| Legend |
|---|
| Justification for qualification based on EPPO PM 4 Standards |
| Justification for disqualification |
| Additional or non-conclusive information |
| Standard text |
NAME OF THE ORGANISM: Verticillium dahliae (VERTDA)
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: Fruits (including hops) 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: Fruits (including hops) sector
Justification (if necessary):
-
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):
Austria (2014); Belgium (2015); Bulgaria (1986); Croatia (2016); Cyprus (2011); Czech Republic (2011); Denmark (1986); France (1986); Germany (2012); Greece (2013); Greece/Kriti (2013); Hungary (1986); Italy (2007); Malta (2007); Netherlands (2018); Portugal (1986); Slovakia (2012); Slovenia (2017); Spain (2021)
Conclusion:
Justification (if necessary):
Data of the presence of this pest on the EU territory are available in EPPO Global Database (https://gd.eppo.int/). V. dahliae is present in most EU Member States (MSs), with the exception of Ireland (absent, no pest records) and Poland (absent/uncertain). The current status of V. dahliae in the MSs where the pathogen is known to occur ranges from “restricted distribution” to “widespread” (EFSA, 2014).
HOST PLANT N°1: Pistacia vera (PIAVE) for the Fruits (including hops) sector.
Origin of the listing:
Commission Implementing Directive (EU) 2014/98/EU and Commission Implementing Regulation (EU) 2019/2072
Plants for planting:
Plants intended for planting
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):
?
Conclusion:
Candidate by default
Justification:
Verticillium dahliae is a soil-borne fungus that causes Verticillium wilt diseases in an extremely wide host range of annual and perennial dicotyledonous plant. Its primary economic hosts include: artichoke, aubergine, bell pepper, cotton, hop, lettuce, mints (Mentha spp.), oilseed rape, olive, potato, strawberry, tomato (CABI, 2021) and pistachio (UC PMG, 2019); citrus and pome fruits, however, are the exception (Smith et al. 1988).
Verticillium dahliae can survive for 14 years in soil as microsclerotia (form of resting spores) (Wilhelm, 1955), either free or embedded in plant debris, which are stimulated to germinate in response to root exudates (Mol, 1995). Infection of plants, both individuals and populations, is directly related to the inoculum density of microsclerotia in the soil (Pullman & DeVay, 1982; Harris & Yang, 1996; Mol et al., 1996; Xiao & Subbarao, 1998).
Verticillium dahliae is seed transmitted (CABI, 2021)
Verticillium dahliae can easily be dispersed by propagation material (nursery stock) of both herbaceous and woody hosts (e.g. Keykhasaber et al., 2018).
Verticillium wilt is favored by cool temperatures. Extended spring weather and mild summers often are accompanied by severe losses to this disease. The fungus apparently is eliminated from aboveground portions of pistachio trees in hot summer weather. Repeated attacks of wilt apparently represent new infections each year (UC PMG, 2019).
Verticillium dahliae can survive for 14 years in soil as microsclerotia (form of resting spores) (Wilhelm, 1955), either free or embedded in plant debris, which are stimulated to germinate in response to root exudates (Mol, 1995). Infection of plants, both individuals and populations, is directly related to the inoculum density of microsclerotia in the soil (Pullman & DeVay, 1982; Harris & Yang, 1996; Mol et al., 1996; Xiao & Subbarao, 1998).
Verticillium dahliae is seed transmitted (CABI, 2021)
Verticillium dahliae can easily be dispersed by propagation material (nursery stock) of both herbaceous and woody hosts (e.g. Keykhasaber et al., 2018).
Verticillium wilt is favored by cool temperatures. Extended spring weather and mild summers often are accompanied by severe losses to this disease. The fungus apparently is eliminated from aboveground portions of pistachio trees in hot summer weather. Repeated attacks of wilt apparently represent new infections each year (UC PMG, 2019).
5 - Economic impact:
Are there documented reports of any economic impact on the host?
Yes
Justification:
Generally Verticillium wilt causes a rapid desiccation and death of one or more scaffolds or the entire pistachio tree, usually in late spring or early summer. The first symptoms are interveinal patches of yellowing or scorching of the leaves on affected branches. In some instances, however, it may also cause a condition known as thin leaf decline where the disease develops slowly over several years before the tree becomes economically unproductive or dies. Thin leaf decline is characterized by slow loss of vigour, reduction in growth and yield, and gradual thinning of the canopy until most of the remaining leaves are clustered in tufts at the ends of branches and shoots (UC IPM, 2019).
Fotoohiyan et al (2014) reported that Verticillium dahliae is one of the most devastating diseases in pistachio orchards in the world including Iran; historically it is also the most destructive disease for pistachio in California (Trouillas, 2017). However, this is more linked to infected fields than to infected plant material. Solutions are found in control and resistant/tolerant rootstocks (Epstein et al., 2004; Triki et al., 2014; Fotoohiyan et al., 2014;). In California, resistant rootstocks have solved the problem (Trouillas, 2017).
Fotoohiyan et al (2014) reported that Verticillium dahliae is one of the most devastating diseases in pistachio orchards in the world including Iran; historically it is also the most destructive disease for pistachio in California (Trouillas, 2017). However, this is more linked to infected fields than to infected plant material. Solutions are found in control and resistant/tolerant rootstocks (Epstein et al., 2004; Triki et al., 2014; Fotoohiyan et al., 2014;). In California, resistant rootstocks have solved the problem (Trouillas, 2017).
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?
No
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:
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:
Healthy soil
Healthy propagation material
Healthy seed (rootstock seedlings)
Reduction of fungal presence: Verticillium is very common when orchards are planted in soil formerly planted to susceptible row crops such as cotton, tomatoes, melons, etc. Avoid interplanting young orchards with these susceptible crop plants. Inoculum levels can be reduced by flooding in summer, solarizing the soil, growing several seasons of grass rotational crops (especially rye or sudangrass), or a combination of these treatments. When replanting in an area where susceptible perennials were previously grown, try to remove as many roots of the previous crop as possible. Fumigating with chloropicrin before planting will reduce inoculum (UC IPM, 2023).
Solutions are found in control and resistant/tolerant rootstocks (Fotoohiyan et al., 2014; Epstein et al., 2004).
Healthy propagation material
Healthy seed (rootstock seedlings)
Reduction of fungal presence: Verticillium is very common when orchards are planted in soil formerly planted to susceptible row crops such as cotton, tomatoes, melons, etc. Avoid interplanting young orchards with these susceptible crop plants. Inoculum levels can be reduced by flooding in summer, solarizing the soil, growing several seasons of grass rotational crops (especially rye or sudangrass), or a combination of these treatments. When replanting in an area where susceptible perennials were previously grown, try to remove as many roots of the previous crop as possible. Fumigating with chloropicrin before planting will reduce inoculum (UC IPM, 2023).
Solutions are found in control and resistant/tolerant rootstocks (Fotoohiyan et al., 2014; Epstein et al., 2004).
7- Is the quality of the data sufficient to recommend the pest to be listed as a RNQP?
No
Conclusion:
Candidate by default
Justification:
Uncertainty whether plants for planting is a significant pathway compared to infection from soil.
CONCLUSION ON THE STATUS:
Recommended for listing as an RNQP, by default (uncertainty on plants for planting being a significant pathway). Conclusion was that there is insufficient evidence to recommend changes from the current regulation and measures.
8 - Tolerance level:
Is there a need to change the Tolerance level:
No
Proposed Tolerance levels:
9 - Risk management measures:
Is there a need to change the Risk management measure:
No
Proposed Risk management measure:
REFERENCES:
- CABI (2020) Verticillium dahliae (verticillium wilt), CABI Digital Library (Accessed 30/May/2024).
- Fradin EF & Thomma BP (2006). Physiology and molecular aspects of Verticillium wilt diseases caused by V. dahliae and V. albo-atrum. Molecular Plant Pathology 7(2), 71-86. doi: 10.1111/j.1364-3703.2006.00323.x.
- Epstein L, Beede R, Kaur S & Ferguson L (2004). Rootstock effects on pistachio trees grown in Verticillium dahliae-infested soil. Phytopathology 94:388-395.
- Fotoohiyan Z, Rezaee S, Shahidi Bonjar GH, Mohammadi AH & Moradi M (2014). Biocontrol potential of Trichoderma harzianum in controlling wilt disease of pistachio caused by Verticillium dahliae. Journal of Plant Protection Research 57(2), 185–193. DOI: 10.1515/jppr-2017-0025
- Harris DC & Yang JR (1996). The relationship between the amount of Verticillium dahliae in soil and the incidence of strawberry wilt as a basis for disease risk prediction. Plant Pathology 45(1), 106-114.
- Keykhasaber M., Thomma BPHJ & Hiemstra JA (2018) Verticillium wilt caused by Verticillium dahliae in woody plants with emphasis on olive and shade trees. European Journal of Plant Pathology 150, 21-37.
- Mol L, Halteren JM van, Scholte K & Struik PC (1996). Effects of crop species, crop cultivars and isolates of Verticillium dahliae on the population of microsclerotia in the soil, and consequences for crop yield. Plant Pathology 45(2), 205-214.
- Pullman GS & DeVay JE (1982). Epidemiology of Verticillium wilt of cotton: a relationship between inoculum density and disease progression. Phytopathology 72(5), 549-554.
- Smith IM, Dunez J, Phillips DH, Lelliot RA & Archer SA (eds) (1988) European handbook of diseases: Verticillium dahlia Kleb. and Verticillium albo-atrum Reinke & Berthold. Blackwell Scientific Publications Oxford, UK. 299-302.
- Triki MA, Chelli Chaabouni A, Rhouma A, Cheffi M, Mseddi A & Boudaya M (2014) Evaluation of susceptibility of pistacia genotypes to verticillium wilt disease. Acta Horticulturae 1028, 205-210.
- Trouillas F (2017) Soil-Borne Diseases of Pistachio. Powerpoint presentation (Accessed 30/Jul/2024). https://ucanr.edu/sites/PistachioShortCourse/files/274452.pdf.
- UC PMG (2019) Verticillium wilt. In Pest management guidelines for agriculture – Pistachio. University of California, Agriculture and Natural Resources, publication 3461, page 62. https://anrcatalog.ucanr.edu/Details.aspx?itemNo=3461.
- Wilhelm S (1955) Longevity of Verticillium wilt fungus in the laboratory and the field. Phytopathology 45, 180-181.
- Xiao CL & Subbarao KV (1998). Relationships between Verticillium dahliae inoculum density and wilt incidence, severity, and growth of cauliflower. Phytopathology 88(10), 1108-1115