Johanna Boberg

Pest risk assessment of Atropellis spp. for the EU territory

Abstract Following a request from the European Commission, the EFSA Plant Health (PLH) Panel performed a risk assessment for Atropellis spp. in the EU focusing on the risk of entry, the host range and the potential impacts. Atropellis is a fungal pathogen of several Pinus spp. in North America. The pathogen has not been reported from Europe and is a quarantine pest regulated in Annex IIAI of Council Directive 2000/29/EC on plants (other than fruit and seeds), isolated bark and wood of Pinus. The main pathways of entry considered were Pinus plants, wood and isolated bark. Given the ban of importing Pinus plants from outside Europe into the EU and the lack of information on EU imports of isolated Pinus bark, only the wood pathway was assessed quantitatively. The conclusion of the assessment of entry for scenario A0 (current regulatory situation) is that the risk of entry of Atropellis spp. is close to zero. This conclusion is expected to apply also in the case of removing the specific Atropellis regulations, because of the remaining generic Pinus requirements, as well as in a scenario with additional risk reduction options. The uncertainty associated with this assessment is relatively limited, given that all the quartiles of the estimated distribution of the number of potential founder populations are close to zero. For the North American Pinus spp. known to be susceptible and widely planted in the EU (mainly P. contorta and P. strobus), the damage observed in North America (loss of wood quality, stem deformations, mortality in young stands, environmental consequences) is expected in the EU to a similar (or higher) degree, should the pathogen be introduced. Similar impacts are expected on the European Pinus spp. known to be host of Atropellis spp. These include widespread and locally abundant species such as P. nigra, P. sylvestris and P. pinaster. There are, however, large uncertainties associated with this impact assessment due to the unknown susceptibility of several other Pinus spp. present in Europe. There is a need for research on the susceptibility to Atropellis spp. of those European Pinus spp.

Pest categorisation of Sphaerulina musiva

Abstract Following a request from the European Commission, the EFSA Plant Health Panel performed a pest categorisation of Sphaerulina musiva, a well‐defined and distinguishable fungal species of the family Mycosphaerellaceae. Following a recent phylogenetic analysis of the genus Septoria and other closely related genera, a new name (S. musiva) was introduced for the species. The former species name Mycosphaerella populorum is used in the Council Directive 2000/29/EC. The pathogen is regulated in Annex IAI as a harmful organism whose introduction into the EU is banned. S. musiva is reported from North and South America and not known to occur in the EU. S. musiva causes Septoria leaf spots and cankers of poplar (Populus spp.). Of the poplars native to Europe, Populus nigra is reported as susceptible and Populus tremula as susceptible when planted in North America. The hybrid Populus x canadensis (arising from a cross of P. nigra and the North American Populus deltoides), widely grown in the EU, is also susceptible. The pest could enter the EU on plants for planting, cut branches, isolated bark and wood with and without bark. S. musiva could establish in the EU, as hosts are common and favourable climatic conditions are widespread, and could spread following establishment by natural dispersal and movement of infected plants for planting, cut branches, isolated bark and wood with or without bark. The pest introduction would have impacts in woodlands, plantations and nurseries. The pathogen is considered the most serious disease affecting hybrid poplar production in North America. Selection, breeding and planting of resistant species and clones are the main methods used to control the damage caused by the pathogen. There is some uncertainty on the geographical distribution of the pest in the Caucasus, the Crimean Peninsula and South America and on the level of susceptibility among Populus species native to Europe as well as Salix spp. The criteria assessed by the Panel for consideration as a potential quarantine pest are met. For regulated non‐quarantine pests, the criterion on the pest presence in the EU is not met.

Pest categorisation of Melampsora medusae

Abstract Following a request from the European Commission, the EFSA Plant Health Panel performed a pest categorisation of Melampsora medusae, a well‐defined and distinguishable fungal species of the family Melampsoraceae. The pathogen is regulated in Annex IAI of Council Directive 2000/29/EC as a harmful organism whose introduction into the EU is banned. M. medusae is a heteroecious rust fungus with Populus spp. as primary telial hosts and various conifers (Larix, Pinus, Pseudotsuga, Abies, Picea and Tsuga spp.) as secondary aecial hosts. M. medusae is native to North America and has spread to South America, Africa, Asia, Oceania, as well as the EU, where M. medusae f. sp. deltoidae has been reported with a restricted distribution and low impacts from Belgium, south‐west France and southern Portugal. The pest could spread to other EU countries, via dissemination of spores, movement of host plants for planting and cut branches. Climate is assumed not to be a limiting factor for the establishment of the pathogen in the EU. M. medusae is the most widespread and important Melampsora rust in North America. In western Canada, extensive damage has been reported to conifers and Populus spp. in nurseries and plantations as well as in woodlands. M. medusae is damaging in both Australia and New Zealand. The pest could have economic and environmental impacts in the EU if aggressive isolates of M. medusae were introduced into the EU. Import prohibition of host plants for planting is an available measure to reduce the risk of further introductions. Some resistant Populus cultivars are available. Moreover, increasing the genetic diversity of poplar plantations can prevent disease impacts. The main uncertainty concerns the factors explaining the low pathogenicity of the populations of M. medusae present in the EU. The criteria assessed by the Panel for consideration as a potential quarantine pest are met (the pest is present, but with a restricted distribution, and is officially under control). Given that plants for planting are not the main pathway of spread, not all criteria for consideration as a regulated non‐quarantine pest are met.

Pest categorisation of Bretziella fagacearum

Abstract Following a request from the European Commission, the EFSA Plant Health (PLH) Panel performed a pest categorisation of Bretziella fagacearum, a well‐defined and distinguishable fungal species of the family Ceratocystidaceae. The species was moved from the genus Ceratocystis to a new genus Bretziella following phylogenetic analysis of the species and its close relatives. The former species name Ceratocystis fagacearum is used in the Council Directive 2000/29/EC. The pathogen is regulated in Annex IAI as a harmful organism whose introduction into the EU is banned. B. fagacearum is only reported from the USA, where it causes a wilt disease on Quercus spp. Other hosts are reported based on inoculation trials, although Chinese chestnut (Castanea mollissima) is reported to be naturally infected. No North American oak species has been found to be immune to the disease. The European oak species Quercus robur, Quercus petraea and Quercus pubescens were found to be susceptible in inoculation experiments. The pest could enter the EU via wood (with and without bark, including wood packaging material), plants for planting and cut branches. Hosts and favourable climatic conditions are common in the EU, thus facilitating establishment. The pest would be able to spread following establishment by means of root grafts, insect vectors and movement of wood, plants for planting and other means. The pest introduction would have impacts in woodland and plantations, as oak wilt disease is often lethal in a short period of time. Wood treatment (debarking, kiln drying, fumigation), prompt removal of affected trees and creating root‐free zones between affected and healthy stands are available control measures. The main knowledge gaps concern (i) the survival of the fungus in wood during transport and the association with propagation material, (ii) the presence of suitable vectors in Europe and (iii) the relative susceptibility of the oak species native to Europe under natural conditions. The criteria assessed by the Panel for consideration as a potential quarantine pest are met. For regulated non‐quarantine pests, the criterion on the pest presence in the EU is not met.

Pest categorisation of Anisogramma anomala

Abstract Following a request from the European Commission, the EFSA Plant Health (PLH) Panel performed a pest categorisation of Anisogramma anomala, a well‐defined and distinguishable fungal species of the family Valsaceae. The pathogen is regulated in Annex IIAI of Council Directive 2000/29/EC as a harmful organism whose introduction into the EU is banned on plants of Corylus L., intended for planting, other than seeds, originating in Canada and the USA. The fungus is native to eastern North America and causes eastern filbert blight on cultivated hazel, Corylus avellana, as well as on wild hazel (Corylus spp.). In the 1960s, the disease spread on infected plant material to Oregon, where it then threatened US hazelnut production in the Willamette Valley. The pest could enter the EU via plants for planting. Hosts and favourable climatic conditions are common in the EU, thus facilitating establishment. The pest would be able to spread following establishment through infected plants for planting and ascospore dispersal. A. anomala leads to canopy and yield loss and can cause death of Corylus trees. Should the pathogen be introduced into the EU, impacts can be expected not just on hazel as a crop and as an ornamental but also in coppices and woodlands, where Corylus species provide an important habitat. In Oregon, scouting for cankers, therapeutic pruning and copious fungicide applications are reported to be necessary (but costly measures) to continue hazelnut production in the presence of the disease. Breeding for resistance led to the selection of resistant cultivars. The main knowledge gaps concern (i) the role of deadwood and cut branches as potential entry pathways and means of spread and (ii) the susceptibility of C. avellana cultivars and of Corylus spp. in the wild in the EU. The criteria assessed by the Panel for consideration as a potential quarantine pest are met. For regulated non‐quarantine pests, the criterion on the pest presence in the EU is not met.

Pest categorisation of Melampsora farlowii

Abstract Following a request from the European Commission, the EFSA Panel on Plant Health performed a pest categorisation of Melampsora farlowii, a well‐defined and distinguishable fungus of the family Melampsoraceae. M. farlowii is the causal agent of a leaf and twig rust of hemlocks (Tsuga spp.) in eastern North America. The pathogen is regulated in Council Directive 2000/29/EC (Annex IAI) as a harmful organism whose introduction into the EU is banned. M. farlowii is not reported to be present in Europe and could enter the EU via host plants for planting and cut branches. Cones and fruits are listed as plant parts that can carry the pest in trade and transport, but are not regulated. The pathogen could establish in the EU, as climatic conditions are favourable and Tsuga spp. have been planted as ornamentals and in plantations in several EU countries. M. farlowii would be able to spread following establishment by human movement of host plants for planting and cut branches, as well as natural spread. Should the pathogen be introduced in the EU, impacts can be expected on Tsuga spp. plantations, ornamental trees and especially nurseries. Hemlock rust is considered a destructive rust attacking Tsuga spp., particularly Tsuga canadensis in nurseries. The main uncertainties concern whether the impact of the pathogen in plantations under European conditions could be different than observed in eastern North America, whether fruit/cones of Tsuga can be a pathway of entry, and the dissemination potential of the pathogen under European conditions. However, M. farlowii is found in North America in most of the natural distribution range of T. canadensis, suggesting little dispersal limitation of the pathogen. The criteria assessed by the Panel for consideration as a potential quarantine pest are met, whilst, for regulated non‐quarantine pests, the criterion on the pest presence in the EU is not met.

Pest categorisation of Guignardia laricina

Abstract Following a request from the European Commission, the EFSA Panel on Plant Health performed a pest categorisation of Guignardia laricina, a well‐defined and distinguishable fungal species of the family Phyllostictaceae. The pathogen is regulated in Council Directive 2000/29/EC (Annex IAI) as a harmful organism whose introduction into the EU is banned. G. laricina is native to East Asia and causes a shoot blight disease of Larix spp. Major hosts of G. laricina are European larch (Larix decidua) and two North American larch species (Larix laricina (tamarack) and Larix occidentalis (Western larch)). Larix kaempferi (Japanese larch) is reported as susceptible. The only other host in nature is Douglas fir (Pseudotsuga menziesii), which is reported as an incidental host, but various other conifers have been reported as susceptible following artificial inoculation, including Picea abies. The fungus is not known to occur in the EU but could enter via plants for planting (including artificially dwarfed plants) and cut branches of Larix spp. It could establish in the EU, as hosts are present and climatic conditions are favourable. The pathogen would be able to spread following establishment by natural dissemination of ascospores and pycnospores and by human movement of infected plants for planting. Should the pathogen be introduced in the EU, impacts can be expected in larch forests, plantations and nurseries, leading to reduced tree growth and ecosystem service provision. The key uncertainties concern the current distribution and level of impacts in the native range of the pathogen. The criteria assessed by the Panel for consideration as a potential quarantine pest are met. As the pest is not present in the EU, not all criteria for consideration as a regulated non‐quarantine pest are met.

Pest categorisation of Cronartium harknessii, Cronartium kurilense and Cronartium sahoanum

Abstract Following a request from the European Commission, the EFSA Panel on Plant Health performed a pest categorisation of Cronartium harknessii, Cronartium kurilense and Cronartium sahoanum, which are well‐defined and distinguishable tree fungal pathogens of the family Cronartiaceae. In 2018, these species were moved from the genus Endocronartium to the genus Cronartium. These pathogens are not known to be present in the EU and are regulated in Council Directive 2000/29/EC (Annex IAI) (as non‐European Endocronartium spp.) as harmful organisms whose introduction into the EU is banned. These three fungi are autoecious rusts completing their life cycle on Pinus spp. C. harknessii is known as the western gall rust or pine‐pine gall rust in North America (Canada, the USA and Mexico). C. kurilense and C. sahoanum are reported from Russia (North Kuril Islands) and Japan. The pathogens could enter the EU via host plants for planting and cut branches. The pathogens could establish in the EU, as climatic conditions are favourable and Pinus spp. are common. The pathogens would be able to spread following establishment by movement of host plants for planting and cut branches, as well as natural spread. Should these pathogens be introduced in the EU, impacts can be expected on pine forests, plantations, ornamental trees and nurseries. The pathogens cause formation of stem galls, which kill young trees and result in stem defect in older trees. The main knowledge gap concerns the limited available information on C. kurilense and C. sahoanum compared to C. harknessii. The criteria assessed by the Panel for consideration of C. harknessii, C. kurilense and C. sahoanum as potential quarantine pests are met, whilst, for regulated non‐quarantine pests, the criterion on the pest presence in the EU is not met.

Pest categorisation of Coniferiporia sulphurascens and Coniferiporia weirii

Abstract Following a request from the European Commission, the EFSA Panel on Plant Health performed a pest categorisation of Coniferiporia sulphurascens and Coniferiporia weirii, two well‐defined and distinguishable fungal species of the family Hymenochaetaceae. The pathogens are regulated in Council Directive 2000/29/EC (Annex IAI, under the previous name Inonotus weirii for both species) as a harmful organism whose introduction into the EU is banned. The two pathogens are native to North America, where C. sulphurascens causes laminated root rot primarily in Douglas fir (Pseudotsuga menziesii) and grand fir (Abies grandis), while C. weirii causes cedar laminated root and butt rot mainly in cedars (Thuja plicata and Cupressus nootkatensis). C. weirii has been reported from Japan and China, and C. sulphurascens from China, Russia and Turkey. Neither species has been reported from the EU. C. sulphurascens may infect all conifers, while C. weirii is reported to mainly cause disease in tree species of Thuja spp. and Cupressus spp. The two pathogens could enter the EU mainly via wood with bark, isolated bark and plants for planting (including artificially dwarfed plants) of Pinaceae and Cupressaceae. Both fungi could establish in the EU, as hosts are present and climatic conditions are favourable. The two pathogens would be able to spread following establishment by the pathways mentioned for entry and also by dissemination of basidiospores and root contact with infected root/wood. Should the pathogen be introduced in the EU, impacts can be expected on coniferous woodlands, plantations and ornamental trees, thus leading to reduced tree growth and ecosystem service provision. The key uncertainties concern (i) the distribution of the two pathogens in Asia, (ii) the level of susceptibility of conifers native to Europe and (iii) the role of plants for planting as a pathway of entry and spread. For both pathogens, the criteria assessed by the Panel for consideration as a potential quarantine pest are met. As the two pests are not present in the EU, not all the criteria for consideration as regulated non‐quarantine pests are met.

Pest categorisation of Chrysomyxa arctostaphyli

Abstract Following a request from the European Commission, the EFSA Panel on Plant Health performed a pest categorisation of Chrysomyxa arctostaphyli, a well‐defined and distinguishable fungal species of the family Coleosporiaceae. The pathogen is regulated in Council Directive 2000/29/EC (Annex IAI) as a harmful organism whose introduction into the EU is banned. C. arctostaphyli is native to North America and is the causal agent of spruce broom rust. C. arctostaphyli is a heteroecious rust with a 2‐year life cycle alternating between the aecial host Picea spp. and the telial host Arctostaphylos spp. The main reported aecial host is P. engelmannii, but also P. abies, P. pungens, P. sitchensis, P. glauca, P. mariana and P. rubens (as well as Picea as a genus) are reported as hosts. The fungus is not known to occur in the EU but could enter via host plants for planting and cut branches. It could establish in the EU, as hosts are present and climatic conditions are favourable. The extent of overlap between the ranges of the telial and aecial hosts is greater in the EU than in North America. The pathogen would be able to spread following establishment by dissemination of spores and human movement of infected host plants. Should the pathogen be introduced in the EU, impacts can be expected in spruce woodland, plantations and on ornamental spruce trees, leading to reduced tree growth and associated ecosystem service provision. The main uncertainty concerns the level of susceptibility of P. abies and P. sitchensis under European conditions. The criteria assessed by the Panel for consideration as a potential quarantine pest are met. As the pest is not present in the EU, not all criteria for consideration as a regulated non‐quarantine pest are met.