NAME OF THE ORGANISM: Verticillium dahliae (VERTDA)

Evaluation continues

Remark: Inspection for 'Verticillium spp.' is recommended in EPPO Standard PM 4-31 Certification scheme for hazelnut. Any plant found to be infected should be recorded and immediately removed.

Candidate by default

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 and tomato (CABI, 2021) and Corylus (Houshyarfard, 2020); 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 et al., 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).
[In the responses to the questionnaire, SI supported deregulation in the EU because infections of Corylus avellana are relatively rare.]

Candidate

Healthy propagation material
Healthy soil (free from Verticillium dahliae microsclerotia)
Healthy seed

Candidate by default

Uncertainty whether plants for planting is a significant pathway compared to infection from soil.

Evaluation continues

Remark: Inspection for ' Verticillium spp.' recommended in EPPO Standard PM 4-27 Pathogen-tested material of Malus, Pyrus and Cydonia.

Candidate by default

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 and tomato (CABI, 2021); 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 et al., 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).

Evaluation continues

Remark: Inspection for ' Verticillium spp.' recommended in EPPO Standard PM 4-27 Pathogen-tested material of Malus, Pyrus and Cydonia.

Candidate by default

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 and tomato (CABI, 2021); 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).

Evaluation continues

Candidate by default

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).

Yes

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).

Major

No

Candidate

Candidate

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).

Candidate by default

Uncertainty whether plants for planting is a significant pathway compared to infection from soil.

Evaluation continues

Remark: The assessment performed covers the given host species as well as interspecific hybrids with other Prunus species.

Candidate by default

Verticillium dahlia 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 apricot (UC PMG, 2023); 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).

Yes

Disease symptoms may comprise wilting, chlorosis, stunting, necrosis and vein clearing. Brown vascular discoloration may be observed in stem tissue cross-sections (Frandin & Thomma, 2006). Symptoms of Verticillium wilt diseases can vary between hosts; thus, there are no unique symptoms that develop on all plants infected by V. dahliae (Fradin and Thomma, 2006). Moreover, symptoms can vary depending upon strains (pathotypes) of the pathogen (Korolev et al., 2008; Jiménez-Díaz et al., 2012).
Verticillium wilt becomes apparent when leaves on one or more branches, often on only one side of the apricot tree, turn yellow and/or wilt early in the growing season. The symptoms progress until the infected shoots die and dry in a curled position often called a "shepherd's crook". When shoot, branch, or trunk tissue of infected trees is dissected, the vascular ring and often much of the heartwood will display dark discoloration. Foliar symptoms usually appear only on young trees (2nd to 4th leaf). Older trees do not normally present symptoms of Verticillium wilt. Apricot tree yields can be reduced by Verticillium, even when foliar symptoms are not readily apparent. Specific rootstock and scion varieties may vary in susceptibility and are not well known. Orchards can be adversely affected by the disease even when low pathogen numbers in soil (2–3 propagules per gram) are present. Verticillium is very common when orchards are planted in soil formerly planted to susceptible row crops such as cotton, tomatoes, melons, etc. (UC IPM, 2023).
On apricot, initial symptoms appear as a sudden wilting of leaves on one or more branches in early summer. Leaves become dull in appearance and rapidly tan and wither. Often the leaves remain attached, resulting in a one-sided, flagged appearance. At times, symptoms develop on leaves at the base of branches and progress upward until the entire branch is affected. Young trees may be killed by this pathogen, but affected branches of older trees may leaf out the following year, only to be attacked again. The result of repeated wilting is generally stunted terminal growth and low productivity or death (Gubler, 1995).
[In the responses to the questionnaire, SI supported deregulation in the EU because infections of Prunus spp. are relatively rare.]

Medium

No

Candidate

Economic impact assessed for rootstocks

Candidate

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).

Candidate by default

Uncertainty whether plants for planting is a significant pathway compared to infection from soil.

Evaluation continues

Remark: The assessment performed covers the given host species as well as interspecific hybrids with other Prunus species.

Candidate by default

Verticillium dahlia 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 and tomato (CABI, 2021); 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).

Candidate

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).

Candidate by default

Uncertainty whether plants for planting is a significant pathway compared to infection from soil.

Evaluation continues

Remark: The assessment performed covers the given host species as well as interspecific hybrids with other Prunus species.

Candidate by default

Verticillium dahlia 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 and tomato (CABI, 2021); 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).

Yes

Disease symptoms may comprise wilting, chlorosis, stunting, necrosis and vein clearing. Brown vascular discoloration may be observed in stem tissue cross-sections (Frandin & Thomma, 2006). Symptoms of Verticillium wilt diseases can vary between hosts; thus, there are no unique symptoms that develop on all plants infected by V. dahliae (Fradin and Thomma, 2006). Moreover, symptoms can vary depending upon strains (pathotypes) of the pathogen (Korolev et al., 2008; Jiménez-Díaz et al., 2012; cited in EFSA, 2014).
Leaves on one or more branches, often on only one side of the tree, will turn yellow or wilt early in the growing season. The symptoms progress until the affected shoots die and dry up later in the season. Affected young shoots often resemble a shepherd's hook. When shoot, branch, or trunk tissue of infected trees is cut in cross section, the vascular ring and often much of the heartwood will display dark discoloration. Foliar symptoms usually appear only on young trees (first to fifth or sixth leaf). Older trees do not normally exhibit symptoms of Verticillium wilt. Research has shown that trees’ yields can be reduced by Verticillium wilt, even when foliar symptoms are not readily apparent. Specific rootstock or scion varieties may vary in susceptibility. Second-to fourth-year trees are usually the most susceptible to Verticillium wilt (UC IPM, 2019).
On almond, initial symptoms appear as a sudden wilting of leaves on one or more branches in early summer. Leaves become dull in appearance and rapidly tan and wither. Often the leaves remain attached, resulting in a one-sided, flagged appearance. At times, symptoms develop on leaves at the base of branches and progress upward until the entire branch is affected. Young trees may be killed by this pathogen, but affected branches of older trees may leaf out the following year, only to be attacked again. The result of repeated wilting is generally stunted terminal growth and low productivity or death (Gubler, 1995).
Almond wilt due to V. dahliae, also known as ‘black heart', is an occasionally serious disease problem in Californian orchards (US). Verticillium wilt is most severe on trees 2–6-year-old, and symptoms lessen as trees mature. Usually only a few trees in a young orchard are affected, though sometimes many young trees die. Severe economic losses of 9000-11 000 USD per ha resulting from verticillium wilt in almond orchards have been recorded (Stapleton, 1997).
[In the responses to the questionnaire, SI supported deregulation in the EU because infections of Prunus spp. are relatively rare.]

Major

No

Candidate

Candidate

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).

Candidate by default

Uncertainty whether plants for planting is a significant pathway compared to infection from soil.

Evaluation continues

Remark: The assessment performed covers the given host species as well as interspecific hybrids with other Prunus species.

Candidate by default

Verticillium dahlia 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 and tomato (CABI, 2021); 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).

Yes

Disease symptoms may comprise wilting, chlorosis, stunting, necrosis and vein clearing. Brown vascular discoloration may be observed in stem tissue cross-sections (Frandin & Thomma, 2006). Symptoms of Verticillium wilt diseases can vary between hosts; thus, there are no unique symptoms that develop on all plants infected by V. dahliae (Fradin and Thomma, 2006). Moreover, symptoms can vary depending upon strains (pathotypes) of the pathogen (Korolev et al., 2008; Jiménez-Díaz et al., 2012; cited in EFSA, 2014).
On peach, Verticillium wilt can be a serious disease in young trees and is known to occur in all major production areas of the United States, Canada, the Mediterranean Basin, Bulgaria, and New Zealand. However, some cultivars show almost complete recovery with age (Gubler, 1995).
Orchards can be adversely affected by the disease even when low pathogen numbers in soil (2–3 propagules per gram) are present. Avoid interplanting young orchards with susceptible crop plants, such as cotton, tomatoes, melons, etc. Verticillium dahliae is usually present in these soils. Inoculum levels can be reduced by fumigating the soil, flooding fallow fields in summer, solarizing the soil, growing several seasons of grass cover crops (especially sudangrass or ryegrass), or a combination of these methods. When replanting in an area where susceptible perennials were previously grown, try to remove as many roots of the previous crop as possible (UC PMG, 2017).
[In the responses to the questionnaire, SI supported deregulation in the EU because infections of Prunus spp. are relatively rare.]

Major

No

Candidate

Candidate

Verticillium wilt of stone fruits can best be controlled by planting in soil that has low or undetectable inoculum densities and that has been cropped to various grasses or other nonhosts, as there are no resistant rootstocks. Soil fumigation with chloropicrin or with methyl bromide and chloropicrin destroys inoculum of V. dahliae. Proper fertilization and irrigation of orchards may enable trees to recover from infection (Gubler, 1995).

Candidate by default

Uncertainty whether plants for planting is a significant pathway compared to infection from soil.

Evaluation continues

Remark: The assessment performed covers the given host species as well as interspecific hybrids with other Prunus species.

Candidate by default

Verticillium dahlia 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 and tomato (CABI, 2021); 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).

Candidate

Verticillium wilt of stone fruits can best be controlled by planting in soil that has low or undetectable inoculum densities and that has been cropped to various grasses or other nonhosts, as there are no resistant rootstocks. Soil fumigation with chloropicrin or with methyl bromide and chloropicrin destroys inoculum of V. dahliae. Proper fertilization and irrigation of orchards may enable trees to recover from infection (Gubler, 1995).

Candidate by default

Uncertainty whether plants for planting is a significant pathway compared to infection from soil.

Evaluation continues

Remark: Inspection for ' Verticillium spp.' recommended in EPPO Standard PM 4-27 Pathogen-tested material of Malus, Pyrus and Cydonia.

Candidate by default

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 and tomato (CABI, 2021); 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).