NAME OF THE ORGANISM: Rhizoctonia (anamorphic genus) 1RHIZG

GENERAL INFORMATION ON THE PEST

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

Rhizoctonia spp.

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?:

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?

No: Vegetable propagating and planting material (other than seeds) sector, Ornamental 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:

Not candidate: Vegetable propagating and planting material (other than seeds) sector, Ornamental sector

Justification (if necessary):

When answering to the RNQP Questionnaire, for the Vegetable reproductive and planting material (excluding seeds) Sector, no EU Member State identified this entry as important and justified to keep Rhizoctonia listed at a higher level than the species level. No EU Member State proposed to replace this entry by pests listed at the Species level.
For the Ornamental sector, [except a selection (by accident) of this entry by FR as important for Begonia x hiemalis,] no EU Member State identified this entry as important and justified to keep Rhizoctonia listed at a higher level than the species level. Rhizoctonia solani on Lilium and Begonia x hiemalis, and Rhizoctonia tuliparum on Lilium are the main species identified by the experts on these two host plants. Numerous studies have been carried out on these ubiquitous and polyphagous fungus in order to characterize the diversity of its strains. Indeed, these differ in particular by their cultural characteristics, their virulence and in particular their host specificity. Experts recommended neither a listing at a higher level than the species level, nor to analyse the RNQP status of these two species. They considered that these pest/host combinations are more relevant for the vegetable sector.

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 worldwide in distribution.

HOST PLANT N°1: Begonia x hiemalis (BEGEH) for the Ornamental sector.

Origin of the listing:

Commission Directive 93/49/EEC

Plants for planting:

Plants intended for planting

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:

Justification:

Wilting may be caused by infection of the base of plants by Rhizoctonia spp. hampering upward water transport. Seedlings, cuttings or transplanted material of ornamental plants rot near the soil surface and die. Such damping off or collar rot is caused by a variety of soil fungi, including Rhizoctonia solani (EPPO, 1998).
Plants for planting are a pathway, however because of the wide host range and longevity of inoculum sources in the environment, planting material (transplants) are not considered to be the main pathway for introduction under outdoor field conditions (though they are mainly indoor plants). Remark: It may also be present in some substrates and compost, or peat. It is not uncommon for it to pollute non-disinfected equipment used in nurseries.
Transplants produced under at-risk situations could be considered the main pathway if the intended use was for a protected facility that used uninfested soil media and had been thoroughly cleaned of potential infection sources before use. However experts considered that the risks of transfer are limited from Begonia x hiemalis (or elatior) which is mainly a pot-cultivated crop, contrary to some Begonia tuberhybrida cultivars, or rhizomatous Begonias. To favor the use of quality substrates and care about prophylactic measures is more relevant than regulating the pest.

5 - Economic impact:

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

Yes

Justification:

Many records are noted for economic impact, e.g. the need for fungicide treatments against Rhizoctonia infection has been outlined (Raabe et al., 1978), and one of the main pathogens in potted plants in Denmark is Rhizoctonia solani which has been a severe problem in cuttings from Begonia elatior [B. x hiemalis] (Petersen, 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: No EU Member State considered this entry as important in the answers to the RNQP Questionnaire and gave justification(s) for a listing at a higher level than the species level. This entry will be covered by the 'Substantially free from' requirement that will remain in the Ornamental EU Marketing Directives.

8 - Tolerance level:

Is there a need to change the Tolerance level:

Proposed Tolerance levels:

Delisting.

9 - Risk management measures:

Is there a need to change the Risk management measure:

Proposed Risk management measure:

Delisting.

REFERENCES:

EPPO (1998) PP 2/13 (1). Good plant protection practice. Ornamental Plants under Protected Cultivation. Bulletin OEPP/EPPO Bulletin 28, 363–386;
Petersen L (1996) Some major pests in nurseries in Denmark in 1995. SP Rapport - Statens Planteavlsforsøg 4, 265-267;
Raabe RD, Hurlimann JH & Farnham DS (1978) Control of seedling diseases in tuberous begonias - progress report. Flower and Nursery Report No.Spring pp.1;

HOST PLANT N°2: Cucumis sativus (CUMSA) for the Vegetable propagating and planting material (other than seeds) sector.

Origin of the listing:

2 - Vegetable seedling sector: Commission Directive 93/61/EC

Plants for planting:

Plants intended for planting

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:

Justification:

5 - Economic impact:

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

Justification:

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?

Conclusion:

Justification:

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:

8 - Tolerance level:

Is there a need to change the Tolerance level:

Proposed Tolerance levels:

Delisting.

9 - Risk management measures:

Is there a need to change the Risk management measure:

Proposed Risk management measure:

Delisting.

REFERENCES:

HOST PLANT N°3: Lilium (1LILG) for the Ornamental sector.

Origin of the listing:

Commission Directive 93/49/EEC

Plants for planting:

Plants intended for planting

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:

Justification:

5 - Economic impact:

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

Yes

Justification:

There were a few references for economic impact, and the need for treatments, e.g. in Israel on lily (Lilium longiflorum) rot in these plants, when grown as cut flowers, caused serious economic damage expressed in reduction in yield and quality. This was caused by (not separately recorded) Rhizoctonia AG-A [R. solani], Rhizoctonia solani, Pythium oligandrum, Fusarium proliferatum and F. oxysporum (Lebiush-Mordechai et al., 2014).

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?

Conclusion:

Justification:

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:

8 - Tolerance level:

Is there a need to change the Tolerance level:

Proposed Tolerance levels:

Delisting.

9 - Risk management measures:

Is there a need to change the Risk management measure:

Proposed Risk management measure:

Delisting.

REFERENCES:

EPPO (1998) PP 2/13 (1). Good plant protection practice. Ornamental Plants under Protected Cultivation. Bulletin OEPP/EPPO Bulletin 28, 363–386;
Tsror L (2014) Bulb and root rot in lily (Lilium longiflorum) and onion (Allium cepa) in Israel. Journal of Phytopathology 162, 466-471;