NAME OF THE ORGANISM: Fusarium oxysporum f. sp. Lini FUSALI
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?
Yes
Conclusion:
- Candidate: Oil and fibre plants sector
Justification (if necessary):
F. oxysporum f. sp. Lini is the most damaging Fusarium pathotype on Linum.
2 – Status in the EU:
Is this pest already a quarantine pest for the whole EU?
No
Presence in the EU:
Yes
List of countries (EPPO Global Database):
Conclusion:
candidate
Justification (if necessary):
The pest is present in France, Germany and UK (Fitt et al., 1991), Poland (Wielgusz et al., 2009). This list is not exhaustive.
HOST PLANT N°1: Linum usitatissimum (LIUUT) for the Oil and fibre plants 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):
No
Conclusion:
Not candidate
Justification:
At present Fusarium spp. are included in the EU Marketing Directive 2002/57/EC with a threashold of 5%.
This fungus can also be soil borne and infects via the roots, entering through root tips, hairs, emerging rootlets and wounds. It then crosses the root cortex and enters the vascular system, within which it spreads up into the stems causing vascular wilt (Brayford, 1996). F. oxysporum is very rarely transmitted by seed with 1.5% of colonies isolated from seed samples (Placinta & Murariu, 2016). In India, growth and sporulation of F. oxysporum f.sp. lini was completely inhibited by seed treatments and this increased seed germination and lowered pre-emergence mortality (Sharma et al., 2002). Transmission is "in seed" (Brayton 1996).
F. oxysporum f.sp. lini, which is present on the surface of seeds, in the endocarp region and at the level of the embryo, can cause organic and physiological disorders during germination and the first few days of seedling growth. During germination the fungus acts as an inhibitor. Later it has a stimulating effect characterized mainly by an abnormal elongation of the hypocotyl and, on some cvs. there are malformations and necrotic lesions on the rootlets, hypocotyl and cotyledons. After the period of stimulation the seedlings degenerate and die (Zad, 1978).
In Belarus, seeds sown in a controlled climate chamber had a higher germination percentage (98-100%) than those in the field, mainly due to the lower incidence (or absence) of fungal diseases in the chamber. When seeds germinated in the chamber were planted in the field, infection was high at 27.4% (Baturo et al., 1987).
Seeds from F. oxysporum f. sp. lini infected flax were lighter, yellowish to dark brown, rough and dull, and wt./1000 seeds varied from 2.3 to 3 g, depending on percentage of wilt in the field. Seeds from healthy flax fields were heavier, dark brown, smooth and shining, and 1000 seed wt. was 3.6 g. Seeds (from diseased fields) carrying the pathogen varied from 0.42 to 6% and the pathogen was detected within the seed (0.02-0.1%) and on its surface. Sowing seed from a moderately diseased field (26-50% wilt) resulted in 15.7% pre-emergence rot and 7.6% seedling wilt (Tu & Cheng, 1976).
The fungus also persists in the soil, while the mycelia and spores survive for many years in debris of flax and other organic tissue. Wind-blown and run-off soil may also spread the fungus from one field to another (Brayton, 1996).
The SEWG concluded that some of the seed-borne references appear contradictory, and other sources of infection may be present in the field. This particular pathotype is not considered to be primarily spread on seed. F. oxysporum f. sp. Lini is the most damaging Fusarium on Linum but would not qualify for the RNQP status.
This fungus can also be soil borne and infects via the roots, entering through root tips, hairs, emerging rootlets and wounds. It then crosses the root cortex and enters the vascular system, within which it spreads up into the stems causing vascular wilt (Brayford, 1996). F. oxysporum is very rarely transmitted by seed with 1.5% of colonies isolated from seed samples (Placinta & Murariu, 2016). In India, growth and sporulation of F. oxysporum f.sp. lini was completely inhibited by seed treatments and this increased seed germination and lowered pre-emergence mortality (Sharma et al., 2002). Transmission is "in seed" (Brayton 1996).
F. oxysporum f.sp. lini, which is present on the surface of seeds, in the endocarp region and at the level of the embryo, can cause organic and physiological disorders during germination and the first few days of seedling growth. During germination the fungus acts as an inhibitor. Later it has a stimulating effect characterized mainly by an abnormal elongation of the hypocotyl and, on some cvs. there are malformations and necrotic lesions on the rootlets, hypocotyl and cotyledons. After the period of stimulation the seedlings degenerate and die (Zad, 1978).
In Belarus, seeds sown in a controlled climate chamber had a higher germination percentage (98-100%) than those in the field, mainly due to the lower incidence (or absence) of fungal diseases in the chamber. When seeds germinated in the chamber were planted in the field, infection was high at 27.4% (Baturo et al., 1987).
Seeds from F. oxysporum f. sp. lini infected flax were lighter, yellowish to dark brown, rough and dull, and wt./1000 seeds varied from 2.3 to 3 g, depending on percentage of wilt in the field. Seeds from healthy flax fields were heavier, dark brown, smooth and shining, and 1000 seed wt. was 3.6 g. Seeds (from diseased fields) carrying the pathogen varied from 0.42 to 6% and the pathogen was detected within the seed (0.02-0.1%) and on its surface. Sowing seed from a moderately diseased field (26-50% wilt) resulted in 15.7% pre-emergence rot and 7.6% seedling wilt (Tu & Cheng, 1976).
The fungus also persists in the soil, while the mycelia and spores survive for many years in debris of flax and other organic tissue. Wind-blown and run-off soil may also spread the fungus from one field to another (Brayton, 1996).
The SEWG concluded that some of the seed-borne references appear contradictory, and other sources of infection may be present in the field. This particular pathotype is not considered to be primarily spread on seed. F. oxysporum f. sp. Lini is the most damaging Fusarium on Linum but would not qualify for the RNQP status.
5 - Economic impact:
Are there documented reports of any economic impact on the host?
Yes
Justification:
Plants can be attacked by F. oxysporum f.sp. lini at any stage in their development. Although this disease primarily causes wilt, seedling blight can occur when seedlings are grown at high temperatures. In typical wilt, the leaves turn yellow or greyish yellow, the top leaves thicken, growth stops, and the plants die and turn light brown. Frequently the plant is only stunted, in which case the leaves turn yellow and die prematurely, or the stem dies and new, apparently healthy, lateral branches develop. A late infection or a weak attack may be evidenced by premature ripening.
The amount of damage may vary from a very little when only a few plants are attacked, to catastrophic with almost all of the crop killed. Bhargava and Shukla (1980), reported that in oil-bearing cultivars, infection by F. oxysporum f.sp. lini may result in a loss of oil yield.
Reports indicate that flax wilt has been the most destructive in the United States and Japan and less so in Argentina and Canada. In most of Europe, where long term rotations have been practised for centuries, the disease has not become a major problem. In Poland it is regarded as one of the very dangerous flax diseases and seed dressings and sprays when applied at the seedling stage limited the occurrence of wilt, and yield was clearly correlated with the occurrence of Fusarium wilt (Wielgusz et al., 2009). From trials, surveys and seed samples Fusarium spp. was observed on seedlings in England, and Fusarium oxysporum f.sp. lini was occasionally severe in England and France and was also one of the most frequent pathogens in Germany (Fitt et al., 1991). In other parts of the world, where soil temperatures are relatively low during the early growth period, flax wilt has never been destructive (Rawlinson and Dover, 1986). In the former Soviet Union, Krylova and Voronova (1981) indicated that 66% of the crops were affected by F. oxysporum f.sp. lini annually. Sharma et al. (1971) reported that in the Rajasthan region of India 70% of linseed crops were affected. During the summer season, Fusarium oxysporum f sp. lini causes epidemic damage the crop in most of the linseed seed growing area in India (Mohit et al, 2014) and fungicide treatments inhibited mycelial growth, reduced wilt incidence, and enhanced the grain yield. Systemic fungicides were the most effective and reduced wilt incidence between 53 and 82%, so increasing yield by 59-97% (Kinshore & Singh, 2008). Fusarium wilt was observed in 53% of flax crops surveyed in southern Manitoba and Saskatchewan, Canada, in 1995 (Rashid et al., 1996). Sowing seed from a moderately diseased field (26-50% wilt) resulted in 15.7% pre-emergence rot and 7.6% seedling wilt (Tu & Cheng, 1976).
A 33% max. loss in caloric value in linseed caused by Fusarium oxysporum was found in india (Prasad et al., 1983).
Control can also be by resistant varieties, biological agents and bio-products, trace elements and destruction of debris and long rotation.
The amount of damage may vary from a very little when only a few plants are attacked, to catastrophic with almost all of the crop killed. Bhargava and Shukla (1980), reported that in oil-bearing cultivars, infection by F. oxysporum f.sp. lini may result in a loss of oil yield.
Reports indicate that flax wilt has been the most destructive in the United States and Japan and less so in Argentina and Canada. In most of Europe, where long term rotations have been practised for centuries, the disease has not become a major problem. In Poland it is regarded as one of the very dangerous flax diseases and seed dressings and sprays when applied at the seedling stage limited the occurrence of wilt, and yield was clearly correlated with the occurrence of Fusarium wilt (Wielgusz et al., 2009). From trials, surveys and seed samples Fusarium spp. was observed on seedlings in England, and Fusarium oxysporum f.sp. lini was occasionally severe in England and France and was also one of the most frequent pathogens in Germany (Fitt et al., 1991). In other parts of the world, where soil temperatures are relatively low during the early growth period, flax wilt has never been destructive (Rawlinson and Dover, 1986). In the former Soviet Union, Krylova and Voronova (1981) indicated that 66% of the crops were affected by F. oxysporum f.sp. lini annually. Sharma et al. (1971) reported that in the Rajasthan region of India 70% of linseed crops were affected. During the summer season, Fusarium oxysporum f sp. lini causes epidemic damage the crop in most of the linseed seed growing area in India (Mohit et al, 2014) and fungicide treatments inhibited mycelial growth, reduced wilt incidence, and enhanced the grain yield. Systemic fungicides were the most effective and reduced wilt incidence between 53 and 82%, so increasing yield by 59-97% (Kinshore & Singh, 2008). Fusarium wilt was observed in 53% of flax crops surveyed in southern Manitoba and Saskatchewan, Canada, in 1995 (Rashid et al., 1996). Sowing seed from a moderately diseased field (26-50% wilt) resulted in 15.7% pre-emergence rot and 7.6% seedling wilt (Tu & Cheng, 1976).
A 33% max. loss in caloric value in linseed caused by Fusarium oxysporum was found in india (Prasad et al., 1983).
Control can also be by resistant varieties, biological agents and bio-products, trace elements and destruction of debris and long rotation.
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:
The Fusarium wilt disease results in economical damage in flax and linseed (Linum usitatissimum L.) (Beaudoin, 1988) and is caused by Fusarium oxysporum f.sp. lini (Bolley) Snyd. and Hans. Flax wilt is well known now in all main flax and linseed growing countries and may cause severe losses (Kroes, I. 1997).
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: Seeds are not considered to be a significant pathway compared to other pathways. The listing of this pest is covered by the listing of the Fusarium complex on Linum usitatissimum.
8 - Tolerance level:
Is there a need to change the Tolerance level:
No
Proposed Tolerance levels:
Not recommended for the RNQP status.
9 - Risk management measures:
Is there a need to change the Risk management measure:
No
Proposed Risk management measure:
Not recommended for the RNQP status.
REFERENCES:
- Baturo SA, Portyankin D & Korenskiĭ NG (1996) Yield and quality of flax seeds following growth under artificial climatic conditions. Selektsiya i Semenovodstvo, Moscow 2, 20-22;
- Brayford D (1996) Fusarium oxysporum f. sp. lini. IMI Descriptions of Fungi and Bacteria 127, Sheet 1267;
- Fitt BDL, Jouan B, Sultana C, Paul VH & Bauers F (1991) Occurrence and significance of fungal diseases on linseed and fibre flax in England, France, and Germany. Aspects of Applied Biology 28, 59-64;
- Kishore R & Singh J (2008) Evaluation of fungicides against Fusarium oxysporum f. sp. lini of linseed. Annals of Plant Protection Sciences 16, 165-167;
- Mohit K, Tripathi UK, Ajay T & Singh PKA (2014) Screening of linseed germplasm for resistance/tolerance against Fusarium oxysporum f sp. Lini (Bolley) disease. Journal of Plant Pathology and Microbiology 5, 235;
- Plăcintă DD & Murariu D (2016) Fungus evaluation from seeds germplasm before medium and long term storage. Cercetări Agronomice în Moldova 49, 71-82;
- Prasad RB, Thakur MK & Afsar MR (1983) Changes in energy content of linseed due to seed borne fungi. National Academy of Science Letters 6, 1-2;
- Sharma RL, Singh BP, Thakur MP & Verma KP (2002) Chemical management of linseed wilt caused by Fusarium oxysporum F. sp. lini. Annals of Plant Protection Sciences 10, 390-391;
- Tu CC & Cheng YH (1976) Studies on seed transmission of flax Fusarium wilt and its control with seed treatment. Journal of Agricultural Research of China 25, 134-140;
- Wielgusz K, Weber Z & Andruszewska A (2009) Effect of biological protection of flax on the decrease in occurrence of Fusarium wilt and yield quality. Progress in Plant Protection 49, 1991-2002;
- Zad D (1978) Fusarium attacks at the expense of flax seeds. Comptes Rendus des Seances de l'Academie d'Agriculture de France 64, 833-842;