Hans Em Faculty of Forest Sciences, Landscape Architecture and Environmental Engineering

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Planiranje gazdovanje i obnovitelni potencijal izdanačke čiste i mešovite hrastove šume u Severnoj Makedoniji
(2019)
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Dubravac, Tomislav
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Investigating population dynamics of the chestnut blight in North Macedonia through time (1995-2000 and 2022).
(Croatian Forest Research Institute, 2023-02)
Risteski, Mihajlo
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INVESTIGATING POPULATION DYNAMICS OF THE CHESTNUT BLIGHT FUNGUS IN NORTH MACEDONIA THROUGH TIME (1995-2000 AND 2022) Mihajlo Risteski1*, Kiril Sotirovski1 1Ss Cyril and Methodius University in Skopje, Hans Em Faculty of Forest Sciences, Landscape Architecture and Environmental Engineering *mihajlo.risteski@gmail.com The plant pathogenic fungus Cryphonectria parasitica and the infamous disease known as chestnut blight were initially discovered in the USA in 1904 on Castanea dentata and were recorded already in the late 1930-ties in Italy, on European sweet chestnut. Ever since, it has been disseminated in all European chestnut regions and has reached the eastern area of distribution of chestnut - Georgia, Azerbaijan and Iran. In 1950-ties, cankers showing “spontaneous healing” yielded isolates of the fungus expressing decreased virulence and sporulation. The phenomenon was named hypovirulence and is caused by mycoviruses of the genus Hypovirus. Ever since, scientists and practitioners have used hypovirulent isolates as a method for control of this devastating disease. It was additionally discovered that vegetative incompatibility between isolates of the fungus, is a restricting factor both for immediate suppression of growth of cankers and for the dissemination of hypovirulence within subpopulations of the fungus. Thus, vegetative compatibility (vc), and related aspects such as mating type (MAT), have been subjected to extensive research, both in Europe and the USA. In North Macedonia, in the period 1995-2000, C. parasitica from all larger chestnut populations was collected, isolated and analyzed for vc type diversity and MAT. Of the 786 isolates, the most dominant vc type was EU-12 (94 %), and only other 4 vc types were discovered (EU-1, EU-2, EU-10, EU-22). Regarding MAT, 96 % of the isolates were MAT-1. Hypovirulence incidence varied between subpopulations, ranging from 63 % (Skudrinje) to much lower or completely absent in others, while on the national level incidence was 19,5 % of 488 screened isolates. During 2022, over 500 samples have been collected from the same locations and will be subjected to analyses for the same aspects, with the main objective - comparison with data derived from previous research. We herewith present preliminary data and expected results. Keywords: Castanea sativa, Cryphonectria parasitica, hypovirulence, mating type, vc types
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Clone dependent reaction of chestnuts to infections of hypovirulent Cryphonectria parasitica isolates
(УКИМ Шумарски факултет - Скопје, 2017-10)
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Srebrova, Katerina
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Papazova-Anakieva, Irena
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Risteski, Mihajlo
The devastating effects of the chestnut blight fungus Cryphonectria parasitica have been controlled with relative success in Europe due to the natural spread of hypovirulence. This phenomenon is caused by dsRNA viruses named CHV, and in particular the Italian subtype of type CHV1 has proved to be with best results. In our study, we investigated host dependency at clonal level to canker size and morphology/fructification, as well as if hypovirulent isolates of differing virulence will cause significantly different sizes of cankers, and possibly variability in conidiation (hypovirus-isolate dependent). For this purpose, we converted 1 virulent isolate (Smo062B) with 2 hypovirus clones (J12 and Sk28, labeled HV1 and HV2 respectively, for this study) previously described as being of different virulence towards the host fungus. The obtained hypovirulent isolates were used for inoculations of thin chestnut (1,5 – 5cm diam.) stems within chestnut clusters. The trials were performed on 2 separate sites, on a total of 78 inoculation (39 pairs) in Brezno (25 clusters), and 68 (34 pairs) on 10 clusters in Kalishte. For comparison of the reaction of the host plants to hypovirulent isolates, both hypovirulent isolates were inoculated in stems of exact width on the same chestnut clusters (i.e. stems), multiple times per cluster, up to 18 (i.e. 9 pairs) in Kalishte and 6 (i.e. 3 pairs) in Brezno. Control inoculations were with virulent isolate Smo062B. 140 days after inoculation cankers were assessed for conidiation and their width and length were measured. Stromata were collected from all fruiting cankers, and used for reisolation. Obtained cultures were determined as hypovirulent or virulent depending on culture morphology. Canker surface area was highly dependent on the host clone. In Kalishte, surface area of cankers caused by HV2 ranged on average per cluster from 408mm2 , up to 3020mm2 . In Brezno, the range was even more pronounced with HV2 cankers ranging from 131mm2 up to 3159mm2 on average per cluster of chestnut stems. Cankers caused by HV1 were on average with a significantly smaller surface area when compared to cankers caused by HV2. The extreme case was in cluster 9 in Kalishta, were the average surface of cankers caused by HV1 were 560mm2 , while HV2 caused cankers with nearly 4 times bigger area (3020mm2 ). Similarly, in Brezno, canker area in clonal stems for HV1 on average was 245mm2 , and for HV2 was 1677mm2 . Counterintuitively, the smaller cankers, caused by HV1 containing the more virulent hypovirus (J12) produced as often or more spore baring stromata as isolates containing the less virulent hypovirus. This partially explains the spread and sustainability of even very virulent hypoviruses within populations of C. parasitica.
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First records and general distribution of the plane tree lace bug (Corytucha ciliata) and the sycamore seed bug (Belonochilus numenius) in Kosovo
(University of Forestry, Sofia, 2021-05)
Muja, Ibrahim
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Risteski, Mihajlo
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Srebrova, Katerina
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The oriental plane tree (Platanus orientalis L.) is a common natural floristic element in Southern Balkans (Albania, Greece, North Macedonia, Serbia and Kosovo,) and is widely used in urban greenspace, as is also London plane tree (P. x acerifolia), especially in the last 2-3 decades. Unfortunately, both tree species are increasingly threatened by plant pathogenic fungi (Apiognomonia veneta (Sacc. & Speg.) Höhn; Ceratocystis platani (Walter) Engelbrecht & Harrington), as well as insect pests (Corythucha ciliata Say). The invasive plane tree lace bug (C. ciliata) and the sycamore seed bug (Belonochilus numenius Say), are Nearctic insect species which were firstly reported in Europe in 1964 and 2008, respectively. Both have spread in most plane tree regions of Europe and in the Balkans as well. The recent find of the seed bug in North Macedonia (2019) and its widespread presence, as well as omnipresence and high population density of the plane tree lace bug in that country (unpublished), prompted us to inspect urban and peri-urban plane trees in Kosovo, for which there are no previous records of these insects. During early October 2019 we registered presence of both insect species in urban and periurban plane tree populations Kosovo. Specimens were collected from all visited sites in Prishtina, Gjakova, Pegja, Uroshevac and Prizren from leaves and seed balls of P. x acerifolia and in the case of Prishtina from P. orientalis, and were identified in compliance to morphological characteristics typical for C. ciliata and B. numenius. Populations of C. ciliata were generally high, in extreme cases over 200 individuals (adults and larvae of all stages) per individual leaf. Further research is underway for detailed assessment of the distribution of both insect species on the total territory of Kosovo, as well as for establishment of population density, especially of C. ciliata which can pose a serious threat to the health status of plane populations. Although both species are well established and have been overlooked for many years (B. numenius) and many decades (C. ciliata), these are the first records for both the plane tree lace bug and the sycamore seed bug in Kosovo.
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Detected changes of population structure within a Cryphonectria parasitica population at the site Osoj, North Macedonia, during a time-span of over two decades
("Hans Em" Faculty for Forest Sciences, Landscape Architecture and Environmental Engineering, Skopje, 2022-06)
Risteski, Mihajlo
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Cokoski, Kristijan
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Tanovski, Vladimir
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Cryphonectria parasitica is historically considered as one of the most threatening plant diseases, and affects several species of Castanea worldwide. Applicability and success of control measures for the pathogenic fungus, consequently for control of its impact on European sweet chestnut Castanea sativa is highly dependent on presence of hypovirulence on populational levels, as well as on the population structure characteristics, most prominently vc-type diversity. In this study we compared the main characteristics of isolates of C. parasitica collected on 2 occasions with a time gap of 22 years (1998 and 2020) from the same site Osoj in the Kicevo region, in North Macedonia. We analyzed culture morphology, v-c type, and presence of hypovirulence of 72 isolates collected in 1998 and 39 isolates in 2020, by standard methods in vitro. In terms of the v-c type, from the total of 72 isolates collected in 1998, 49 (68%) were EU-12, 22 (30,55%) were EU-2 and 1 (1,38%) was EU-1. Of the 39 isolates collected in 2020, 32 (82%) were EU-12, 7 (18%) were EU-2, and no other vc types were detected, including EU-1. In 1998, 7 (13%) out of 54 assessed isolates were designated as hypovirulent, while in 2020 the proportion of hypovirulent isolates was much increased (33.33%), i.e. 13 of the total of 39. For the two-decade time frame, v-c type EU-12 remained dominant, with an additional increment of its prevalence on the populational level. From a practical point of view, it is more important that prevalence of hypovirulence was increased by over two-fold (x 2.57). This is likely the most important reason for difficulty during collection of viable samples, ultimately leading to a much lesser number of samples collected in 2020. As a conclusion, the C. parasitica population in Osoj has not only not diversified, but the most dominant vc type has become even more established with time. The relatively high proportion of hypovirulent isolates and the large increment detected in just over two decades timeframe, is interesting to further investigate in relation to overall health status of the chestnut population in Osoj
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First report of Cryphonectria carpinicola in the Balkans and Cryphonectria radicalis in Bulgaria
("Hans Em" Faculty for Forest Sciences, Landscape Architecture and Environmental Engineering, Skopje, 2022-06)
Corneo, Carolina
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Risteski, Mihajlo
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Rigling, Daniel
The members of Cryphonectria are known to infect deciduous tree genera of forests, orchards and urban spaces. Its most infamous representative, C. parasitica, causes the blight disease in chestnut trees and is considered as the most aggressive Cryphonectria species in Europe. To study the invasion dynamics of C. parasitica, we have conducted sampling campaigns of symptomatic Castanea sativa in the Balkans since the mid 1990-ties. During isolation of fungi from the bark material, in some cases we encountered atypical mycelia, suggesting that different Cryphonectria species may be present in this region. The aim of this study was to identify the species of atypical cultures, excluding the well-studied C. parasitica. For this purpose, we combed through our isolate collection, preserved on dried glass filter, and recultivated up-to-25-year-old samples to obtain DNA from the cultures. If the dry samples were no longer alive, we applied forensic DNA extraction to recover DNA directly from the glass filter. We sequenced the ITS barcode of twelve atypical specimens preserved in our collection, and confirm here the presence of the recently described Cryphonectria carpinicola on a Carpinus tree from the Berkovska Stara Planina Mountain in Bulgaria, collected in 2007. Additionally, we also report the occurrence of Cryphonectria radicalis in the region of Blagoevgrad in Bulgaria isolated from C. sativa in 2005 and 2007. The oldest examined specimen dates from 1998 and is Cryphonectria radicalis from Belasitsa Mountain in North Macedonia, also previously reported. Cryphonectria carpinicola became noticeable only in the last two decades on declining hornbeam trees in urban areas of Central Europe. It shows only slight differences in morphology and anatomy to the two closely related species C. radicalis and C. naterciae, and differs from most other Cryphonectria species due to its preference for Carpinus trees as main hosts, while other Cryphonectria species are found on Castanea or Quercus trees.
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Phytopthora spp. isolated from chestnut populations in the Republic of Macedonia
(УКИМ Шумарски факултет - Скопје, 2017-10)
Risteski, Mihajlo
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Rigling, Daniel
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Jezic, Marin
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Biological control of chestnut blight - Efficiency of natural hypovirulence
(УКИМ Шумарски факултет - Скопје, 2017-10)
Schwartz, Janine
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Jezic, Marin
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Risteski, Mihajlo
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Curkovic Perica, Mirna
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Prospero, Simone
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Biological control of chestnut blight by induced mass conidia production of hypovirulent isolates of Cryphonectria parasitica on excised chestnut stems
(IUFRO 125th Anniversary Congress, 18 – 22 September 2017, Freiburg, Germany, 2017-09)
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Risteski, Mihajlo
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Jezic, Marin
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Curkovic Perica, Mirna
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Katanic, Zorana
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Phytophthora species associated with woody plants in Macedonia
(IUFRO 125th Anniversary Congress, 18 – 22 September 2017, Freiburg, Germany, 2017-09)
Risteski, Mihajlo
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Jezic, Marin
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Curkovic Perica, Mirna
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Woodward, Stephen
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Hans Em Faculty of Forest Sciences, Landscape Architecture and Environmental Engineering

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