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The Panel on Plant Health performed a pest categorisation of the six-toothed bark beetle, Ips sexdentatus (B€orner) (Coleoptera: Curculionidae, Scolytinae), for the EU. I. sexdentatus is a well-defined and distinguishable species, native to Eurasia and recognised mainly as a pest of pine (Pinus spp., in the pest’s whole range) and spruce (mainly Picea orientalis in Turkey and Georgia). It also might occasionally attack Larix spp. and Abies spp. It is distributed throughout the EU (24 Member States). It is a protected zone quarantine pest in Ireland, Cyprus and the United Kingdom (Northern Ireland, Isle of Man), listed in Annex IIB of Council Directive 2000/29/EC. Wood, wood products, bark and wood packaging material are considered as pathways for this pest, which is also able to disperse by flight over tens of kilometres. The adults normally establish on fallen or weakened trees (e.g. after a fire or a drought) and can also massattack healthy trees. The males produce aggregation pheromones that attract conspecifics of both sexes. The insects also inoculate pathogenic fungi to their hosts. There are one to five generations per year. The wide current geographical range of I. sexdentatus suggests that it is able to establish anywhere in the EU where its hosts are present. Sanitary thinning or clear-felling are the major control methods. Pheromone mass-trapping is also locally implemented. Quarantine measures are implemented to prevent entry into the protected zones. All criteria for consideration as potential protected zone quarantine pest are met. The criteria for considering I. sexdentatus as a potential regulated non-quarantine pest are not met since plants for planting are not viewed as a pathway.

The EFSA Panelon Plant Health performed a pest categorisation of Palm lethal yellowing phytoplasmas for the EU territory. This name is used to describe diseases that share the same succession of symptoms in palms that are caused by a number of strains of phytoplasma, for which efficient molecular detection assays are available. The pest is not known to occur in the EU and therefore does not meet one of the criteria for being a Union regulated non-quarantine pest. For Candidatus Phytoplasma palmae', the planthopper Haplaxius crudus, which is not known to be present in the EU, is the confirmed vector, but for the other strains, the vectors are unknown. The host range of the pest is restricted to Arecaceae species, in particular coconut. The pest is regulated on all known hosts in Annex IIAI of Directive 2000/29/EC. It could potentially enter the EU via plants for planting or through infected vectors. The phytoplasmas could become established in the EU as host plants are present. It is unknown whether arthropods present in the EU could be vectors. The potential impact of the pest if introduced into the EU is difficult to assess given this uncertainty but is estimated to be limited. The main knowledge gaps concern the status of potential vector insects in the EU; the possibility for seed transmission of the phytoplasmas; the origin and volume of the trade in palm seeds and plants for planting; the host status and susceptibility of many palm species grown in the EU and the potential new assignments of phytoplasmas to this categorisation that might have associated alternate hosts. Palm lethal yellowing phytoplasmas meet the criteria assessed by EFSA for consideration as Union quarantine pest. (C) 2017 European Food Safety Authority. EFSA Journal published by John Wiley and Sons Ltd on behalf of European Food Safety Authority.

The EFSA Panel on Plant Health performed a pest categorisation of non‐EU isolates of Beet curly top virus (BCTV) for the European Union territory. The virus causes severe diseases in beet, tomatoes and pepper crops, occurs predominantly in warm and dry zones and is reported from many countries outside the EU in particular from western USA and Mexico. New data from complete virus genomes make BCTV a well characterised virus species of which currently 11 strains are known and for which diagnostic methods are available. BCTV has a very broad host range of more than 300 species some of which may remain symptomless. Aside from vegetative propagation of infected plants, the only mode of BCTV transmission and spread is by the leafhopper Circulifer tenellus which efficiently transmits the virus in a persistent mode and which is present in several southern EU Member States. No current reports of BCTV presence in the EU exist and because of doubts about the accuracy of older reports, BCTV likely is absent from the EU territory. BCTV can enter into the EU with viruliferous insects and with imports of plants not subject to specific EU regulation. Because both the virus and its vector have a wide host range, BCTV is expected to establish and spread in the Member States where its vector is present and to cause severe diseases in sugar beet and tomato as well as in other crops. Overall, BCTV non‐EU isolates meet all the criteria evaluated by EFSA to qualify as a Union quarantine pest and do not meet the criterion of presence in the EU to qualify as a Union regulated non‐quarantine pest (RNQP). The main uncertainties concern (1) the presence of BCTV in the EU, (2) the distribution of C. tenellus and (3) the main commodities for virus entry.

Following the 2014 EFSA’s Panel on Plant Health scientific opinion on the pest categorisation of the spider mite Eotetranychus lewisi, the European Commission requested the Panel to perform a pest risk assessment and evaluate the risk reduction options. A stochastic model was used to assess entry, establishment and spread and related uncertainties. In the EU, E. lewisi has only been reported to occur in Portugal (Madeira). Entry pathways assessed were strawberry plants for planting from the USA, poinsettia and raspberry plants for planting, and orange and lemon fruits from third countries. Entry is most likely via poinsettia. Under current EU phytosanitary requirements, there is around a one in ten chance that E. lewisi will establish outdoors over the next 10 years. Although unlikely, establishment would most likely occur in southern Europe where environmental conditions, temperature and host density, are most suitable. If E. lewisi did establish, pest spread is expected to be mainly human assisted, most likely the mite being transported long distances on plants for planting. Nevertheless, while remaining a regulated pest, spread would be slow and most likely confined to one NUTS 2 area after 10 years. Under a scenario with enhanced measures (pest free place of production) at origin, the Panel’s assessment indicate that it is extremely unlikely that E. lewisi would establish within 10 years hence spread is also extremely unlikely. The absence of trade of host plants from Madeira to other parts of the EU could explain why E. lewisi has not spread to other EU Member States. E. lewisi is reported as reducing yield and quality of peaches and poinsettia and is regarded as a growing concern for strawberry and raspberry growers in the Americas. The Panel concludes that should E. lewisi be introduced in the EU similar impacts could be expected.

As requested by the European Commission, the EFSA Panel on Plant Health (PLH) Panel assessed the risk of Diaporthe vaccinii in the EU, focusing on entry, establishment, spread and impacts on cultivated and wild Vaccinium species, the principal hosts being American and European cranberry and blueberry. Several outbreaks occurred in the EU since 1956, but most were eradicated except in Latvia. The Panel considered entry via fruits and plants for planting. The risk of establishment from discarded infected berries is much lower than from infected plants for planting, of which, potted plants and cuttings pose the greatest risk, while plug plants, derived from tissue culture and grown in pest free structures, pose a low risk. Nine per cent of the EU is highly suitable for establishment of the pathogen, mostly in the SE and NE. Following establishment, the pathogen could spread naturally over short range, and by human assistance over long range. Calculations with an integrated model for entry, establishment and spread, indicate that with current regulations, over a period of 5 years, a few hundred cultivated Vaccinium plants and several thousand Vaccinium plants in natural ecosystems would contract the disease. The associated loss of commercial production is small, less than one tonne of berries per year. On natural vegetation, the median impact after 5 years was estimated to be negligible affecting a negligible proportion of the natural Vaccinium population (2 x 10 8). However, the uncertainty of this estimate was high, due to uncertainty about the rate of spread; in a worst-case scenario (99th percentile), almost 1% of plants in natural areas would become infected. Complete deregulation (scenario A1) was predicted to increase the impact substantially, especially in natural areas, while additional measures (scenario A2) would effectively eliminate the entry of infected plants for planting, further reducing the impacts below the current situation.

Following a request from the European Commission, the EFSA Plant Health (PLH) Panel performed a pest categorisation of Gremmeniella abietina, a well-defined species and distinguishable fungus of the family Godroniaceae. The species G. abietina includes several varieties, races and biotypes that are found in different geographical locations, on different hosts and that vary in aggressiveness. The pathogen causes diseases on Pinus species and other conifers such as Abies spp., Picea spp., Larix spp. and Pseudotsuga spp. known as Scleroderris canker in North America and Brunchorstia dieback in Europe. G. abietina has been reported from 19 EU Member States, without apparent ecoclimatic factors limiting establishment. The pathogen is a protected zone (PZ) quarantine pest (Annex IIB) for Ireland and the UK (Northern Ireland). The main European hosts are widespread throughout most of the EU and have been frequently planted in the PZ. The main means of spread are wind-blown ascospores, rain-splashed conidia, plants for planting and traded Christmas trees. Given that G. abietina is most damaging to species that are grown towards the limit of their range, impacts can be expected in the PZ, should the pathogen be introduced there. Risk reduction options include selection of disease-free planting material, nursery inspections, selection of planting sites at some distance from infested plantations, appropriate spacing between plants and thinning. The main uncertainties concern the indeterminate endophytic stage of the fungus, the pathogen distribution and the future taxonomic status of G. abietina, given its intraspecific diversity. All the criteria assessed by the Panel for consideration as potential PZ quarantine pest are met. The criterion of plants for planting being the main pathway for spread for regulated non-quarantine pests is not met: plants for planting are only one of the means of spread of the pathogen.

The Panel on Plant Health performed a pest risk assessment on Radopholus similis, the burrowing nematode for the EU. The quantitative assessment focused on entry, establishment, spread and impact on tropical and subtropical ornamental host plants, the main pathways for entry of R. similis into the EU. Infested consignments are expected to enter the risk assessment area on ornamentals under all scenarios. For citrus, which is a closed pathway for entry, outdoor establishment was assessed. Establishment may only take place after successful transfer from ornamental plants to citrus production systems. This event is called ‘shift’ in this assessment, to indicate that this is an unusual transfer. It has been estimated that establishment of this nematode in the open field in the EU citrus production areas under current temperatures is possible in most parts of the citrus production area in the EU. Temperature conditions will prevent the nematode from establishing only in the northernmost citrus areas and at higher altitudes in the south. Host plants for planting originating from infested places of production (greenhouses) within the risk assessment area are considered the main pathway for spread within the risk assessment area. Under current climatic conditions, the population of R. similis is not expected to reach damaging population levels in the open field. In case of increased temperatures due to global warming, the nematode population may reach damaging levels in very few places outdoors. Currently, main impact is considered for ornamental greenhouse production in the risk assessment area. Impact will be either caused by direct plant growth reductions or loss due to phytosanitary measures applied on regulated plants. Despite the fact that R. similis is globally considered as one of the most destructive plant parasitic nematodes, the impact in the risk assessment area is considered low.

Following a request from the European Commission, the EFSA Plant Health (PLH) Panel performed a pest categorisation of Pseudocercospora pini-densiflorae, a well-defined and distinguishable fungal species of the family Mycosphaerellaceae. The regulated harmful organism is the anamorph Cercoseptoria pini-densiflorae (synonym Cercospora pini-densiflorae) with the corresponding teleomorph Mycosphaerella gibsonii. P. pini-densiflorae causes a needle blight of Pinus spp. also known as Cercospora blight of pines or Cercospora needle blight. P. pini-densiflorae is reported from sub-Saharan Africa, Central and South America, Asia and Oceania, but not from the EU. The pathogen is regulated in Council Directive 2000/29/EC (Annex IIAI) as a quarantine organism whose introduction into the EU is banned on plants (other than fruit and seeds) and wood of Pinus. The pest could enter the EU via plants for planting and other means (uncleaned seed, cut branches of pine trees, isolated bark, growing media accompanying plants, and mycorrhizal soil inocula). Hosts are widespread in the EU and favourable climatic conditions are present in Mediterranean countries. Pinus halepensis, Pinus nigra, Pinus pinea, Pinus pinaster and Pinus sylvestris are reported to be highly susceptible to the pathogen. The pest would be able to spread following establishment after introduction in the EU mainly on infected plants for planting. The pest introduction could have impacts in nurseries and young plantations. Cleaning seeds from needles and removing infected seedlings and pine litter from affected nurseries can reduce the risk of establishment in nurseries and of spread from nurseries to forests, especially given the limited scale of splash dispersal. The main knowledge gaps concern (i) the role of means of entry/spread other than plants for planting and (ii) the potential consequences in mature tree plantations and forests. The criteria assessed by the Panel for consideration as potential quarantine pest are met. For regulated nonquarantine pests, the criterion on the pest presence in the EU is not met.

Following a request from the European Commission, the EFSA Panel on Plant Health (PLH) was asked to assess two publications, authored by Magarey et al. and Martinez-Minaya et al. from 2015, with regard to a need to update the EFSA Scientific Opinion from 2014 on the risk of Phyllosticta citricarpa (Guignardia citricarpa) for the EU territory. The EFSA PLH Panel was also requested to assess any other relevant scientific information published after the finalisation of the EFSA Scientific Opinion. The fungus P. citricarpa (McAlpine) Van der Aa causes the citrus disease citrus black spot (CBS), and is regulated as quarantine organism in Council Directive 2000/29/EC. The Panel assessed the two publications in detail as well as all relevant publications published until 31 March 2016. A comparison with the EFSA PLH Panel (2014) was made, survey data on CBS from South Africa used in Magarey et al. (2015) were evaluated, and the citrus production areas in the EU were characterised and compared with results from Magarey et al. (2015). Uncertainty and model sensitivity were discussed. It was concluded that the evidence presented in Magarey et al. from 2015 does not require an updating of EFSA PLH Panel (2014). The conclusion in the Opinion that probability of CBS establishment in the EU is moderately likely is not affected by the paper by Magarey et al. (2015) predicting establishment in some of the EU locations they selected. The high level of uncertainty regarding the probability of establishment is also unchanged by Magarey et al. (2015). The Panel concluded that Martinez-Minaya et al. (2015) does not provide new evidence requiring an update to EFSA PLH Panel (2014), principally because it had already been concluded that global climate zones are based on factors and thresholds that are broad and not necessarily representative of those that are critical for the pathogen and its host.

This opinion addresses the question of the efficacy of current treatment solutions to cure Xylella fastidiosa diseased plants, and discusses the experimental treatments under evaluation by two research groups in Apulian olive orchards infected by strain CoDiRO (Complesso del Disseccamento Rapido dell’Olivo). The increasing problems from newly emerging vascular bacterial diseases and the limited success to cure plants from such infections have stimulated numerous studies on treatments with chemical and biological compounds. Under field conditions, various formulations of copper and zinc as spray or root drench are currently used while further options, for example the application of bioactive substances, are at an experimental stage. In Apulia, preliminary results from intensive treatments with such formulations, in combination with the use of good crop management practices, reported more vigorous new growth of diseased trees. However, results provided so far confirmed the continued presence of X. fastidiosa after the treatments under evaluation. This is in agreement with current knowledge that there are no means to cure plants from this bacterial disease, in the sense of eliminating the pathogen from plant tissues. The reported positive response of the treated olive trees is most probably due to the effect of micronutrients and other bioactive compounds that, together with soil cultivation and agronomical practices, improve the vigour of the plants and their resilience to stress caused by bacterial infections. Notwithstanding the preliminary status of these findings, the Panel acknowledged the potentially positive effects of such treatments in prolonging the productive phase of olive trees and their putative relevance for the management of olive orchards, particularly in the containment area where eradication of the pathogen is considered no longer possible. The Panel also concluded that long-term studies are needed to confirm that the reported positive effects on crop performance can be sustained over many years.

Following a request from the European Commission, the EFSA Plant Health Panel analysed a dossier submitted by Costa Rica Authorities to reach a conclusion on the host status of Phoenix roebelenii for Xylella fastidiosa. The Panel wishes first to stress the difficulties faced in providing compelling evidence for the non-susceptibility status of any particular plant species. The Panel acknowledges that the listing of P. roebelenii as a host of X. fastidiosa rests on a single report from California. Because isolation of X. fastidiosa from some hosts can be difficult, the Panel considers that the failure to isolate X. fastidiosa from P. roebelenii cannot be used to totally discard the detection of X. fastidiosa by ELISA and PCR. The Panel concludes that the detection of X. fastidiosa by two independent techniques provides sufficient evidence, although not totally conclusive, for the listing of P. roebelenii as a X. fastidiosa host plant. Concerning the survey data provided in the Costa Rican dossier, the Panel wishes to stress that such surveys cannot demonstrate the non-host status but can only provide a probability bound, upper estimate of the proportion of infected plants in the field. In the present case, and assuming all survey parameters to be optimal, the 95% confidence incidence threshold obtained is 0.2%, leaving the possibility that close to 25,000 P. roebelenii plants could be infected but undetected in the country. Accepting a scenario of local, non-systemic infection of P. roebelenii by X. fastidiosa would further increase uncertainties. In addition, the absence of data on the vector infection pressure further affects the ability to derive meaningful information on the P. roebelenii host status from the survey data. Appropriately conducted mechanical and/or vector-mediated inoculation experiments are critical to reach a more solid conclusion on the X. fastidiosa host status of P. roebelenii.

The Panel on Plant Health performed a pest categorisation of the great spruce bark beetle, Dendroctonus micans (Kugelann), (Coleoptera: Curculionidae, Scolytinae), for the EU. D. micans is a well-defined and distinguishable species, recognised mainly as a pest of spruce (Picea spp.) and pine (Pinus spp.) in Eurasia. Attacks on other conifers (Abies spp., Larix decidua, Pseudotsuga menziesii) are also reported. Supposedly originating from north-eastern Eurasia, D. micans has spread westward and is now distributed throughout the EU (22 Member States). It is a quarantine pest listed in Annex IIB of Council Directive 2000/29/EC for Greece, Ireland and the United Kingdom (Northern Ireland, Isle of Man and Jersey) as protected zones. Wood, wood products, bark and wood packaging material of the conifers genera listed as hosts are considered as the main pathways for the pest, which is also able to disperse several kilometres by flight. The sib-mating habits of the species allow each single female to start a new colony on her own. The pest’s wide current geographic range suggests that it is able to establish anywhere in the EU where its hosts are present. The beetles attack living trees and usually complete their life cycle without killing their host, except under epidemic conditions at the limits of their distribution range, where hundreds of thousands of trees can be killed. Sitka spruce (Picea sitchensis) is particularly susceptible. Biological control using the very specific predatory beetle, Rhizophagus grandis, is a widespread and efficient option that has been implemented in all areas suffering from outbreaks. It is complemented by sanitary thinning or clear-felling. All criteria assessed by EFSA for consideration as potential protected zone quarantine pest were met. The criteria for considering D. micans as a potential regulated non-quarantine pest are not met since plants for planting are not the main pathway.

Following a request from the European Commission, the EFSA Panel on Plant Health (PLH) performed a quantitative analysis of the risk posed by the Flavescence doree phytoplasma (FDp) in the EU territory. Three scenarios were analysed, one with current measures in place (scenario A0), one designed to improve grapevine propagation material phytosanitary status (scenario A1) and one with reinforced eradication and containment (scenario A2). The potential for entry is limited, FDp being almost non-existent outside the EU. FDp and its major vector, Scaphoideus titanus, have already established over large parts of the EU and have the potential to establish in a large fraction of the currently unaffected EU territory. With the current measures in place (A0), spread of FDp is predicted to continue with a progression of between a few and ca 20 newly infested NUTS 2 regions during the next 10 years, illustrating the limitations of the current control measures against spread. FDp spread is predicted to be roughly similar between scenarios A1 and A2, but more restricted than under scenario A0. However, even with reinforced control scenarios, stabilisation or reduction in the number of infested NUTS 2 regions has only relatively low probability. Under scenario A0, FDp has a 0.5–1% impact on the overall EU grapes and wine production, reflecting the effectiveness of the current control measures against impact. Under both scenarios A1 and A2, FDp impact is predicted to be reduced, by approximately one-third (A1) to two-thirds (A2) as compared to A0, but the associated uncertainties are large. The generalised use of hot water treatment for planting material produced in infected zones has the most important contribution to FDp impact reduction in scenario A1 and has high feasibility. Both increased eradication and containment measures contribute to impact reduction under scenario A2 but the overall feasibility is lower.

Following a request from the European Commission, the EFSA Plant Health Panel analysed a dossier submitted by the Italian Authorities to reach a conclusion on the status of Vitis spp., Citrus spp. and Quercus ilex as hosts for Xylella fastidiosa strain CoDiRO. The Panel acknowledges the difficulty to provide compelling evidence for non-susceptibility of a particular plant species. In the case of Vitis spp., the Panel considers that convergent lines of evidence provide sufficient demonstration that at least the tested varieties (Cabernet Sauvignon, Negroamaro and Primitivo) do not support a systemic infection by the CoDiRO strain. The extension of this conclusion to other grapevine varieties and to Vitis species other than Vitis vinifera is associated with significant uncertainties. The Panel therefore considers it premature to conclude that all Vitis species are unable to support a CoDiRO systemic infection. In addition, although the local accumulation detected in the mechanical inoculation experiments may represent an artefact, the Panel considers it premature to conclude that the tested grapevine varieties are not able to support local multiplication of the CoDiRO strain. Further extension of this conclusion to other grapevine varieties and to non-vinifera species is also premature. For Citrus spp., the data available provide coherent and converging lines of evidence suggesting that sweet orange may be a non-systemic host of strain CoDiRO. However, given the limited scope of the data available on other species, the Panel considers it premature to reach a general conclusion for all Citrus species. The potential epidemiological consequences of non-systemic infections remain to be fully evaluated. In the case of Quercus ilex, the Panel concludes that the limited data available provides some evidence suggesting that it may not be a systemic host of the CoDiRO strain, but that it would be premature to consider this tentative conclusion as firmly established.