European And Mediterranean Plant Protection Organization Research Articles

High-Quality Complete Genome Sequence of Xanthomonas phaseoli pv. dieffenbachiae Outbreak Strain D182: The Causative Agent of Anthurium Bacterial Blight in Hawaii

Xanthomonas phaseoli pv. dieffenbachiae (Xpd), the causal agent of anthurium blight, is classified as an A2 quarantine organism on the European and Mediterranean Plant Protection Organization (EPPO) list due to its devastating impact on the anthurium industry. In this study, we sequenced strain D182, representative of the Hawaiian anthurium blight outbreak (1981 to 1986), using PacBio RS II SMRT technology. High-quality de novo assembly of 5,217,888 bp (65% GC) was generated with a mean coverage of 351× using HGAP v4. Strain D182 harbors one plasmid (73.5 kb, 60.8% GC). Average nucleotide identity and digital DNA–DNA hybridization values of 99.86 and 98.9%, respectively, showed close phylogenetic relationships with Xpd strain LMG 695PT. The genome information will be useful in providing insights into the genomic biology, virulence mechanisms, and evolutionary relationships of Xpd and other strains associated with anthurium blight outbreaks worldwide. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Field-Deployed Spectroscopy from 350 to 2500 nm: A Promising Technique for Early Identification of Powdery Mildew Disease (Erysiphe necator) in Vineyards

This study explores spectroscopy in the 350 to 2500 nm range for detecting powdery mildew (Erysiphe necator) in grapevine leaves, crucial for precision agriculture and sustainable vineyard management. In a controlled experimental vineyard setting, the spectral reflectance on leaves with varying infestation levels was measured using a FieldSpec 4 spectroradiometer during July and September. A detailed assessment was conducted following the guidelines recommended by the European and Mediterranean Plant Protection Organization (EPPO) to quantify the level of infestation; categorising leaves into five distinct grades based on the percentage of leaf surface area affected. Subsequently, spectral data were collected using a contact probe with a tungsten halogen bulb connected to the spectroradiometer, taking three measurements across different areas of each leaf. Partial Least Squares Regression (PLSR) analysis yielded coefficients of determination R2 = 0.74 and 0.71, and Root Mean Square Errors (RMSEs) of 12.1% and 12.9% for calibration and validation datasets, indicating high accuracy for early disease detection. Significant spectral differences were noted between healthy and infected leaves, especially around 450 nm and 700 nm for visible light, and 1050 nm, 1425 nm, 1650 nm, and 2250 nm for the near-infrared spectrum, likely due to tissue damage, chlorophyll degradation and water loss. Finally, the Powdery Mildew Vegetation Index (PMVI) was introduced, calculated as PMVI = (R755 − R675)/(R755 + R675), where R755 and R675 are the reflectances at 755 nm (NIR) and 675 nm (red), effectively estimating disease severity (R2 = 0.7). The study demonstrates that spectroscopy, combined with PMVI, provides a reliable, non-invasive method for managing powdery mildew and promoting healthier vineyards through precision agriculture practices.

Naturalised Hakea. What species are we actually talking about in Europe?

ABSTRACT Hakea sericea Schrad. & J.C.Wendl. (Proteaceae) is a shrub or small tree native to south-eastern Australia. The species has been introduced to other countries; it has naturalised and become invasive in France, New Zealand, Portugal, and South Africa. During the review process of the Pest Risk Analysis for the European and Mediterranean Plant Protection Organization (EPPO) on Hakea sericea in 2017, the actual identity of the plant causing major negative biodiversity impact in Portugal was questioned. Flowering material from Portugal and additional collections from South Africa and New Zealand were collected in order to clarify the taxonomical status. To make the survey on the proper identity of the Hakea plants invasive in Portugal more concise, all Hakea species encountered in Portugal, France, South Africa and New Zealand were included. For morphological distinction of the species the length of the pistil and fruit characters were used. For molecular analysis Illumina sequencing in combination with de novo assembly and extraction of loci was used. Results show that invasive populations of Hakea in Portugal belong to H. decurrens R.Br a species that, although very similar and sometimes considered synonymous with H. sericea, can be distinguished both morphologically and on the basis of cpDNA. Both species occur in France and in New Zealand, while only H. sericea occurs in South Africa. Both species are invasive and seem to have similar impacts on biodiversity in invaded ranges. The morphologically similar species H. gibbosa (J.White) Cav. occurs in both New Zealand and South Africa. By adopting the H. sericea sensu lato concept for inclusion of the species on the List of Union Concern pursuant of Regulation (EU) No 1143/2014, a potential legislative controversy can be prevented.

Testing a modified version of the EPPO decision-support scheme for release of classical biological control agents of plant pests using Ganaspis cf. brasiliensis and Cleruchoides noackae as case studies

The 6/04 standard of the European and Mediterranean Plant Protection Organisation (EPPO) on the safe use of biological control is a decision-support scheme (DSS) for the import and release of biological control agents in Europe. It was recently developed by the Joint EPPO/International Organisation of Biological Control (IOBC) Panel on Biological Control Agents. The DSS can be used to assess the potential environmental impacts of biological control agents. It is valid for different types of biological control: classical and augmentative biological control of invertebrates, pathogens and weeds. However, the DSS is not yet widely implemented in Europe and, during preliminary trials, it was found that its broad range of usages could lead to some confusion or misunderstandings, as well as requiring unnecessary information in some cases. Thus, the scheme was modified to specifically assess classical biological control against plant pests, i.e. the introduction of exotic natural enemies of plant pests for establishment and long-term control. The new version of the scheme was then tested on two parasitoids that are presently being released in Europe, the figitid Ganaspis cf. brasiliensis against the spotted wing drosophila Drosophila suzukii and the mymarid Cleruchoides noackae against the Eucalyptus bronze bug Thaumastocoris peregrinus. Both parasitoids were successfully assessed with the new version of the DSS. No major issues were encountered during the assessments and most questions were answered with low levels of uncertainty. Both assessments concluded that the parasitoids were safe to release in the impact assessment areas, with positive impacts exceeding negative impacts. Suggestions for potential improvements are provided.

EPPO ontology: a semantic-driven approach for plant and pest codes representation.

The agricultural industry and regulatory organizations define strategies and build tools and products for plant protection against pests. To identify different plants and their related pests and avoid inconsistencies between such organizations, an agreed and shared classification is necessary. In this regard, the European and Mediterranean Plant Protection Organization (EPPO) has been working on defining and maintaining a harmonized coding system (EPPO codes). EPPO codes are an easy way of referring to a specific organism by means of short 5 or 6 letter codes instead of long scientific names or ambiguous common names. EPPO codes are freely available in different formats through the EPPO Global Database platform and are implemented as a worldwide standard and used among scientists and experts in both industry and regulatory organizations. One of the large companies that adopted such codes is BASF, which uses them mainly in research and development to build their crop protection and seeds products. However, extracting the information is limited by fixed API calls or files that require additional processing steps. Facing these issues makes it difficult to use the available information flexibly, infer new data connections, or enrich it with external data sources. To overcome such limitations, BASF has developed an internal EPPO ontology to represent the list of codes provided by the EPPO Global Database as well as the regulatory categorization and relationship among them. This paper presents the development process of this ontology along with its enrichment process, which allows the reuse of relevant information available in an external knowledge source such as the NCBI Taxon. In addition, this paper describes the use and adoption of the EPPO ontology within the BASF's Agricultural Solutions division and the lessons learned during this work.

Real-time on-site detection of the three 'Candidatus Liberibacter' species associated with HLB disease: a rapid and validated method.

Huanglongbing (HLB) is a devastating disease that affects all commercial citrus species worldwide. The disease is associated with bacteria of three species of the genus 'Candidatus Liberibacter' transmitted by psyllid vectors. To date, HLB has no cure, so preventing its introduction into HLB-free areas is the best strategy to control its spread. For that, the use of accurate, sensitive, specific, and reliable detection methods is critical for good integrated management of this serious disease. This study presents a new real-time recombinase polymerase amplification (RPA) protocol able to detect the three 'Ca. Liberibacter' species associated with HLB in both plant and insect samples, validated according to European and Mediterranean Plant Protection Organization (EPPO) guidelines and tested on 365 samples from nine different geographic origins. This new protocol does not require nucleic acid purification or specialized equipment, making it ideal to be used under field conditions. It is based on specific primers and probe targeting a region of fusA gene, which shows a specificity of 94%-100%, both in silico and in vitro, for the 'Ca. Liberibacter' species associated with HLB. The analytical sensitivity of the new protocol is excellent, with a reliable detection limit in the order of 101 copies per microliter in HLB-infected plant and insect material. The repeatability and reproducibility of the new methods showed consistent results. Diagnostic parameters of the new RPA protocol were calculated and compared with the gold standard technique, a quantitative real-time PCR, in both crude extracts of citrus plants and insect vectors. The agreement between the two techniques was almost perfect according to the estimated Cohen's kappa index, with a diagnostic sensitivity and specificity of 83.89% and 100%, respectively, and a relative accuracy of 91.59%. Moreover, the results are obtained in less than 35min. All these results indicate the potential of this new RPA protocol to be implemented as a reliable on-site detection kit for HLB due to its simplicity, speed, and portability.

Citizen science at school increases awareness of biological invasions and contributes to the detection of exotic ambrosia beetles

The serious and growing threat posed by biological invasions to biodiversity and livelihoods means that public engagement in dealing with problems of invasive alien species is ever more urgent and necessary hence a citizen science experiment was carried out in north-eastern Italy. The study aimed i) to raise awareness of invasive alien species threatening trees and forests, and ii) to perform monitoring activities of a group of wood borers as an example, involving teachers and students (aged 11 to 18) of high schools. Students and teachers were given background knowledge and trained about the protocol for collecting data in schoolyards/grounds. Native (Anisandrus dispar (Fabricius, 1792), Xyleborinus saxesenii (Ratzeburg, 1837)) and exotic ambrosia beetles (Anisandrus maiche Kurentsov, Cnestus mutilatus (Blandford), Xylosandrus crassiusculus (Motschulsky, 1866), Xylosandrus germanus (Blandford, 1894)) were used as the target species, as they could be easily detected through accessible and low-cost traps requiring limited effort. The traps were exposed for 24 hours weekly between March and June 2021. The experiment also aimed to strengthen public involvement, connecting environmental education and experiential outdoor learning. The mutual collaboration resulted in a wider knowledge of the potential impact of exotic species. It also led to new geographical citizen-science records of two alien ambrosia beetles considered to be quarantine pests by the European Union: C. mutilatus, new for the European part of the EPPO (European and Mediterranean Plant Protection Organization) region, and A. maiche, which was previously found only in Eastern European EPPO member countries.

Molecular Diagnostics in Tomato: Chip Digital PCR Assays Targeted to Identify and Quantify Clavibacter michiganensis subsp. michiganensis and Ralstonia solanacearum in planta

Clavibacter michiganensis subsp. michiganensis (Cmm) and Ralstonia solanacearum (Rs) are important bacterial pathogens of tomatoes (Solanum lycopersicum), are included in A2 list in the EPPO (European and Mediterranean Plant Protection Organization) region and are recommended for regulation as quarantine pests. The control of quarantine pathogens requires accurate and rapid detection tools. In this study, a method based on chip digital PCR (cdPCR) was developed to identify and quantify Cmm and Rs. The assays were tested on pure bacteria samples and on tomato samples naturally contaminated or spiked with bacteria DNA. For a better estimation of infection level in host plants, duplex assays that are able to simultaneously amplify plant and bacteria DNA were developed. The two cdPCR assays proposed can be used for the rapid and timely detection of this group of high-risk quarantine bacteria to prevent the spread of pathogens and the occurrence of disease in other areas.

The Need and a Vision for a Diagnostic Assay Validation Network

Plant biosecurity depends heavily on early detection of biological pest and disease threats and accurate diagnosis of causal agents. The information from these activities is disseminated and communicated with decision makers to promote effective mitigation. In the United States, most land-grant university, state, and private diagnostic and expert pest identifier labs are successfully networked via the U.S. Department of Agriculture Animal Plant Health Inspection Service, Plant Protection and Quarantine (USDA APHIS PPQ; https://www.aphis.usda.gov/ ), the National Plant Diagnostic Network (NPDN; https://www.npdn.org ), and the National Clean Plant Network (NCPN; https://www.nationalcleanplantnetwork.org/ ). These organizations provide access to training, shared protocols, and standardized communications. For example, the NPDN has secure communications tools that network leadership built into its IT infrastructure and deploys a formal communications process and protocol for regulatory and high-risk samples. Additionally, the diagnostic networks adopt protocols from regulatory organizations such as the USDA-APHIS, European and Mediterranean Plant Protection Organization (EPPO), North American Plant Protection Organization (NAPPO), and other international and national plant protection organizations (NPPOs). However, plant health diagnosticians also need access to validated protocols for endemic and nonregulated organisms. Although there is strong networking of diagnostic laboratories, plant disease diagnostic assay development and validation are siloed, representing a critical gap in our biosecurity infrastructure, especially for new or emerging pathogens. Most assays are developed in independent research labs and then chosen independently by the end-use laboratory. Assay developers, those who provide reference materials, labs that can provide ring testing for validation, and assay end users could be connected and integrated for more streamlined operations. Terminology and validation protocols need to be standardized within the United States and harmonized with our trade partners to ensure understanding. The ideal would be availability of standard, taxon-specific validation protocols, essential reference materials, and appropriate control materials for use to quickly develop and deploy assays in emergencies, as well as for day-to-day testing. This perspective article provides a summary of principles of assay validation, fitness-for-purpose concepts, and the need for continuous evaluation of assay performances. We describe the existing capacity and resources needed to efficiently develop, validate, and use diagnostic tests, as well as the inefficiencies and resource shortfalls currently faced. We propose development of a Diagnostic Assay Validation Network (DAVN) system to coordinate resources at the national level and harmonize with our partners at the international level. Here, we outline a project to set up the DAVN with the objectives of standardizing terminology and statistics and facilitating location of reference materials used in diagnostic assay development and validation via a portal of tools designed by and for the plant disease research and extension community. Although many of the concepts are also relevant to insects and other pests, the focus of this article is primarily plant pathogens.[Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Development of New Preventive Strategies for Pine Pitch Canker Caused by Fusarium circinatum in Irrigation Water and Evaluation in a Real Nursery Context

Fusarium circinatum is one of the many threats to forests and Pinus nurseries all over the world, being classified as a quarantine organism by several organizations and governing bodies, such as the European and Mediterranean Plant Protection Organization (EPPO) and the European Union (EU), with associated phytosanitary measures in place to prevent its spread through the various means of dispersal. One such means of dispersal is the water used for irrigation in nurseries, which can contain fungal propagules. Three different treatments, namely, Desogerme, Intra Hydrocare and sodium hypochlorite (NaClO), were tested for their efficacy in eliminating F. circinatum spores in water at several concentrations. Those that showed 100% disinfection rates were selected for further assays regarding seed germination and water quality impact. From these studies, Desogerme 1% and Intra Hydrocare 4% were then selected for large-scale seed germination and plant certification assays in nurseries, where they showed promising results in regard to the prevention of infections in nurseries, and in this way, contribute to the efforts of mitigating this disease.

POTENTIALLY DANGEROUS CAUSES OF BACTERIAL DISEASES OF POTATOES IN UKRAINE

An overview of bacterial causative agents of soft (wet) rot of potatoes is given, the epidemiological and etiological aspects of the diseases caused by them are analyzed. When preparing the article, general scientific methods were used: generalization, comparison, system analysis. Data from the European and Mediterranean Plant Protection Organization (EOPO), as well as data from phytosanitary services of EU countries and Ukraine, scientific literature served as material for the analytical study. Trade in plant materials, including potato seed tubers and ornamental plants, is largely responsible for the widespread distribution of pathogens. Locally, pathogens are also spread through plant debris, soil, waterways, aerosols, alternative hosts, and/or farm machinery. The main causative agents of bacterial wet rot of potatoes are gram-negative bacteria of the genera Pectobacterium and Dickeya and quarantine phytopathogens of the genera Clavibacter and Ralstonia. The main methods of detection and identification in asymptomatic potato tubers on an industrial scale are: phytopathological (visual examination of plantations and registration of symptoms of soft rot), microbiological (cultural-morphological and biochemical method, use of test systems for accelerated identification of microorganisms), immunoenzymatic ( enzyme immunosorbent assay), molecular genetic (PCR with specific primers, BIOLOG, DNA fingerprinting and nucleotide sequencing). To date, there are no completely effective pesticides to control all pathogens, so disease control measures will continue to rely primarily on avoiding infection during plant cultivation, and especially during the production of healthy certified seed. For a crop like potatoes, this is primarily based on obtaining bacteria-free minibulbs, applying strict seed certification schemes and strict phytosanitary restrictions. Knowledge of the sources of pathogens and routes of infection should be the basis for the application of phytosanitary measures, especially during and after harvest. Control of quarantine phytopathogens requires special attention. Soft rot pathogens are the main cause of limiting potato production in many regions of the world, particularly Clavibacter michiganensis subsp. sepedonicum and R. solanacearum are quarantine objects of the A-2 list of the European and Mediterranean Organization for Quarantine and Plant Protection. Upon entering our country, R. solanacearum has a high probability of acclimatization and spread in the country.

PLATYNOTA STULTANA WALSINGHAM, 1884 (LEPIDOPTERA TORTRICIDAE) FOUND IN ITALY, INVASIVE PEST IN EUROPE

Notes on the presence of the Omnivorous Leafroller, Platynota stultana (Lepidoptera Tortricidae), in Italy and its presence and interception in other European countries are reported. Geographical distributions and principal morphological and biological characters are illustrated. Considering the wide host range of P. stultana, this pest has the potential to damage many cultivated and wild plants in the European and Mediterranean Plant Protection Organization (EPPO) region. Its interception in England, the Netherlands, and Germany and its introduction into Spain and Italy clearly demonstrates that it has the potential to enter and establish itself in the Southern and Mediterranean parts of Europe. Key Words: Platynota stultana, Lepidoptera Tortricidae, Italy, Europe, pest risk.

Being prepared for huanglongbing disease of citrus: a simulation exercise workshop for contingency planning held in Valencia, Spain

AbstractContingency plans aim to ensure a rapid and effective response to an outbreak of a pest likely which is to have a major impact. Huanglongbing is a devastating disease of citrus not yet present in the European and Mediterranean Plant Protection Organization (EPPO) region. A simulation exercise workshop for contingency planning was held in Valencia, Spain over 3 days in October 2021 as part of the PRE‐HLB project funded by the European Union Horizon 2020 programme. In total, 49 experts from the EPPO region attended the workshop. Participants represented a range of stakeholders from citrus cooperatives, grower associations, nursery workers, citrus exporters, landscapers and gardeners, scientists, Regional Plant Health Authorities, National Plant Protection Organizations and the European Commission. Participants were split into five groups and each group acted as an outbreak management team for a scenario based on a finding of a quarantine pest. The scenario followed the first (fictitious) finding of Diaphorina citri (the insect vector of ‘Candidatus Liberibacter asiaticus’, a causal agent of huanglongbing) at a citrus orchard in Spain. As the scenario developed over a month time scale, each team had to organize themselves to manage a number of issues designed to mimic the development of an outbreak of huanglongbing of citrus over the course of the exercise. The groups acknowledged the usefulness of the Spanish contingency plans for huanglongbing and its vectors, the EPPO Standards, and the risk‐based surveillance design tool RiBESS+.

Intra-Laboratory Evaluation of DNA Extraction Methods and Assessment of a Droplet Digital PCR for the Detection of Xanthomonas citri pv. citri on Different Citrus Species

Xanthomonas citri pv. citri (Xcc) and X. citri pv. aurantifolii (Xca), causal agents of citrus bacterial canker, are both regulated by the European Union to prevent their introduction. Xcc is responsible for severe outbreaks of citrus production worldwide, therefore, a prompt and reliable detection is advisable for the early detection of this bacterium either in symptomatic or asymptomatic plant material. The current EPPO (European and Mediterranean Plant Protection Organization) diagnostic protocol, PM 7/44(1), includes several diagnostic tests even if new assays have been developed in the latter years for which validation data are needed. Recently, a test performance study was organized within the Valitest EU Project to validate Xcc diagnostic methods and provide evidence on the most reliable assays; however, the influence of DNA extraction methods (DEM) on the reliability of the detection has never been assessed. In this study we evaluate four different DEM, by following two different approaches: (i) a comparison by real-time PCR standard curves of bacterial DNA versus bacterial DNA added to plant DNA (lemon, leaves and fruit; orange fruit); and (ii) the evaluation of performance criteria of spiked samples (plant extract added with ten-fold diluted bacterial suspensions at known concentrations). Droplet digital PCR is developed and compared with real-time PCR, as the detection method.

Effect of Different Substrates, and Irrigation with Water with Different Saline Concentrations, on the Development of Tomato Fungal Diseases in an Almería-Type Greenhouse

The aim of this research was to assess the effect of both the salinity level and the type of growing system on the vegetative health of a tomato crop (Solanum lycopersicum). The study was carried out in Almería (Spain) in a local typical greenhouse. Two different growing media were tested: (i) the artificial soil “enarenado” and (ii) a coconut fiber substrate. Each of these growing media was irrigated with water with three different saline concentrations: (i) T1 with an electrical conductivity of 0.6 dS/m, (ii) T2 with 1.5 dS/m, and (iii) T3 with 3.0 dS/m. Using the European and Mediterranean Plant Protection Organization (EPPO) regulations, two diseases were identified: (i) powdery mildew (Leveillula taurica) with a lower disease incidence in tomato plants grown in soil and in plants irrigated with decreasing salinity treatments and (ii) crown and root rot in tomato (Fusarium f. sp. radicis-lycopersici) with a lower incidence in tomato plants grown in soil and a higher incidence in tomato plants grown in coconut substrate. A higher yield was observed in tomato plants transplanted in enarenado than in coconut substrate, although a higher level of Brix degrees was observed in the crops with higher disease severity and salinity stress.

Kocaeli ili Cerambycidae (Coleoptera) üzerine faunistik bir çalışma

Due to the importation of lumber, timber, and wooden packaging materials via international ports, Kocaeli province is at risk of contamination of invasive forest pests, which is mentioned in the European and Mediterranean Plant Protection Organization (EPPO) alarm list. Fieldworks were carried out between March 2016 and October 2017 to determine the fauna of the family Cerambycidae (Coleoptera) in Kocaeli province. Species and specimen numbers were evaluated. Sixty-two species belonging to 39 genera were identified within 24 tribes, that classified under five subfamilies of Cerambycidae. Cerambycinae was the most represented subfamily with 30 species (634 specimens), and Prioninae was the least represented subfamily with three individuals in two species. Thirty of 62 species were the new records for Kocaeli province. Among them, Leptura aurulenta was reported for the second time in Turkey.

Xanthomonas arboricola pv. juglandis and pv. corylina: Brothers or distant relatives? Genetic clues, epidemiology, and insights for disease management.

BackgroundThe species Xanthomonas arboricola comprises up to nine pathovars, two of which affect nut crops: pv. juglandis, the causal agent of walnut bacterial blight, brown apical necrosis, and the vertical oozing canker of Persian (English) walnut; and pv. corylina, the causal agent of the bacterial blight of hazelnut. Both pathovars share a complex population structure, represented by different clusters and several clades. Here we describe our current understanding of symptomatology, population dynamics, epidemiology, and disease control.Taxonomic statusBacteria; Phylum Proteobacteria; Class Gammaproteobacteria; Order Lysobacterales (earlier synonym of Xanthomonadales); Family Lysobacteraceae (earlier synonym of Xanthomonadaceae); Genus Xanthomonas; Species X. arboricola; Pathovars: pv. juglandis and pv. corylina.Host range and symptomsThe host range of each pathovar is not limited to a single species, but each infects mainly one plant species: Juglans regia (X. arboricola pv. juglandis) and Corylus avellana (X. arboricola. pv. corylina). Walnut bacterial blight is characterized by lesions on leaves and fruits, and cankers on twigs, branches, and trunks; brown apical necrosis symptoms consist of apical necrosis originating at the stigmatic end of the fruit. A peculiar symptom, the vertical oozing canker developing along the trunk, is elicited by a particular genetic lineage of the bacterium. Symptoms of hazelnut bacterial blight are visible on leaves and fruits as necrotic lesions, and on woody parts as cankers. A remarkable difference is that affected walnuts drop abundantly, whereas hazelnuts with symptoms do not.DistributionBacterial blight of walnut has a worldwide distribution, wherever Persian (English) walnut is cultivated; the bacterial blight of hazelnut has a more limited distribution, although disease outbreaks are currently more frequently reported. X. arboricola pv. juglandis is regulated almost nowhere, whereas X. arboricola pv. corylina is regulated in most European and Mediterranean Plant Protection Organization (EPPO) countries.Epidemiology and controlFor both pathogens infected nursery material is the main pathway for their introduction and spread into newly cultivated areas; additionally, infected nursery material is the source of primary inoculum. X. arboricola pv. juglandis is also disseminated through pollen. Disease control is achieved through the phytosanitary certification of nursery material (hazelnut), although approved certification schemes are not currently available. Once the disease is present in walnut/hazelnut groves, copper compounds are widely used, mostly in association with dithiocarbamates; where allowed, antibiotics (preferably kasugamycin) are sprayed. The emergence of strains highly resistant to copper currently represents the major threat for effective management of the bacterial blight of walnut.Useful websites https://gd.eppo.int/taxon/XANTJU, https://gd.eppo.int/taxon/XANTCY, https://www.euroxanth.eu, http://www.xanthomonas.org

Common bacterial blight of bean: a model of seed transmission and pathological convergence.

Background Xanthomonas citri pv. fuscans (Xcf) and Xanthomonas phaseoli pv. phaseoli (Xpp) are the causal agents of common bacterial blight of bean (CBB), an important disease worldwide that remains difficult to control. These pathogens belong to distinct species within the Xanthomonas genus and have undergone a dynamic evolutionary history including the horizontal transfer of genes encoding factors probably involved in adaptation to and pathogenicity on common bean. Seed transmission is a key point of the CBB disease cycle, favouring both vertical transmission of the pathogen and worldwide distribution of the disease through global seed trade.TaxonomyKingdom: Bacteria; phylum: Proteobacteria; class: Gammaproteobacteria; order: Lysobacterales (also known as Xanthomonadales); family: Lysobacteraceae (also known as Xanthomonadaceae); genus: Xanthomonas; species: X. citri pv. fuscans and X. phaseoli pv. phaseoli (Xcf‐Xpp).Host rangeThe main host of Xcf‐Xpp is the common bean (Phaseolus vulgaris). Lima bean (Phaseolus lunatus) and members of the Vigna genus (Vigna aconitifolia, Vigna angularis, Vigna mungo, Vigna radiata, and Vigna umbellata) are also natural hosts of Xcf‐Xpp. Natural occurrence of Xcf‐Xpp has been reported for a handful of other legumes such as Calopogonium sp., Pueraria sp., pea (Pisum sativum), Lablab purpureus, Macroptilium lathyroides, and Strophostyles helvola. There are conflicting reports concerning the natural occurrence of CBB agents on tepary bean (Phaseolus acutifolius) and cowpea (Vigna unguiculata subsp. unguiculata).SymptomsCBB symptoms occur on all aerial parts of beans, that is, seedlings, leaves, stems, pods, and seeds. Symptoms initially appear as water‐soaked spots evolving into necrosis on leaves, pustules on pods, and cankers on twigs. In severe infections, defoliation and wilting may occur.DistributionCBB is distributed worldwide, meaning that it is frequently encountered in most places where bean is cultivated in the Americas, Asia, Africa, and Oceania, except for arid tropical areas. Xcf‐Xpp are regulated nonquarantine pathogens in Europe and are listed in the A2 list by the European and Mediterranean Plant Protection Organization (EPPO).GenomeThe genome consists of a single circular chromosome plus one to four extrachromosomal plasmids of various sizes, for a total mean size of 5.27 Mb with 64.7% GC content and an average predicted number of 4,181 coding sequences.Disease controlManagement of CBB is based on integrated approaches that comprise measures aimed at avoiding Xcf‐Xpp introduction through infected seeds, cultural practices to limit Xcf‐Xpp survival between host crops, whenever possible the use of tolerant or resistant bean genotypes, and chemical treatments, mainly restricted to copper compounds. The use of pathogen‐free seeds is essential in an effective management strategy and requires appropriate sampling, detection, and identification methods.Useful websites https://gd.eppo.int/taxon/XANTPH, https://gd.eppo.int/taxon/XANTFF, and http://www.cost.eu/COST_Actions/ca/CA16107.

Incidence of the emerging pathogen Neonectria neomacrospora on Abies taxa in the National Arboreta in England (UK)

In 2008 a severe canker disease of firs (Abies spp.) caused by Neonectria neomacrospora was reported in Norway. In 2011, the same disease was reported in Denmark and, in 2013, it was included in EPPO (European and Mediterranean Plant Protection Organization) Reporting Service as a new emerging disease. In 2015 the disease was detected in England causing dieback on firs. Different studies suggest different susceptibility levels of Abies species to N. neomacrospora. Therefore, the objectives of this study were to investigate the incidence of N. neomacrospora on two of the most important tree collections in England, Bedgebury National Pinetum (BNP) and Westonbirt The National Arboretum (WTNA). Surveys were carried out during January and February 2020. Visual assessment using a health scale from 0 to 10 was carried out on 780 trees comprising 46 different Abies species. Samples were collected from 290 symptomatic trees and isolations were performed in the laboratory to confirm the presence of the pathogen. Identification of the pathogen was confirmed by colony morphology and by real-time PCR. The disease was detected on 32 Abies species. In BNP, N. neomacrospora was isolated from 29% of the sampled trees on 25 different Abies spp., while at WTNA, N. neomacrospora was isolated on 44% of the sampled trees on 18 different Abies species. In total, there were 11 Abies species from which N. neomacrospora was isolated consistently in both BNP and WTNA: A. cephalonica, A. cilicica, A. concolor, A. firma, A. grandis, A. homolepis, A. nordmannniana, A. numidica, A. procera, A. vejarii and Abies × vilmorinii. Additionally, pathogenicity of N. neomacrospora was tested on 400 one-year-old seedlings of eight Abies taxa: A. alba, A. amabilis, A. concolor var. concolor, A. concolor var. lowiana, A. fraseri, A. grandis, A. nordmanniana and A. procera. Neonectria neomacrospora was pathogenic in all species. The largest lesions were detected on A. concolor, A. alba and A. amabilis and disease symptoms differed from species to species. Although N. neomacrospora is present in the tree collections studied, the damage caused by the fungus was not severe and no death of trees was recorded during this survey. However, climate change could play an important role on disease development and trees should be monitored in the future.

Identification, detection and eradication ofHymenoscyphus fraxineusfrom ash (Fraxinus excelsior) seeds

AbstractThe European and Mediterranean Plant Protection Organization (EPPO) real-time PCR protocol for the detection of ash dieback (Hymenoscyphus fraxineus (T. Kowalski) Barak, Queloz, Hosoya) was optimized for diagnostics on ash (Fraxinus excelsior L.) fruits. Ash fruits were collected from a range of sites in Britain, from trees with various levels of infection. To assess the potential pathway and the presence of H. fraxineus, tissue components of ash fruits as well as ash flowers were tested for the presence of H. fraxineus DNA and RNA. The fungus was detected on ash fruits from trees on all five sampled sites including symptomless, lightly and highly infected sites. DNA of H. fraxineus was detected on the pericarps of all fruit lots and on seeds from fruit lots that included damaged and empty fruits, but not on embryos or flowers. RNA of H. fraxineus was never detected on any of the samples or sample types, indicating that H. fraxineus was only detected in an inactive form (i.e. dormant or dead). The absence of RNA from the pathogen suggests that only spores of H. fraxineus are present on ash fruits. A double hot-water treatment was evaluated as a control measure for the eradication of H. fraxineus on ash fruits; these were treated before and after warm stratification. Large proportions of ash fruits survived the double hot-water treatments, with a 60.4 ± 28.4 per cent germination success rate depending on crop year. Double hot-water treatment of ash fruits proved to be an efficient, low cost and low-tech approach for the eradication of H. fraxineus on ash fruits.