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The European Food Safety Authority (EFSA) requested the Panel on Plant Health (PLH Panel) to provide guidance for the evaluation of the effectiveness of the options for plants and plant products for reducing the risk of introduction and spread of harmful organisms in the European Union territory. Two operational tools are presented: a checklist for evaluating a proposed risk reduction option (RRO) and a database of references corresponding to published guidance documents or experimental assessments of RROs. The checklist can be used by the Panel or the dossier-submitting parties to verify whether all required information is provided in support of a RRO, to quickly describe information supplied to EFSA and to identify major gaps in the data. Four types of RRO assessments are distinguished in the proposed checklist according to their purposes and characteristics: experimental assessment of the effectiveness of the option to reduce pest infestation in plant material/products under laboratory/controlled conditions; experimental assessment of the effectiveness of the option to reduce pest infestation in plant material/products under operational conditions; analysis of the applicability of the RRO; and assessment of the effectiveness of the option to reduce the risk of pest entry from an infested area to a pest-free area. The database of references is intended to assist the Panel in (i) identifying potential RROs for a given pest and plant material, and (ii) quickly retrieving relevant experimental data and guidance documents for assessing a proposed RRO. In addition, the current document provides recommendations for assessing RROs, specifically: on experimental design; on the use of statistical methods including approaches for studying uncertainty; on the use of quantitative pathway analysis and spread models describing their advantages and limitations; and on recommendations for general surveillance and specific surveys. The European Food Safety Authority (EFSA) requested the Panel on Plant Health (PLH Panel) to provide guidance for the evaluation of the effectiveness of the options for plants and plant products for reducing the risk of introduction and spread of harmful organisms in the European Union territory. Two operational tools are presented: a checklist for evaluating a proposed risk reduction option (RRO) and a database of references corresponding to published guidance documents or experimental assessments of RROs. The checklist can be used by the Panel or the dossier-submitting parties to verify whether all required information is provided in support of a RRO, to quickly describe information supplied to EFSA and to identify major gaps in the data. Four types of RRO assessments are distinguished in the proposed checklist according to their purposes and characteristics: experimental assessment of the effectiveness of the option to reduce pest infestation in plant material/products under laboratory/controlled conditions; experimental assessment of the effectiveness of the option to reduce pest infestation in plant material/products under operational conditions; analysis of the applicability of the RRO; and assessment of the effectiveness of the option to reduce the risk of pest entry from an infested area to a pest-free area. The database of references is intended to assist the Panel in (i) identifying potential RROs for a given pest and plant material, and (ii) quickly retrieving relevant experimental data and guidance documents for assessing a proposed RRO. In addition, the current document provides recommendations for assessing RROs, specifically: on experimental design; on the use of statistical methods including approaches for studying uncertainty; on the use of quantitative pathway analysis and spread models describing their advantages and limitations; and on recommendations for general surveillance and specific surveys.

In 2011, the EFSA Panel on Plant Health was asked by the European Commission to provide an opinion on a technical file submitted by the US Authorities to support a request to list a new heat treatment (60 °C/60 min) among the EU import requirements for wood of Agrilus planipennis host plants. After a thorough analysis of the documents provided the Panel concluded that, with a low uncertainty, A. planipennis is likely to survive the proposed heat treatment of 60 °C/60 min, and that, to ensure a control level of 99 % the temperature of the heat treatment of 60 min should be higher than 70 °C. Following the publication of this scientific opinion, the US Authorities submitted a new proposal to the European Commission, consisting in a new heat treatment (71.1 °C/60 min). The EFSA Panel on Plant Health was asked to consider whether this new proposal was within the scope of the published opinion and, if not, to clarify its conclusion and indicate what data would be needed to assess the effectiveness of the new treatment. The Panel concluded that the new proposal is not within the scope of the opinion as the data provided by the US Authorities cannot be used to evaluate the effectiveness of the new proposed heat treatment. An accurate assessment of the new proposed heat treatment (71.1 °C/60 min) would require an experiment including several temperatures higher than 70 °C (one corresponding to the proposed treatment). Regarding the data requirements for assessing the effectiveness of the new treatment, the Panel lists the information required in the checklist presented in the Panel’s draft guidance document on methodology for evaluation of the effectiveness of options to reduce the risk of introduction and spread of organisms harmful to plant health in the EU territory, currently under public consultation on EFSA website. In 2011, the EFSA Panel on Plant Health was asked by the European Commission to provide an opinion on a technical file submitted by the US Authorities to support a request to list a new heat treatment (60 °C/60 min) among the EU import requirements for wood of Agrilus planipennis host plants. After a thorough analysis of the documents provided the Panel concluded that, with a low uncertainty, A. planipennis is likely to survive the proposed heat treatment of 60 °C/60 min, and that, to ensure a control level of 99 % the temperature of the heat treatment of 60 min should be higher than 70 °C. Following the publication of this scientific opinion, the US Authorities submitted a new proposal to the European Commission, consisting in a new heat treatment (71.1 °C/60 min). The EFSA Panel on Plant Health was asked to consider whether this new proposal was within the scope of the published opinion and, if not, to clarify its conclusion and indicate what data would be needed to assess the effectiveness of the new treatment. The Panel concluded that the new proposal is not within the scope of the opinion as the data provided by the US Authorities cannot be used to evaluate the effectiveness of the new proposed heat treatment. An accurate assessment of the new proposed heat treatment (71.1 °C/60 min) would require an experiment including several temperatures higher than 70 °C (one corresponding to the proposed treatment). Regarding the data requirements for assessing the effectiveness of the new treatment, the Panel lists the information required in the checklist presented in the Panel’s draft guidance document on methodology for evaluation of the effectiveness of options to reduce the risk of introduction and spread of organisms harmful to plant health in the EU territory, currently under public consultation on EFSA website.

Following a request by the European Commission, EFSA’s Panel on Plant Health was asked to deliver a statement to clarify the current scientific knowledge regarding the identity of the apple snails in the context of the evaluation of the pest risk analysis prepared by the Spanish Ministry of Environment and Rural and Marine Affairs (EFSA Panel on Plant Health (PLH), 2012). The Panel concludes on the risk to plant health posed by Pomacea species in the ‘canaliculata complex’, that out of the around 50 species in the genus of Pomacea, four species P. canaliculata, P. insularum, P. lineata and P. maculata belong to the ‘canaliculata complex’, where P. insularum and P. maculata are recently considered to be synonyms. Current methods of identification imply high uncertainty if risk reduction options are applied at the Pomacea single species level. The Spanish pest risk analysis identifies important plant health risks connected to Pomacea species. The available scientific evidence indicates that other Pomacea species may pose similar risks to plant health as identified for P. insularum. The Panel clarifies that risk reduction options should not be targeted to single species of the genus Pomacea considering: (i) the dynamical situation in the current study on the systematics of the Ampullariidae species and the genus Pomacea in particular; (ii) the uncertainties and the possible unexpected evolution of the invasive potential of species of Pomacea other than P. insularum and P. canaliculata; (iii) the poor knowledge on the trophic habits of many species of the genus Pomacea, with possible overlaps in the trophic niche (macrophytes); (iv) the high uncertainty on the identification of the different Pomacea species. Following a request by the European Commission, EFSA’s Panel on Plant Health was asked to deliver a statement to clarify the current scientific knowledge regarding the identity of the apple snails in the context of the evaluation of the pest risk analysis prepared by the Spanish Ministry of Environment and Rural and Marine Affairs (EFSA Panel on Plant Health (PLH), 2012). The Panel concludes on the risk to plant health posed by Pomacea species in the ‘canaliculata complex’, that out of the around 50 species in the genus of Pomacea, four species P. canaliculata, P. insularum, P. lineata and P. maculata belong to the ‘canaliculata complex’, where P. insularum and P. maculata are recently considered to be synonyms. Current methods of identification imply high uncertainty if risk reduction options are applied at the Pomacea single species level. The Spanish pest risk analysis identifies important plant health risks connected to Pomacea species. The available scientific evidence indicates that other Pomacea species may pose similar risks to plant health as identified for P. insularum. The Panel clarifies that risk reduction options should not be targeted to single species of the genus Pomacea considering: (i) the dynamical situation in the current study on the systematics of the Ampullariidae species and the genus Pomacea in particular; (ii) the uncertainties and the possible unexpected evolution of the invasive potential of species of Pomacea other than P. insularum and P. canaliculata; (iii) the poor knowledge on the trophic habits of many species of the genus Pomacea, with possible overlaps in the trophic niche (macrophytes); (iv) the high uncertainty on the identification of the different Pomacea species.

The Panel on Plant Health has delivered a scientific opinion on the different risks posed by European and non-European populations of the potato cyst nematodes (PCN) Globodera pallida and Globodera rostochiensis to solanaceous plants in the EU and on the effectiveness of current control measures. Although PCN, particularly G. rostochiensis, are widespread in the EU, crop damage is limited because breeders have been able to develop varieties that are resistant to the small number of genotypes that are present. These genotypes represent a minor subset of the gene pool and virulence that is present in South America. As new South American genotypes are very likely to have a similar potential for establishment and spread as existing European genotypes, the potato varieties currently grown in Europe will not be resistant to new virulent genotypes. As resistant varieties take a very long time to develop, the consequences of a new introduction of South American PCN would be major. The Panel therefore concluded that it is very important to maintain the current phytosanitary measures to prevent the entry of South American PCN. However, uncertainties over the effectiveness of the measures in Annex IVAI relating to place of production freedom and soil origin were noted, and the Panel identified additional risk reduction options for certain plants for planting (e.g. bulbs) and additional requirements to confirm the absence of PCN in places of production. The Panel also identified some problems with the existing control measures to reduce the spread of PCN within the EU. A thorough and well-coordinated EU-wide survey using standardized methods would be necessary to evaluate the need to maintain these measures. The monitoring of PCN populations should exploit new diagnostic techniques (e.g. mitochondrial DNA sequences) to ensure that the resistance available is deployed appropriately. The Panel on Plant Health has delivered a scientific opinion on the different risks posed by European and non-European populations of the potato cyst nematodes (PCN) Globodera pallida and Globodera rostochiensis to solanaceous plants in the EU and on the effectiveness of current control measures. Although PCN, particularly G. rostochiensis, are widespread in the EU, crop damage is limited because breeders have been able to develop varieties that are resistant to the small number of genotypes that are present. These genotypes represent a minor subset of the gene pool and virulence that is present in South America. As new South American genotypes are very likely to have a similar potential for establishment and spread as existing European genotypes, the potato varieties currently grown in Europe will not be resistant to new virulent genotypes. As resistant varieties take a very long time to develop, the consequences of a new introduction of South American PCN would be major. The Panel therefore concluded that it is very important to maintain the current phytosanitary measures to prevent the entry of South American PCN. However, uncertainties over the effectiveness of the measures in Annex IVAI relating to place of production freedom and soil origin were noted, and the Panel identified additional risk reduction options for certain plants for planting (e.g. bulbs) and additional requirements to confirm the absence of PCN in places of production. The Panel also identified some problems with the existing control measures to reduce the spread of PCN within the EU. A thorough and well-coordinated EU-wide survey using standardized methods would be necessary to evaluate the need to maintain these measures. The monitoring of PCN populations should exploit new diagnostic techniques (e.g. mitochondrial DNA sequences) to ensure that the resistance available is deployed appropriately.

The European Commission requested the Panel on Plant Health to deliver a scientific opinion on the phytosanitary risk of plants (other than fruits and seeds) of Pinus pinea and of the genera Chamaecyparis, Cryptomeria and Juniperus for the spread of pine wood nematode (PWN) via movement of infested plants or untreated plant products or by supporting natural spread of PWN in conjunction with European species of the vector. The Panel analysed the data submitted by Portugal regarding surveys on the Tróia Peninsula where P. pinaster and P. pinea co-occur, and the related laboratory results of Naves et al. (2006) on feeding and oviposition preferences of Monochamus galloprovincialis. The Panel also undertook a comprehensive review of the literature. The zero infestation of PWN recorded on P. pinea on the Tróia Peninsula was not significantly different from the result for P. pinaster, because of the small P. pinea sample. Hence, the conclusion that P. pinea is not a host plant for PWN is not supported by the data submitted, principally because of low statistical confidence arising from the few P. pinea trees present. Moreover, the limited presence of P. pinea in the study areas means that the results are representative neither of the Tróia Peninsula nor of other parts of Portugal. Naves et al. (2006) recorded some oviposition by M. galloprovincialis on P. pinea, but less than on other hosts. No differences in feeding of M. galloprovincialis on P. pinaster and P. pinea were detected, thus potentially allowing PWN transmission to trees by this route. The available information regarding the genera Chamaecyparis, Cryptomeria and Juniperus as potential hosts of Monochamus spp. and PWN suggests overall a low susceptibility to PWN or its vectors; the uncertainty concerning PWN is high and would require supplementary research. The European Commission requested the Panel on Plant Health to deliver a scientific opinion on the phytosanitary risk of plants (other than fruits and seeds) of Pinus pinea and of the genera Chamaecyparis, Cryptomeria and Juniperus for the spread of pine wood nematode (PWN) via movement of infested plants or untreated plant products or by supporting natural spread of PWN in conjunction with European species of the vector. The Panel analysed the data submitted by Portugal regarding surveys on the Tróia Peninsula where P. pinaster and P. pinea co-occur, and the related laboratory results of Naves et al. (2006) on feeding and oviposition preferences of Monochamus galloprovincialis. The Panel also undertook a comprehensive review of the literature. The zero infestation of PWN recorded on P. pinea on the Tróia Peninsula was not significantly different from the result for P. pinaster, because of the small P. pinea sample. Hence, the conclusion that P. pinea is not a host plant for PWN is not supported by the data submitted, principally because of low statistical confidence arising from the few P. pinea trees present. Moreover, the limited presence of P. pinea in the study areas means that the results are representative neither of the Tróia Peninsula nor of other parts of Portugal. Naves et al. (2006) recorded some oviposition by M. galloprovincialis on P. pinea, but less than on other hosts. No differences in feeding of M. galloprovincialis on P. pinaster and P. pinea were detected, thus potentially allowing PWN transmission to trees by this route. The available information regarding the genera Chamaecyparis, Cryptomeria and Juniperus as potential hosts of Monochamus spp. and PWN suggests overall a low susceptibility to PWN or its vectors; the uncertainty concerning PWN is high and would require supplementary research.

The Panel considers the Spanish pest risk analysis (PRA) to be clear and to provide appropriate supporting evidence. However, (i) the environmental impact assessment is incomplete and (ii) the estimates for the potentially endangered area are too limited. The Panel points out that large areas of the European Union have climatic conditions, that are very similar to those of the areas of native distribution of Pomacea spp. snails, and suitable host plants are available. The Panel agrees with the Spanish PRA on the following points with regard to the risk assessment area: (i) the potential consequences of the organism for rice crops are major; (ii) the probability for establishment of the organism is very likely and (iii) the probability of spread is estimated as likely. The Panel disagrees with the Spanish PRA on the following points and considers (i) the effects on the environment to be massive under suitable environmental conditions in the PRA area and (ii) the probability of entry of the organism to be high. Regarding risk reduction options the Panel agrees with the Spanish PRA that no single risk reduction method is sufficient to halt the introduction and spread of Pomacea spp. snails in the PRA area. However, a legislative ban on import of Pomacea spp. is the only risk reduction option identified that can reduce the probability of entry. The many other risk reduction options listed will help to reduce the probability of spread within the PRA area. The Panel considers that the risk reduction options should target the canaliculata complex, as Pomacea insularum and P. canaliculata, as well as other species from the complex, are almost indistinguishable. This is of particular importance for risk reduction options addressing both breeding and trade of the organism. The Panel considers the Spanish pest risk analysis (PRA) to be clear and to provide appropriate supporting evidence. However, (i) the environmental impact assessment is incomplete and (ii) the estimates for the potentially endangered area are too limited. The Panel points out that large areas of the European Union have climatic conditions, that are very similar to those of the areas of native distribution of Pomacea spp. snails, and suitable host plants are available. The Panel agrees with the Spanish PRA on the following points with regard to the risk assessment area: (i) the potential consequences of the organism for rice crops are major; (ii) the probability for establishment of the organism is very likely and (iii) the probability of spread is estimated as likely. The Panel disagrees with the Spanish PRA on the following points and considers (i) the effects on the environment to be massive under suitable environmental conditions in the PRA area and (ii) the probability of entry of the organism to be high. Regarding risk reduction options the Panel agrees with the Spanish PRA that no single risk reduction method is sufficient to halt the introduction and spread of Pomacea spp. snails in the PRA area. However, a legislative ban on import of Pomacea spp. is the only risk reduction option identified that can reduce the probability of entry. The many other risk reduction options listed will help to reduce the probability of spread within the PRA area. The Panel considers that the risk reduction options should target the canaliculata complex, as Pomacea insularum and P. canaliculata, as well as other species from the complex, are almost indistinguishable. This is of particular importance for risk reduction options addressing both breeding and trade of the organism.

The Panel on Plant Health was requested by the European Commission to deliver a scientific opinion on the risk posed by the oriental chestnut gall wasp, Dryocosmus kuriphilus to the EU territory and to identify and evaluate risk management options. Additional analyses were conducted by the Panel to a) determine the distribution of the endangered area within the EU territory; b) investigate the pattern and rate of pest diffusion and c) consider the environmental risk of introduction of the biological control agent Torymus sinensis identified as a potential management option. The Panel concluded in its assessment that a) Castanea plants for intended planting represent the main pathway for entry of D. kuriphilus to the EU; b) D. kuriphilus has a very high potential for establishment in the EU and the climate is suitable wherever Castanea sativa is grown in southern, central and western Europe; c) the average rate of spread of D. kuriphilus is estimated as 8 km/yr; d) spread within the EU is likely, due to adult dispersal by flight and the movement of plants containing eggs and larvae which remain undetected within dormant buds; e) the potential effects on fruit yield reduction are considered moderate and the environmental impact in Castanea woodland is considered as low; f) all EU chestnut production is endangered but the areas of fruit production with the highest degree day accumulations where D. kuriphilus is absent, e.g. in northern Portugal, northern Spain and south-west France, are identified as particularly at risk; g) management options to reduce likelihood of introduction and spread consist of certifying Castanea planting material from pest free areas/places of production; h) classical biological control and plant varietal resistance are identified as management options to reduce the magnitude of impact. The Panel on Plant Health was requested by the European Commission to deliver a scientific opinion on the risk posed by the oriental chestnut gall wasp, Dryocosmus kuriphilus to the EU territory and to identify and evaluate risk management options. Additional analyses were conducted by the Panel to a) determine the distribution of the endangered area within the EU territory; b) investigate the pattern and rate of pest diffusion and c) consider the environmental risk of introduction of the biological control agent Torymus sinensis identified as a potential management option. The Panel concluded in its assessment that a) Castanea plants for intended planting represent the main pathway for entry of D. kuriphilus to the EU; b) D. kuriphilus has a very high potential for establishment in the EU and the climate is suitable wherever Castanea sativa is grown in southern, central and western Europe; c) the average rate of spread of D. kuriphilus is estimated as 8 km/yr; d) spread within the EU is likely, due to adult dispersal by flight and the movement of plants containing eggs and larvae which remain undetected within dormant buds; e) the potential effects on fruit yield reduction are considered moderate and the environmental impact in Castanea woodland is considered as low; f) all EU chestnut production is endangered but the areas of fruit production with the highest degree day accumulations where D. kuriphilus is absent, e.g. in northern Portugal, northern Spain and south-west France, are identified as particularly at risk; g) management options to reduce likelihood of introduction and spread consist of certifying Castanea planting material from pest free areas/places of production; h) classical biological control and plant varietal resistance are identified as management options to reduce the magnitude of impact.

Following a request from the European Commission, the Panel on Plant Health was asked to deliver a scientific opinion on the appropriateness of a composting method proposed by Portugal as a heat treatment to eliminate pine wood nematode (PWN), Bursaphelenchus xylophilus (Steiner and Buhrer) Nickle from bark of pine trees. The Panel evaluated the dossier entitled “Technical requirements for heat treatment of isolated bark of conifers” submitted by the Portuguese Authorities and concluded that a) the process is not adequately described and information on a number of key aspects is not provided, b) the heat treatment protocol does not allow for a full characterisation of the temperature profile within each treated lot, c) the treatment process described does not provide evidence that all the bark particles within the lot achieve a continuous core temperature of 56 °C for 30 minutes and d) insufficient evidence on the sampling methodology is provided to determine the reliability of the testing method provided by the Portuguese document to determine freedom from PWN. Although there is potential for development of a composting method as a heat treatment to eliminate PWN from bark of pine trees, the technical requirements presented in the Portuguese dossier do not adequately demonstrate the effectiveness and reliability of the proposed composting method as a treatment to ensure freedom of treated pine bark from live PWN Following a request from the European Commission, the Panel on Plant Health was asked to deliver a scientific opinion on the appropriateness of a composting method proposed by Portugal as a heat treatment to eliminate pine wood nematode (PWN), Bursaphelenchus xylophilus (Steiner and Buhrer) Nickle from bark of pine trees. The Panel evaluated the dossier entitled “Technical requirements for heat treatment of isolated bark of conifers” submitted by the Portuguese Authorities and concluded that a) the process is not adequately described and information on a number of key aspects is not provided, b) the heat treatment protocol does not allow for a full characterisation of the temperature profile within each treated lot, c) the treatment process described does not provide evidence that all the bark particles within the lot achieve a continuous core temperature of 56 °C for 30 minutes and d) insufficient evidence on the sampling methodology is provided to determine the reliability of the testing method provided by the Portuguese document to determine freedom from PWN. Although there is potential for development of a composting method as a heat treatment to eliminate PWN from bark of pine trees, the technical requirements presented in the Portuguese dossier do not adequately demonstrate the effectiveness and reliability of the proposed composting method as a treatment to ensure freedom of treated pine bark from live PWN

Following a request from the European Commission, the EFSA Panel on Plant Health examined the report “Evaluation of Strawberry Nursery Plant Cold Treatments on Survival of the Whitefly, Bemisia tabaci”, submitted to the European Commission by the United States Department of Agriculture (USDA). The report serves as technical justification for a derogation from requirements listed in Annex IV, Part A, Section 1, point 46 of the Council Directive 2000/29/EC. The Panel concluded that due to shortcomings in the report itself and in the experimental design of the study, this report does not demonstrate the effectiveness of the cold treatment proposed for the elimination of B. tabaci from strawberry plant consignments prepared for shipment to the EU. In addition, the Panel conducted a preliminary review of the available literature on viruses of strawberry and concluded that no B. tabaci-transmitted viruses are currently known to infect strawberry and that no viruses of Fragaria listed in European Council Directive 2000/29/EC are known to be transmitted by B. tabaci. However, adult whiteflies of B. tabaci on strawberry consignments can carry plant viruses irrespective of whether strawberry is a host plant for these viruses and thus represent a pathway for the introduction of non-European viruses. There is also some uncertainty concerning the extent to which known or unknown B. tabaci-transmitted viruses could infect strawberry. Irrespective of the presence of B. tabaci, strawberry transplants from the US may represent a pathway for the introduction of any non-European virus (and other potentially harmful organisms) of Fragaria Following a request from the European Commission, the EFSA Panel on Plant Health examined the report “Evaluation of Strawberry Nursery Plant Cold Treatments on Survival of the Whitefly, Bemisia tabaci”, submitted to the European Commission by the United States Department of Agriculture (USDA). The report serves as technical justification for a derogation from requirements listed in Annex IV, Part A, Section 1, point 46 of the Council Directive 2000/29/EC. The Panel concluded that due to shortcomings in the report itself and in the experimental design of the study, this report does not demonstrate the effectiveness of the cold treatment proposed for the elimination of B. tabaci from strawberry plant consignments prepared for shipment to the EU. In addition, the Panel conducted a preliminary review of the available literature on viruses of strawberry and concluded that no B. tabaci-transmitted viruses are currently known to infect strawberry and that no viruses of Fragaria listed in European Council Directive 2000/29/EC are known to be transmitted by B. tabaci. However, adult whiteflies of B. tabaci on strawberry consignments can carry plant viruses irrespective of whether strawberry is a host plant for these viruses and thus represent a pathway for the introduction of non-European viruses. There is also some uncertainty concerning the extent to which known or unknown B. tabaci-transmitted viruses could infect strawberry. Irrespective of the presence of B. tabaci, strawberry transplants from the US may represent a pathway for the introduction of any non-European virus (and other potentially harmful organisms) of Fragaria.