Category Archives: Plant Pathogens

Plant Pathology (plant diseases)

Chrysanthemum white rust – Puccinia horiana (Hennings 1901)

California Pest Rating Proposal for

Chrysanthemum white rust | Puccinia horiana (Hennings 1901)
Current Rating: Q
Proposed Rating: A

Comment Period: 6/6/2019 through 7/21/2019


Author/Responsible Party:

Dr. Heather J. Scheck, Primary State Plant Pathologist/Nematologist, California Department of Food and Agriculture, 204 West Oak Ave, Lompoc, CA 805-736-8050 email: plant.health[@]cdfa.ca.gov.

*NOTE:

You must be registered and logged in to post a comment. If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.

Comment Format:

Comments should refer to the appropriate California Pest Rating Proposal Form subsection(s) being commented on, as shown below.

EXAMPLE COMMENT:
Consequences of Introduction: 1. Climate/Host Interaction: 
[Your comment that relates to “Climate/Host Interaction” here.]

Posted comments will not be able to be viewed immediately.

Comments may not be posted if they:

  • Contain inappropriate language which is not germane to the
    pest rating proposal;
  • Contains defamatory, false, inaccurate, abusive, obscene, 
    pornographic, sexually oriented, threatening, racially offensive,
    discriminatory or illegal material;
  • Violates agency regulations prohibiting sexual harassment or 
    other forms of discrimination;
  • Violates agency regulations prohibiting workplace violence, 
    including threats.

Comments may be edited prior to posting to ensure they are entirely germane.

Posted comments shall be those which have been approved in content and posted to the website to be viewed, not just submitted.


Proposed Pest Rating: A


Posted by ls

Lethal yellowing of palm phytoplasma | CANDIDATUS PHYTOPLASMA PALMAE

California Pest Rating Proposal for

Candidatus Phytoplasma palmae (Lethal yellowing of palm phytoplasma)
[syn. Coconut lethal yellowing pathogen (Nutman & Roberts, 1955)]
Current Rating: A
Proposed Rating: A

Comment Period: 6/6/2019 through 7/21/2019


Author/Responsible Party:

Dr. Heather J. Scheck, Primary State Plant Pathologist/Nematologist, California Department of Food and Agriculture, 204 West Oak Ave, Lompoc, CA 805-736-8050 email: plant.health[@]cdfa.ca.gov.

*NOTE:

You must be registered and logged in to post a comment. If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.

Comment Format:

Comments should refer to the appropriate California Pest Rating Proposal Form subsection(s) being commented on, as shown below.

EXAMPLE COMMENT:
Consequences of Introduction: 1. Climate/Host Interaction:
[Your comment that relates to “Climate/Host Interaction” here.]

Posted comments will not be able to be viewed immediately.

Comments may not be posted if they:

  • Contain inappropriate language which is not germane to the
    pest rating proposal;
  • Contains defamatory, false, inaccurate, abusive, obscene,
    pornographic, sexually oriented, threatening, racially offensive,
    discriminatory or illegal material;
  • Violates agency regulations prohibiting sexual harassment or
    other forms of discrimination;
  • Violates agency regulations prohibiting workplace violence,
    including threats.

Comments may be edited prior to posting to ensure they are entirely germane.

Posted comments shall be those which have been approved in content and posted to the website to be viewed, not just submitted.


Proposed Pest Rating: A


Posted by ls

Colletotrichum fioriniae

California Pest Rating Profile for

Colletotrichum fioriniae (Marcelino & Gouli) Pennycook 2017
Pest Rating: B


*Comment Period CLOSED: 4/17/2019 through 6/1/2019


Author/Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture. Phone: 916-738-6693, plant.health[@]cdfa.ca.gov.


Pest Rating: B


Updated on 7/10/2019 by ls

Erysiphe peckii (U. Braun) U. Braun & S. Takam. 2000

California Pest Rating Profile for

Erysiphe peckii (U. Braun) U. Braun & S. Takam. 2000
Pest Rating: B
Comment Period CLOSED: 4/4/2019 – 5/19/2019

Author/Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, Phone: 916-738-6693, plant.health[@]cdfa.ca.gov.


Pest Rating: B

Updated on 7/10/2019 by ls

Alstroemeria necrotic streak virus

California Pest Rating Profile for

Alstroemeria necrotic streak virus
Pest Rating: A

Comment Period CLOSED: 4/3/2019 – 5/18/2019


Author/Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, Phone: 916-738-6693, plant.health[@]cdfa.ca.gov.


Pest Rating: A


Updated on 7/10/2019 by ls

Neocercosporidium smilacis (Thüm.) U. Braun, C. Nakash., Videira & Crous 2017

California Pest Rating Profile for

Neocercosporidium smilacis (Thüm.) U. Braun, C. Nakash., Videira & Crous 2017
Pest Rating: B


Comment Period CLOSED: 2/22/2019 – 4/8/2019

Author/Responsible Party:

John J. Chitambar, Primary PlantPathologist/Nematologist, California Department of Food and Agriculture, plant.health[@]cdfa.ca.gov.


Pest Rating: B


Updated on 7/10/2019 by ls 


Tomato Brown Rugose Fruit Virus

California Pest Rating for
Tomato Brown Rugose Fruit Virus
Pest Rating:      A

PEST RATING PROFILE

Initiating Event:

On September 25, 2018, Tongyan Tian, CDFA Plant Pathologist, was notified by Kai-Shu Ling, Plant Pathologist, USDA ARS, Charleston, South Carolina, of his detection of Tomato brown rugose fruit virus (ToBRFV) in a tomato plant tissue sample sent to him by a private company in California.   The sample had been collected from tomato plants grown in the company’s greenhouse in Santa Barbara County.  On September 13, 2018, the company had also sent an unofficial symptomatic tomato leaf sample to CDFA for diagnosis of the associated pathogen. On November 2, 2018, Tongyan Tian, CDFA, identified the associated pathogen as Tomato brown rugose fruit virus. On further investigation of the situation in California, CDFA was notified by the company that all ToBRFV-infested and symptomatic plant material had been voluntarily destroyed, thereby preventing the collection of an official sample. Nevertheless, the risk associated with the possible introduction of ToBRFV and a proposed rating for this pathogen is documented here.

History & Status:

Background:  Tomato brown rugose fruit virus is a relatively new Tobamovirus – the genus that bears other economically important and contagious pathogens that infect Solanaceae, such as Tobacco mosaic virus (TMV) and Tomato mosaic virus (ToMV). ToBRFV was initially isolated from tomato plants grown in greenhouses in Jordan in 2015 (Salem et al., 2016).  Prior to this, in 2014, an outbreak of a new disease infecting resistant tomato cultivars grown in net houses was observed in Southern Israel and was determined to be caused by the Israeli isolate of ToBRFV with high genomic sequence identity to the Jordan isolate (Luria et al., 2017).  Most recently, ToBRFV was detected in tomato and chili pepper plants growing in nurseries in Yurecuaro, Michoacan, Mexico (NAPPO, 2018).  There have been no previous reports of ToBRFV from the USA. The recent detection in greenhouse tomato plants in California that subsequently resulted in the destruction of all infested plants, does not verify the establishment of ToBRFV in the country (see ‘Initiating Event’).

Tobamoviruses infecting tomato are of great concern, but ToBRFV is of special concern because of its ability to overcome resistance of the TM-22 resistance gene which is genetically bred into tomato plants for resistance against Tobamoviruses (Luria et al., 2017).  The Israeli isolate of ToBRFV was found to infect pepper (Capsicum annuum) plants harboring the L resistance genes, when cultivated in contaminated soil from previous grown infected tomato plants, especially in hot temperatures above 30°C (Luria et al., 2017).  Disease caused by ToBRFV is infectious and local spread can occur rapidly through mechanical means (see ‘Dispersal and spread’).

Hosts:  Tomato (Solanum lycopersicum) and pepper (Capsicum annuum) are the main hosts (Salem et al., 2016; Luria et al., 2017; NAPPO, 2018).  Petunia (Petunia hybrida) and certain weeds like black nightshade (S. nigrum) were shown to be asymptomatic hosts in experiments (Luria et al., 2017).

Symptoms:  The Jordan isolate of ToBRFV in tomato caused mild foliar symptoms and strong brown rugose symptoms on fruit thereby affecting market value of the crop.   Mechanically inoculated plants exhibited a range of local and systemic symptoms (Salem et al., 2016).  Symptoms caused by the Israeli isolate of ToBRFV were mild and severe mosaic of leaves with occasional narrowing of the leaves.  Yellow spots on fruit affected 10-15% of the total number of fruit produced on symptomatic plants (Luria et al., 2017).

In pepper plants cultivated in ToBRFV-contaminated soil from previously grown infected tomato plants, especially in temperatures above 30°C, the hypersensitivity response included necrotic lesions on roots and stems resulting in inhibited plant growth and possibly plant collapse.  Petunia and certain weeds are symptomless hosts, while eggplant and potatoes are non-hosts for the virus (Luria et al., 2017).

Dispersal and spread: ToBRFV is transmitted mechanically (plant to plant) via externally contaminated seed (over long distances), common cultural practices (worker’s hand, clothes), tools, equipment and circulating water (Salem et al., 2016).  Tobamoviruses are capable of preserving infectivity in seeds and contaminated soil (Broadbent, 1976; Luria et al., 2017).  Weed hosts can serve as reservoirs of inoculum for infection of the main hosts.

Damage Potential: Tobamoviruses are of main concern in tomato crops, especially when cultivated in protected environments such as greenhouses, where conditions favor rapid spread of the pathogen.  The ability of ToBRFV to break resistance in tomato plants harboring the TM-22 resistance gene and, under certain conditions also pepper plants harboring the L resistance genes, makes the potential for damage a main concern. The stability and infectious nature of this Tobamovirus via mechanical transmission by workers, tools and equipment during the handling of plants, with infection most likely occurring when seedlings are thinned in nurseries or transplanted, plus transmission through contaminated seed, soil and circulating water, render a high potential for damage in tomato and pepper.  Crop production and quality of ToBRFV-consumable tomato and pepper fruit can be affected thereby significantly impacting their market value.

Worldwide Distribution: Asia: Jordan (Salem et al., 2016), Israel (Luria et al., 2017); North America: Mexico (NAPPO, 2018).

Official Control: None reported.

California Distribution: Tomato brown rugose fruit virus is not present in California.  The detection of ToBRFV in greenhouse tomato plants in Santa Barbara County resulted in the destruction of the plants (see ‘Initiating Event’).

California Interceptions: None reported.

The risk Tomato brown rugose fruit virus would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: It is likely that Tomato brown rugose fruit virus can establish a widespread distribution in California wherever tomato and pepper plants are cultivated.

Evaluate if the pest would have suitable hosts and climate to establish in California.

Score: 3

– 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.

2) Known Pest Host Range: The main hosts of ToBRFV are tomato and pepper cultivars.  Experimentally, petunia and few weeds have been proven to be asymptomatic hosts and weeds may serve as reservoirs of inoculum for subsequent infections of main cultivated hosts.

Evaluate the host range of the pest.

Score: 1

Low (1) has a very limited host range.

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

3) Pest Dispersal Potential: Tomato brown rugose fruit virus is a stable and readily infectious virus plant pathogen. It is easily transmitted from plant to plant by mechanical means which include common cultural practices, contaminated tools, equipment, hands, clothes, soil, and infected plants, and seed. Infections most likely occur in protected environments, where favorable conditions for pathogen spread exist, as when seedlings are thinned in nurseries or transplanted. Transmission of ToBRFV by insect vectors has not been reported.

Evaluate the natural and artificial dispersal potential of the pest.

Score: 3

– 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.

4) Economic Impact: ToBRFV can break resistance in tomato plants harboring the TM-22 resistance gene and under certain conditions, also pepper plants harboring the L resistance genes. The stability and infectious nature of this Tobamovirus render a high potential for damage in tomato and pepper particularly under protected environments such as greenhouses.  Crop production and quality of ToBRFV consumable tomato and pepper fruit can be affected thereby significantly impacting their market value.

Evaluate the economic impact of the pest to California using the criteria below.

Economic Impact: A, B, C, D, G.

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.

Economic Impact Score: 3

– 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.

5) Environmental Impact: The natural host range is limited to tomato and pepper which are cultivated crops.  Home/urban gardening of these host plants may be impacted if infected with ToBRFV. Consequently, the establishment of this resistance-breaking Tobamovirus species in California could trigger additional official or private treatment programs.

Evaluate the environmental impact of the pest on California using the criteria below.

Environmental Impact: D, E

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.

Environmental Impact Score: 3

– 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.

Consequences of Introduction to California for Tomato brown rugose fruit virus:

Add up the total score and include it here. 13

-Low = 5-8 points

-Medium = 9-12 points

High = 13-15 points

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.

Evaluation is ‘0’.  ToBRFV is not established in California.

Score: 0

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.

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 = 13

Uncertainty:  

The potential for weed plants, especially those commonly found in tomato and pepper fields in California, to serve as hosts and inoculum reservoirs of the pathogen is not known.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Tomato brown rugose fruit virus is A.


References:

Broadbent, L.  1976.  Epidemiology and control of Tomato mosaic virus.  Annual Review of Phytopathology, 14:75-96.

Luria, N. Smith, E., Reingold, V., Bekelman, I., Lapidot, M., Levin, I., Elad, N., Tam., Y., Sela, Abu-Ras, A., Ezra, N., Haberman, A., Yitzhak, L., Lachman, O. and Dombrovsky, A.  2017.  A new Israeli Tobamovirus isolate infects tomato plants harboring Tm-22 resistance genes.  PLoS ONE 12 (1):e0170429.  doi:10.1371/journal.pone.0170429

NAPPO. 2018. Tomato Brown Rugose Fruit Virus: detected in the municipality of Yurecuaro, Michoacan. North American Plant Protection Organization (NAPPO) Phytosanitary Alert System.  September 17, 2018. https://www.pestalerts.org/oprDetail.cfm?oprID=765.

Salem, N., Mansour, A., Ciuffo, M., Falk, B. W., and Turina, M.  2016.  A new Tobamovirus infecting tomato crops in Jordan.  Archives of Virology, 161:503-506.


Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-738-6693, plant.health[@]cdfa.ca.gov.


Comment Period:* CLOSED

11/07/18 – 12/22/18


*NOTE:

You must be registered and logged in to post a comment.  If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.


Comment Format:

♦  Comments should refer to the appropriate California Pest Rating Proposal Form subsection(s) being commented on, as shown below.

Example Comment:
Consequences of Introduction:  1. Climate/Host Interaction: [Your comment that relates to “Climate/Host Interaction” here.]

♦  Posted comments will not be able to be viewed immediately.

♦  Comments may not be posted if they:

Contain inappropriate language which is not germane to the pest rating proposal;

Contains defamatory, false, inaccurate, abusive, obscene, pornographic, sexually oriented, threatening, racially offensive, discriminatory or illegal material;

Violates agency regulations prohibiting sexual harassment or other forms of discrimination;

Violates agency regulations prohibiting workplace violence, including threats.

♦  Comments may be edited prior to posting to ensure they are entirely germane.

♦  Posted comments shall be those which have been approved in content and posted to the website to be viewed, not just submitted.


Pest Rating: A


Posted by ls 

Cercospora insulana Sacc. 1915

California Pest Rating for
Cercospora insulana Sacc. 1915
Pest Rating: C

PEST RATING PROFILE

Initiating Event: 

On May 11, 2018 a postal shipment of statice dried flowers showing symptoms of leaf spots was intercepted by the CDFA at a Federal Express (FedEx) office.  The shipment was destined to a private owner in Alameda County and had originated in Hawaii.  A sample of the symptomatic flowers was sent to the CDFA Plant Pathology Lab for disease diagnoses.  On May 17, 2018 Cheryl Blomquist, CDFA plant pathologist, identified the fungus, Cercospora insulana associated with the leaf spots.  The present status and rating of C. insulana is reevaluated here.

History & Status:

Background:  Cercospora insulana is a fungal plant pathogen in the Mycosphaerellaceae family, that causes leaf spot of statice and other host plants.

The pathogen is globally widespread.  In the USA, Cercospora insulana has only been reported from Florida and California (Farr & Rossman, 2018).  In California, prior to its most recent detection, the pathogen has been reported on Armeria sp. and Limonium spp. in northern and southern coastal region of California (French, 1989).

Disease cycle: In general, plants infected with Cercospora species produce conidiophores (specialized hypha) that arise from the plant surface in clusters through stomata and form conidia (asexual spores) successively.  Conidia are easily detached and blown by wind often over long distances.  On landing on surfaces of a plant host, conidia require water or heavy dew to germinate and penetrate the host.  Substomatal stroma (compact mycelial structure) may form from which conidiophores develop.  Development of the pathogen is favored by high temperatures and the disease is most destructive during summer months and warmer climates.  High relative humidity is necessary for conidial germination and plant infection.  The pathogen can overwinter in or on seed and as mycelium (stromata) in old infected leaves (Agrios, 2005).   

Dispersal and spread: Dispersal and spread: air-currents, infected nursery plants, infected leaves, seeds (Agrios, 2005).

Hosts: Armeria sp., A. maritima (thrift seapink), Limonium sp., L. bonducellii (Algerian statice), L. californicum (California sea lavender/marsh rosemary), L. gmelinii (syn. Statice gmelinii; Siberian statice), L. sinuatum (syn. Statice sinuata; statice/wavyleaf sea lavender), L. vulgare (common sea lavender) (CABI, 2018; French, 1989); Nerium indicum (Indian oleander) (XueWen et al., 2017)

Symptoms:  Leaf spot symptoms caused by Cercospora insulana in field-grown statice were reported from Italy as circular, brown lesions with a darker edge, 3-6 mm in diameter and surrounded by an orange or reddish halo.  Old lesions enlarged and coalesced, causing yellowing and senescence of leaves.  Heavy infections resulted in severe defoliation and retarded growth or death in panicles. Lesions were also present on the wings of the flower scapes, while scapes proper were not involved (Nicoletti et al., 2003).

Damage Potential: Quantitative losses due to Cercospora insulana have not been reported.  If left uncontrolled, leaf spotting may lead to disease outbreaks under favorable conditions, wherein photosynthetic areas can be reduced.  Heavy infections may result in severe defoliation, retarded plant growth and death of flowers in statice, and likely, in other ornamental host plants.  Nursery productions of ornamental hosts under controlled and conducive conditions for pathogen development would also be of concern in California.  However, damage potential due to this pathogen is likely to be similar to other Cercospora diseases which is usually low (Agrios, 2005).  Furthermore, fungicide applications and sanitary measures including the use of clean seed have been used to successfully control Cercospora diseases (Agrios, 2005).

Worldwide Distribution: Asia: China (XueWen et al., 2017), India, Myanmar; Africa: Kenya, Malta, South Africa, Zimbabwe; Europe: Caucasus, Italy, Portugal, Russia: North America: USA (California, Florida), Haiti; Oceania: Australia, New Zealand (Farr & Rossman, 2018)

Official Control: Presently, Cercospora insulana is on the ‘Harmful Organism’ list for Brazil, Colombia, Ecuador and Israel (USDA PCIT, 2018).

California Distribution:  Cercospora insulana is distributed in northern and southern coastal areas of the State (French, 1989).

California Interceptions To date, the recent detection of C. insulana (see ‘initiating event’) has been the only interception reported.

The risk Cercospora insulana would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Cercospora insulana has only been detected in northern and southern coastal regions in California. These limited regions provide adequate moisture that favor development of the pathogen in host plants like statice.

Evaluate if the pest would have suitable hosts and climate to establish in California.  Score: 2

– 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.

2) Known Pest Host Range: The known host range is limited to statice, thrift seapink and Indian oleander in the genera Limonium, Armeria and Neria.

Evaluate the host range of the pest. Score: 1

Low (1) has a very limited host range.

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

3) Pest Dispersal Potential: Cercospora insulana has high reproductive potential resulting in the successive production of conidia which primarily depend on air currents, infected plants and seed for dispersal and spread.

Evaluate the natural and artificial dispersal potential of the pest.

Score: 3

– 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.

4) Economic Impact: Quantitative losses due to Cercospora insulana have not been reported. However, for nurseries particularly, infected host plants with leaf spots could result in lowered value resulting in use of fungicidal treatments thereby increasing production costs, and loss of markets.

Evaluate the economic impact of the pest to California using the criteria below.

Economic Impact: B, C

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.

Economic Impact Score: 2

– 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.

5) Environmental Impact: Home garden plantings of statice species may be impacted if the pathogen was to establish under favorable environmental conditions and in the absence of adequate disease control.  The pathogen has not been detected in oleander in California.

Evaluate the environmental impact of the pest on California using the criteria below.

Environment Impact: E 

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.

Environmental Impact Score: 2

– 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.

Consequences of Introduction to California for Cercospora insulana:

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 to California = 10

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.

Evaluation is ‘Medium’ in California.

Score: (-2)

-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.

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 = 8

Uncertainty:  

None.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Cercospora insulana is to continue as C.


References:

Agrios, G. N.  2005.  Plant Pathology (Fifth Edition).  Elsevier Academic Press, USA.  922 p.

Farr, D.F., & A. Y. Rossman.  2016.  Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA.  Retrieved May 18, 2018, from http://nt.ars-grin.gov/fungaldatabases/

French, A. M. 1989. California Plant Disease Host Index. California Department of Food and Agriculture, Sacramento (Updated online version by T. Tidwell, May 2, 2017).

Nicoletti, R., F. Raimo, C. Pasini, and F. D’Aquila.  2003.  Occurrence of Cercospora insulana on statice (Limonium sinuatum) in Italy.  Plant Pathology 52: 418.  DOI: 10.1046/j.1365-3059.2003.00840.x

USDA PCIT.  2018.  USDA Phytosanitary Certificate Issuance & Tracking System. Retrieved May 18, 2018. 12:45:06 pm CDT.  https://pcit.aphis.usda.gov/PExD/faces/ReportHarmOrgs.jsp.

XueWen, X., Z. Qian and G. YingLan.  2017.  New records of Cercospora and Pseudocercospora in China.  Mycosystema 36: 1164-1167.


Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-738-6693, plant.health[@]cdfa.ca.gov.


Comment Period:* CLOSED

9/13/18 – 10/28/18


*NOTE:

You must be registered and logged in to post a comment.  If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.


Comment Format:

♦  Comments should refer to the appropriate California Pest Rating Proposal Form subsection(s) being commented on, as shown below.

Example Comment:
Consequences of Introduction:  1. Climate/Host Interaction: [Your comment that relates to “Climate/Host Interaction” here.]

♦  Posted comments will not be able to be viewed immediately.

♦  Comments may not be posted if they:

Contain inappropriate language which is not germane to the pest rating proposal;

Contains defamatory, false, inaccurate, abusive, obscene, pornographic, sexually oriented, threatening, racially offensive, discriminatory or illegal material;

Violates agency regulations prohibiting sexual harassment or other forms of discrimination;

Violates agency regulations prohibiting workplace violence, including threats.

♦  Comments may be edited prior to posting to ensure they are entirely germane.

♦  Posted comments shall be those which have been approved in content and posted to the website to be viewed, not just submitted.


Pest Rating: C


Posted by ls 

Citrus Viroid V

California Pest Rating  for
Citrus viroid V
Pest Rating: B

PEST RATING PROFILE

Initiating Event:  

The risk of infestation of Citrus viroid V (CVd-V) in California is evaluated and a permanent rating is herein proposed. 

History & Status:

Background: The origin of Citrus viroid V (CVd-V) is uncertain (Serra et al., 2008a).  In a study in Spain on the response of Citrus species and citrus-related genera to viroid infections, Serra and other researchers (2008a) originally detected CVd-V in Atalantia citroides, a citrus relative plant propagated on rough lemon rootstock and graft-inoculated with artificial mixtures of different viroids.  The viroid source was provided to them by a researcher at the University of California, Riverside and purified preparations were shown to be infectious in Etrog citron (Citrus medica), a classical indicator plant of citrus viroids.  Subsequently, CVd-V was considered a new species of the genus Apscaviroid in the family Pospiviroidae (Serra et al., 2008a).  Viroids are classified within two families: Pospiviroidae and Avsunviroidae.  Citrus are natural hosts of several viroid species that belong to the family Pospiviroidae.  Therefore, A. citroides was identified as an unusual viroid host since it was resistant to all previously known citrus viroids, yet capable of replicating CVd-V (Serra et al., 2008b).  Infectious assays conducted by Sierra et al. (2008) showed that CVd-V in Etrog citron exhibited mild symptoms, however, co-infections with either Citrus bent leaf viroid (CBLVd) or Citrus dwarfing viroid (CDVd, previously Citrus viroid III), also belonging to the genus Apscaviroid, showed synergistic effects in contrast to single infections of CVd-V or the other two viroids, however, titers of the viroids remained the same in singly or doubly infected plants (Serra et al., 2008a).

While the origin of CVd-V is not known, Pakistan may be one of the geographic origins of the viroid (Serra et al., 2008a, b; Parakh et al., 2017).  Serra et al. (2008a) suggested that the viroid was present, but overlooked or unnoticed, in field sources containing Hop stunt Viroid or Citrus dwarfing viroid – both of which have electrophoretic mobilities similar to CVd-V.  CVd-V has been found with some variations in its nucleotide sequence, in several countries in Africa, Asia, Europe, and North America (see ‘Worldwide Distribution).

In June 2016, the Citrus Clonal Protection Program-National Clean Plant Network (CCPP-NCPN), University of California, Riverside, California detected Citrus Viroid V in citrus budwood samples submitted by the CDFA for virus and viroid testing under the mandatory California (CA 3701) Citrus Nursery Stock Pest Cleanliness Program.  These budwood samples were taken from asymptomatic redblush grapefruit (Citrus paradisi) and variegated calamondin (C. madurensis) from a nursery in Tulare County.  This find marked the natural occurrence of CVd-V in California and corroborated the earlier report of CVd-VCA variant in the State (Dang et al., 2018; Serra et al., 2008b).

Hosts: Citrus spp.  including ‘Sanguinelli’, Salustiana’, and ‘Ricart navelina’ sweet oranges (Citrus x sinensis),  ‘Oroval’ and ‘Hernandina clementines (C. clementina), ‘Fino’ and ‘Verna’ lemons (C. limon), ‘Sevilano’ and ‘Cajel’ sour orange (C. aurantium), ‘Clausellina’ satsuma (C. unshiu), Temple mandarin (C. temple), Tahiti lime, Palestine sweet lime (C. limettioides), calamondin (C. madurensis), ‘Calabria’ bergamot (C. bergamia), ‘Orlando’ tangelo (C. paradisi x C. tangerina), ‘Page’ mandarin [(C. paradisi x C. tangerina) x C. clementina], and ‘Nagami’ kumquat (Fortunella margarita),  and Etrog citrus (Atlantia citroides) (Serra et al., 2008); ‘Shiranui’ [(C. unshiu x C. sinensis) x C. reticulata] (Ito and Ohta, 2010); ‘Moro blood’ sweet orange (Citrus x sinensis) (Bani Hashemian et al., 2013); redblush grapefruit (C. paradisi) (Dang et al., 2018).

Symptoms:   Citrus viroid V induced mild characteristic symptoms of very small necrotic lesions and cracks, sometimes filled with gum, in the stems of the viroid indicator plant, Etrog citron.  However, CVd-V reacted synergistically when Etrog citrus was co-infected with either citrus bent leaf viroid (CBLVd) or Citrus dwarfing viroid (CDVd), and showed severe stunting and epinasty with multiple lesions in the midvein.  Plants co-infected with CBLVd and CVd-V exhibited severe stem cracking characteristic of CBLVd, but without gum exudates, whereas plant co-infected with CDVd showed necrotic lesions (Serra et al., 2008a). Symptoms induced by CVd-V alone in commercial species and varieties are presently not known since commercial trees may be co-infected with several viroids (Ito and Ohta, 2010; Serra et al., 2008a).  Citrus viroid V may be present in asymptomatic citrus plant tissue – as recently evidenced by its detection in asymptomatic budwood collected from Tulare County, California.

Damage Potential:  The effect of CVd-V in commercial citrus rootstock-scion combinations, alone and in combination with other viroids, is yet unknown, however, Serra et al. (2008b) suggested that CVd-V could reduce tree size and yield as has been reported for clementine trees grafted on trifoliate orange co-infected with several viroids. Therefore, the need for nursery planting stock free of CVd-V is important.

Transmission:  Similar to other citrus viroids, CVd-V is graft-transmitted and is spread mainly through the propagation of infested material.

Worldwide Distribution:  Africa: Oman (Serra et al., 2008), Tunisia (Hamdi et al., 2015); Asia: China, Japan, Nepal, Pakistan (Cao et al., 2013), Iran (Bani Hashemian et al., 2010), Turkey (Önelge and Yurtmen, 2012); Europe: Spain (Serra et al., 2008); North America: USA (Serra et al., 2008).

Official Control: Citrus viroid V is a disease agent of concern that is tested for in the CDFA Citrus Nursery Stock Pest Cleanliness Program (3 CCR §§ 3701, et seq.).

California Distribution Tulare County (Dang et al., 2018).

California Interceptions: None reported.

The risk Citrus viroid V would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Citrus viroid V is likely to establish within infested propagative citrus materials in all citrus-growing regions of California.

Evaluate if the pest would have suitable hosts and climate to establish in California.

Score: 3

– 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.

2) Known Pest Host Range: Citrus viroid V has a moderate host range that is limited to several species and varieties of Citrus.

Evaluate the host range of the pest.

Score: 2

– Low (1) has a very limited host range.

Medium (2) has a moderate host range.

– High (3) has a wide host range.

3) Pest Dispersal Potential: Citrus viroid V replicates autonomously within infested plants and is spread mainly through the propagation and movement of infested planting materials to non-infested regions.

Evaluate the natural and artificial dispersal potential of the pest.

Score: 2

– 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.

4) Economic Impact: The effect of CVd-V in commercial citrus rootstock-scion combinations, alone and in combination with other viroids, is yet unknown, however, it has been suggested by Serra et al. (2008b) that CVd-V could reduce tree size and yield.

Evaluate the economic impact of the pest to California using the criteria below.

Score: A, B, C

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.

Economic Impact Score: 3

– 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.

5) Environmental Impact: It is probable that home, urban, public garden and landscape plantings of CVd-V-infested citrus plantings may be significantly impacted by the viroid singly or in combination with other viroids.

Evaluate the environmental impact of the pest on California using the criteria below.

Environmental Impact: E

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.

Environmental Impact Score: 2

– 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.

Consequences of Introduction to California for Citrus Viroid V

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 CVd-V to California = 12.

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)Currently, Citrus viroid V has only been detected in a nursery in Tulare County.

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 = 11.                                                                             

Uncertainty: 

The effect of CVd-V in commercial citrus rootstock-scion combinations, alone and in combination with other viroids, is yet unknown.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Citrus viroid V is B.


References:

Bani Hashemian, SM, Taheri, H, Duran-Vila, N, and Serr, P.  2010.  First report of Citrus viroid V in Moro blood sweet orange in Iran.  Plant Disease 94: 129.

Cao, M. J., Liu, Y. Q., Wang, X. F., Yang, F. Y., and Zhou, C. Y.  2010.  First report of Citrus bark cracking viroid and Citrus viroid V infecting Citrus in China.  Plant Disease 94: 922. https://doi.org/10.1094/PDIS-94-7-0922C

Dang, T., Tan, S. H., Bodaghi, S., Greer, G., Lavagi, I., Osman, F., Ramirez, B., Kress, J., Goodson, T., Weber, K., Zhang, Y. P., Vidalakis, G.  First report of Citrus Viroid V naturally infecting grapefruit and calamondin trees in California.  Plant Disease, Posted online on August 10, 2018. https://doi.org/10.1094/PDIS-01-18-0100-PDN

Hamdi, I., Elleuch, A., Bessaies, N., Grubb, C. D., and Fakhfakh, H. 2015. First report of Citrus viroid V in North Africa. Journal of General Plant Pathology 81, 87

Ito, T., and Ohta, S.  2010.  First report of Citrus viroid V in Japan.  Journal of General Plant Pathology 76: 348-350.

Önelge, N., and Yurtmen, M. 2012. First report of Citrus viroid V in Turkey. Journal of Plant Patholology 94 (Suppl. 4), 88.

Parakh, D. B., Zhu, S., and Sano, T.  2017.  Geographical distribution of viroids in South, Southeast, and East Asia.  In: Apscaviroids Infecting Citrus Trees by Tessitori, M, Viroids and Satellites, Edited by Hadidi, A, Flores, R, Randles, JW, and Palukaitis, P, Academic Press Ltd-Elsevier Science Ltd, Pages 243-249

Serra, P., Barbosa, C. J, Daros, J. A., Flores, R., Duran-Vila, N. 2008a. Citrus viroid V: molecular characterization and synergistic interactions with other members of the genus Apscaviroid. Virology 370, 102112.

Serra, P., Eiras, M., Bani-Hashemian, S. M., Murcia, N., Kitajima, E.W., Daro`s, J. A., et al., 2008b. Citrus viroid V: occurrence, host range, diagnosis, and identification of new variants. Phytopathology 98, 11991204.


Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-738-6693, plant.health[@]cdfa.ca.gov.


Comment Period:* CLOSED

9/13/18 – 10/28/18


*NOTE:

You must be registered and logged in to post a comment.  If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.


Comment Format:

♦  Comments should refer to the appropriate California Pest Rating Proposal Form subsection(s) being commented on, as shown below.

Example Comment:
Consequences of Introduction:  1. Climate/Host Interaction: [Your comment that relates to “Climate/Host Interaction” here.]

♦  Posted comments will not be able to be viewed immediately.

♦  Comments may not be posted if they:

Contain inappropriate language which is not germane to the pest rating proposal;

Contains defamatory, false, inaccurate, abusive, obscene, pornographic, sexually oriented, threatening, racially offensive, discriminatory or illegal material;

Violates agency regulations prohibiting sexual harassment or other forms of discrimination;

Violates agency regulations prohibiting workplace violence, including threats.

♦  Comments may be edited prior to posting to ensure they are entirely germane.

♦  Posted comments shall be those which have been approved in content and posted to the website to be viewed, not just submitted.


Pest Rating: B


Posted by ls