis (A. tabescens), and Eurasian A. socialis (A. tabescens) clades; (ii) Mellea superclade including undescribed annulate North American Armillaria sp. (Mexico) and four separate clades of A. mellea (Europe and Iran, eastern Asia, and two groups from North America); (iii) Gallica superclade including Armillaria Nag E (Japan), multiple clades of A. gallica (Asia and Europe), A. calvescens (eastern North America), A. cepistipes (North America), A. altimontana (western USA), A. nabsnona (North America and Japan), and at least two A. gallica clades (North America); and (iv) Solidipes/Ostoyae superclade including two A. solidipes/ostoyae clades (North America), A. gemina (eastern USA), A. solidipes/ostoyae (Eurasia), A. cepistipes (Europe and Japan), A. sinapina (North America and Japan), and A. borealis (Eurasia) clade 2. Of note is that A. borealis (Eurasia) clade 1 appears basal to the Solidipes/Ostoyae and Gallica superclades. The Neighbor-net analysis showed similar phylogenetic relationships. This study further demonstrates the utility of tef1 for global phylogenetic studies of Armillaria species and provides critical insights into multiple taxonomic issues that warrant further study.

Looking for relationships between the populations of Dothistroma septosporum in northern Europe and Asia

Dothistroma septosporum, a notorious pine needle pathogen with an unknown historical geographic origin and poorly known distribution pathways, is nowadays found almost in all areas inhabited by pines (Pinus spp.). The main aim of this study was to determine the relationship between North European and East Asian populations. In total, 238 Eurasian D. septosporum isolates from 11 countries, including 211 isolates from northern Europe, 16 isolates from Russian Far East and 11 isolates from Bhutan were analysed using 11 species-specific microsatellite and mating type markers. The most diverse populations were found in northern Europe, including the Baltic countries, Finland and European Russia. Notably, D. septosporum has not caused heavy damage to P. sylvestris in northern Europe, which may suggest a long co-existence of the host and the pathogen. No indication was obtained that the Russian Far East or Bhutan could be the indigenous area of D. septosporum, as the genetic diversity of the fungus there was low and evidence suggests gene flow from northern Europe to Russian Far East. On the western coast of Norway, a unique genetic pattern was observed, which differed from haplotypes dominating other Fennoscandian populations. As an agent of dothistroma needle blight, only D. septosporum was documented in northern Europe and Asia, while D. pini was found in Ukraine and Serbia.

The influence of phosphite treatments on oak leaves and damage caused by powdery mildew Erysiphe alphitoides

Abstract The aim of the project was to check the influence of ammonium phosphite preparation − Actifos on the physiology of leaves and a possible reduction of infection by the fungus a year after the application of fertilizer. Three observation plots were selected in Karczma Borowa, Krotoszyn and Piaski Forest Districts (FD). In each of these observation plots, trees were chosen randomly. In Karczma Borowa FD, the trees were treated by watering them with a 3% solution of Actifos. In Krotoszyn FD, the leaves of trees were sprayed twice (in July and September) from the plane using a 50% solution of Actifos; and in Piaski FD, only the trunks of tress were sprayed twice the same way, but in July 2012 and September 2013. In October 2013, from each tested tree, ten leaves were selected randomly from the upper, well-lit parts of their crowns. The assessment of leaf surface damaged by mycelium and chlorophyll a fluorescence was performed. After the application of the phosphite, no negative physiological consequences for the treated trees were noticed − neither concerning the average leaf area nor the fluorescence of chlorophyll. The manner of phosphite application (leaves, trunks or roots) did not cause any negative consequences for the vitality/health of the treated trees as compared to the control trees. A certain tendency in the reduction of oak mildew on the treated leaves with phosphite was observed, however these observations should be continued in the next years.

Review of the most important pathogens in Serbian forest nurseries

Successful reforestation depends on the quality and health of seedlings. Targeted production in forest nurseries should produce plants that will be able to survive unfavorable environmental and weather conditions in Serbia. Pathogens can reduce the vitality of seedlings and decrease survival after outplanting. The most common pathogens identified on seeds of both conifer and broadleaved seedlings are presented. The most frequently used fungicides for the control of pathogens in Serbian forest nurseries, as well as the best time of their application, are reviewed.

European oak decline phenomenon in relationto climatic changes

Abstract The complex phenomenon of decline in European oak is currently triggered by changing climatic conditions and their consequences like heavy rains, local floods and pest development. Especially, pathogens from Phytophthora genus profit from soil saturation with water. They are alien invasive species, which attack and severely damage fine roots. In drought conditions occurring in the subsequent year, many oaks die as they encounter problem with water uptake. Additionally, insect defoliators followed by oak mildew infections accelerate the level of tree mortality. Secondary insects, butt and root pathogens are usually the final cause of death of many oaks. More research is needed in the direction to determine (i) measurable factors (e.g. chlorophyll florescence) that can indicate that the process of tree decline has already started, (ii) the correlation between the root decay and the crown symptoms (scanners, software), (iii) which combination of stressors stimulate the best development of pathogens that lead to the high plant mortality and (iv) the difference between the mortality caused by the native and the invasive Phytophthora species.

Assesment of forest products market potential as a basis for forest sector development in the Jablanica District

One of the main tasks of marketing research is the assessment of market potential. The aim of this research was to analyze the dynamics of selling and buying of wood and nonwood forest products (NWFPs) within the analyzed enterprises in the Jablanica District. The purpose of this research was to examine the possibilities for the development of small and medium-sized enterprises (SMEs) directed towards a sustainable use of forest products in the area of the Jablanica District. The subject of this research is: purchased and placed quantities in the analyzed enterprises, as well as the prices that were realized for the products, with special emphasis on commercially important mushrooms. The research was conducted in the territory of Jablanica and it included five enterprises engaged in the purchasing, processing and sale of NWFPs and the Forest Estate (FE) “Forest” Leskovac. The purchase of raw forest fruits and herbs had a growing trend (+ 17.8%) in the 2006-2013 period. The average annual growth rate (AAGR) of sales was 3.4% for medicinal plants and 30.6% for mushrooms. The AAGR of NWFPs export was + 32.6%. The placement of beech wood assortments (K class) recorded a purchase AAGR of app. + 12.7%. In 2013, it was found that the NWFPs with the highest market value were: blueberry, dried boletus and chanterelle. In 2013, their total gross revenue in the domestic market amounted to 82.3 million RSD, whereas the total gross revenue of the analyzed beech wood assortments was 87 million RSD. [Projekat Ministarstva nauke Republike Srbije, br. 37008: Održivo gazdovanje ukupnim potencijalima suma u Republici Srbiji i br. TP 31041: Sumski zasadi u funkciji povecanja posumljenosti Srbije]