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Due to intense ash dieback, this research tested the bioactivity of Thymus vulgaris, Lavandula angustifolia, and Cupressus sempervirens essential oils (EO) against Hymenoscyphus fraxineus. In vitro testing showed that EOs had a pronounced fungitoxic effect on H. fraxineus. The most effective EO was extracted from T. vulgaris, while EOs obtained from L. angustifolia and C. sempervirens were less effective and showed the same effect. At a concentration of 1%, all tested EOs inhibited mycelial growth, while 0.01% and 0.1% concentrations of EO extracted from T. vulgaris also inhibited the growth of H. fraxineus. The in planta test of EO extracted from T. vulgaris conducted on three‐year‐old Fraxinus angustifolia seedlings showed a reduction in the size of necrotic lesions and a better crown condition compared to untreated seedlings. This research demonstrates, for the first time, the efficiency of EOs in suppressing ash dieback making a path for the development of new biological protection measures against H. fraxineus. [ABSTRACT FROM AUTHOR]

During a survey of Phytophthora diversity in Panama, fast-growing oomycete isolates were obtained from naturally fallen leaves of an unidentified tree species in a tropical cloud forest. Phylogenetic analyses of sequences from the nuclear ITS, LSU and ßtub loci and the mitochondrial cox1 and cox2 genes revealed that they belong to a new species of a new genus, officially described here as Synchrospora gen. nov., which resided as a basal genus within the Peronosporaceae. The type species S. medusiformis has unique morphological characteristics. The sporangiophores show determinate growth, multifurcating at the end, forming a stunted, candelabra-like apex from which multiple (8 to >100) long, curved pedicels are growing simultaneously in a medusa-like way. The caducous papillate sporangia mature and are shed synchronously. The breeding system is homothallic, hence more inbreeding than outcrossing, with smooth-walled oogonia, plerotic oospores and paragynous antheridia. Optimum and maximum temperatures for growth are 22.5 and 25–27.5 °C, consistent with its natural cloud forest habitat. It is concluded that S. medusiformis as adapted to a lifestyle as a canopy-dwelling leaf pathogen in tropical cloud forests. More oomycete explorations in the canopies of tropical rainforests and cloud forests are needed to elucidate the diversity, host associations and ecological roles of oomycetes and, in particular, S. medusiformis and possibly other Synchrospora taxa in this as yet under-explored habitat. [ABSTRACT FROM AUTHOR]

Revision of the taxonomically complicated European Melanoleuca taxa with well-developed macrocystidia (subgenus Melanoleuca) is presented. The species are delimited by macro- and micromorphological characters and by multilocus molecular data based on internal transcribed spacer (ITS), second largest subunit of RNA polymerase I (rpb2), and translation elongation factor 1-alpha (tef1) genes. The study is based on both type material and recent collections. Phylogenetically, these taxa form 10 clades recognized as 11 separate species: M. albomarginata, M. ammophila, M. bataillei, M. cavipes, M. friesii, M. granadensis, M. melaleuca, M. pallidicutis, M. polioleuca, M. strictipes, and M. variabilis. Three species, M. albomarginata, M. ammophila, and M. variabilis, are described as new. Melanoleuca melaleuca is discussed here as the type species of the genus. Discussion of other older names and their taxonomic status is also provided. [ABSTRACT FROM AUTHOR]

Slow growing oomycete isolates with morphological resemblance to Phytophthora were obtained from forest streams during routine monitoring for the EU quarantine forest pathogen Phytophthora ramorum in Ireland and Northern Ireland. Internal Transcribed Spacer (ITS) sequence analysis indicated that they belonged to two previously unknown species of Nothophytophthora, a recently erected sister genus of Phytophthora. Morphological and temperature-growth studies were carried out to characterise both new species. In addition, Bayesian and Maximum-Likelihood analyses of nuclear 5-loci and mitochondrial 3-loci datasets were performed to resolve the phylogenetic positions of the two new species. Both species were sterile, formed chlamydospores and partially caducous nonpapillate sporangia, and showed slower growth than any of the six known Nothophytophthora species. In all phylogenetic analyses both species formed distinct, strongly supported clades, closely related to N. chlamydospora and N. valdiviana from Chile. Based on their unique combination of morphological and physiological characters and their distinct phylogenetic positions the two new species are described as Nothophytophthora irlandica sp. nov. and N. lirii sp. nov. Their potential lifestyle and geographic origin are discussed. [ABSTRACT FROM AUTHOR]

Caliciopsis pinea has been historically described as a secondary pathogen of pines. However, it has recently been associated with severe damages on Pinus radiata in Italy. Our study focused on the description of the seasonal spore dispersal of C. pinea and its relation to meteorological conditions (temperature, leaf wetness, relative humidity and precipitations). For this experiment one infected P. radiata plantation was sampled in Tuscany (Italy). A rotating arm spore trap together with a weather station were installed to sample the aerospora for 24 h every week from May to November 2016. Exposed tapes from spore traps were directly analyzed after DNA extraction by qPCR using specific primers and TaqMan MGB probe. The study shows an irregular occurrence of the inoculum of C. pinea throughout the whole sampling period with peak levels in mid-June and early August. The statistical analysis of the DNA and climatic data clearly show the strong influence of precipitation on the spore production of this pathogen. Furthermore, the very low detection limit of the qPCR experiment shows the efficacy and suitability of rotating arm spore traps for early detection of this pathogen. [ABSTRACT FROM AUTHOR]

We investigated the ability of Hymenoscyphus fraxineus mitovirus 1 (HfMV1) to spread in nature through the airborne inoculum of its fungal host, the devastatingHymenoscyphus fraxineus. Eight rotating-arm spore traps were installed to collect the airborne spores (presumably ascospores) ofH. fraxineusin four ecologically different ash forests in the Czech Republic. Spore trap samples were subjected to direct DNA and RNA extractions and subsequent qPCR and mitovirus-specific reverse transcription (RT) qPCR for detection and quantification ofH. fraxineusand HfMV1, respectively. The prevalence of HfMV1 was confirmed in 57% ofH. fraxineussampled inocula, showing that its occurrence is significantly correlated with its fungal hostH. fraxineus. Furthermore, the ratio of mitovirus carrying spores was shown to be constant at any level ofH. fraxineusinfection pressure independently of the studied locality. Temperatures of 19–21°C at the time of spore trapping correlated with the highest levels of both HfMV1 andH. fraxineus. Our data confirmH. fraxineusairborne inoculum as an efficient transport means for HfMV1 in nature. Moreover, this research uses a new technology to directly study a mycovirus through its host aerospora. [ABSTRACT FROM PUBLISHER]