| Legend |
|---|
| Justification for qualification based on EPPO PM 4 Standards |
| Justification for disqualification |
| Additional or non-conclusive information |
| Standard text |
NAME OF THE ORGANISM: Pratylenchus penetrans (PRATPE)
GENERAL INFORMATION ON THE PEST
Name as submitted in the project specification (if different):
Pest category:
Nematoda
1- Identity of the pest/Level of taxonomic listing:
Is the organism clearly a single taxonomic entity and can it be adequately distinguished from other entities of the same rank?
Yes
Is the pest defined at the species level or lower?:
Yes
Can listing of the pest at a taxonomic level higher than species be supported by scientific reasons or can species be identified within the taxonomic rank which are the (main) pests of concern?
- Not relevant: Fruits (including hops) sector
If necessary, please list the species:
-
Is it justified that the pest is listed at a taxonomic rank below species level?
Not relevant
Conclusion:
- Candidate: Fruits (including hops) sector
Justification (if necessary):
-
2 – Status in the EU:
Is this pest already a quarantine pest for the whole EU?
No
Presence in the EU:
Yes
List of countries (EPPO Global Database):
Belgium (2003); Bulgaria (2003); Cyprus (2011); Czech Republic (2003); Denmark (2003); Estonia (2003); France (2003); Germany (2003); Greece (2003); Hungary (2003); Italy (2003); Netherlands (2003); Poland (2012); Portugal (2020); Romania (2003); Slovakia (2003); Spain (2003); Sweden (2003)
Conclusion:
Candidate
Justification (if necessary):
Pratylenchus penetrans is cosmopolitan but mainly found in temperate regions, whereas Pratylenchus vulnus is present mostly on woody plants in warmer (subtropical and Mediterranean) climates in different continents (Moens & Perry, 2009). Data of the presence of this pest on the EU territory are available in EPPO Global Database (https://gd.eppo.int/).
HOST PLANT N°1: Prunus avium (PRNAV) for the Fruits (including hops) sector.
Origin of the listing:
Commission Implementing Directive (EU) 2014/98/EU and Commission Implementing Regulation (EU) 2019/2072
Plants for planting:
Plants intended for planting
3 - Is the pest already listed in a PM4 standard on the concerned host plant?
No
Conclusion:
Evaluation continues
Justification (if necessary):
Remark: The assessment performed covers the given host species as well as interspecific hybrids with other Prunus species.
4 - Are the listed plants for planting the main* pathway for the "pest/host/intended use" combination? (*: significant compared to others):
Yes
Conclusion:
Candidate
Justification:
Pratylenchus penetrans is cosmopolitan and has more than 350 hosts including woody plants (e.g., fruit trees, roses) and herbaceous plants (e.g., potato, vegetables) (Moens & Perry, 2009, CABI, 2021), e.g., Malus is a good host for Pratylenchus penetrans (aaltjesschema, 2019). Also Pyrus spp., Cydonia oblonga, Pistacia vera and many Prunus spp. can be hosts of P. penetrans (Hoekstra & Oostenbrink, 1962; Askary et al., 2012; Merrifield, 2000). Ficus carica is not mentioned as hosts and information of Pratylenchus penetrans on Pistacia vera is scarce (PlantwisePlus Knowledge Bank, 2023; Fatemy, 2009), this could be linked to P. penetrans being a nematode from mostly temperate climates and fig and pistachio being more Mediterranean crops. P. penetrans can complete its entire life cycle within the roots of plants.
Pratylenchus spp. are migratory endoparasites that enter the host root for feeding and reproduction and move freely within the tissue. Consequently, they spend much of their life cycle in roots and are found in soil when the host plants are senescing, stressed or diseased, or when their hosts have been ploughed up after harvest (Castillo and Vovlas, 2007).
P. penetrans occurs mostly on sandy and peaty soil. The transport of infected plants or those growing in infested soils is one of the principal means by which these nematodes are disseminated (Lehman, 1994; Anonymous, 1999). Bare-rooted plants are often contaminated by soil particles which may contain nematodes. Roots can host endoparasitic nematodes that are not removed by washing treatments (Lehman, 1994). In this context, it is essential that the plant propagation material be free of this pathogen (Allen, 1949). Because it can survive in soil, it can be dispersed by land vehicles etc.; within a field by cultivation, and can be introduced to non-infested sites by poorly sanitized farm equipment. However, measures (including hygiene) can limit the importance of such alternative pathways.
In responses to the questionnaire, DE, FR and NL supported deregulation in the EU because soilborne and widespread in production areas.
Considering the numerous bibliographic references that highlight the importance of plants for planting as an important pathway, and the existence of measures that can reduce the role of the others reported pathways, host plants for planting with roots, with or without soil or growing media, are considered as a main pathway.
Pratylenchus spp. are migratory endoparasites that enter the host root for feeding and reproduction and move freely within the tissue. Consequently, they spend much of their life cycle in roots and are found in soil when the host plants are senescing, stressed or diseased, or when their hosts have been ploughed up after harvest (Castillo and Vovlas, 2007).
P. penetrans occurs mostly on sandy and peaty soil. The transport of infected plants or those growing in infested soils is one of the principal means by which these nematodes are disseminated (Lehman, 1994; Anonymous, 1999). Bare-rooted plants are often contaminated by soil particles which may contain nematodes. Roots can host endoparasitic nematodes that are not removed by washing treatments (Lehman, 1994). In this context, it is essential that the plant propagation material be free of this pathogen (Allen, 1949). Because it can survive in soil, it can be dispersed by land vehicles etc.; within a field by cultivation, and can be introduced to non-infested sites by poorly sanitized farm equipment. However, measures (including hygiene) can limit the importance of such alternative pathways.
In responses to the questionnaire, DE, FR and NL supported deregulation in the EU because soilborne and widespread in production areas.
Considering the numerous bibliographic references that highlight the importance of plants for planting as an important pathway, and the existence of measures that can reduce the role of the others reported pathways, host plants for planting with roots, with or without soil or growing media, are considered as a main pathway.
5 - Economic impact:
Are there documented reports of any economic impact on the host?
Yes
Justification:
Pratylenchus penetrans is well recognized as economically important pest of stone-fruits (Mai and Parker, 1967; Townshend, 1990; Clavero-Camacho et al., 2024).
Much of the damage caused by root-lesion nematodes in stone fruits (Prunus spp.) results from their ability to induce extensive root necrosis. Nematode invasion of young roots induces reddish brown, elongated lesions. Root lesions darken with age, necrosis often spreads to affect the entire root, growth ceases, and the root dies. Severe infection may destroy the fine roots. Heavy infections often result in small root systems and stunted trees. Symptoms are more common on young trees than on old trees (Bird & Melakeberhan, 1995).
Depending on the level of P. penetrans present in the soil, damage might occur :
- Prunus dulcis: in the NEMAPLEX (2024) database, Prunus dulcis is reported as susceptible (= high level of nematode reproduction) to Pratylenchus penetrans (Siddiqui et al., 1973).
- Prunus armeniaca & Prunus domestica: mentioned as host. In the NEMAPLEX (2024) database, Prunus armeniaca is reported as susceptible (= high level of nematode reproduction) to Pratylenchus penetrans (Siddiqui et al., 1973).
- Prunus avium & Prunus cerasus: Initial population of 80/100 g soil necessary for growth reduction (Nyczepir and Halbrendt 1993). In NE U.S., reduced yield and shortened productive life of Montmorency cherry on Mazard and Mahaleb rootstocks; parasitized trees were less winter hardy (Nyczepir and Halbrendt 1993). In pots, seedlings grown for 12 weeks in steam-fumigated orchard soil with a history of replant disease containing a mixed population of 7 P. penetrans and P. projectus/100 g weighed 46% more and were 64% taller than seedlings grown in non-treated soil (Mai and Abawi 1978), (Cited in Merrifield, 2000). Pratylenchus penetrans has been responsible for severe decline and for replating failure in many cherry orchards. Also, this nematode can lower the resistance of plants to other pathogens (Anonymous, 1999).
- Prunus cerasifera: Initial population of 320/100 g soil necessary for growth reduction (Nyczepir and Halbrendt 1993). (Cited in Merrifield, 2000)
- Prunus persica: 5/100 g soil (Barker et al. 1976). Root impairment results in loss of vigour and yields of mature trees, but P. penetrans’ role in orchard replant problems is probably more economically important (Nyczepir and Halbrendt 1993). Pratylenchus penetrans has been responsible for severe decline and for replating failure in many peach orchards. Also, this nematode can lower the resistance of plants to other pathogens (Anonymous, 1999). In pots, seedling height was significantly reduced 40% by 114/100 cm3, 60% by 228/100 cm3, and 75% by 457/100 cm3 (Cited in Merrifield, 2000).
- Prunus salicina: In a Prunus salicina (var. Santa Rosa) orchard located in India, Pratylenchus penetrans was the predominant plant-parasitic nematode, with populations of 150-380 nematodes per 200 cc soil (Sharma et al., 2005).
In the responses to the questionnaire, FR supported deregulation in the EU, commenting that the pest had a 'low nuisance level on fruit plants'.
Much of the damage caused by root-lesion nematodes in stone fruits (Prunus spp.) results from their ability to induce extensive root necrosis. Nematode invasion of young roots induces reddish brown, elongated lesions. Root lesions darken with age, necrosis often spreads to affect the entire root, growth ceases, and the root dies. Severe infection may destroy the fine roots. Heavy infections often result in small root systems and stunted trees. Symptoms are more common on young trees than on old trees (Bird & Melakeberhan, 1995).
Depending on the level of P. penetrans present in the soil, damage might occur :
- Prunus dulcis: in the NEMAPLEX (2024) database, Prunus dulcis is reported as susceptible (= high level of nematode reproduction) to Pratylenchus penetrans (Siddiqui et al., 1973).
- Prunus armeniaca & Prunus domestica: mentioned as host. In the NEMAPLEX (2024) database, Prunus armeniaca is reported as susceptible (= high level of nematode reproduction) to Pratylenchus penetrans (Siddiqui et al., 1973).
- Prunus avium & Prunus cerasus: Initial population of 80/100 g soil necessary for growth reduction (Nyczepir and Halbrendt 1993). In NE U.S., reduced yield and shortened productive life of Montmorency cherry on Mazard and Mahaleb rootstocks; parasitized trees were less winter hardy (Nyczepir and Halbrendt 1993). In pots, seedlings grown for 12 weeks in steam-fumigated orchard soil with a history of replant disease containing a mixed population of 7 P. penetrans and P. projectus/100 g weighed 46% more and were 64% taller than seedlings grown in non-treated soil (Mai and Abawi 1978), (Cited in Merrifield, 2000). Pratylenchus penetrans has been responsible for severe decline and for replating failure in many cherry orchards. Also, this nematode can lower the resistance of plants to other pathogens (Anonymous, 1999).
- Prunus cerasifera: Initial population of 320/100 g soil necessary for growth reduction (Nyczepir and Halbrendt 1993). (Cited in Merrifield, 2000)
- Prunus persica: 5/100 g soil (Barker et al. 1976). Root impairment results in loss of vigour and yields of mature trees, but P. penetrans’ role in orchard replant problems is probably more economically important (Nyczepir and Halbrendt 1993). Pratylenchus penetrans has been responsible for severe decline and for replating failure in many peach orchards. Also, this nematode can lower the resistance of plants to other pathogens (Anonymous, 1999). In pots, seedling height was significantly reduced 40% by 114/100 cm3, 60% by 228/100 cm3, and 75% by 457/100 cm3 (Cited in Merrifield, 2000).
- Prunus salicina: In a Prunus salicina (var. Santa Rosa) orchard located in India, Pratylenchus penetrans was the predominant plant-parasitic nematode, with populations of 150-380 nematodes per 200 cc soil (Sharma et al., 2005).
In the responses to the questionnaire, FR supported deregulation in the EU, commenting that the pest had a 'low nuisance level on fruit plants'.
What is the likely economic impact of the pest irrespective of its infestation source in the absence of phytosanitary measures? (= official measures)
Medium to Major
Is the economic impact due to the presence of the pest on the named host plant for planting, acceptable to the propagation and end user sectors concerned?
No
Is there unacceptable economic impact caused to other hosts (or the same host with a different intended use) produced at the same place of production due to the transfer of the pest from the named host plant for planting?
Conclusion:
Candidate
Justification:
Evidence of its economic impact is available in the literature and confirmed by Spanish experts.
The damage caused by Pratylenchus is usually most severe in light-textured soils that are low in nutrients (e.g. nitrogen, potassium, or calcium) and in organic matter (Anonymous, 1999). pH and soil texture were the most influential variables in Pratylenchus distribution and abundance during the study of Clavero-Camacho et al. (2024) on plant parasitic nematodes affecting Prunus species in Spain.
The damage caused by Pratylenchus is usually most severe in light-textured soils that are low in nutrients (e.g. nitrogen, potassium, or calcium) and in organic matter (Anonymous, 1999). pH and soil texture were the most influential variables in Pratylenchus distribution and abundance during the study of Clavero-Camacho et al. (2024) on plant parasitic nematodes affecting Prunus species in Spain.
6 - Are there feasible and effective measures available to prevent the presence of the pest on the plants for planting at an incidence above a certain threshold (including zero) to avoid an unacceptable economic impact as regards the relevant host plants?
Yes
Conclusion:
Candidate
Justification:
Crop rotation is difficult because of the wide host range of Pratylenchus penetrans, including weeds. Pratylenchus penetrans can propagate well on many crops, sometimes without causing damage (symptomless) (aaltjesschema). Recent research indicated that with proper choice of selected cultivars of cover crops, P. penetrans can be controlled but further breeding efforts are needed. Although some cover crops can reduce the population of Pratylenchus penetrans (Taning et al., 2023). Since many weeds can also be a host, adequate weed control is important (Aaltjesschema, 2019). Crop rotation is also a limited option since woody crops remain in soil for decades and the host-range of many of this of the plant parasitic nematodes is wide (Castillo y Vovlas, 2007).
Growing Tagetes spp. (e.g. Tagetes patula) can reduce the population considerably (Evenhuis et al., 2004). The authors predicted that strawberries could be grown for about 7 successive years without economic damage due to the root lesion nematode. Pudasaini et al. (2006) showed that Tagetes can reduce P. penetrans exponentially in time under marigold. The effect of marigold was persistent as no increase in P. penetrans densities over the whole soil profile was noticed after two crop cycles of host plants.
Use of clean soil: The propagation material is kept either in containers of sterilized growing medium or in soil that has been tested and found free from various nematodes (e.g. EPPO 2022).
Soil fumigation: dependent on legislation. Preplant soil fumigation does not eradicate nematodes but dramatically reduces nematode numbers. The nematodes return to their original population density (or greater) within 2 or 3 years after planting, but the absence of nematode pressure during the initial years of establishment is critical for trees to develop strong, healthy root systems (Abawi & Mai, 2014). With the progressive phase-out of chemical nematicides such as Aldicarb, Carbofuran, and 1,3-Dichloropropene, the effectiveness and sustainability of current plant-parasitic nematode management strategies remain limited (Barbosa et al., 2022).
Healthy plants: To prevent the introduction of nematode problems, new orchards should be established with trees obtained from reputable nurseries that treat their soils for nematodes (Abawi & Mai, 2014).
Growing Tagetes spp. (e.g. Tagetes patula) can reduce the population considerably (Evenhuis et al., 2004). The authors predicted that strawberries could be grown for about 7 successive years without economic damage due to the root lesion nematode. Pudasaini et al. (2006) showed that Tagetes can reduce P. penetrans exponentially in time under marigold. The effect of marigold was persistent as no increase in P. penetrans densities over the whole soil profile was noticed after two crop cycles of host plants.
Use of clean soil: The propagation material is kept either in containers of sterilized growing medium or in soil that has been tested and found free from various nematodes (e.g. EPPO 2022).
Soil fumigation: dependent on legislation. Preplant soil fumigation does not eradicate nematodes but dramatically reduces nematode numbers. The nematodes return to their original population density (or greater) within 2 or 3 years after planting, but the absence of nematode pressure during the initial years of establishment is critical for trees to develop strong, healthy root systems (Abawi & Mai, 2014). With the progressive phase-out of chemical nematicides such as Aldicarb, Carbofuran, and 1,3-Dichloropropene, the effectiveness and sustainability of current plant-parasitic nematode management strategies remain limited (Barbosa et al., 2022).
Healthy plants: To prevent the introduction of nematode problems, new orchards should be established with trees obtained from reputable nurseries that treat their soils for nematodes (Abawi & Mai, 2014).
7- Is the quality of the data sufficient to recommend the pest to be listed as a RNQP?
Yes
Conclusion:
Candidate
Justification:
CONCLUSION ON THE STATUS:
Recommended for listing as an RNQP, based on data.
8 - Tolerance level:
Is there a need to change the Tolerance level:
No
Proposed Tolerance levels:
9 - Risk management measures:
Is there a need to change the Risk management measure:
Yes
Proposed Risk management measure:
Non-Certified material (‘Conformitas Agraria Communitatis (CAC)’):
• Mother plants have been produced in a pest free place/site of production
or
• Material obtained from mother plants does not contain roots and soil
AND
• Plants have been produced in soil/growing medium considered free from P. penetrans (e.g. tested soil, use of sterilized growing media or soil-free).
• Mother plants have been produced in a pest free place/site of production
or
• Material obtained from mother plants does not contain roots and soil
AND
• Plants have been produced in soil/growing medium considered free from P. penetrans (e.g. tested soil, use of sterilized growing media or soil-free).
Justification (if necessary):
The risk of transmission of this nematode is restricted to materials with roots and soil. Generally, material obtained from mother plants (e.g. buds, cuttings...) doesn’t contain roots and soil. The critical point to avoid the spread of this pest is in the nurseries where certified and CAC seedlings are produced for marketing to growers or end users. Considering that detection by inspection is practically impossible when no symptoms are observed, that symptomology is non-specific (both above and below ground) and the complexity to perform laboratory testing, the fruit SEWG considered that PFA should not be proposed as an option. The Fruit SEWG also considered that an option requiring not growing hosts during > 5 years was not realistic considering how polyphagous the pest is.
Hot water treatments with some time-temperature schedules have been shown to be effective against the pest (Anonymous, 1999; Lim et al., 2024). Further work would be needed to validate if these schedules are applicable to the different host species under practical circumstances.
[During consultation on draft recommendations, NL commented that it will be very difficult if not impossible to find production sites that are free, unless the plants are grown indoor in pots.] The Fruit SEWG considered that on one hand the pest has a very wide host range and is widespread in some countries (e.g. in NL); on the other hand, in other countries (e.g. in ES or other countries), soils are not so infested. But plant for planting is a significant pathway. It is an endoparasite, moving with plants for planting. It is difficult to see the symptoms since this involves uprooting the plant (only possible for Fragaria). The fruit SEWG considered that the decision should be taken later by risk managers on whether the measure is maintained to limit economic impact to end users or withdrawn to limit economic burden to the producer of plants for planting.
Hot water treatments with some time-temperature schedules have been shown to be effective against the pest (Anonymous, 1999; Lim et al., 2024). Further work would be needed to validate if these schedules are applicable to the different host species under practical circumstances.
[During consultation on draft recommendations, NL commented that it will be very difficult if not impossible to find production sites that are free, unless the plants are grown indoor in pots.] The Fruit SEWG considered that on one hand the pest has a very wide host range and is widespread in some countries (e.g. in NL); on the other hand, in other countries (e.g. in ES or other countries), soils are not so infested. But plant for planting is a significant pathway. It is an endoparasite, moving with plants for planting. It is difficult to see the symptoms since this involves uprooting the plant (only possible for Fragaria). The fruit SEWG considered that the decision should be taken later by risk managers on whether the measure is maintained to limit economic impact to end users or withdrawn to limit economic burden to the producer of plants for planting.
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