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Justification for qualification based on EPPO PM 4 Standards
Justification for disqualification
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NAME OF THE ORGANISM: Aphelenchoides ritzemabosi (APLORI)

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):

Remark: DE suggested to list all Aphelenchoides at genus level to reduce diagnostic workload. Although differentiation between species may be difficult, the Fruit SEWG suggested to perform an assessment at species level. If needed, measures addressing the risk with different Aphelenchoides species can be defined.

2 – Status in the EU:

Is this pest already a quarantine pest for the whole EU?

Presence in the EU:

Yes

List of countries (EPPO Global Database):

Bulgaria (2000); Germany (2000); Hungary (2000); Ireland (2000); Italy (2000); Latvia (2000); Netherlands (2000); Poland (2000); Portugal (2000); Portugal/Madeira (2000); Spain (2000); Spain/Islas Canárias (2000)

Conclusion:

Candidate

Justification (if necessary):

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: Ribes (1RIBG) 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?

Yes

Conclusion:

Evaluation continues

Justification (if necessary):

The pest is listed in Standard PM 4-9 Certification scheme for Ribes. However, when responding to the questionnaire, NL considered that economic impact was acceptable and supported deregulation. Evaluation continues especially on the economic impact.

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:

At least 124 genera are alternate hosts of A. ritzemabosi, and these are mainly in the Compositae (Ferris 2022; cited in Westerdahl & Bello, 2023; CABI, 2021). Several weeds including goosegrass, chickweed, buttercup, sowthistle, and speedwell are hosts of A. ritzemabosi highlighting that for crop rotation to succeed it is important to control weeds in the alternate crops (CABI, 2021). It has also been reported on Ribes spp. (Kohl et al., 2011; Chałańska et al., 2014).
A. ritzemabosi is an obligate plant parasite, inhabiting leaves, buds, growing points and outer layers of stem; in soil it does not complete its life cycle or survive the winter. It feeds endoparasitically on mesophyll cells of leaves, and ectoparasitically on buds and growing points (Southey, 1952; Siddiqi, 1974; cited in CABI 2021). The nematodes move in the water film over plants, not within the stem tissue, to reach the leaves and buds. Rain splashes and leaf contacts contribute to re-infestation and spread (Wallace, 1959; cited from CABI, 2021). The leaves are invaded through the stomata. The nematodes feed on the parenchymatous tissue of the mesophyll and destroy the cells, resulting in leaf spots or blotches, easily seen on the under surface. The nematodes leave brown tissue through the stomata and migrate in the water film on the surface to infect terminal flower buds which produce deformed and under-sized blossoms (CABI, 2021).
Plants for planting is considered to be a significant pathway.

5 - Economic impact:

Are there documented reports of any economic impact on the host?

Justification:

Although A. ritzemabosi has been recorded on Ribes spp. there are no records on impact of this foliar nematode on Ribes.

What is the likely economic impact of the pest irrespective of its infestation source in the absence of phytosanitary measures? (= official measures)

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?

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:

Not candidate

Justification:

Although A. ritzemabosi occur on and cause damage to strawberries, the fruit SEWG considered that there was not enough data to consider regulating the pest on Ribes for indirect economic impact on strawberry.

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?

Conclusion:

Justification:

The results of more than 8 years of voluntary certification schemes for strawberry stocks in Italy indicate that A. ritzemabosi, A. fragariae, D. dipsaci and Meloidogyne spp. can be successfully controlled by means of plant certification schemes (Tacconi and Lamberti, 1994; cited in CABI 2021)

7- Is the quality of the data sufficient to recommend the pest to be listed as a RNQP?

Conclusion:

Justification:

CONCLUSION ON THE STATUS:

Disqualified: no data of economic impact on Ribes

8 - Tolerance level:

Is there a need to change the Tolerance level:

Yes

Proposed Tolerance levels:

Delisting

9 - Risk management measures:

Is there a need to change the Risk management measure:

Yes

Proposed Risk management measure:

Delisting

REFERENCES:

CABI (2021) Aphelenchoides ritzemabosi (Chrysanthemum foliar eelworm). CABI Crop Protection Compendium (Accessed 9/Aug/2024). https://www.cabidigitallibrary.org/doi/full/10.1079/cabicompendium.6384.
Chałańska A, Bogumił A, Machnicka K & Dzięgielewska M (2014) First record of chrysanthemum foliar nematode Aphelenchoides ritzemabosi (Schwarz 1911) Steiner & Buhrer 1932 (Nematoda: Aphelechoididae) in leaf buds of black currant (Ribes nigrum L.) in Poland. Progress In Plant Protection 54(4),403-406. DOI: http://dx.doi.org/10.14199/ppp-2014-068.
Kohl LM (2011) Floria nematodes: a summary of biology and control with a compilation on the host range. Online. Plant Health Progress doi:10.1094/PHO-2011-1129-01-RV.
Siddiqi MR (1974) Aphelenchoides ritzemabosi. CIH Descriptions of Plant-parasitic Nematodes, Set 3, No. 32. Wallingford, UK: CAB International.
Southey JF (1952) Unusual chrysanthemum eelworm symptoms. Plant Pathology 1, 48-49.
Wallace HR (1959) Movement of eelworms. V. Observations on Aphelenchoides ritzema-bosi (Schwartz, 1912) Steiner, 1932 on florists' chrysanthemums. Annals of Applied Biology 47, 350-360.
Westerdahl BB & Bello OM (2023) Leaf and bud nematodes in agricultural crops and their management by biotechnological approaches (chapter 16). In Novel biological and biotechnological applications in plant nematode management (ed Kahn MJ). Springer, Singapore. 359-376.