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Poziom wiedzy społeczeństwa nt. GMO stale się zmienia. W listopadzie i grudniu 2019 r. studenci UKSW w Warszawie przeprowadzili ankiety wśród 699 anonimowych respondentów na temat zastosowania produktów GMO w codziennym życiu Polaków. Osoby ankietowane podzielono wg czterech kryteriów: płci, wieku, wykształcenia i miejsca zamieszkania z podziałem na miasto i wieś, zadając 7 pytań merytorycznych odnośnie do poziomu wiedzy i osobistego podejścia do konsumpcji produktów GMO. Analizę statystyczną wyników wykonano w programie STATISTICA 12. Wykazano, że w ostatnich latach rośnie wiedza mieszkańców w Polsce nt. GMO, ale obawy przed produktami genetycznie modyfikowanymi nadal występują u ponad połowy społeczeństwa. Większość kobiet obawia się GMO, zwraca większą uwagę na oznakowanie produktów zawierających GMO i nie podałaby ich swoim dzieciom. Osoby w wieku poniżej 20 lat są pozytywnie nastawione do GMO, natomiast osoby w wieku powyżej 35 lat obawiają się negatywnych skutków spożywania produktów GMO. Większość osób mieszkających na wsi obawia się produktów GMO, opinia zaś mieszkańców miasta jest podzielona na dwie, prawie równe grupy: zarówno zwolenników, jak i przeciwników GMO. Różnice w odpowiedziach odnośnie obawy przed negatywnymi skutkami spożywania produktów zawierających GMO były statystycznie istotne (p < 0,001) i wykazały większe obawy wśród osób zamieszkujących tereny wiejskie (67%) niż u mieszkańców miast (49%). Jednocześnie, prawie ten sam duży odsetek osób ze wsi i z miasta (67%) był przychylny stosowaniu leków wyprodukowanych drogą inżynierii genetycznej (p < 0,01).

The genus Phytophthora plays an important role not only in agriculture but also in forest ecosystems. As the number of known Phytophthora species continues to grow, identifying new isolates in this genus has become increasingly challenging even by DNA sequencing. Therefore, the development of proper techniques for detection and identification is crucial for monitoring and control of these pathogens in the forestry sector. In recent years, new molecular methods using innovative approaches have indeed been developed. However, the majority of these methods was designed to detect single Phytophthora species. Techniques that are able to target multiple species would offer advantages, especially for the assessment of Phytophthora diversity in the environment. This paper describes a multiplex assay for the identification of eight Phytophthora isolates, down to the species level, based on a Fluidigm platform employing pyrosequencing. The obtained results showed that for an accurate determination of the species, it is sufficient to know the sequence of two markers, ITS and COX1. The sensitivity of this test is sufficient to identify Phytophthora in a pure culture. Unfortunately, analysis based on a pyrosequencing platform does not provide enough data to simultaneous identify multiple Phytophthora species in samples collected in the field. This problem could be resolved in the future by sequencing using more efficient platforms like Illumina or IonTorrent.

Black Alder Alnus glutinosa (L.) Gaertn. is an important tree commonly growing in Poland. Alders are actinorhizal plants that play an important ecological role in riparian ecosystems through atmospheric nitrogen fixation, filtration and purification of waterlogged soils as well as providing a refuge for terrestrial and aquatic organisms thus helping to stabilize stream banks. Black alder used to be considered a very pest and disease resistant species but, the situation changed in 2000, when an unprecedented decline of Alders was observed in Poland. In the Białowieża Forest District, this decline has been observed on wet meadow habitats and along rivers or watercourses. Currently, there are several hypotheses explaining Alder dieback, among them climatic changes and Phytophthora infections. In terms of climate, Black Alder requires a high atmospheric humidity during all phases of its reproductive cycle. It tolerates neither long-term summer flooding nor a significant decrease in the groundwater level. In terms of pests, oomycete pathogens of the genus Phytophthora are the most destructive plant pathogens known and many of them are present in forests and nurseries all over Europe. The aim of this study was to evaluate the health of Black Alder along the Narewka River in the Białowieża Forest District. Selected areas were monitored in 2012 and 2018, but no relationship between drought and alder health was found. A preliminary analysis of soil and water samples by real time PCR revealed the presence of two Phytophthora species: P. alni and P. cactorum. Further and more detailed research is required to elucidate the role of these pathogens in Alder dieback.

The protective effects of Trichoderma asperellum IZR D-11 as a biocontrol agent against the powdery mildew Erysiphe alphitoides infecting leaves of Quercus robur were evaluated for the first time. A strain of Trichoderma had earlier been isolated in Belarus, and was identified in this study as T. asperellum by sequencing of three genomic markers: internal transcribed spacer, translation elongation factor 1 alpha and RNA polymerase II subunit 2, with over 99.2% identity to corresponding genomic sequences in GenBank. When applied once in the first year just after onset of powdery mildew disease, T asperellum IZR D-11 reduced disease progression and continued to reduce powdery mildew levels during the following three years. Photosynthetic activity as represented by chlorophyll fluorescence measured in oak seedlings was increased in treated plants, and greater assimilate production was also found. The use of this antagonistic fungus increased the total water content in oak leaves suggesting that T. asperellum IZR D-11 can serve as a preventive measure to reduce energy losses in the process of water transpiration. GC-MS analysis detected 49 volatile compounds in the headspace of pure cultures of T. asperellum. Sesquiterpenes represented mainly by daucene, dauca-4(11),8-diene and isodaucene were the largest group of compounds emitted. We speculate that these volatiles from T. asperellum IZR D-11 may be involved in induced resistance in the plant, but further research is needed. The above results suggest that T. asperellum strain IZR D-11 has potential as a biocontrol agent of oak powdery mildew in forest nurseries.

The present study was inspired by scientific reports describing the positive effects of silicon preparations on fruit and vegetables in horticulture. The use of silicon preparations in forest protection represents a new research application, especially in the cases of oak seedlings that are damaged by oak powdery mildew. Additionally, these preparations increase the photosynthetic efficiency of the seedlings, and thus promote increased biomass and better nutritional value of the root systems. The new idea of using silicon formulations in forestry, based on the initial test results, is particularly important for seedlings in the post-planting period in forest plantations. In particular, these preparations increase yield and plant growth, and improve plant health. So far, no comparable studies have been conducted on forest tree species. To this end, one year-old pine (Pinus sylvestris L.) and two year-old English oak (Quercus robur L.) seedlings were sprayed with silicon preparations of different concentrations, and changes in growth parameters and photosynthetic efficiency were observed. The main objective of the study was to determine the effect of the silicon preparation on the seedlings during their first life span, i.e., the first year after planting. In this study, 50 pine and 50 oak seedlings were sprayed three times with the silicon preparation, in five variants (control; concentrations of 1%, 2%, 3% and 5%), as well as the chlorophyll fluorescence, height, thickness and biomass of the roots, were measured. It was found that the treatment with a concentration of 2% was better and statistically, significantly different from the other variants, e.g., in terms of increasing photosynthetic efficiency.

Forests are an essential component of the natural environment, as they support biodiversity, sequester carbon, and play a crucial role in biogeochemical cycles—in addition to producing organic matter that is necessary for the function of terrestrial organisms. Forests today are subject to threats ranging from natural occurrences, such as lightning-ignited fires, storms, and some forms of pollution, to those caused by human beings, such as land-use conversion (deforestation or intensive agriculture). In recent years, threats from pests and pathogens, particularly non-native species, have intensified in forests. The damage, decline, and mortality caused by insects, fungi, pathogens, and combinations of pests can lead to sizable ecological, economic, and social losses. To combat forest pests and pathogens, biocontrol may be an effective alternative to chemical pesticides and fertilizers. This review of forest pests and potential adversaries in the natural world highlights microbial inoculants, as well as research efforts to further develop biological control agents against forest pests and pathogens. Recent studies have shown promising results for the application of microbial inoculants as preventive measures. Other studies suggest that these species have potential as fertilizers.

In recent years, the decline of pine stands in Europe, including Poland, has been caused by the emerging needle pathogen Dothistroma septosporum. Although this fungus appears to preferentially infect Pinus pini, P. pinaster or P. radiata in Southern Europe, it has been reported in stands of P. nigra, P. mugo and P. sylvestris from Southern Poland. Our preliminary tests of symptomatic needles of diseased pines, including black pine (P. nigra), showed the presence of both D. septosporum and D. pini—the latter as the first report in Poland. No other endophytic pathogen, i.e., Lecanosticta acicola or Cenangium ferruginosum, were found. More extensive molecular surveying based on β-tub2 amplification of DNA in needle samples from 72 seed trees of P. sylvestris in nine different Forest Districts of Southern Poland did not find the presence of D. septosporum. Our study revealed that the seed trees from which we collected propagation material were free from the pathogen, and its endophytic behavior was not confirmed in our testing. Consequently, these investigated trees of P. sylvestris should be suitable for seed collection and propagation, following the requirements of “good” phytosanitary quality as “pathogen-free” pine seeds used for reforestation.

Producción Científica, Fusarium circinatum is a harmful pathogenic fungus mostly attacking Pinus species and also Pseudotsuga menziesii, causing cankers in trees of all ages, damping-of in seedlings, and mortality in cuttings and mother plants for clonal production. This fungus is listed as a quarantine pest in several parts of the world and the trade of potentially contaminated pine material such as cuttings, seedlings or seeds is restricted in order to prevent its spread to disease-free areas. Inspection of plant material often relies on DNA testing and several conventional or real-time PCR based tests targeting F. circinatum are available in the literature. In this work, an international collaborative study joined 23 partners to assess the transferability and the performance of nine molecular protocols, using a wide panel of DNA from 71 representative strains of F. circinatum and related Fusarium species. Diagnostic sensitivity, specifcity and accuracy of the nine protocols all reached values >80%, and the diagnostic specifcity was the only parameter difering signifcantly between protocols.The rates of false positives and of false negatives were computed and only the false positive rates difered signifcantly, ranging from 3.0% to 17.3%.The diference between protocols for some ofthe performance values were mainly due to cross-reactions with DNA from non-target species, which were either not tested or documented in the original articles. Considering that participating laboratories were free to use their own reagents and equipment, this study demonstrated that the diagnostic protocols for F. circinatum were not easily transferable to endusers. More generally, our results suggest that the use of protocols using conventional or real-time PCR outside their initial development and validation conditions should require careful characterization of the performance data priorto use under modifed conditions (i.e. reagents and equipment). Suggestions to improve the transfer are proposed., European Cooperation in Science and Technology (COST Action FP1406 PINESTRENGTH), Estonian Science Foundation (grants PSG136 and IUT21-04), Centro de Estudios do Ambiente e do Mar (CESAM) (projects UID/AMB/50017/2013 and POCI-01- 0145- FEDER-007638), Slovenian Research Agency (project P4-0107)

Ash dieback caused by an alien, invasive fungus Hymenoscyphus fraxineus is a serious disease of European ash species in many parts in Europe. In Poland, the disease was recorded in the beginning of the 1990s. This study was performed in 2016–2017 with the aim to identify fungi isolated from ash shoots showing dieback symptoms in the Wolica Nature Reserve in Poland, as well as from shoots of two years-old ash seedlings inoculated with H. fraxineus in the greenhouse. The most frequently isolated fungi from shoots of common ash (associated with the pathogenic fungus H. fraxineus) were identified on the basis of sequencing of the internal transcribed spacer region (ITS1) of fungal rDNA. In total, 19 fungal taxa were identified for ash shoots as follows: H. fraxineus, Fusarium avenaceum, Alternaria spp., Phomopsis oblonga, Diplodia mutila and other Phomopsis spp. The pathogen H. fraxineus was not found for all the shoots samples; one year after inoculation the aforementioned fungi and other species as: Alternaria alternata, Bionectria ochroleuca, Epicoccum nigrum, F. acuminatum, F. avenaceum, and Paraphaesphaeria neglecta were identified in inoculation point, as well as H. fraxineus. The same quantitative and qualitative changes of organisms were observed in the case of artificially colonised ash seedlings in the greenhouse, as well as in the shoots of adult ash trees in the forest.

In natural environments, plants develop adaptive mechanisms at the cellular and molecular levels to cope with many external factors, e.g., insects and soil pathogens. We studied physiological stress induced by different levels of foliage removal (defoliation 30% and 60%) and by infection of root rot pathogen Phytophthora plurivora on the common Polish tree species, Betula pendula, grown in an open greenhouse. This study showed that P. plurivora damaged the root system which negatively impacted all morphological parameters. However the loss of 30% of the leaves had a positive effect on defense responses. Chlorophyll-a fluorescence parameters indicated a decrease in photosynthetic efficiency in defoliated plants, but plants inoculated with the pathogen had a higher performance index showing increased vigor of the infected plant than birches. The study demonstrated the intense immunity response of birch to P. plurivora through the expression of Hsp90 and Hsp83 genes. The trees weakened by P. plurivora became more susceptible to infection by Erysiphe ornata var. ornata.

Plant growth promoting bacteria (PGPB) have been the target of intensive research studies toward their efficient use in the field as biofertilizers, biocontrol, and bioremediation agents among numerous other applications. Recent trends in the field of PGPB research led to the development of versatile multifaceted PGPB that can be used in different field conditions such as biocontrol of plant pathogens in metal contaminated soils. Unfortunately, all these research efforts lead to the development of PGPB that failed to perform in salty environments. Therefore, it is urgently needed to address this drawback of these PGPB toward their efficient performance in salinity context. In this paper we provide a review of state-of-the-art research in the field of PGPB and propose a road map for the development of next generation versatile and multifaceted PGPB that can perform in salinity. Beyond soil desalinization, our study paves the way towards the development of PGPB able to provide services in diverse salty environments such as heavy metal contaminated, or pathogen threatened. Smart development of salinity adapted next generation biofertilizers will inevitably allow for mitigation and alleviation of biotic and abiotic threats to plant productivity in salty environments.

Kryzys środowiskowy jest jednym z najbardziej aktualnych i ważnych problemów, z jakimi obecnie zmaga się ludzkość. Organizacje międzynarodowe, rządy, samorządy, religie, społeczności lokalne, organizacje pozarządowe, a nawet poszczególne osoby szukają odpowiedzi na wyzwania, przed jakimi przyszło stanąć ludzkiej cywilizacji. Chodzi bowiem o to, by zgodnie z ideą zrównoważonego rozwoju wypracować takie rozwiązania, które zaspakajając aspiracje człowieka respektowałyby możliwości przyrody, zarówno w perspektywie obecnego, jak i przyszłych pokoleń. Szczegółowym problemem podjętym w niniejszym opracowaniu jest stosunek społeczności lokalnych do obszarów chronionych. Rola tych obszarów jest bowiem nie do przecenienia zarówno dla podtrzymania dobrostanu człowieka, jak i kondycji ziemskiej biosfery. Tematyka ta została podjęta w ramach wspólnego projektu Instytutu Ekologii i Bioetyki (obecnie Centrum Ekologii i Ekofilozofii) na Uniwersytecie Kardynała Stefana Wyszyńskiego w Warszawie (UKSW), Instytutu Badawczego Leśnictwa (IBL) oraz Kampinoskiego Parku Narodowego (KPN). Projekt ten obejmował organizację XIII ogólnopolskiej konferencji z cyklu „Ekologia humanistyczna" pt. ,,Przyroda wyzwaniem dla kultury. Społeczności lokalne wobec obszarów chronionych". Konferencja ta stanowiła swoistą platformę wymiany myśli i doświadczeń przedstawicieli różnych dziedzin wiedzy, przedstawicieli administracji rządowej i samorządowej, przedstawicieli parków narodowych i rezerwatów przyrody oraz organizacji ekologicznych...

Black alder Alnus glutinosa (l.) gaertn. is an important tree commonly growing in Poland. alders are actinorhizal plants that play an important ecological role in riparian ecosystems through atmospheric nitrogen fixation, filtration and purification of waterlogged soils as well as providing a refuge for terrestrial and aquatic organisms thus helping to stabilize stream banks. Black alder used to be considered a very pest and disease resistant species but, the situation changed in 2000, when an unprecedented decline of Alders was observed in Poland. In the Białowieża Forest District, this decline has been observed on wet meadow habitats and along rivers or watercourses. Currently, there are several hypotheses explaining Alder dieback, among them climatic changes and Phytophthora infections. In terms of climate, Black Alder requires a high atmospheric humidity during all phases of its reproductive cycle. It tolerates neither long-term summer flooding nor a significant decrease in the groundwater level. In terms of pests, oomycete pathogens of the genus Phytophthora are the most destructive plant pathogens known and many of them are present in forests and nurseries all over Europe. The aim of this study was to evaluate the health of Black Alder along the Narewka River in the Białowieża Forest District. Selected areas were monitored in 2012 and 2018, but no relationship between drought and alder health was found. A preliminary analysis of soil and water samples by real time PCR revealed the presence of two Phytophthora species: P. alni and P. cactorum. Further and more detailed research is required to elucidate the role of these pathogens in Alder dieback.

Fungi and oomycetes release volatiles into their environment which could be used for olfactory detection and identification of these organisms by electronic-nose (e-nose). The aim of this study was to survey volatile compound emission using an e-nose device and to identify released molecules through solid phase microextraction&ndash, gas chromatography/mass spectrometry (SPME&ndash, GC/MS) analysis to ultimately develop a detection system for fungi and fungi-like organisms. To this end, cultures of eight fungi (Armillaria gallica, Armillaria ostoyae, Fusarium avenaceum, Fusarium culmorum, Fusarium oxysporum, Fusarium poae, Rhizoctonia solani, Trichoderma asperellum) and four oomycetes (Phytophthora cactorum, P. cinnamomi, P. plurivora, P. ramorum) were tested with the e-nose system and investigated by means of SPME-GC/MS. Strains of F. poae, R. solani and T. asperellum appeared to be the most odoriferous. All investigated fungal species (except R. solani) produced sesquiterpenes in variable amounts, in contrast to the tested oomycetes strains. Other molecules such as aliphatic hydrocarbons, alcohols, aldehydes, esters and benzene derivatives were found in all samples. The results suggested that the major differences between respective VOC emission ranges of the tested species lie in sesquiterpene production, with fungi emitting some while oomycetes released none or smaller amounts of such molecules. Our e-nose system could discriminate between the odors emitted by P. ramorum, F. poae, T. asperellum and R. solani, which accounted for over 88% of the PCA variance. These preliminary results of fungal and oomycete detection make the e-nose device suitable for further sensor design as a potential tool for forest managers, other plant managers, as well as regulatory agencies such as quarantine services.

The purpose of this study was to better understand the interactive impact of two soil-borne pathogens, Phytophthora cactorum and Armillaria gallica, on seedlings of silver birch (Betula pendula Roth.) subjected to stress caused by mechanical defoliation, simulating primary insect feeding. This is the first experimental confirmation of silver birch seedling root damage (and in consequence shoot mortality) caused by the additive effect of defoliation stress and P. cactorum inoculation via soil. However, the most severe damage to roots occurred after A. gallica inoculation. One year after treatments, chlorophyll fluorescence measurement, and gas chromatography coupled with mass spectrometry (GC-MS) were used to analyze the photosynthetic activity in leaves, the volatile organic compounds (VOCs) emitted by the birch leaves, and chemical compounds from the roots. The cumulative effect of the two pathogens and partial defoliation reduced photosynthetic activity, suggesting dysfunction of photosystem PSII due to the applied stresses. In summary, it seems that the main differences in photosynthetic performance could be attributed to Armillaria infection. The birch leaves in seedlings exposed to 50% defoliation, and inoculation with P.cactorum and A. gallica, emitted more aromatic carbonyls and alcohols, as well as half as much aliphatic esters, compared to controls. In infected birch roots, the production of phenols, triterpenes, and fatty alcohols increased, but fatty acids decreased. Higher levels of aromatic carbonyls and alcohols in leaves, as well as phenolic compounds in the roots of stressed birches (compared to control) suggest an activation of plant systemic acquired resistance (SAR).

The purpose of this study was to better understand the interactive impact of two soil-borne pathogens, Phytophthora cactorum (as the primary pathogen) and Armillaria gallica (as secondary), on two-year-old seedlings of silver birch (Betula pendula) subjected to stress caused by mechanical defoliation simulating primary insect feeding. One year after treatments, the chlorophyll fluorescence measurement and gas chromatography coupled with mass spectrometry (GC-MS) were used to analyze the photosynthetic activity in leaves, the volatile organic compounds (VOCs) emitted by birch leaves and chemical compounds from roots. Only the infection of roots by P. cactorum increased photosynthetic rates in the leaves, which may suggest its cryptic development in contrast to fungi. The birch leaves in seedlings exposed to 50% defoliation, inoculation with P. cactorum and A. gallica emitted more aromatic carbonyls and alcohols, as well as half as much aliphatic esters, compared to untreated controls. In infected birch roots, the production of phenols, triterpenes and fatty alcohols increased, but fatty acids decreased. This was the first experimental confirmation of the pathogenicity of P. cactorum on silver birch seedlings in Poland. The most severe damage to roots took place only in the case of two-way or three-way interactions. Higher levels of aromatic carbonyls and alcohols in leaves, as well as phenolic compounds in roots of stressed birches (compared to control) suggest an activation of plant systemic acquired resistance (SAR).

A current ongoing unprecedented outbreak of Ips typographus (L.) (Coleoptera, Curculionidae, Scolytinae) in the Białowieża Primeval Forest (BPF) has nearly eliminated Norway spruce (Picea abies L. Karst) as a major forest tree species there, since over 1 million trees have died. In this part of Europe, Norway spruce has grown for hundreds of years, previously accounting for 30% of forest species composition. The aim of this study was to evaluate 47 &ldquo, Monuments of Nature&rdquo, of Norway spruce as follows: (i) their current health status in the managed forests of Białowieża Forest District, (ii) possible causes and changes in their health during the last bark beetle outbreak, and (iii) potential losses from the gene pool. Our findings from ground and remote sensing inventories showed that only 12 out of 47 (25%) monumental trees protected by law survived until 2017 in the study area. The rest (75%) of the investigated trees had died. An analysis of meteorological data from Białowieża suggested that the beginning of the I. typographus outbreak in 2012 was associated with diminishing precipitation during growing seasons prior to this time and subsequent increases in annual temperature, coupled with heavy storms in 2017 toppling weakened trees. A comparison of old-growth &ldquo, spruce in the region (n = 47, average age 225 years) to seven reference spruce stands (n = 281, average age 132 years) revealed a loss of unique genetic features based on frequencies of eleven nuclear microsatellite loci. Although all studied populations had similar genetic background (FST(without NA) = 0.003 and no STRUCTURE clustering), all monumental spruce trees shared the highest parameters such as the mean observed and expected number of alleles per locus (Na = 15.909 and Ne = 7.656, respectively), mean allelic richness (AR(11) = 8.895), mean private alleles (Apriv = 0.909), and mean Shannon diversity index (I = 1.979) in comparison to the younger stands. Our results demonstrate that the loss of the old spruce trees will entail the loss of genetic variability of the Norway spruce population within the exceptionally valuable Białowieża Primeval Forest.

Działalność człowieka od zawsze miała wpływ na skład gatunkowy i strukturę genetyczną gatunków tworzących ekosystem leśny. Wyniki badań DNA potwierdzają wpływ obecnej i przeszłej gospodarki leśnej na obecny poziom zmienności genetycznej populacji drzew leśnych. Analiza molekularna pozwala określić pokrewieństwo genetyczne gatunków drzew leśnych, umożliwia badanie przepływu genów między pokoleniami, oraz odzwierciedla historię polodowcowej migracji gatunków z refugiów południowej Europy do Polski. Dzięki markerom DNA można precyzyjnie odróżnić mieszańce gatunkowe np. modrzewia japońskiego i europejskiego. Porównanie profili DNA kradzionego drzewa z pniakiem pozostawionym w lesie, dostarcza mocnych dowodów w sprawach dotyczących nielegalnego handlu drewnem. Genetyczna transformacja genomu drzew pozwala uzyskać drewno o zmienionej strukturze lignin, oraz zwiększoną asymilację CO2 w liściach. Modyfikacje genetyczne zmierzają też w kierunku wzmocnionej odporności hodowanych gatunków drzew na patogeny grzybowe lub szkodniki owadzie oraz na środki ochrony roślin na plantacjach drzew szybkorosnących GMO.

Silver birch, (Betula pendula), is an important forest tree species in Poland used for afforestation in rural areas and planted in wet forest types to ameliorate excess water. Physiological stress may increase susceptibility of trees to disease and it is hypothesized that insect defoliation can predispose birch to Phytophthora plurivora infection. In order to evaluate the effect of defoliation stress and phytophthora infection, removal of all (100%) or partial (50%) foliage from one-year-old B. pendula seedlings simulating insect damage was carried out in the greenhouse. Inoculation with P. plurivora mycelium at the base of the stem was performed by cutting the bark tissue 5–7 cm above the soil. Stem damage was assessed after 70 days in 2016 and after 365 days (at the end of the next growing season in September 2017) by measuring lesions sizes. We found that B. pendula can serve as a host of the soil-borne pathogen P. plurivora which causes mortality of birch seedlings in Polish nurseries. The results als...

Bacillus velezensis gram-positive bacterium, is frequently isolated from diverse niches mainly soil, water, plant roots, and fermented foods. B. velezensis is ubiquitous, non-pathogenic and endospore forming. Being frequently isolated from diverse plant holobionts it is considered host adapted microorganism and recognized of high economic importance given its ability to promote plant growth under diverse biotic and abiotic stress conditions. Additionally, the species suppress many plant diseases, including bacterial, oomycete, and fungal diseases. It is also able after plant host root colonization to induce unique physiological situation of host plant called primed state. Primed host plants are able to respond more rapidly and/or effectively to biotic or abiotic stress. Moreover, B. velezenis have the ability to resist diverse environmental stresses and help host plants to cope with, including metal and xenobiotic stresses. Within species B. velezensis strains have unique abilities allowing them to adopt different life styles. Strain level abilities knowledge is warranted and could be inferred using the ever-expanding new genomes list available in genomes databases. Pangenome analysis and subsequent identification of core, accessory and unique genomes is actually of paramount importance to decipher species full metabolic capacities and fitness across diverse environmental conditions shaping its life style. Despite the crucial importance of the pan genome, its assessment among large number of strains remains sparse and systematic studies still needed. Extensive knowledge of the pan genome is needed to translate genome sequencing efforts into developing more efficient biocontrol agents and bio-fertilizers. In this study, a genome survey of B. velezensis allowed us to (a) highlight B. velezensis species boundaries and show that Bacillus suffers taxonomic imprecision that blurs the debate over species pangenome; (b) identify drivers of their successful acquisition of specific life styles and colonization of new niches; (c) describe strategies they use to promote plant growth and development; (d) reveal the unlocked strain specific orphan secondary metabolite gene clusters (biosynthetic clusters with corresponding metabolites unknown) that product identification is still awaiting to amend our knowledge of their putative role in suppression of pathogens and plant growth promotion, and (e) to describe a dynamic pangenome with a secondary metabolite rich accessory genome.

Pathogens of Phytophthora genus are common not only in forest nurseries and stands, but also in water courses. Species of Phytophthora spread with plants for plantings (and soil attached to them) and with water courses as well, attacking the plants growing in riparian ecosystems. Several specialized organisms damaging only one tree species were identified like P. alni on alders or P. quercina on oaks. Some Phytophthora species can develop on several hosts like P. plurivora and P. cactorum on oaks, beeches, alders, ashes and horse chestnuts. Other oomycetes like P. gallica species was found for the first time in Poland in water used for plant watering in forest nursery. Species P. lacustris and P. gonapodyides were found in superficial water. Phytophthora species P. polonica was identified in the declining alder stands for the first time in the world, and P. taxon hungarica and P. megasperma were found in the rhizosphere of seriously damaged ash stands for the first time in Poland. The most often isolated species were P. plurivora (clade 2) with frequency 37% and P. lacustris with frequency 33% (clade 6). The best represented clade 6 revealed the occurrence of 6 species: P. gonapodyides, P. lacustris, P. megasperma, P. sp. raspberry, P. taxon hungarica and P. taxon oak soil.

Illegal logging is a major problem in many European countries. Recent progress in molecular biology, however, has significantly improved the ability to accurately identify wood material. In this paper, the first application of microsatellite DNA markers is described in a case of illegal logging of European ash wood in Polish State Forests. The genetic fingerprints of seized ash wood samples were determined using six nuclear and four chloroplast microsatellite loci, characterized by sufficient stringency in forensic analyses. By comparing the DNA profiles obtained, the origin of one sample of ash wood used as evidence material was confirmed, from among three samples serving as reference material with 99.99999% of probability. This work demonstrates how DNA authenticity testing can serve as an important technical tool in monitoring the legality of the suspected ash timber and confirms the utility of these techniques in detecting illegally logged timber in general.

The study was conducted in 2015 in six spruce stands situated in different forest districts administratively belonging to the Regional Directorate of State Forests in Krosno. Each spruce population was represented by 30 trees and assessed in terms of their current health status. Genetic analyses were performed on shoot samples from each tree using nine nuclear DNA markers and one mitochondrial DNA marker (nad1). The health status of the trees was described according to the classification developed by Szczepkowski and Tarasiuk (2005) and the correlation between health classes and the level of genetic variability was computed with STATISTICA (α = 0.05). Nuclear DNA analyses revealed a low level of genetic variability among spruce populations (only 3% of the total genetic variation (F ST = 0.028) and a high variability within populations (97%). The total heterozygosity in all stands (H T) was calculated as 0.646. Based on UPGMA analysis, the most genetically similar populations are spruce stands in the Bieszczady National Park and the Ustrzyki Dolne Forest District, which have the smallest genetic divergence of all populations (D N = 0.0165). Our analysis of the mitochondrial gene nad1 revealed the presence of six different haplotypes ‘a’, ‘a1’, ‘b’, ‘c’, ‘d’ and ‘d1’. Comprising 56% of all haplotypes, ‘a’ was the most common showing a predominant impact on spruce migration from the Carpathian area. The analysis based on mitochondrial markers (by Nei) revealed a heterozygosity of 0.525. Based on the observations of disease symptoms, 29% of the trees belong to health class 1, 30% to class 2, 28% to class 3 and class 4 contains 13% of trees. The comparison between health status and the level of genetic variation in the analysed stands showed a positive correlation. Spruce stands with better health were also characterised by a greater degree of genetic variability. Since most of the investigated spruce populations shared the mitochondrial haplotype ‘a’, we have ascertained their Hercynian–Carpathian origin. Only one stand (Cisna) had a high frequency (43.3%) of the Nordic haplotype ‘c’ suggesting that this provenance is derived from the Baltic post-glacial refugium of P. abies in europe.

Producción Científica, Pines are major components of native forests and plantations in Europe, where they have both economic significance and an important ecological role. Diseases of pines are mainly caused by fungal and oomycete pathogens, and can significantly reduce the survival, vigor, and yield of both individual trees and entire stands or plantations. Pine pitch canker (PPC), caused by Fusarium circinatum (Nirenberg and O’Donnell), is among the most devastating pine diseases in the world, and is an example of an emergent invasive disease in Europe. The effects of microbial interactions on plant health, as well as the possible roles plant microbiomes may have in disease expression, have been the focus of several recent studies. Here, we describe the possible effects of co-infection with pathogenic fungi and oomycetes with F. circinatum on the health of pine seedlings and mature plants, in an attempt to expand our understanding of the role that biotic interactions may play in the future of PPC disease in European nurseries and forests. The available information on pine pathogens that are able to co-occur with F. circinatum in Europe is here reviewed and interpreted to theoretically predict the effects of such co-occurrences on pine survival, growth, and yield. Beside the awareness that F. circinatum may co-occurr on pines with other pathogens, an additional outcome from this review is an updating of the literature, including the so-called grey literature, to document the geographical distribution of the relevant pathogens and to facilitate differential diagnoses, particularly in nurseries, where some of them may cause symptoms similar to those induced by F. circinatum. An early and accurate diagnosis of F. circinatum, a pathogen that has been recently introduced and that is currently regulated in Europe, is essential to prevent its introduction and spread in plantings and forests., Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (Proyect AGL2015-69370-R), Russian Foundation for Basic Research (Grant No. 17-04-01486), Portuguese Foundation for Science and Technology (PTDC/AGR-FOR/2768/2014), Ministry of Education, Youth and Sports of the Czech Republic and the European Regional Development Fund, Grant No. CZ.02.1.01/0.0/0.0/15_003/0000453., Romanian National projects PN18040105/2018 and PN19070206/2019

International audience; The number of invasive alien pest and pathogen species affecting ecosystem functioning, human health and economies has increased dramatically over the last decades. Discoveries of invasive pests and pathogens previously unknown to science or with unknown host associations yet damaging on novel hosts highlights the necessity of developing novel tools to predict their appearance in hitherto naive environments. The use of sentinel plant systems is a promising tool to improve the detection of pests and pathogens before introduction and to provide valuable information for the development of preventative measures to minimize economic or environmental impacts. Though sentinel plantings have been established and studied during the last decade, there still remains a great need for guidance on which tools and protocols to put into practice in order to make assessments accurate and reliable. The sampling and diagnostic protocols chosen should enable as much information as possible about potential damaging agents and species identification. Consistency and comparison of results are based on the adoption of common procedures for sampling design and sample processing. In this paper, we suggest harmonized procedures that should be used in sentinel planting surveys for effective sampling and identification of potential pests and pathogens. We also review the benefits and limitations of various diagnostic methods for early detection in sentinel systems, and the feasibility of the results obtained supporting National Plant Protection Organizations in pest and commodity risk analysis.

Polymerase chain reaction-amplified and sequenced isolates of Antrodia gossypium, Phlebiopsis gigantea and Heterobasidion parviporum from decaying Norway spruce wood blocks after three and six months, which exhibited linear growth, were investigated. P. gigantea strains showed the fastest growth, whereas A. gossypium growth was five times slower. The differences between the mean daily increment of A. gossypium and the other examined isolates (except Hp2) were statistically significant. There were also significant differences in wood decay between densities over time. These results were confirmed by the decay acceleration index (DAI) and decay activity index, which were positively correlated with wood density regardless of the fungus species. The registered P. gigantea strains (Rotstop and PG Suspension) exhibited a strong decomposition ability (28% after six months); the weight loss caused by A. gossypium after six months of decay (15.2%) was similar to the results of P. gigantea (GB) after just t...

Our aim was to examine the virulence of eight Phytophthora isolates belonging to three species (Phytophthora cryptogea, Phytophthora plurivora and Phytophthora quercina) obtained from diverse European ecosystems (in Bulgaria, Poland and Germany) towards three forest tree hosts – English oak (Quercus robur L.), Turkey oak (Quercus cerris L.) and European beech (Fagus sylvatica L.). All plants grown from seeds in a greenhouse conditions were artificially inoculated under the stem bark with Phytophthora cultures. The tested isolates turned to be more aggressive to Turkey oaks than to English oak trees. In case of European beech, the isolates of P. cryptogea and P. plurivora exposed various virulence. The potential hazard of the introduced foreign isolates for the oak and beech forests in Poland and Bulgaria is discussed. Amongst the tested isolates, P. quercina P290 from German highly infected Bulgarian Turkey oaks; therefore, its negative potential impact on Bulgarian oak forests could be considered as high (if unintentionally introduced). Also, two Bulgarian isolates belonging to P. cryptogea and P. plurivora are risky for Polish beech forests, if exposed to the pathogen. The observed pathogenicity of the tested Phytophthora species proved their potential as important contributors to decline of valuable forest ecosystems dominated by oaks (Q. robur and Q. cerris) or beech (F. sylvatica), in both Poland and Bulgaria. We found that investigated Phytophthora pathogens could develop in the living plant stem tissues without causing any disease symptoms, which is another demonstration that phytosanitary control by simple observation of plant material is not effective.

Summary The pathogenic fungus Heterobasidion annosum was identified in the rhizome of a couch grass (Elymus repens) using genetic markers. The couch grass grew in the proximity of a Scots pine stand that was visibly affected by the pathogen. The rDNA analysis showed 100% sequence similarity between two H. annosum sequences of ITS1 and ITS2 obtained from fruiting bodies found on the couch grass rhizome and on the stem of the Scots pine. These results indicate a close relationship between the two isolates of H. annosum and that they are derived from a common ancestor. The results show that H. annosum mycelia can infect couch grass rhizomes and subsequently produce fruiting bodies. It also suggests that the known modes of infection of tree roots by this pathogen in coniferous stands should take into account couch grass rhizomes in the dispersal of the disease in afforested post-agricultural soils.

Phosphite preparations are now an important alternative in plant protection against new, invasive pathogens of the genus Phytophthora and/or Pythium. It is crucial to intervene when alien, invasive oomycetes are carried to plantations or forest stands and attack fine roots via zoospores. The aim of this paper was to demonstrate the possibility of phosphite application to induce resistance to tree pathogens. Phosphate-based fertilizers have been used successfully in nurseries, where application is relatively easy by means of foliar sprays. the traditional fungicides, which are effective in combating fungi, however, fail to control oomycetes. Instead, they mask the disease, which, in turn, causes serious damage to seedlings after they have been planted in a suitable environment. Moreover, the number of effective fungicides available for forest plant protection has continued to decrease in the last decade. The effectiveness of the chemicals is reduced due to their frequent use and their similarity in terms of the active compound or the mechanism of action. Given the low diversity of active compounds, it is necessary to monitor the development of resistance of pathogens to fungicides by means of molecular biology (sequencing and quantitative PCR). Minimising the undesired side effects of chemicals on both, mycorrhizal fungi and pathogens can be achieved by strict adherence to rigorous security measures and, where possible, frequently changing the active compounds to alternatives such as phosphites. The significance of phosphate and phosphite uptake by trees is still a matter of debate, especially under field conditions. Nevertheless, phosphites are environmentally friendly compounds, which constitute an alternative or complement to the traditional chemicals (in accordance with the Directive on Integrated Plant management).

Producción Científica, Fusarium circinatum (Nirenberg and O’ Donnell) is the causal agent of pine pitch canker (PPC) disease, one of the most devastating forest diseases worldwide. Long-distance spread occurs mainly through the movement of infected seeds whereas at regional level, the movement of seedlings, substrates, or containers may play an important role in fungal dispersal. Invasion of nurseries takes place via infected seeds and further spread can occur by planting contaminated seedlings, especially due to the possibility of infected plants remaining symptomless. Once established, F. circinatum spreads by rain, wind, and insects. The natural spread of the pathogen is limited due to the short dispersal distances of the spores and the fairly short flight distances of disseminating insects. In this review, we summarize the currently known dispersal pathways of the pathogen, discussing both natural and human-assisted processes. With the purpose of understanding how to best intervene in the disease’s development in nurseries and forests, we outline the epidemiology of the pathogen describing the key factors influencing its spread. Preventive measures to control the spread of F. circinatum locally and globally are described with special emphasis on the challenges in implementing them., European Cooperation in Science and Technology (COST Action FP1406 PINESTRENGTH), Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project AGL2015-69370-R), Centro de Estudios do Ambiente e do Mar (CESAM) (project UID/AMB/50017/2019), Portuguese Foundation for Science and Technology (projects PTDC/AGR-FOR/2768/2014 , SFRH/BPD/122928/2016), French National Research Agency (grant ANR-11-LABX-0002-01)

The occurrence of Phytophthora species in Alnus glutinosa stands in the Karacabey and Igneada floodplain forests was investigated. Twenty‐seven soil samples taken from the rhizosphere of declining trees (without bark symptoms) were baited for Phytophthora. In total, 311 Phytophthora isolates were obtained following culturing on selective medium. On the basis of the morphological characteristics and the ITS sequences of the rDNA, Phytophthora plurivora accounted for 83% of the rhizosphere isolates. In addition to P. plurivora, P. gonapodyides (9%), P. chlamydospora (3.8%), P. lacustris (2.5%) and P. aff. cactorum (2%) were isolated from the surveyed areas. No P. × alni was detected in the present work. This paper is the first to report the isolation of P. plurivora and P. aff. cactorum from the rhizosphere of Alnus species in Turkey.

In the circumstances of only a limited number of pesticides being approved for use in forest nurseries, it is necessary to also examine the efficacy of new products available on the European market that stimulate growth and improve resilience and vitality among seedlings and saplings, with a view to the application of these products forming part of an integrated programme of plant protection. This paper describes trials of the three commercially available fertilizer products Actifos, Zielony Busz and Effective Microorganisms (EM), as carried out in seven Polish nurseries in an attempt to promote the growth of shoots and root systems of seedlings and saplings. In 64% of cases of it being used, Actifos was shown to stimulate growth significantly beyond control levels in the shoots of oak, beech, pine, spruce and alder saplings as well as the roots of young alders and oaks.

Summary Five Phytophthora species were isolated from the rhizosphere of ash-dominated areas of the Bialowieza European lowland forest nature reserve area. Morphological and DNA analyses identified Phytophthora fragariaefolia, P. plurivora, P. cactorum, P. lacustris and P. pseudosyringae. This is the first record of P. fragariaefolia in ash forests and demonstrates that several species in the potentially highly damaging Phytophthora genus are present within a near-pristine ecosystem.

Pathogens of Phytophthora genus are common not only in forest nurseries and stands, but also in water courses. Species of Phytophthora spread with plants for plantings (and soil attached to them) and with water courses as well, attacking the plants growing in riparian ecosystems. Several specialized organisms damaging only one tree species were identified like P. alni on alders or P. quercina on oaks. Some Phytophthora species can develop on several hosts like P. plurivora and P. cactorum on oaks, beeches, alders, ashes and horse chestnuts. Other oomycetes like P. gallica species was found for the first time in Poland in water used for plant watering in forest nursery. Species P. lacustris and P. gonapodyides were found in superficial water. Phytophthora species P. polonica was identified in the declining alder stands for the first time in the world, and P. taxon hungarica and P. megasperma were found in the rhizosphere of seriously damaged ash stands for the first time in Poland. The most often isolated species were P. plurivora (clade 2) with frequency 37% and P. lacustris with frequency 33% (clade 6). The best represented clade 6 revealed the occurrence of 6 species: P. gonapodyides, P. lacustris, P. megasperma, P. sp. raspberry, P. taxon hungarica and P. taxon oak soil.

The paper describes a number of molecular methods used in the past and now to analyze forest tree species. Taking into account the economic importance of forest trees and in view of the timber economy, wood properties and characteristics are essential factors subjected to control, observation and research. Molecular techniques that support traditional selection methods allow for genetic diversity analyses considering a range of research aspects. The development of these techniques at the turn of the last two decades has enabled wide-ranging use of molecular data in studies on forest tree populations. On the example of pine (Pinus L.), the paper presents data based on molecular studies as well as a variety of possibilities to apply the obtained results.

Pathogen diseases are increasingly threatening forest trees under the current climate change, causing a remarkable decrease in the stability of forest ecosystems. Ash (Fraxinus excelsior L.) dieback due to Hymenoscyphus fraxineus has been noted in Poland since 1992 and has spread over many European countries. The aim of this study was to test the hypothesis that ash trees affected by dieback could exhibit a reduced vessel size and density along the trunk, as well as a lowered width of annual wood rings, leading to the weakening of water transport towards the crown. Dead and dying ash trees were sampled in a forest district severely affected by ash decline in southern Poland. Wood samples were collected at different height along the trunk and several wood anatomical characteristics of annual tree rings over the period 2002-2011 were examined. Dead trees showed a stronger reduction in radial growth than dying trees over the period considered. Moreover, the diameter of vessels increased from the crown to the base in both dead and dying trees, while the density decreased. Significant differences between dead and dying trees were detected in size and density of vessels in the period analyzed, as well as in the width of annual rings. DNA extracted from wood samples was analyzed using SSR markers and the main genetic parameters of dead and dying trees were estimated, finding similar levels of polymorphism and only slight non-significant differences between the two health groups. Our results are consistent with the hypothesis that pathogens could disrupt the hormonal control of wood formation by interfering with the polar auxin transport, progressively leading to the death of ash trees.

Global climate change is associated with higher concentrations of atmospheric carbon dioxide (CO2). The ongoing changes are likely to have significant, direct or indirect effects on plant diseases caused by many biotic agents such as phytopathogenic fungi. This study results showed that increased CO2 concentration did not stimulate the growth of 1-year-old beech Fagus sylvatica L seedlings but it activated pathogenic Phytophthora species (P. plurivora and P. cactorum) which caused significant reduction in the total number of fine roots as well as their length and area. The results of the greenhouse experiment indicated that pathogens once introduced into soil survived in pot soil, became periodically active (in sufficient water conditions) and were able to damage beech fine roots. However, the trees mortality was not observed during the first year of experiment. DNA analyses performed on soil and beech tissue proved persistence of introduced Phytophthora isolates.

Achieving high quality propagative material is difficult today due to the limited number of pesticides recommended for use. Simultaneously, EU regulations on Integrated Pest Management (IPM) in forest nurseries came into a force, requiring a search for alternative plant protection methods that are safe for humans, animals and the environment. In this paper, we present the possibilities of using bio-fungicides against diseases in forest nurseries, their mechanisms of action, as well as the direction of their development (according to IPM rules). We reviewed the results achieved by different research teams presenting the possibilities and trends in combatting Oomycetes and Fusarium spp. pathogens currently having the most important economic impact.

In Poland, about 20% of forest nurseries use irrigation water coming from natural superficial reservoirs, presumed to be the first source of infection caused by harmful pathogens belonging to the Oomycota class, especially Phytophthora genus and Pythium genus. The forest nursery is the only place where forest managers can react before pathogens leave it with asymptomatic plants or soil attached to their roots. The aim of this research was detection and identification phytopathogens in water samples. In order to recognise genus Phytophthora or Pythium in water collected from 33 places in five different forest districts in Poland, two DNA-based approaches of identification were applied: (i) the TaqMan probes, and (ii) sequencing of the ITS6/4 region. The genomic DNA was obtained from 17 of 33 investigated water samples. TaqMan probes helped to identify 8 oomycetes present in 17 water samples. Based on ITS rDNA sequencing data, pathogens were identified in 17 cases, and this to the genus level (6 cases) and to the species level (11 cases). In total five Oomycetes species were identified, i.e. 3 Pythium species (Py. citrinum, Py. angustatum, Py. helicoides) and two Phytophthora species (P. lacustris sp. nov. – former taxon Salixsoil, P. gallica sp. nov.).

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. The research was performed within the frame of LIFE+ ENV/PL/000459 HESOFF ongoing European project ?Evaluation of the health state of forests and an effect of phosphate treatments with the use of photovoltaic unmanned aerial vehicle (UAV)?. Przemys?aw Szmit

To investigate susceptibility of young Scots pine seedlings to four Phytophthora species: Phytophthora cactorum, Phytophthora cambivora, Phytophthora plurivora and Phytophthora pini; seven-day-old seedlings of Scots pine (15 seedlings per experiment) were infected using agar plugs of the respective species. Control group also consisted of 15 seedlings and was inoculated with sterile agar plugs. Results unambiguously show that after 4.5 days, all seedlings show clear signs of infection and display severe symptoms of tissue damage and necrosis. Moreover, three and two seedlings in the P. cactorum and P. cambivora infected seedlings groups, respectively, collapsed. The length of largest necrosis measured 13.4±3.90 mm and was caused by P. cactorum. To rule out any putative contamination or infection by secondary pathogens, re-isolations of pathogens from infection sites were performed and were positive in 100% of plated pieces of infected seedlings. All re-isolations were, however, negative in the case of the control group. Detailed microscopic analyses of infected tissues of young seedlings confirmed the presence of numerous Phytophthora species inside and on the surface of infected seedlings. Therefore, our results suggest Phytophthora spp. and mainly P. cactorum and P. cambivora as aggressive pathogens of Scots pine seedlings and highlight a putative involvement of these species in the damping off of young Scots pine seedlings frequently observed in forest nurseries.

Our aim was to examine the virulence of eight Phytophthora isolates belonging to three species (Phytophthora cryptogea, Phytophthora plurivora and Phytophthora quercina) obtained from diverse European ecosystems (in Bulgaria, Poland and Germany) towards three forest tree hosts – English oak (Quercus robur L.), Turkey oak (Quercus cerris L.) and European beech (Fagus sylvatica L.). All plants grown from seeds in a greenhouse conditions were artificially inoculated under the stem bark with Phytophthora cultures. The tested isolates turned to be more aggressive to Turkey oaks than to English oak trees. In case of European beech, the isolates of P. cryptogea and P. plurivora exposed various virulence. The potential hazard of the introduced foreign isolates for the oak and beech forests in Poland and Bulgaria is discussed. Amongst the tested isolates, P. quercina P290 from German highly infected Bulgarian Turkey oaks; therefore, its negative potential impact on Bulgarian oak forests could be considered as high (if unintentionally introduced). Also, two Bulgarian isolates belonging to P. cryptogea and P. plurivora are risky for Polish beech forests, if exposed to the pathogen. The observed pathogenicity of the tested Phytophthora species proved their potential as important contributors to decline of valuable forest ecosystems dominated by oaks (Q. robur and Q. cerris) or beech (F. sylvatica), in both Poland and Bulgaria. We found that investigated Phytophthora pathogens could develop in the living plant stem tissues without causing any disease symptoms, which is another demonstration that phytosanitary control by simple observation of plant material is not effective.

Fungi colonising oak seedlings in forest plantations in north-eastern Poland were identified in 2014-2015. The evaluated 4- to 6-year bare root oaks originated from the Olsztynek Forest District (Regional Directorate of the State Forests in Olsztyn). In total, 744 fungal isolates belonging to 11 different species, and 11 genera, were identified in tested plants. Amongst them, 186 cultures (25%) were classified as plant pathogens. The most commonly isolated pathogenic fungi belonged to the Fusarium and Cylindrocarpon genera.

To investigate susceptibility of young Scots pine seedlings to four Phytophthora species: Phytophthora cactorum, Phytophthora cambivora, Phytophthora plurivora and Phytophthora pini; seven-day-old seedlings of Scots pine (15 seedlings per experiment) were infected using agar plugs of the respective species. Control group also consisted of 15 seedlings and was inoculated with sterile agar plugs. Results unambiguously show that after 4.5 days, all seedlings show clear signs of infection and display severe symptoms of tissue damage and necrosis. Moreover, three and two seedlings in the P. cactorum and P. cambivora infected seedlings groups, respectively, collapsed. The length of largest necrosis measured 13.4±3.90 mm and was caused by P. cactorum. To rule out any putative contamination or infection by secondary pathogens, re-isolations of pathogens from infection sites were performed and were positive in 100% of plated pieces of infected seedlings. All re-isolations were, however, negative in the case of the control group. Detailed microscopic analyses of infected tissues of young seedlings confirmed the presence of numerous Phytophthora species inside and on the surface of infected seedlings. Therefore, our results suggest Phytophthora spp. and mainly P. cactorum and P. cambivora as aggressive pathogens of Scots pine seedlings and highlight a putative involvement of these species in the damping off of young Scots pine seedlings frequently observed in forest nurseries.