Pepino Mosaic Virus (PepMV)

California Pest Rating for
Pepino Mosaic Virus (PepMV)
Pest Rating: B

 


PEST RATING PROFILE
Initiating Event: 

In January 2015, Tongyan Tian, CDFA Plant Pathologist, detected Pepino mosaic virus(PepMV) in two official tomato samples collected from plants grown in a greenhouse in San Diego County.  The virus has been previously reported by researchers who collected non-official samples also from greenhouse tomatoes in Camarillo, Ventura County, California (Ling et al., 2008).   The current regulatory status of PepMV and its potential risk of infestation in California are reassessed here for the proposal of a permanent rating.

History & Status:

Background:   Pepino mosaic virus was first described in 1980 when it was isolated from pepino (Solanum muricatum) plants that were collected in 1974 from the coastal region of Peru (Jones et al., 1980).  Following its original detection, it was not until 1999 that this pathogen was discovered infecting tomato plants grown in many greenhouses in the Netherlands, and later in the early 2000 in the UK, France and Germany.  Since then, it initially spread to several countries in Europe but was subsequently eradicated from Croatia, Czech Republic, Norway, and Slovakia (EPPO, 2014a).   Soon it was reported worldwide as a significant disease of greenhouse tomatoes in North America, South America, Asia and Africa.  In North America, PepMV was first reported in 2001 (French et al., 2001).  In their study of a US isolate of PepMV, Maroon-Lango and other scientists first reported the detection of the virus in tomato samples obtained from California (Maroon-Lango et al., 2003).

Pepino mosaic virus belongs to the genus Potexvirus in the family Alphaflexiviridae and RNA viruses group.  Two strains of the virus are currently recognized: the pepino strain and the tomato strain (CABI, 2014).  Ling (2007) reported that almost all North America PepMV isolates belonged to the European tomato strain.  This was confirmed by Ling et al. (2008) in their study of genetic diversity and distribution of PepMV genotypes in North America.  These scientists found four major genotypes of PepMV in the North America and only the European (EU) genotype in California.

Hosts: Pepino mosaic virus was originally described on pepino (Solanum muricatum).  The natural and experimental host range is limited primarily to Solanceous plants.  In addition to pepino, major and main hosts of PepMV are Solanum lycopersicum (tomato), S. melongena (eggplant) and S. tuberosum (potato).  Natural infections have not been observed in potato and eggplant crops (EPPO, 2014b). During surveys in Peru the pathogen was found to be naturally present in several wild Lycopersicum species (L. chilense, L. chmielewskii, L. parviflorum, L. peruvianum) (EPPO, 2014b). Ocimum basilicum (basil) is a minor host.  A number of wild and weed plants are hosts including, Amaranthus graecizans (tumbleweed/pigweed), A. retroflexus (red-root amaranth), A. viridis (green amaranth), Calendula arvensis, Chenopodium murale, Chrysanthemum segetum, Convolvulus arvensis, C. humilis, Datura stramonium (jimsonweed), Lycopersicon pimpinellifolium (currant tomato), Malva neglecta, M. nicaeensis, M. parviflora, M. sylvestris, Nicotiana glauca (tree tobacco), N. rustica (wild tobacco), Plantago lagopus, P. major, Solanum nigrum (black nightshade), Sonchus asper, S. oleraceus (common sowthistle) and S. tenerrimus (CABI, 2014; EPPO, 2014a, 2014b).

Symptoms:  Symptoms may depend on climate conditions and become more distinct under low light conditions. Because of the variable influence of climate, leaf symptoms may be weak and difficult to observe thereby enabling PepMV-infected plants to escape unnoticed.  Initial symptoms on tomato plants include small yellow leaf spots.  However later, older, mature leaves may exhibit mottling, while top leaves may show slight curling. Fruit may show orange mottling which may differ between trusses (cluster of small stems bearing flowers and fruit) in a single plant. In Peru, young leaves of infected pepino exhibited yellow mosaic, while in the Netherlands affected tomato plants showed yellow spots, mild interveinal chlorosis and sometimes minor malformation (enation) of leaves.  In UK, affected plants showed leaf distortion, chlorosis and bubbling of leaf surfaces, stunted and distorted plants (EPPO, 2014b; Mumford & Jones, 2005).

Damage Potential:  Tomato plants infected with PepMV do not always result in significant economic damage since fruit symptoms may be absent.  On the other hand, fruit setting may be delayed and yield affected. The virus can cause significant crop losses if early infections are not eliminated (EPPO, 2014b). Greenhouse-grown plants are particularly affected by the virus.

TransmissionPepino mosaic virus is a very contagious pathogen that is transmitted mainly through mechanical means including contaminated tools, hands, clothing, direct plant to plant contact, grafting, cuttings, and seeds. High concentrations of the virus can be present in plant materials, leaves, fruits and roots of infected plants.  The virus can be present in the seed coat of immature and mature tomato seeds, but not within the seed (embryo) (Ling, 2008).  Damage or death of roots may release the virus in soil and drainage/irrigation water. Experimentally the virus has been shown to be spread by contact with bumble bees (Bombus terrestris, Bombus spp.) used as pollinators of tomato plants (EPPO, 2014b; CABI, 2014).

Worldwide Distribution: Asia: Syria, Turkey; Africa: South Africa; Europe: Austria, Belgium, Bulgaria, Cyprus, Denmark, France, Germany, Greece, Hungary, Ireland, Italy, Lithuania, Netherlands, Poland, Spain, Switzerland, United Kingdom; North America: Canada, Mexico, USA; South America: Chile, Ecuador, Peru (EPPO, 2014a, CABI, 2014).

The recorded absence of Pepino mosaic virus from China, Taiwan, Madagascar, Morocco and Guatemala is considered unreliable (EPPO, 2014a; CABI, 2014).

In the USA it is present in Alabama, Arizona, California, Colorado, Florida, Maryland, Minnesota, Oklahoma, and Texas.

Official Control: Currently, Pepino mosaic virus is on the ‘Harmful Organism List’ for 45 countries: Albania, Austria, Belgium, Brazil, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Georgia, Germany, Greece, Guatemala, Holy See (Vatican City State), Honduras, Hungary, India, Ireland, Italy, Japan, Republic of Korea, Latvia, Lithuania, Luxembourg, Malta, Monaco, Montenegro, Netherlands, New Zealand, Poland, Portugal, Romania, San Marino, Serbia, Slovakia, Slovenia, SPaid, Sweden, Switzerland, Taiwan, Turkey and United Kingdom (PCIT, 2014).

In California, PepMV is currently a Q-rated, quarantine pathogen.

California Distribution:  Greenhouse environments within San Diego and Ventura Counties.

California Interceptions:  There are no official records of PSbMV detected in incoming plant shipments to California.

The risk Pepino mosaic virus would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Evaluate if the pest would have suitable hosts and climate to establish in California. Score:

– Low (1) Not likely to establish in California; or likely to establish in very limited areas.
– Medium (2) may be able to establish in a larger but limited part of California.
High (3) likely to establish a widespread distribution in California.

 Risk is High (3)PepMV is likely to establish wherever its hosts are cultivated or grow naturally in California.  Tomato, the primary host, is a major crop that is widely cultivated in the State.

2) Known Pest Host Range: Evaluate the host range of the pest. Score:

Low (1) has a very limited host range.
– Medium (2) has a moderate host range.
– High (3) has a wide host range.

Risk is Low (1)The host range is limited primarily to Solanaceous plants of which tomato is the primary host that is cultivated over significant acreage throughout California.  Eggplant and potato are also affected, although natural infection of both crops has not been reported.

3) Pest Dispersal Potential: Evaluate the natural and artificial dispersal potential of the pest. Score:

– Low (1) does not have high reproductive or dispersal potential.
– Medium (2) has either high reproductive or dispersal potential.
– High (3) has both high reproduction and dispersal potential.

Risk is High (3) Pepino mosaic virus is a very contagious pathogen that is artificially spread mainly through mechanical means including contaminated tools, hands, clothing, direct plant to plant contact, grafting, cuttings, and seeds.  It is externally seed-borne, and is also spread through infected planting materials. Experimentally, it has been transmitted by contact with bumble bees.  Since symptoms are not always readily recognized, there is the potential for this virus to spread rapidly and unnoticed within nursery greenhouse environments as well as to outdoor field environments.

4) Economic Impact: Evaluate the economic impact of the pest to California using the criteria below. Score:

A. The pest could lower crop yield.
B. The pest could lower crop value (includes increasing crop production costs).
C. The pest could trigger the loss of markets (includes quarantines).
D. The pest could negatively change normal cultural practices.
E. The pest can vector, or is vectored, by another pestiferous organism.
F. The organism is injurious or poisonous to agriculturally important animals.
G. The organism can interfere with the delivery or supply of water for agricultural uses.

– Low (1) causes 0 or 1 of these impacts.
– Medium (2) causes 2 of these impacts.
High (3) causes 3 or more of these impacts.

Risk is High (3)PepMV could lower tomato yield, value and marketability particularly when infected fruit are symptomatic.  Due to its contagious nature soil and irrigation water may become contaminated when infected roots and plant residue in soil are damaged or break down, thereby causing changes in normal cultivation practices.

5)  Environmental Impact: Evaluate the environmental impact of the pest on California using the criteria below.

A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes.
B. The pest could directly affect threatened or endangered species.
C. The pest could impact threatened or endangered species by disrupting critical habitats.
D. The pest could trigger additional official or private treatment programs.
E. The pest significantly impacts cultural practices, home/urban gardening or ornamental plantings.

Score the pest for Environmental Impact. Score:

Low (1) causes none of the above to occur.
– Medium (2) causes one of the above to occur.
– High (3) causes two or more of the above to occur.

Risk is Low (1) – Several Solanaceous weeds have been experimentally shown to be hosts of PepMV.  Natural infestations of such hosts could serve as reservoirs for the pathogen – although this would need to be confirmed through further research.  The virus could negatively affect home/urban gardening and cultivation of tomato and eggplant in particular.

Consequences of Introduction to California for Peas seed-borne mosaic virus

Add up the total score and include it here. (Score)

-Low = 5-8 points
-Medium = 9-12 points
-High = 13-15 points

 Total points obtained on evaluation of consequences of introduction of PepMV to California = (11).

6)  Post Entry Distribution and Survey Information: Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included. (Score)

-Not established (0) Pest never detected in California, or known only from incursions.
Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).
-Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.
-High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Evaluation is Low (-1)

 Final Score:

7) The final score is the consequences of introduction score minus the post entry distribution and survey information score: (Score)

Final Score:  Score of Consequences of Introduction – Score of Post Entry Distribution and Survey Information = 10     

Uncertainty:

The presence and distribution of PepMV in California agricultural field production and environmental sites is not known.  Such information would be obtained through periodic surveys and may affect the current proposed rating.  Due to the nature of its transmission, it is possible for the virus to escape detection and spread to non-infected sites.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Pepino mosaic virus is B.

References:

CABI   2014.  Pepino mosaic virus full datasheet.  Crop Protection Compendium.  http://www.cabi.org/cpc/datasheet/1695

EPPO, 2014a.  Pepino mosaic virus (PEPMV0).  New PQR database.  Paris, France:  European and Mediterranean Plant Protection Organization.  http://newpqr.eppo.int

EPPO. 2014b.  Pepino mosaic virus.  European and Mediterranean Plant Protection Organization. http://www.eppo.int/QUARANTINE/Alert_List/viruses/PEPMV0.htm (Panel review date 2014-03).

Ferguson, G.  2001. Management of Pepino mosaic virus in greenhouse tomatoes – factsheet. Modified November 13, 2013.  Ontario Ministry of Agriculture, Food and Rural Affairs. http://www.omafra.gov.on.ca/english/crops/facts/01-017.htm .

French, C. J., M. Bouthillier, M. Bernardy, G. Fergusen, M. Sabourin, R. C. Johnson, C. Masters, S. Godkins and R. Mumford.  2001. First report of Pepino mosaic virus in Canada and the United States.  Plant Disease 85:1121.

Jones, R. A. C., R. Koenig, D. E. Lesemann. 1980. Pepino mosaic virus, a new potexvirus from pepino (Solanum muricatum). Annals of Applied Biology, 94(1):61-68

Mumford, R. A., and R. A. C. Jones.  2005.  Description of Plant Viruses: Pepino mosaic virus. Association of Applied Biologists 411 (DPV 350 revised version).  http://www.dpvweb.net/dpv/showdpv.php?dpvno=411 .

Ling, K. S., 2007.  The population genetics of Pepino mosaic virus in North America greenhouse tomatoes.  Phytopathology 97:S65.

Ling, K. S., 2008. Pepino mosaic virus on tomato seed: virus location and mechanical transmission. Plant Disease, 92:1701-1705.

PCIT.  2014.  USDA Phytosanitary Certificate Issuance & Tracking System.  https://pcit.aphis.usda.gov/PExD/faces/ReportHarmOrgs.jsp .

Responsible Party:

Dr. John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-262-1110, plant.health[@]cdfa.ca.gov.


Comment Period:  CLOSED

The 45-day comment period opened on Tuesday,  April 7, 2015 and closed on May 22, 2015.


Pest Rating: B


Posted by ls