NAME OF THE ORGANISM: Cadophora gregata (Phialophora gregata) PHIAGR

GENERAL INFORMATION ON THE PEST

Name as submitted in the project specification (if different):

Pest category:

Fungi

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: Oil and fibre plants 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: Oil and fibre plants sector

Justification (if necessary):

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):

Croatia (2007)

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: Glycine max (GLXMA) for the Oil and fibre plants sector.

Origin of the listing:

3 - Oil and fibre plants sector: Council Directive 2002/57/EC

Plants for planting:

Seeds

3 - Is the pest already listed in a PM4 standard on the concerned host plant?

Conclusion:

Evaluation continues

4 - Are the listed plants for planting the main* pathway for the "pest/host/intended use" combination? (*: significant compared to others):

Conclusion:

Not candidate

Justification:

Only one reference to the possible seed-borne nature of this pathogen could be found, which said there was a reduced seedling emergence in the field, though no further details were given available in the abstract (Ellis et al., 1979).
Phialophora gregata is associated with soil residues (Zecchinelli & Gaudenzi, 2002) and these authors implied that as Directive 92/9/EEC (now 2002/57) requires that inert material should not exceed 0.3% of the total weight of a seed sample, this will help with control. The pest is not mentioned by name in the directive. In a rotation experiment, Phialophora gregata infection was lower, plant height and seed size were greater and yield was 13% higher than in an area continually cropped for four years (Kennedy & Lambert, 1981). Incidence of Phialophora gregata is reduced by soil fumigation and seed yields are increased (Gray, 1978). The use of a conventional tillage system significantly decreases the inoculum density of the pathogen. A reduction of the saprophytic population decreases its capability to overwinter and, therefore, results in a lower infection pressure during the next year (Adee & Grau, 1992).
The above information suggests crop debris or soil borne carry-over sources are more important pathways compared to possible seed-borne infection.

5 - Economic impact:

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

Justification:

Brown stem rot (BSR), caused by the fungus Phialophora gregata (syn. Cadophora gregata), causes yield losses up to 38% (McCabe et al., 2016). Attacks by this fungus cause significant yield losses in the Brazilian states of Rio Grande do Sul and Santa Catarina and disease severity was 0-10% in a low infestation area and 0-100% in a high infestation area, varying with susceptibility of variety. Mean yield reductions were 9% for the varieties with foliar symptoms under 1%, and 38.2% for those with foliar symptoms over 20% (Bonato & Costamilan, 1996).

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:

Justification:

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:

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: crop debris or soil borne carry-over sources are more important pathways compared to possible seed-borne infection.

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:

Adee E A & Grau C R (1992) Influence of tillage method on inoculum density of Phialophora gregata in overwintering soybean residue. Presentation at the 1992 APS/MPS Annual Meeting, Portland, OR, USA. Phytopathology 82, 1158;
Bonato E & Costamilan L (1996) Performance of soyabean genotypes in areas with different levels of infestation by Phialophora gregata. Fitopatologia Brasileira 21, 275-280;
Ellis MA, Pascha EH, Powell PE & Tenne FD (1979) Internally seedborne fungi of soya bean in Puerto Rico and their effect on seed germination and field emergence. Tropical Agriculture 56, 171-174;
Kennedy B & Lambert J (1981) Influence of brown stem rot and cropping history on soybean performance. Plant Disease 65, 896-897;
McCabe C, Singh A K, Leandro L F, Cianzio S & Graham M (2016) Identifying new sources of resistance to brown stem rot in soybean. Crop Science 56, 2287-2296;
Zecchinelli R & Gaudenzi S (2002) Plant health requirements envisaged by the quality norms for seeds of soyabeans. Sementi Elette 48, 31-33;