NAME OF THE ORGANISM: Ustilago avenae (USTIAV)
GENERAL INFORMATION ON THE PEST
Name as submitted in the project specification (if different to the preferred name):
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: Cereals (including rice) sector
Is it justified that the pest is listed at a taxonomic rank below species level?
Not relevant
Conclusion:
- Candidate: Cereals (including rice) sector
2 – Status in the EU:
Is this pest already a quarantine pest for the whole EU?
No
Presence in the EU:
Yes
Conclusion:
candidate
Justification (if necessary):
This pest is present worldwide, including Europe (CABI 2016).
HOST PLANT N°1: Avena sativa (AVESA) for the Cereals (including rice) sector.
Origin of the listing:
RNQP Questionnaire
Plants for planting:
Seeds
3 - Is the pest already listed in a PM4 standard on the concerned host plant?
No
Conclusion:
Evaluation continues
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:
Ustilago avenae causes loose smut on oats and seed is a pathway. On emergence, the ears of infected plants are totally transformed into a black powdery spore mass of teliospores which are released in great number during flowering, spread by the wind to infect new grains, or during threshing. During germination seedlings are systemically infected by spores carried on the outside of the seeds. (It is not inside the embryo of the seed). To avoid the disease it is important to use disease-free certified seed or fungicide-treated seed (EPPO, 2002). Avena sativa was listed as a host species which was the least resistant to Ustilago spp. (Bogachkov et al., 1990).
The EU Directive 66/402 has a requirement for the seed producing crop that Ustilaginaceae shall be at the lowest possible level, but no seed-testing requirements are given and no seed test is described by ISTA.
Volunteer plants grown from spilt contaminated seed from the previous year could in theory act as a disease source but this appears to be very rare because no references to this could be found. It is concluded seed can be considered as a significant pathway for the pest.
The EU Directive 66/402 has a requirement for the seed producing crop that Ustilaginaceae shall be at the lowest possible level, but no seed-testing requirements are given and no seed test is described by ISTA.
Volunteer plants grown from spilt contaminated seed from the previous year could in theory act as a disease source but this appears to be very rare because no references to this could be found. It is concluded seed can be considered as a significant pathway for the pest.
5 - Economic impact:
Are there documented reports of any economic impact on the host?
Yes
Justification:
Losses from loose smut in oats generally average less than 1%, but losses of up to 40% have been recorded. A formula can be used to calculate losses from loose smut and the percentage of infected ears is directly proportional to grain loss. The risk of serious loss of in-crop yield from sowing seed saved from certified and treated seed is considered to be low but of high risk where seed is saved repeatedly without treatment. The risk to adjacent crops of oats is negligible unless used for seed (Paveley et al., 1996). In Canada in 1992-1994 the percentage of fields affected by smuts ranged from 2% in 1994 to 23% in 1992, with means of 0.1% or fewer infected plants (Thomas and Menzies, 1997). The disease is now practically unknown in intensive cereal cultivation in Europe due to the use of disease-free certified seed or fungicide-treated seed. However, in low intensive areas with untreated farmer-saved seed it can be still a problem (EPPO, 2002). For example, in 2015 in Bosnia, infection symptoms were found on 55% of the oats acreage, and in 2016 on 43% (Delalić, 2016).
What is the likely economic impact of the pest irrespective of its infestation source in the absence of phytosanitary measures? (= official measures)
Medium
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
Conclusion:
Candidate
Justification:
Generally yield losses are low 1% but can be as high as 40%. The percentage of infected ears is directly proportional to grain loss. Spores from infected ears are wind blown onto healthy plants and contaminate the caryopsis and glumes, re-establishing the disease in the next generation of seed produced. Some infestation may also occur during threshing. Potential for the disease to multiply within a few years is great if seed sown untreated.
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:
Control through standards for field inspection and seed, and through seed treatment fungicides. These fungicides are not allowable for organic farming.
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:
Yes
Proposed Tolerance levels:
Tolerance level in the field (1 affected plant per 100m2), with an alternative option based on treatments or other approved physical technique.
9 - Risk management measures:
Is there a need to change the Risk management measure:
Yes
Proposed Risk management measure:
For all categories of material:
(a) Field inspection of a representative sample of the plants in the crop at an appropriate time at which not more than 1 affected plant per 100m2 is seen.
or, if this tolerance is not achieved at field inspection,
(b) Seed treatment with an approved fungicide or by an approved physical technique known to be effective against Ustilago avenae.
(a) Field inspection of a representative sample of the plants in the crop at an appropriate time at which not more than 1 affected plant per 100m2 is seen.
or, if this tolerance is not achieved at field inspection,
(b) Seed treatment with an approved fungicide or by an approved physical technique known to be effective against Ustilago avenae.
REFERENCES:
- CABI (Centre for Agricultural Bioscience International), online, 2016. Datasheets Ustilago avenae (loose smut of oats). Invasive species compendium. CABI, Wallingford, UK. Available from http://www.cabi.org/isc/datasheet/55931;
- Delalić Z (2016) Smut of oats (Ustilago avenae) increasing problem in oats crops on the territory of Una-Sana Canton (B&H). Biljni Lekar (Plant Doctor) 44, 248-254;
- EPPO (2002) Good plant protection practice PP 2/24 (1) Oat. Bulletin OEPP/EPPO Bulletin 32, 367–369;
- Paveley ND, Rennie WJ, Reeves JC, Wray MW, Slawson DD, Clark WS, Cockerell V & Mitchell AG (1996) Cereal seed health and seed treatment strategies. HGCA Research Review 34, IV-131;
- Thomas PL & Menzies JG (1997) Cereal smuts in Manitoba and Saskatchewan, 1989-95. Canadian Journal of Plant Pathology 19, 161-165;