The number of alien plant pests and pathogens is rapidly increasing in many countries as a result of increasing trade, particularly the trade in living plants. Sentinel plantings in exporting countries to detect arthropod pests and agents of diseases prior to introduction provide information about the likelihood of introduction and the potential impact on plants native to the importing country. Such plantings can consist of species that are native to exporting or importing countries ("in-patria" and "ex-patria" plantings). In-patria plantings consist of young woody plants of species that are commonly exported and can be used to identify pests that may be introduced to new countries via the trade in live plants. Ex-patria plantings consist of exotic young or mature woody plants and surveys may provide information about potential impacts of pests if these were to become established in a new country. We discuss the methods and benefits of this powerful tool and list examples of studies that highlight the large number of unknown organisms and pest-host relationships that can be detected. The usefulness of sentinel plantings is illustrated using examples of arthropod pests and fungal pathogens of European and Asian tree species that were identified in sentinel studies in China and the Asian Russia. Keywords Woody plants • Exotic pests and pathogens • Early warning Key message • Many exotic plant pests and pathogens are unknown prior to their establishment, making prevention and management difficult. • Sentinel plantings to detect pests and pathogens prior to introduction provide information about the likelihood of introduction and the potential impact on plants native to the importing country. • This paper discusses the different types of sentinel plantings based on the native range and age of the plants, their purpose, limitations and benefits. • Summarised results from published studies illustrate the benefits of sentinel plantings.

The Phytophthora genus includes some of the most devastating plant pathogens. Here we report draft genome sequences for three ubiquitous Phytophthora species—Phytophthora chlamydospora, Phytophthora gonapodyides, and Phytophthora pseudosyringae. Phytophthora pseudosyringae is an important forest pathogen that is abundant in Europe and North America. Phytophthora chlamydospora and Ph. gonapodyides are globally widespread species often associated with aquatic habitats. They are both regarded as opportunistic plant pathogens. The three sequenced genomes range in size from 45 Mb to 61 Mb. Similar to other oomycete species, tandem gene duplication appears to have played an important role in the expansion of effector arsenals. Comparative analysis of carbohydrate-active enzymes (CAZymes) across 44 oomycete genomes indicates that oomycete lifestyles may be linked to CAZyme repertoires. The mitochondrial genome sequence of each species was also determined, and their gene content and genome structure were compared. Using mass spectrometry, we characterised the extracellular proteome of each species and identified large numbers of proteins putatively involved in pathogenicity and osmotrophy. The mycelial proteome of each species was also characterised using mass spectrometry. In total, the expression of approximately 3000 genes per species was validated at the protein level. These genome resources will be valuable for future studies to understand the behaviour of these three widespread Phytophthora species.

Pectobacterium brasiliense (Pbr) is considered as one of the most virulent species among the Pectobacteriaceae. This species has a broad host range within horticulture crops and is well distributed elsewhere. It has been found to be pathogenic not only in the field causing blackleg and soft rot of potato, but it is also transmitted via storage causing soft rot of other vegetables. Genomic analysis and other cost-effective molecular detection methods such as a quantitative polymerase chain reaction (qPCR) are essential to investigate the ecology and pathogenesis of the Pbr. The lack of fast, field deployable point-of-care testing (POCT) methods, specific control strategies and current limited genomic knowledge make management of this species difficult. Thus far, no comprehensive review exists about Pbr, however there is an intense need to research the biology, detection, pathogenicity and management of Pbr, not only because of its fast distribution across Europe and other countries but also due to its increased survival to various climatic conditions. This review outlines the information available in peer-reviewed literature regarding host range, detection methods, genomics, geographical distribution, nomenclature and taxonomical evolution along with some of the possible management and control strategies. In summary, the conclusions and a further directions highlight the management of this species.

Destructive soft rot Pectobacteriaceae affect a number of vegetable crops and cause high economic loses in the field and storage. The diversity of Pectobacterium and Dickeya causing soft rot of vegetables in Northern Ireland is unknown. This study provides details of Pectobacterium and Dickeya spp. detected in vegetables from several locations in Northern I r e l a n d i n t h e y e a r s 2 0 1 5-2 0 1 7. S o f t r o t Pectobacteriaceae were identified based on DNA sequences. Thirty three strains were selected for further phylogenetic analysis based on the recA gene region. Results from the testing of over 3456 potato samples for plant health statutory purposes in the years 2005-2017 demonstrated that Dickeya spp. is not the major pathogen causing soft rot or blackleg in Northern Ireland. The most predominant species causing soft rot of vegetables in Northern Ireland were Pectobacterium atrosepticum and Pectobacterium carotovorum subsp. carotovorum. Pectobacterium atrosepticum was also detected on hosts other than potato. Testing of bacteria isolated from carrots led to the detection of P. carotovorum and Dickeya sp. This is the first study to provide knowledge about Pectobacterium and Dickeya spp. diversity causing soft rot of vegetables in Northern Ireland confirmed by real-time PCR and DNA sequences. This is also the first report of the detection of D. aquatica from a source other than water.

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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 naïve 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.

This investigation sought to examine if there was a difference between the ectomycorrhizal (ECM) communities in plots of native oak and introduced Scots pine and Sitka spruce forest. The ECM communities in four plots of each forest type were described, from five soil cores collected in each plot, by morphotyping, internal transcribed spacer (ITS)-restriction fragment length polymorphism matching of mycorrhizas and sporocarps and ITS sequencing. Fifty-one distinct taxa were distinguished; 25 were identified to species level, 11 to genus and 15 remained unidentified. Seventy-one ECM species were recorded as sporocarps from the forest plots; most (43 species) were found in the Sitka spruce plots. The below-ground ECM communities of the different forest types did not differ significantly with respect to species richness of taxa on roots, but differed in species composition. Multivariate analysis produced a clear separation of the communities of the different forest types using below-ground data, but the above-ground sporocarp data did not separate the forest types. Moreover, results of a Mantel test found no relationship between the above- and below-ground similarity matrices. The oak plots had the most distinctive ECM community, with Laccaria amethystina and Elaphomyces granulatus being frequent. The Sitka spruce plots showed the lowest intra-forest type similarity and were often dominated by "nursery type" ectomycorrhizas. There was only 10% similarity between the above- and below-ground ECM species in these plots, different colonisation methods of ectomycorrhizal taxa and insufficient below-ground sampling being possible reasons for this disparity. Our results indicate that plantations of non-native Sitka spruce can support similar levels of ECM diversity as native forests.