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Justification for qualification based on EPPO PM 4 Standards
Justification for disqualification
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NAME OF THE ORGANISM: Sclerotinia sclerotiorum (SCLESC)

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):

Conclusion:

Candidate

Justification (if necessary):

The pest is present in Albania, Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Malta, Netherlands, Poland, Portugai, Romania, Slovakia, Spain, Sweden, Switzerland and UK (CABI, 2005).

HOST PLANT N°1: Brassica napus (BRSNN) for the Oil and fibre plants sector.

Origin of the listing:

Council Directive 2002-57-EC and Commission Implementing Regulation (EU) 2019/2072

Plants for planting:

Seeds

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

Conclusion:

Evaluation continues

Justification (if necessary):

Remark: According to the project proposal, only risk mitigation measures should be discussed for this pest/host combination. Assessment of the RNQP status as done during RNQP Project part 1 has not been revised.

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:

The white mould or Sclerotinia stem rot (SSR) disease, caused by Sclerotinia sclerotiorum, is one of the most important worldwide diseases in the oil crop Brassica napus. The pathogen overwinters as sclerotia in the soil or debris, which germinate and release ascospores which then infect the crop. They are weak pathogens and do not usually infect healthy plant tissue but invade through dead or injured tissue, or spent flower blossoms. Thus sclerotia infection of seed means they can be sown adjacent to seed and then have the potential to germinate within the susceptible crop. It has a wide host range and is widespread in the environment in weeds and other crops, and is controlled by crop rotation, isolation from other susceptible crops, fungicides and reduction of moisture and poor air circulation where possible.

5 - Economic impact:

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

Yes

Justification:

Frequent occurrences of the disease in mild to severe form have been reported from Denmark, Finland, France, Germany, Sweden and United Kingdom (Sharma et al., 2015). Yield losses in susceptible crops vary and may be as high as 100 per cent. The shattering of prematurely-ripened seed pods before harvest, and loss of quality in the form of smaller, shrunken and chaffy seeds has been observed. Reported yield loss estimates due to Sclerotinia rot (SR) in rapeseed varied from very heavy in Germany. In central and eastern parts of Finland, losses by SR were so great that the cultivation of rapeseed is considered beneficial only in the southern and western areas (Sharma et al., 2015).

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

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?

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:

Economic impact is considered major, subject to variation between the years.

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:

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 during the RNQP Project part 1, based on data.

8 - Tolerance level:

Is there a need to change the Tolerance level:

Proposed Tolerance levels:

No justification for a difference in threshold was available between Brassica napus, Helianthus annus, Brassica rapa and Sinapis alba.

Justification (if necessary):

Remark: The threshold was not changed during RNQP Project 1. EU regulation includes a threshold at 10 sclerotia or fragments of sclerotia in a sample of the weight specified in column 4 of Annex III, for basic and certified seeds for Brassica napus and Helianthus annus, and 5 for Brassica rapa and Sinapis alba. Weight specified in column 4 of Annex III are 1000g for Helianthus annuus, 100g for Brassica napus, 70g for Brassica rapa and 200g for Sinapis alba. According to ISTA (2024) , ‘each sample size is derived from a nominal thousand-seed weight for each species which, on the available evidence, is expected to be adequate for the majority of samples tested’. ‘The working sample weights for purity analyses are calculated to contain at least 2500 seeds’.

Cleaning seeds for oil seed rape is easier than for sunflower seeds.

9 - Risk management measures:

Is there a need to change the Risk management measure:

Proposed Risk management measure:

Only give a threshold, as currently in EU regulation 2019/2072.

Justification (if necessary):

Remark: The disease seems less damageable than it was 20 years ago.

REFERENCES:

Atkins SL, Atkins SD, Latunde-Dada AO, Stonard JF & West JS (2013) Detection and quantification of airborne ascospores of Sclerotinia sclerotiorum by quantitative-PCR. Proceedings of the IOBC/WPRS Working Group "Integrated Control in Oilseed Crops", Paris, France, 29 September-01 October 2008 (Eds Koopmann B, Cook S, Evans N & Ulber B) IOBC/WPRS Bulletin 92, 173-178;