Tag Archives: plant pathogen

Septocyta ruborum (Lib.) Petrak. 1967

California Pest Rating Proposal for

Septocyta ruborum (Lib.) Petrak. 1967
(syn. Rhabdospora ramealis (Roberge ex Desm.) Sacc.)
Current Pest Rating: Q
Proposed Pest Rating: C

Comment Period: 7/24/2019 through 9/7/2019


Responsible Party:

Heather J. Scheck, CDFA Primary Plant Pathologist/Nematologist. 204 West Oak Ave, Lompoc, CA
93463. 805-736-8050. 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.


Posted by ls

Marasmiellus Palmivorus

California Pest Rating for
Marasmiellus palmivorus (Sharples) Desjardin comb. prov.
Pest Rating: C

 


PEST RATING PROFILE

Initiating Event:   

None.  The risk of infestation of M. palmivorus in California evaluated and a permanent rating is herein proposed.

History & Status:

Background:   Marasmiellus palmivorus is a Basidiomycete fungus in the order Agaricales.  The species was described by Sharples in 1936, but, in the 1920s, was reported to have caused significant losses to oil palm and coconut in Malaysia 1920 (Pong et al., 2012).  In 1980, specimens of the fungus from coconut and oil palm were initially identified as Marasmiellus semiustus, a species that is generally regarded synonymous with M. palmivorus (CABI, 2018).  There has been confusion over the taxonomy of M. palmivorus and the species was previously attributed to the genus Marasmius (palmivorus).  However, Hemmes and Desjardin (2002) and Wilson and Desjardin (2005), in their taxonomic revision of the genus, regarded the genus Marasmius as a synonym of Marasmiellus until further DNA phylogenetic analysis is done to support its accurate identification (Pong et al., 2012).

Marasmiellus palmivorus can be saprophytic on a range of dead and dying plant material, or parasitic on tropical plants.  The species is reported to cause bunch rot disease on oil palm fruit, seeds, and seedlings in Malaysia (Almaliky et al., 2012; Pong et al., 2012), and is associated with leaf infection and bud rot of coconut, also causing embryo and shoot rot in germinating nuts and post-emergence damping off disease in Malaysia (Amaliky et al., 2013; CABI, 2018).  Synonymous species of M. palmivorus have also been recorded on pineapple causing trunk and root rot, and root rot of maize and sugarcane (CABI, 2018). In Hawaii, M. palmivorus was listed as a wood-rotting basidiomycete fungus of native and exotic plant species (Gilbertson et al., 2002).

In California, during March 2017, Marasmiellus palmivorus was detected on ginger flower stems from a shipment of ginger cut flowers that originated in Hawaii and was intercepted in Humboldt County by Humboldt County Agricultural officials. The pathogen was identified at the CDFA Plant Pathology Lab and was given a Q rating, which resulted in the destruction of the shipment.  The pathogen is not known to be established in California.

Disease Development: The fungus is normally saprophytic on decaying and dead materials.  It spreads to a new food source by growth of its hyphal strands or rhizomorphs and requires plenty of moisture for growth and development.  Not much is known of the biology of the fungus.  It is presumed that the fungus becomes parasitic once it has attained a certain inoculum level as infection by a small amount of spores or mycelium is unlikely (Turner, 1981 in CABI, 2018).

Dispersal and spread: Infected plants including flowers, fruits, leaves, roots, stems, true seeds, wood, contaminated coconut seed-nuts, plant decaying and dead materials, windblown rain, water-splash, air-currents (CABI, 2018).

Hosts: Ananas comosus (pineapple), Alpini purpurata (red ginger), Cocos nucifera (coconut), Elaeis guineensis (African oil palm), Etlingera elatior (torch ginger), Hevea brasiliensis (rubber), Musa x paradisiaca (plantain), Zingiber officinale (ginger) (Almaliky et al., 2012, 2013; CABI, 2017; Farr & Rossman, 2017; Gilbertson et al., 2002).

Symptoms:  Marasmiellus palmivorus causes bunch rot disease of oil palm in Malaysia.  In pathogenicity tests conducted by Almaliky et al. (2012), symptoms in fruit included a wet, discolored soft rot that extended upward to the tip of the fruit; infected seeds showed pre-emergence damping off consisting of seed decay, reddish-brown discoloration of shoots and radicles, failure to germinate, and post-emergence damping off; infected seedling initially showed chlorosis that turn brown to black rot lesions on the base of lower leaves, and roots were usually soft, rotten, water-soaked and dark brown or black in color with white mycelia covering the roots and crowns partially. Seedlings reared in a greenhouse developed root and crown rot and leaf blight.  Initial necrosis at the bases of leaves subsequently caused extensive discoloration, softening, rapid drying and wilting of leaves.  Rotting of seedlings initiated near the soil line and moved downwards and upwards resulting in parts of stems and base of leaves turning brown to black in color.  .  Dense white mycelia were formed on the lower stem of base of seedlings.  Basidiocarps (mushroom-like fruiting bodies) were formed at the base of seedlings near the crown.  The fungus also caused post-emergence damping off on coconut seedlings in Malaysia (Almaliky et al., 2013).  The researchers also showed that isolates from coconut were pathogenic to oil palm.

Damage Potential: In California, certain hosts, such as, ginger and plantain that are grown as ornamental plants by nurseries, small businesses, hobbyists, and private residents may be affected by the fungus if it were able to establish within high moisture environments.    

Worldwide Distribution:  Africa: Congo Democratic Republic, Nigeria; Asia: Brunei Darussalam, India (Andaman and Nicobar Islands), Indonesia, Malaysia; Central America and Caribbean: Trinidad and Tobago, North America: USA (Hawaii), South America: Colombia; Oceania: Fiji, Papua New Guinea (CABI, 2017; Farr & Rossman, 2017; Gilbertson et al., 2002).

Official Control: Marasmiellus palmivorus is on the ‘Harmful Organism’ lists for Guatemala, Nicaragua, and Peru (USDA-PCIT, 2017).

California Distribution: Marasmiellus palmivorus has not been reported from California.

California Interceptions: To date, Marasmiellus palmivorus has been detected once in a single shipment of ginger cuttings that were shipped from Hawaii and intercepted in Humboldt County.

The risk Marasmiellus palmivorus would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Marasmiellus palmivorus requires high amounts of moisture to grow and develop. It may be able to establish only in very limited areas of the State, if at all.

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

Score: 1

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 host range is limited to some tropical plants that include, pineapple, African oil palm, coconut, plantain, rubber, and ginger.  It is also a saprophytic and feeds on dead and decaying material.  Presently, its pathogenicity has only been reported on coconut and Oil palm.

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: Infected plants including flowers, fruits, leaves, roots, stems, true seeds, wood, contaminated coconut seed-nuts, plant decaying and dead materials, windblown rain, water-splash, air-currents.

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: Potential losses to oil palm in Malaysia have only been reported.  Economic impact due to the fungus are largely not known.  Most hosts of the fungus are not commercially grown in California. Other hosts, such as, ginger and plantain that are grown as ornamental plants by nurseries may be affected by the fungus if it were able to establish within high moisture environments.

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

Economic Impact: B

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: 1

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:  Under high moisture environments, Marasmiellus palmivorus may impact ornamental plantings of host plants in home/urban gardens.

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 Marasmiellus palmivorus: Low (8)

Add up the total score and include it here.

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 ‘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 = 8

Uncertainty:

None.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Marasmiellus palmivorus is C.


References:

Almaliky, B. S. A., M. A. Zainal Abidin, J. Kadir, and M. Y. Wong.  2012.  Pathogenicity of Marasmiellus palmivorus (Sharples) Desjardin comb. prov. on oil palm Elaeis guineensis.  Wulfenia 19: 1-17.

Almaliky, B. S. A., J. Kadir, M. Y. Wong, and M. A. Zainal Abidin.  2013.  First report of Marasmiellus palmivorus causing post-emergence damping off on coconut seedlings in Malaysia. Plant Disease 97: 143.

CABI, 2017.    Marasmius palmivorus (oil palm bunch rot) full datasheet.  Crop Protection Compendium.  http://www.cabi.org/cpc/datasheet/34926

Farr, D. F., and A. Y. Rossman.  2017.  Fungal Databases, U. S. National Fungus Collections, ARS, USDA. Retrieved April 27, 2017, from http://nt.ars-grin.gov/fungaldatabases/

Gilbertson, R. L., D. M. Bigelow, D. E. Hemmes, and D. E. Desjardin.  2002.  Annotated check list of wood-rotting Basidiomycetes of Hawai’i.  Mycotaxon 82: 215-239

Pong, V. M., M. A. Zainal Abidin, B. S. A. Almaliky, J. Kadir, and M. Y. Wong.  2012.  Isolation, fruiting and pathogenicity of Marasmiellus palmivorus (Sharples) Desjardin (comb.prov.) in oil palm plantations in West Malaysia.  Pertanika Tropical Agricultural Science 35 (S): 38-48.

USDA PCIT.  2017.  USDA Phytosanitary Certificate Issuance & Tracking System. April 26, 2017, 5:04:18 pm CDT.  https://pcit.aphis.usda.gov/PExD/faces/ReportHarmOrgs.jsp.


Responsible Party:

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

1/26/18 – 3/12/18


*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;

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♦  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

Cherry Virus A

California Pest Rating for
Cherry virus A
Pest Rating: C

 


PEST RATING PROFILE

Initiating Event:

A recent request for a rating of Cherry virus A (CVA) was made by Joshua Kress, Nursery, Seed, and Cotton Program, CDFA.  The current status and risk of Cherry virus A to California is assessed here and a permanent rating is proposed.

History & Status:

Background:   Cherry virus A was first discovered in Germany during a study to extract little cherry disease-related dsRNA from sweet cherry plant tissue to enable cDNA cloning.  In that study, a second dsRNA representing a new species of the genus Capillovirus and named Cherry virus A, was discovered in addition to little cherry disease (Jelkmann, 1995).  CVA has usually been found in cherry plants infected with other viruses and in symptomless trees.  It was also determined in the study that CVA cannot be directly associated with any specific disease in its known host, Prunus spp. (Sabanadzovic et al., 2005). CVA has been reported from a few countries and from California, USA (see ‘Worldwide Distribution’). The symptomless nature of CVA-infected plants suggests that the virus is more widely distributed than reported (CABI, 2018).

Hosts:  Prunus spp.: P. armeniaca (apricot), P. avium (sweet cherry), P. avium x P. pseudocerasus cv. ‘Colt’ (colt cherry), P. cerasus (sour cherry), P. domestica (plum), P. domestica subsp. insititia (Mirabelle plum), P. mume (Japanese apricot tree), P persica (peach), P. salicina (Japanese plum), P. serrulata (Japanese flowering cherry), P. serrulata cv. ‘Kwanzan’ (Kwanzan cherry) (CABI, 2017; Jelkmann, 1995; Sabanadzovic et al., 2005; Svanella-Dumas et al., 2005).

 Symptoms:  Cherry virus A has only been found in symptomless trees and therefore, has yet to be associated with any specific disease symptoms in its reported hosts.  The virus has also been found in host plants infected by other viruses, such as, sweet cherry infected by little cherry virus or Mirabelle plum infected by Prune dwarf virus (CABI, 2017).

Dispersal and spread: No vector is known to transmit the virus, however, it is graft-transmissible (Svanella-Dumas et al., 2005).  The capability of CVA being seedborne has been suggested; In Japan, CVA was detected in sweet cherry root stock that had never been grafted with sweet cherry trees (Isogai et al., 2004).  Also, ‘Mazzard’ cherry rootstock grown from seed tested positive, by PCR, for CVA, thereby, suggesting the likelihood of seed transmission (Personal communication: Dr. S. J. Harper, Clean Plant Center Northwest, Washington State University; Dr. M. Al Rwahnih, University of California, Davis).

Damage Potential: There are no reports of fruit damage or yield loss of infected trees caused by Cherry virus A (Komoroska & Cieślińska, 2004). This virus is typically found in Prunus trees that are also infected with other viruses and may then have a synergistic effect in enhancing the severity of symptoms (James & Jelkmann, 1998).

Worldwide Distribution: Asia: China, Japan; North America: Canada, USA (California); Europe: Czech Republic, France, Germany, Italy, Poland, Serbia, United Kingdom (CABI, 2017; Jelkmann, 1995, 1997; Komoroska & Cieślińska, 2004.

Official Control:  Cherry virus A is the on the ‘Harmful Organism’ list for Georgia, Japan, and Taiwan (USDA PCIT, 2018).  Since 2009, CVA has been labeled a ‘quarantine pest’ in Israel (EPPO, 2018).  Presently, in California it has a temporary ‘Z’- rating (indicating that it is an unrated organism of known economic and/or environmental detriment but generally distributed in the state).

California Distribution:  El Dorado, San Joaquin, and Yolo Counties (Sabanadzovic et al., 2005; French, 1989). The symptomless nature of CVA-infected plants suggests that the virus may be more widely distributed than currently reported (CABI, 2018).

California Interceptions: None reported.

The risk Cherry virus A would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Cherry virus A has already been detected in sweet cherry orchards in northern California, including the main cherry production regions of the state. CVA has usually been found in cherry plants infected with other viruses, as well as, in symptomless trees, thereby, suggesting that its distribution in California may be wider than what is currently known.  The virus is likely to establish wherever its host plants are able to grow.  Therefore a ‘High” rating is given to this category.

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: Presently, the known host range of CVA is limited to Prunus spp.

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: CVA is graft-transmitted and may be spread through asymptomatic Prunus stock or those infected with other cherry viruses. No vector is known to transmit the virus.

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: There are no reports of fruit damage or yield loss caused by the virus.  It is suggested that CVA may enhance symptom expression caused by other cherry viruses co-infecting a host plant.

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

Economic Impact: None

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: 1

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: There are no reports of damage to environmental plants and localities caused specifically by CVA.

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

Environmental Impact: None

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: 1

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 Cherry virus A: 8

Add up the total score and include it here.  

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 ‘Low ’.  Presently, Cherry virus A has a localized distribution within San Joaquin, Yolo, and El Dorado Counties.

Score: (-1)

-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 = 7

Uncertainty:  

Specific symptoms and damage to infected host plants is not known.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Cherry virus A is C.


References:

CABI.  2018.  Cherry virus A full datasheet.  CABI Crop Protection Compendium.  https://www.cabi.org/cpc/datasheet/44379

EPPO.  2018.  Cherry virus A (CVA000).  PQR database.  Paris, France: European and Mediterranean Plant Protection Organization.  https://gd.eppo.int/

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).

Isogai, M., J. Aoyagi, M. Nakagawa, Y. Kubodera, K. Satoh, T. Katoh, M. Inamori, K.  Yamashita, and N. Yoshikawa.  2004.  Molecular detection of five cherry viruses from sweet cherry trees in Japan. Journal of General Plant Pathology, 70:288-291.

James, D., and W. Jelkmann.  1998.  Detection of cherry virus A in Canada and Germany. Acta Horticulturae, No. 472:299-303.

Jelkmann, W.  1995.  Cherry virus A: cDNA cloning of dsRNA, nucleotide sequence analysis and serology reveal a new plant capillovirus in sweet cherry. Journal of General Virology, 76:2015-2024.

Komorowska, B., and M. Cieslinska.  2004.  First report of Cherry virus A and Little cherry virus 1 in Poland. Plant Disease, 88:909.

Sabanadzovic, S., N. Abou Ghanem-Sabanadzovic, A. Rowhani, J. A. Grant, and J. K. Uyemoto.  2005.  Detection of Cherry Virus A, Cherry Necrotic Rusty Mottle Virus and Little Cherry Virus 1 in California Orchards. Journal of Plant Pathology, 87:173-177.

Svanella-Dumas, L., A. Marais, J. Lamorte, and T. Candresse.  2005.  First report on the natural occurrence of Cherry virus A in Mirabelle plum (Prunus domestica var. insititia). Plant Disease, 89:433.

USDA PCIT.  2018.  USDA Phytosanitary Certificate Issuance & Tracking System. Retrieved January 17, 2018. 1:15:31 pm CST.  https://pcit.aphis.usda.gov/PExD/faces/ReportHarmOrgs.jsp.


Responsible Party:

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

1/26/18 – 3/12/18


*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

Cucumber Green Mottle Mosaic Virus

 California Pest Rating for
Cucumber Green Mottle Mosaic Virus
Pest Rating: A

 


PEST RATING PROFILE
Initiating Event:  

On December 15, 2017, Cucumber green mottle mosaic virus (CGMMV) was detected in a watermelon seed sample submitted by the USDA to the CDFA Plant Pathology Lab, and collected from a seed company’s storage facility outside of California. The seed crop was produced in California.  The seed company had originally identified the pathogen and reported its findings to the USDA.  An official identification of CGMMV was made by Tongyan Tian, CDFA plant pathologist.  Subsequent investigations are currently underway.  CGMMV is a Federal Actionable Pathogen regulated by USDA.  Currently, both agencies consider CGMMV a quarantine pathogen that is temporary, transitional and under eradication, and therefore, not established within California or anywhere else in the United States.  The current status and rating for the pathogen is reassessed here.

History & Status:

Background:  Cucumber green mottle mosaic virus is an economically important, seed transmitted pathogen known to cause significant losses in cucurbitaceous crop production in many cucurbit growing regions globally. All cucurbits are susceptible to the virus, although some are more tolerant than others (Falk et al., 2017).

Cucumber green mottle mosaic virus was originally described from the United Kingdom in 1935.  Since then, it has spread to several other regions mostly within Europe, Asia and the Middle East, most likely due to its seed-borne nature and trade of cucurbit seed from CGMMV-infected regions to non-infected regions globally.  CGMMV has also been recorded in Nigeria, Africa (Falk et al., 2017) and a possible detection of CGMMV in melon was reported from Brazil, South America, however, this record has not been confirmed (Choudhury & Lin, 1982).

The pathogen was first reported from North America in 2013, from California, USA and from Alberta, Canada.  A detailed account of its first and subsequent detections in California is given below (see ‘Detections in California’).  The first report of CGMMV in Alberta, Canada, was of infected mini-cucumber crops grown in greenhouse. The disease had been previously found in greenhouses in Ontario, British Columbia (Ling et al., 2014; Zhang et al., 2014).  In 2014, CGMMV was reported for the first time from Australia on detection of the pathogen in commercial farm-grown watermelon plants in the Northern Territory, and in 2015 and 2016 was subsequently confirmed in Queensland and Western Australia respectively (QDAF, 2017).

Biology: The virus is a species in the genus Tobamovirus (to which also belongs the well-known Tobacco mosaic virus).  The species has a positive single-stranded RNA genome and coat protein, comprised in rod-shaped particles (virions).  Several strains or isolates of CGMMV have been reported from different countries.  All strains of the virus are extremely stable in plant sap.  Infectivity is lost at 86-100 C (Type strain at 90 C) depending on viral strain. In California, although the precise source or origin of CGMMV has not been determined, research showed that the 2013 detection in Yolo County and the 2014 detections in commercial seedless watermelon production fields represented two separate introductions, as genetic analysis of those two isolates were distinct from each other (Falk et al., 2017).  The California 2013 CGMMV isolate showed 95% DNA sequence identity to those isolates reported from Russia, Spain, and Israel (Tian et al., 2014), whereas, the California 2014 CGMMV isolates and the Canada CGMMV isolates showed very similar DNA sequence identity, thereby, suggesting that they may have originated from the same source (Falk et al., 2017). The Canada CGMMV isolate showed strong sequence identity to the CGMMV Asian isolates thereby, suggesting their likely Asian origin (Zhang et al., 2014; Ling et al., 2015).

Detections in California:  In the USA, cucumber green mottle mosaic virus has only been detected in California, from 2013 to 2017.  An up-to-date account is given of those detections and subsequent regulatory actions.

 In 2013, the Cucumber green mottle mosaic virus (CGMMV) was detected in a melon field (Cucumis melo var. Saski) in Yolo County during a phytosanitary inspection for seed production.  The pathogen was identified by Tongyan Tian, CDFA Plant Pathologist, and confirmed by the USDA APHIS.  This detection marked the first record of the pathogen in California and in the United States (Tian et al., 2014; USDA APHIS, 2013; CDFA-PEA, 2013).   Three contiguous fields planted to cucumber (2 fields) and watermelon (1 field), were also determined as positive for CGMMV.  Subsequent trace back investigations revealed that the source seed for the Yolo County melon site was grown in a seed lot in Sutter County in 2012 and later, was found positive for CGMMV. The 2013 trace back also revealed that in 2012, two sites in Sutter County produced a total of 6 melon, watermelon and cucumber seed lots, of which site 1 was positive for CGMMV in all three cucurbit hosts while site 2 was negative.  Those two sites are currently planted to non-hosts of CGMMV, and in 2013, volunteer cucumber plants in site 1 tested negative for CGMMV.   Two foreign sources of melon and cucumber seed lots planted in the two Sutter County sites were identified as Chile and Romania: no (melon) seed remained for testing from the Chilean source and the Romanian cucumber seed tested positive for CGMMV.     As for the 2013 Yolo County CGMMV positive site, County and State approved abatement measures were implemented.   Eventually, wheat, a non-host, was grown at the site and in 2014, volunteer melon plants tested positive, while volunteer watermelon plants were negative.  Monitoring of volunteer plants was implemented and those in the field are treated with herbicide and biodegraded.  Furthermore, in 2013, approximately 120 trace forward seed lots were evaluated for risk of potential infection with CGMMV.  Pathways identified as possible risk links for potential CGMMV infection were source seed, shared irrigation, proximity to a positive detection, mechanical transmission (equipment and workers), and seed processing operational steps.  Trace-forward investigations revealed that 2012 Sutter County melon seeds infested with CGMMV had been shipped to Romania and Africa.  Thirty-four trace forward and trace back seed lots were sampled and tested for CGMMV of which 3 were positive for the pathogen.  In 2014, additional cucumber seed lots belonging to the 2013 trace forward lots in Sutter County tested negative for CGMMV.

In 2014, during August and September, CGMMV was detected in watermelon plant samples collected from seven watermelon production fields in Fresno, Kern, and San Joaquin Counties.  The CDFA did a trace-back to the seed lots that were linked to the CGMMV-positive fields, but found those seed lots to be negative for the pathogen.  Subsequently, the seeds were traced back to the transplant nursery and CDFA theorized that the seed lots were cross contaminated at the transplant nursery. The CGMMV-positive watermelon fields were placed on a regulatory hold (quarantine) and an abatement order was issued to growers requiring; non-host planting, equipment sanitation, other bio-security measures, and monitoring for the virus for a period of two years (Schnabel, 2017).

In 2016, during February, a seed company reported its detection of CGMMV in imported melon seed.  Consequently, the seed company voluntarily destroyed the seed lots by deep burial at a local landfill.  Later, in June 2016, a seed company reported its detection of CGMMV in seed produced in Sutter County The field had already been disked and planted with rice at the time of the report.  Nevertheless, cucurbit volunteers from the field and adjacent fields were sampled by the County and tested negative for the virus by CDFA.  The field continues to be monitored and planted to a non-host crop.  The CGMMV-positive seeds which were stored at a facility outside of California, were seized by the USDA and destroyed by incineration.  Then, in October 2016, a seed company reported its detection of CGMMV in watermelon seed produced in Yolo County. At the time of testing and reporting, the section of the field that produced the positive detection, was already fallow.  The seed company has maintained the field as fallow and will continue to notify CDFA of any volunteers, which if present, will be sampled in spring of 2018 by CDFA.  Also, the seed was voluntarily destroyed and appropriate sanitation and biosecurity measures have been implemented by the seed company (Schnabel, 2017).

In 2017, during March, a seed company reported its detection of CGMMV in watermelon seeds produced in Colusa County.  The field had already been disked and was fallow at the time of the report.  However, cucurbit volunteers and broadleaf weeds, present at the field site, were sampled and tested negative for the pathogen.  The grower continues to use appropriate best management practices including, sanitation and biosecurity measures.  The CGMMV-positive seeds which were stored outside of California, were seized by the USDA and destroyed by incineration.  In October, a seed company reported its detection of CGMMV in a watermelon seed lot produced in Sutter County.  The production field was fallow at the time of the report and any plant material recovered from the field tested negative for CGMMV.  The field will be monitored next season and the grower will be implementing sanitary and biosecurity measures.  The seed lot was seized and destroyed.  Also, at that time, CGMMV was detected in Opo squash (Lagenaria siceraria) plants grown in a small farm in Fresno County.  Fresno County issued a regulatory hold on the field as well as an abatement notice. No host crops will be grown at the site for the next two years.  The associated seeds were collected for destruction by the County.  In November, two different seed companies provided a total of four separate reports of the detection of CGMMV in watermelon seeds.  The positive seed lots were produced in Sutter, Colusa, and Glenn Counties. Trace-investigations are currently underway for each detection.  The fields were sampled and have tested negative for CGMMV. The fields will be monitored and sanitation and biosecurity measures will be implemented.  Currently, the seed lots are on hold pending voluntary destruction (Schnabel, 2017).

Plant infection:  CGMMV gains entrance into a plant through wounds, infects a few cells, moves from cell to cell (through plasmodesmata) colonizing the plant tissues and reaches the phloem where it travels systemically and infects the entire plant.

Hosts:  All cucurbit species are susceptible to CGMMV.  Main hosts include, Citrullus lanatus (watermelon), Cucumis melo (melon), C. sativus (cucumber), C. anguria (burr gherkin), Gladiolus hybrids (sword lily), Lagenaria siceraria (bottle gourd), Momordica charantia (bitter gourd), Cucurbita moschata (butternut squash), C. pepo (zucchini and button squash), C. maxima (squash), Luffa acutangula (angled luffa), L. cylindrical (smooth luffa), Benincasa hispida (winter melon), Cucumis metuliferus (horned melon), C. myriocarpus (prickly paddy melon), Citrullus colocynthis (bitter paddy melon), Trichosanthes cucumerina (snake gourd) (CABI, 2017; Falk et al., 2017). [Cech (1980) reported that the CGMMV caused apricot bare twig and unfruitfulness disease syndrome in Prunus armeniaca (apricot) only when co-infected with strawberry latent ringspot virus.]

Several experimental hosts have been tested and susceptible hosts are in three families namely, Chenopodiaceae, Cucurbitaceae and Solanaceae.  CGMMV-indicator plant species include Chenopodium album ssp. amaranticolor, Datura stramonium, and Nicotiana benthamiana.  Weeds species may be potential alternate hosts, however, currently, the role of alternate host plants in CGMMV epidemiology is not known (Falk, 2017).  Potential CGMMV weed hosts include: Amaranthus retroflexus (red root or American pigweed), Chenopodium album (lambsquarter), Heliotropium europium (Helitrope), Portulaca oleracea (pigweed), Solanum nigrum (nightshade) and Cucumis myriocarpus (paddy melon) (Falk et al., 2017).

Symptoms: Plant symptoms may vary mainly depending on virus strain, host plant species/cultivar, plant part, time of plant growth, and environmental conditions.  In general, plant symptoms may include leaf mosaic, mottling, distortion, vein clearing, and stunted growth; infected fruit can be mottled, discolored, distorted, internally discolored and deteriorated.  Root systems may be reduced.

Some Asian cultivars of cucumber only show yield losses without showing leaf symptoms.  In cucumber, the type strain causes leaf mottling, blistering and distortion, and stunted growth.  Symptoms appear 7-14 days after infection.  Usually no symptoms are produced on fruit, however, certain strains cause fruit mottling and distortion.  On the other hand, the watermelon strain can cause slight leaf mottling and dwarfing in watermelons and necrotic lesions develop on the peduncle.  Virus infection at fruit set or soon after can result in serious internal discoloration and decomposition in the fruit.

No symptoms are produced in CGMMV infected squirting cucumber (Ecballium elaterium) (CABI, 2017) – a plant native to Europe, North Africa and parts of Asia, grown sometimes for its ornamental and medicinal value. Not present in California (acc. to USDA Natural Resources Conservation Services). It is thought that infected weed species may be asymptomatic – however, this has yet to be proven.

Seed set or appearance is not affected by CGMMV and therefore, infected seed are indistinguishable from non-infected ones (Reingold et al., 2015, 2016).

Plant symptoms due to CGMMV are similar to those of other viruses in cucurbitaceous species.  Therefore, it is difficult to definitively identify the virus solely by the symptoms its causes in host plants.  For a definitive identification, serological, molecular and/or electron microscopy tests are needed.

Damage Potential: In commercial field or greenhouse environments, losses up to 100% can occur, although 40-80% losses are common (Falk et al., 2017).  Yield losses of approximately 15% in Cucurbitaceous vegetable crops are reported (Shang et al., 2011).  In Japan, considerable economic losses in watermelon have occurred.  Severe symptoms in fruit including, fruit pulp deterioration, low sugar accumulation and flavor, and distortion make fruit unmarketable and non-consumable (CABI, 2017).    In India 75%, 80% and 100% losses are reported in watermelon, muskmelon, and bottle gourd respectively. 5-16 % losses occur in cucumber yields and fruit quality.  Increased costs in production of clean planting sites and stock can be expected.  Furthermore, since the pathogen is seedborne in cucurbits, it could negatively impact export of cucurbit seeds.

Transmission: CGMMV is contagious and is transmitted by mechanical contact with contaminated sources.  It can spread through foliage contact, when plants are handled during cultivation or through grafting, when infected rootstocks are used in watermelon or cucumber cultivation.  It can survive on plant pruning equipment, clothing, hands, and machinery and be spread by agricultural practices and mechanical means (Reingold et al., 2016; USDA, 2017).  It can be transmitted from infected plant debris in soil to uninfected plants via roots.  The virus is very stable in the sap of infected plants and therefore, is able to remain active in plant debris in soil long after the death of host plant cells.  Also, it is spread through untreated irrigation water and in recirculated greenhouse water. All of these can serve as sources of inoculum.  The virus is also transmitted by pollen and seed of CGMMV-infected cucurbit plants (Liu et al., 2014) both on and within the seed coat (Hollings, et al., 1975). However, research has shown that the rate of CGMMV infection of seedlings developing from cucurbit seeds containing the pathogen, is typically 1-5% or less, under greenhouse conditions, thereby, indicating that cucurbit seeds may contain infectious CGMMV, but the virus is not always transmitted to developing seedlings (Falk, 2017).  On the other hand, high seed-transmission rates of 76% from CGMMV-infected cucumber plants, have been reported (Liu et al., 2014).

Movement of infected seed appears to be the primary means for long-distance spread, whereas, the virus is spread locally through contact, infested crop residues, and irrigation water.

CGMMV is not spread from plant to plant by specific insect or nematode vectors.   Experimentally, the cucumber leaf beetle Raphidopalpa fevicollis was shown to be a probable vector of CGMMV to test plants, whereas, the green peach aphid (Myzus persicae), the cotton aphid (Aphis gossypii) or cucumber leaf beetles (Aulacophora femoralis) did not transmit the virus (Rao & Varma, 1984).

Experimentally, CGMMV has been transmitted by dodder species (Hollings et al., 1975).

CGMMV was detected in cow dung manure and studies have demonstrated the ability of the virus to pass through the alimentary system of rodents without losing biological activity.

Worldwide Distribution: Asia: China, India, Iran, Israel, Japan, Republic of Korea, Lebanon, Myanmar, Pakistan, Saudi Arabia, Sri Lanka, Syria, Taiwan, Thailand, Turkey;

Africa: Nigeria; North America: Canada, USA (California: temporary, transitional, and under eradication); Europe: Austria, Bulgaria, Czechoslovakia (former), Denmark, Finland, Germany, Greece, Hungary, Latvia, Lithuania, Moldova, Netherlands, Norway, Romania, Russian Federation, Spain, Sweden, Ukraine, United Kingdom and Yugoslavia (former); Oceania: Australia (CABI, 2017; Ling & Li, 2013; Tesoriero et al., 2016).

An unconfirmed record of CGMMV is from Brazil, South America (CABI, 2017)

Official Control: Currently, the following countries include CGMMV on their ‘Harmful Organism’ lists: Chiles, China, Colombia, Ecuador, Georgia, Guatemala, Honduras, Indonesia, Japan, New Zealand, Nicaragua, Panama, Paraguay, Peru, Syrian Arab Republic, Thailand, and Timor-Leste (USDA PCIT, 2017).

In the USA, CGMMV is a Federal Actionable Pathogen of quarantine concern and is considered temporary, transitional and under eradication.  Currently, CGMMV is an A-rated, quarantine actionable pathogen in California.

California Distribution:  CGMMV is not established in California.

California InterceptionsThere are no state reports of CGMMV detections in plant materials intercepted within or at points of entry in California.

The risk Cucumber green mottle mosaic virus would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Since its first detection in 2013, there have been repeated incidences of field detections that directly indicate that CGMMV is likely to establish a widespread distribution in all cucurbit-growing regions within 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: CGMMV has a moderate range of cucurbitaceous host plants which are commonly grown mostly in the warmest areas of California, such as the San Joaquin Valley, the Sacramento, Valley and the low desert valleys.

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: CGMMV is capable of high reproduction and widespread dispersal mainly as it is highly contagious and is easily transmitted through mechanical, plant and human contact, irrigation water and water in contact with infected crop debris.  It can be widely dispersed over long distance through infected seed, and is highly stable and remains active in infected plant debris in soil.

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: CGMMV is capable of significantly lowering crop yield and value thereby, increasing crop production costs.  It can result in the loss of markets through the imposition of quarantines by domestic and international trade partners, change in cultural practices, including adoption of a non-host crop period in infested and treated fields for 3-5 or more years, and alteration of delivery and distribution of irrigation water to and from infested fields.  Furthermore, significant losses in seed and transplant production can result due to a CGMMV infestation.

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

Economic Impact: A, B, C, 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: Detection and establishment of CGMMV would significantly impact existing cultural practices, as well as those followed for home/urban gardening and ornamental production.  Subsequently, it could result in the implementation of additional and costly official and home/urban 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 Cucumber green mottle 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 to California = 14 (High)

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 ‘Not Established (0):  Similar and subsequent to its original detection in 2013, all incidences of Cucumber green mottle mosaic virus detections (detailed above in ‘Detections in California’) have resulted in eradicative actions.  The viral pathogen is, therefore, not considered as established in California and continues to be ‘transient, temporary and under eradication’.

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 = 14.

Uncertainty:

Currently, the precise origin or source of CGMMV introduction into the USA is not known for certain.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Cucumber green mottle mosaic virus continues as A.


References:

Abatement Notice.  2013.  (  ) Seed Company, Cucumber green mottle mosaic virus (CGMMV) Acidovorax avenae subsp. citrulli (BFB) abatement notice.  County of Yolo, John Young Agricultural Commissioner.

CABI   2017.  Cucumber green mottle mosaic virus (white break mosaic) datasheet.  Crop Protection Compendium.  http://www.cabi.org/cpc/datasheet/16951

Cech M., M. Filigarova, J. Pozdena, and H. Branisova.  1980. Strawberry latent ringspot and cucumber green mottle mosaic viruses in apricots with the bare twig and unfruitfulness disease syndrome. Acta Phytopathologica Academiae Scientiarum Hungaricp, 15:391-396

CDFA-PEA.  2013.  Cucumber green mottle mosaic virus and Bacterial fruit blotch detection in California.  Pest Exclusion Advisory no. 29-2013.  California Department of Food and Agriculture, November 27, 2013.

Choudhury, M. M., and M. T. Lin.  1982.  ‘Ocorrência de viroses em plantas de melão e abobrinha na região do sub-médio São Francisco’, EMBRAPA Pesquisa am Andamento, vol. 14, no. 4, pp. 1–2.

Falk, B. W., T. L. Pitman, B. Aegerter, and K-S. Ling.  2017. Recovery Plan for Cucumber green mottle mosaic virus.  Plant Diseases That Threaten U. S. Agriculture Identified and Prepared for Under the National Plant Disease Recovery System.  USDA ARS. https://www.ars.usda.gov/office-of-pest-management-policy/npdrs/ Last modified 3/7/2017.

Hollings M, Y. Komuro, and H. Tochihara.  1975.  Descriptions of Plant Viruses No. 154. Wellesbourne, UK: AAB, 4 pp.

Ling, K. S., and R. Li.  2014.  First report of cucumber green mottle mosaic virus infecting greenhouse cucumber in Canada.  Plant Disease 98 (5): 701.

Liu, H. W., L. X. Luo, J. Q. Li, P. F. Liu, X. Y. Chen,  and J. J. Hao.  2014.  Pollen and seed transmission on Cucumber green mottle mosaic virus in cucumber.  (Published online 17 April 2013.)  Plant Pathology (2014) 63, 62-77.

Lovig, E.  2014.  Email communication from E. Lovig, CDFA, to A. Morris and J. Chitambar, CDFA.  Subject: Cucumber green mottle mosaic virus (CGMMV) and Bacterial fruit blotch (BFB) detections in California.  Dated April 29, 2014.

NPAG.  2013.  Cucumber green mottle mosaic virus (CGMMV).    New Pest Advisory Group, Plant Epidemiology and risk Analysis Laboratory, Center for Plant Health Science & Technology, USDA-APHIS.  NPAG Report 20130819.docx, August 19, 2013: 1-9.

QDAF.  2017.  Cucumber green mottle mosaic virus. The State of Queensland Department of Agriculture and Fisheries, Queensland Government. https://www.daf.qld.gov.au/plants/health-pests-diseases/a-z-significant/cucumber-green-mottle-mosaic-virus# Last updated 01 March, 2017.

Rao A. L. N, and A. Varma. 1984. Transmission studies with cucumber green mottle mosaic virus. Phytopathologische Zeitschrift, 109(4):325-331.

Shang, J., Y. Xie, X. Zhou, Y. Qian, and J. Wu.  2011.  Monoclonal antibody-based serological methods for detection of Cucumber green mottle mosaic virus.  Virology Journal 8:228.

Schnabel, D.  2017.  Email from D. Schnabel, CDFA, to S. Brown and J. Chitambar, CDFA.  Subject: CGMMV. Dated December 11, 2017, 7:16 am.

Reingold V., E. Lachman, A. Koren, and A. Dombrovsky.  2015.  Seed disinfection treatments do not sufficiently eliminate the infectivity of Cucumber green mottle mosaic virus (CGMMV) on cucurbit seeds.  Plant Pathology 64: 245-255.

Reingold V., E. Lachman, O. Beelausov, A. Koren, N. Mor, and A. Dombrovsky.  2016. Epidemiological study of Cucumber green mottle mosaic virus in greenhouses enables reduction of disease damage in cucurbit production. Annals of Applied Biology 168:29-40.

Technical Working Group Responses: Cucumber green mottle mosaic virus.  October 28, 2013.  United States Department of Agriculture, Animal and Plant Health Inspection Service, Plant Protection and Quarantine.

Tesoriero, L. A., G. Chambers, M. Srivastava, S. Smith, B. Conde, and L. T. T. Tran-Nguyen.  2016.  First report of cucumber green mottle mosaic virus in Australia. Australasian Plant Disease Notes, 11:1. http://link.springer.com/article/10.1007/s13314-015-0186-x

Tian, T., K. Posis, C. J. Maroon-Lango, V. Mavrodieva, S. Haymes, T. L. Pitman, and B. W. Falk.  2014.  First report of Cucumber green mottle mosaic virus in melon in the United States.  Plant Disease 98:1163.

USDA APHIS.  July 25, 2013.  Email communication from K. J. Handy, CAPS Database Manager, USDA APHIS PPQ, PDEP to R. A. Bailey (and other APHIS members)  Director, PHPPS, CDFA. Subject: FW: confirmed id: Cucumber green mottle mosaic virus (CGMMV) detection in melon in CA – new US record.

USDA PCIT.  2017.  USDA Phytosanitary Certificate Issuance & Tracking System. December 14, 2017, 3:49:31 pm CDT. https://pcit.aphis.usda.gov/PExD/faces/ReportHarmOrgs.jsp

Zhang, J. W., K-S. Ling, and R. Cramer.  2014.  New Cucumber threat studied.  https://www.greenhousecanada.com/inputs/crop-protection/march-april-2014-4021


Responsible Party:

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.


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Pest Rating: A


Posted by ls

 

Diaporthe pseudophoenicicola R. R. Gomes, C. Glienke & Crous 2013

California Pest Rating for
Diaporthe pseudophoenicicola R. R. Gomes, C. Glienke & Crous 2013
Pest Rating: C

 


PEST RATING PROFILE
Initiating Event:

On June 15, 2017, a shipment of an unknown plant, exhibiting symptoms of leaf spotting and destined to a commercial florist in Los Angeles County, was intercepted by the CDFA Dog Team in Los Angeles County.  The shipment had originated in Kilgore, Texas.  A sample of symptomatic leaves was submitted to the CDFA Plant Pathology Lab for disease diagnosis.  On July 7, 2017, Suzanne Latham, CDFA plant pathologist, detected the fungal pathogen, Diaporthe pseudophoenicicola, in culture and confirmed its identity by PCR testing, as the cause for the disease.  Later, on July 19, 2017, the same pathogen was detected in a date palm (Phoenix dactylifera) sample exhibiting decline and canker symptoms and collected from a tree located off Interstate 5 (I-5), in Orange County.  The sample was collected by Orange County Agricultural officials and sent to the CDFA Plant Pathology Lab for diagnosis.  Suzanne Latham detected D. pseudophoenicicola in culture and confirmed its identity by multi-locus sequencing.  Later, the identity of the pathogen was also confirmed by the USDA APHIS Mycology and Nematology Genetic Diversity and Biology Laboratory at Beltsville, Maryland (Kennedy, 2017).   The current status and rating of D. pseudophoenicicola in California is assessed here and a permanent rating is proposed.

History & Status:

Background:  Diaporthe pseudophoenicicola is a fungal plant pathogen belonging to the order Diaporthales.  The species was named after its morphological similarity to Diaporthe phoenicicola, which was originally isolated from dead leaves of Mangifera indica in Pakistan, however, later reported to differ morphologically from D. phoenicicola (Gomes et al., 2013).  Diaporthe pseudophoenicicola is the sexual state of the pathogen, whereas, the asexual state belongs to the genus Phomopsis.  Presently, D. pseudophoenicicola has only been reported from China, Iraq, and Spain (Farr & Rossman, 2017; Gomes, et al., 2013).

The asexual state of the fungal pathogen has been detected in California prior to the 2017 detection.  In 2007, during a CDFA survey for palm wilt in Southern California, 16 detections were made of unidentified Phomopsis sp. on Phoenix canariensis, P. dactylifera, and P. reclinata in 10 counties.   Only recently, was the Phomopsis species that was detected on P. dactylifera in Riverside County, identified through DNA sequencing as P. pseudophoenicicola (syn. Diaporthe pseudophoenicicola), thereby, indicating that this pathogen has already been established in California for at least 10 years.  Complete identification of the remaining Phomopsis sp. is pending (personal communication: Suzanne Latham, CDFA).

Disease Development While specific information is lacking, it is likely that plant infection and disease development caused by Diaporthe pseudophoenicicola are similar to those caused by other species of Diaporthe occurring as plant pathogens, endophytes or saprobes.  The fungus produces ascospores (sexual spores) in perithecia (sexual fruiting bodies) and conidia (asexual spores) in pycnidia on dead twigs and leaves.  Conidia are the main inoculum causing primary and secondary infections and are spread to host plants by splashing rains.  Ascospores may be involved in long distance dispersal of the pathogen.  The fungus is likely to overwinter as mycelium and/or as conidia within pycnidia (Agrios, 2005).

Dispersal and spread: Windblown/splashing rain and irrigation water, pruning tools, possibly insects, and animals can spread fungal spores to non-infected plants.

Hosts: Mangifera indica (mango), Phoenix dactylifera (date palm), P. canariensis (Canary Island palm) (Farr & Rossman, 2017; Gao et al., 2017; Gomes et al., 2013).

Symptoms:  Diaporthe pseudophoenicicola causes symptoms of dieback and canker in infected mango and date palm.  Dead tops of green leaves have been reported for date palms (Farr & Rossman, 2017; Gomes et al., 2013).

Damage Potential: Quantitative losses caused by Diaporthe pseudophoenicicola have not been reported. The pathogen causes dieback and cankers in mango and date palm.  Therefore, if left uncontrolled, infections may result in reduced fruit and plant production and marketability.  In California, nurseries and other growers of mango and date palms plants may be at risk of damage caused by this pathogen.

Worldwide Distribution: Asia: China, Iraq; Europe: Spain (Farr & Rossman, 2017; Gomes et al., 2013); North America: USA (California) (see: “Initiating Event”).

Official Control: No official control is reported for Diaporthe pseudophoenicicola or Diaporthe spp., however, Phomopsis spp. is presently on the ‘Harmful Organism List’ for French Polynesia (USDA PCIT, 2017).  Currently, D. pseudophoenicicola has a temporary Q rating in California.

California Distribution:  Los Angeles, Orange, and Riverside Counties.

California Interceptions: There has been only one interception.  On July 7, 2017, Diaporthe pseudophoenicicola was detected in a shipment of an unknown plant that originated in Texas (see: ‘Initiating Event’).

The risk Diaporthe pseudophoenicicola would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Mango and palm are the only known hosts and are grown in California.  Diaporthe pseudophoenicicola may be able to infect its hosts under wet conditions and is therefore, only likely to establish in very limited regions of the State where mango and palm are grown mainly Southern California.

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

Score: 1

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 host range of the pathogen is presently limited to Mangifera indica and Phoenix dactylifera.

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: Diaporthe pseudophoenicicola has high reproductive potential with an abundant production of spores, however, the spores are dependent on splashing water for dispersal.

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: Quantitative losses caused by Diaporthe pseudophoenicicola have not been reported. Under favorable wet conditions for spread and disease development the pathogen may cause dieback and cankers in mango and palm.  Therefore, if left uncontrolled, infections may result in reduced fruit and plant production and marketability.  In California, nurseries and other growers of mango and date palms plants may be at risk of damage caused by this pathogen.,

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

Economic Impact: 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:  The pathogen may impact palms used as ornamental plantings in commercial and private environments.

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 Diaporthe pseudophoenicicola: Medium (9)

Add up the total score and include it here.

-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 Low.  The pathogen is already established in at least three counties in Southern California.

Score: (-1)

-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:  

Identification of Phomopsis sp. (asexual state of Diaporthe) detected during the 2007 CDFA survey, is pending.  Positive identification may provide new information on the distribution and hosts of D. pseudophoenicicola in California, while further stabilizing its currently proposed rating.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Diaporthe pseudophoenicicola is C.


References:

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

Farr, D. F., and A. Y. Rossman.  2017.  Fungal Databases, U. S. National Fungus Collections, ARS, USDA. Retrieved September 20, 2017, from http://nt.ars-grin.gov/fungaldatabases/

Gao, Y., F. Liu, W. J. Duan, P. W. Crous, and L. Cai.  2017.  Diaporthe is paraphyletic. IMA Fungus 8(1): 153-187.

Gomes, R.R., C. Glienke, S. I. R. Videira, L. Lombard, J. Z. Groenewald, and P. W. Crous.  2013.  Diaporthe: a genus of endophytic, saprobic and plant pathogenic fungi. Persoonia 31: 1-41.

Kennedy, A. H.  2017.  Email from A. H. Kennedy, Molecular Biologist, USDA APHIS Mycology and Nematology Genetic Diversity and Biology Laboratory, Beltsville, Maryland, to Suzanne Latham, Plant Pathologist, CDFA Plant Pest Diagnostics Branch, dated September 01, 2017, 5:14 am.

USDA PCIT.  2017.  USDA Phytosanitary Certificate Issuance & Tracking System. Sept. 20, 2017, 2:11:43 pm CDT.  https://pcit.aphis.usda.gov/PExD/faces/ReportHarmOrgs.jsp.


Responsible Party:

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

12/29/17 – 2/12/18


*NOTE:

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

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♦  Comments may not be posted if they:

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Pest Rating: C


Posted by ls

Colletotrichum cliviae Y.L. Yang, Zuo Y. Liu, K.D. Hyde & L. Cai, 2009

California Pest Rating for
Colletotrichum cliviae Y.L. Yang, Zuo Y. Liu, K.D. Hyde & L. Cai, 2009
PEST RATING: B

 


PEST RATING PROFILE
Initiating Event:

On October 17, 2017, diseased leaves of variegated croton plants (Codiaeum variegata) exhibiting leaf spotting symptoms, were collected from a nursery in San Diego, by San Diego County officials and sent to the CDFA Plant Pathology Laboratory for diagnoses.  The shipment of croton plants had originated from Florida.  On November 20, 2017, Suzanne Latham, CDFA plant pathologist, identified the pathogen, Collectotrichum cliviae, as the cause for the disease. Furthermore, during 2015-2016, CDFA detections of anthracnose disease of Cymbidium sp., Aglaonema sp., and Dieffenbachia sp. plants in nurseries in San Diego County in California, were attributed to Colletotrichum cf. cliviae (‘cf’ in biological terminology means ‘a significant resemblance to’).  Those detections initiated, and were included in, a pest rating assessment for the closely similar species, C. cliviae, which was eventually given a permanent B-rating. However, those detections were recently shown to be, instead, C. aracearum (Kennedy, 2017; Latham, 2017).  The recent detection of C. cliviae in San Diego marked the first record of this pathogen in California. Consequently, the infected plants were treated by the nursery and are to be periodically re-inspected (Walber, 2017).  The risk of the introduction and establishment of C. cliviae, and its current rating in California are re-evaluated here.

History & Status:

Background Colletotrichum cliviae causes anthracnose and leaf blight disease in its host plants.  The fungal pathogen was originally reported from Clivia miniata (clivia/flame/bush/kaffir lily) leaves growing in Yunnan Province, China and reported as not being host-specific (Yang et al., 2009). Since then, C. cliviae has been found on few tropical and subtropical hosts from China, India, Brazil, and recently, from the USA (California).

Hosts: Arundina graminifolia (Bamboo orchid), Camellia sinensis (tea plant), Clivia miniata (Kaffir lily), Capsicum annuum (pepper), Capsicum sp., Cymbidium hookerianum (orchid), C. pendulum, Glycine max (soybean), Mangifera indica (mango) Phaseolus sp. (bean), Ricinus communis (castor), Saccharum sp., Zamioculcas zamiifolia (Barbieri et al., 2017; Chowpadda et al., 2014; Diao et al., 2017; Farr & Rossman, 2016; Lui et al., 2015; Saini et al., 2017; Sharma et al., 2014; Vieira et al., 2014; Yang et al., 2009; Zhang & Li, 2017).  The recent host, Codiaeum variegata (variegated croton) is added to this list (see ‘Initiating Event’).

Symptoms:  Generally, Colletotrichum-infected host plants exhibit symptoms of anthracnose which include dark brown leaf, stem and fruit spots, fruit rot, and wilting of leaves which often result in dieback and reduction in plant quality. Colletotrichum cliviae produce dark brown to black, ellipsoid lesions in orchid leaves of Cymbidium hookerianum and Arundina graminifolia.  The lesions contain pale yellow conidial (spore) masses (Yang et al., 2011).

Damage Potential:  Anthracnose disease caused by Colletotrichum cliviae can result in reduced plant quality and growth, fruit production and marketability.   Estimates of yield/crop loss due to this pathogen have not been reported. However, in California, nursery and greenhouse production of orchids, croton, and other host plants would be particularly at risk as nursery conditions are often conducive to infection by Colletotrichum species.  In California’s cultivated fields, disease development may be sporadic as it is affected by levels of pathogen inoculum and environmental conditions.

Disease Cycle:  It is likely that Colletotrichum cliviae has a similar life cycle to that of other Colletotrichum species and survives between crops during winter as mycelium on plant residue in soil, on infected plants, and on seeds.  During active growth, the pathogen produces masses of hyphae (stromata) which bear conidiophores, on the plant surface. Conidia (spores) are produced at the tips of the conidiophores and disseminated by wind, rain, cultivation tools, equipment, and field workers.   Conidia are transmitted to host plants.  Humid, wet, rainy weather is necessary for infection to occur.  These requirements in particular may limit the occurrence of the pathogen in California fields and subsequently, the pathogen may be more of a problem under controlled environments of greenhouses.  Conidia germinate, penetrate host tissue by means of specialized hyphae (appresoria) and invade host tissue.

Transmission:  Wind, wind-driven rain, cultivation tools, and human contact.

Worldwide Distribution: Asia: China, India; South America: Brazil (Farr & Rossman, 2016; Liu et al., 2015; Vieira et al., 2014; Yang et al., 2011).

Official Control Colletotrichum cliviae is reportable to the USDA.

California Distribution: Colletotrichum cliviae is not established in California.

California Interceptions Only one interception from Florida is recorded (see ‘Initiating Event).

The risk Colletotrichum cliviae would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Similar to other species of Colletotrichum, C. cliviae requires humid, wet, rainy weather for conidia to infect host plants. This environmental requirement may limit the ability of the pathogen to fully establish and spread under dry field conditions in California.

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: Presently, the host range of Colletotrichum cliviae is limited to few plant species in eight different families – mainly economically important orchid, mango, and nursery ornamentals.

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: The pathogen has high reproductive potential and conidia are produced successively.  They are transmitted by wind, wind-driven rain, cultivation tools, and human contact however conidial germination and plant infection require long, wet periods.

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: Under suitable, wet climates, the pathogen could lower plant growth, fruit production and value and trigger the loss of markets. Nursery orchids and ornamentals, and mango production could be negatively affected.

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

Economic Impact: 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: The pathogen could significantly impact cultural practices or home garden plantings.

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

Environmental Impact:

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 Colletotrichum cliviae: Medium (11)

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 Colletotrichum cliviae 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 Not established in California (-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 = 11.

Uncertainty:

None.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for the anthracnose pathogen, Colletotrichum cliviae is B.


References:

Diao, Y.-Z., C. Zhang, F. Liu, W. –Z, Wang, L. Liu, L. Cai,, and X. –L. Liu.  2017.  Colletotrichum species causing anthracnose disease of chili in China. Persoonia 38: 20-37.

Barbieri, M. C., G., M. Ciampi-Guillardi, S. R. G. Moraes, S. M. Bonaldo, F. Rogerio, R. R. Linhares, and N. S. Massola Jr.  2017.  First report of Colletotrichum cliviae causing anthracnose on soybean in Brazil. Plant Disease 101: 1677.

Chowpadda, P., C. S. Chethana, R. P. Pant, and P. D. Bridge.  2014.  Multilocus gene phylogeny reveals occurrence of Colletotrichum cymbidiicola and C. cliviae on orchids in north east India.  Journal of Plant Pathology 96: 327-334.

Farr, D. F., & A. Y. Rossman.  2016.  Fungal databases, systematic mycology and microbiology laboratory, ARS, USDA. Retrieved April 3, 2016, from

http://nt.ars-grin.gov/fungaldatabases/

Kennedy, A.  2017.  Email from A. H. Kennedy, Molecular Biologist, National Identification Services, USDA APHIS PPQ PM to John Chitambar, CDFA, sent: August 29, 2017, 12:54 pm.

Latham, S.  2017.  Email from A. H. Kennedy, Molecular Biologist, National Identification Services, USDA APHIS PPQ PM to Suzanne Latham, CDFA, sent: August 18, 2017, 12:11 pm.

Liu, F., B. S. Weir, U. Damm, P. W. Crous, Y. Wang, B. Liu, M. Wang, M. Zhang, and L. Cai. 2015. Unravelling Colletotrichum species associated with Camellia: employing ApMat and GS loci to resolve species in the C. gloeosporioides complex. Persoonia 35: 63-86.  http://dx.doi.org/10.3767/003158515X687597.

Saini, T. J., S. G. Gupta, and R. Anandalakshmi.  2017.  Detection of chili anthracnose caused by Colletotrichum cliviae in India. Australasian Plant Disease Notes 12: 33.

Sharma G., A. K. Pinnaka, and B. D. Shenoy.  2013. ITS-based diversity of Colletotrichum from India. Current Research in Environmental & Applied Mycology 3: 194–220.

Vieira, W.A.S., S. J. Michereff, M. A. de Morais, Jr., K. D. Hyde, and M. P. S. Camara. 2014.  Endophytic species of Colletotrichum associated with mango in northeastern Brazil. Fungal Diversity 67: 181-202.

Walber, T.   2017.  Email from G. Hernandez, San Diego County Department of Agriculture/Weights & Measures to T. Walber, CDFA Interior Pest Exclusion.  Dated: December 01, 2017, 11:28:29 am.

Weir, B. S., P. R. Johnston, and U. Damm.  2012.  The Colletotrichum gloeosporioides species complex.  Studies in Mycology, 73:115-180. DOI:10.3114/sim0011.

Yang, Y., L. Cai, Z. Yu, Z. Liu, and K. D. Hyde.  2011.  Colletotrichum species on Orchidaceae in southwest China.  Cryptogamie, Mycologie, 2011, 32 (3): 229-253.

Yang, Y.L., Z. Y. Liu, L. Cai, K. D. Hyde, Z. N. Yu, and E. H. C. McKenzie. 2009. Colletotrichum anthracnose of Amaryllidaceae. Fungal Diversity 39: 123-146.

Zhou, Z., and Y. L. Li.  2017.  First report of Colletotrichum cliviae causing anthracnose on Zamioculcas zamiifolia in Henan Province, China. Plant Disease 101(5): 838.


Responsible Party:

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

12/4/17 – 1/18/18


*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;

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♦  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

Ustilago esculenta

California Pest Rating for
Ustilago esculenta Henn. 1895
PEST RATING: A

 


PEST RISK PROFILE


Initiating Event:   

On October 19 and 20, 2017, Manchurian wild rice plants with slightly swollen lower stems, were collected by Riverside County Agricultural officials, from a private company, in Riverside County and sent to the CDFA’s Plant Pathology Lab for possible detection of the smut fungus, Ustilago esculenta.  On November 20, 2017, Cheryl Blomquist, CDFA plant pathologist, detected U. esculenta, by PCR and sequencing, from the swollen, white interior plant tissue.   The current status and risk of U. esculenta to California is assessed here and a permanent rating is proposed.

History & Status:

Background:  Ustilago esculenta is a biotrophic (i.e., it has a long-term, non-lethal feeding relationship with an infected plant) smut fungus that incites formation of swollen culms or smut galls in the apical internodal (stem) region of perennial Manchurian wild rice, Zizania latifolia.  These swollen culms or smut galls are edible and have unique flavor and delicacy.  The swollen culms are consumed as a vegetable in India (Manipur), China, Japan, and Taiwan (Chung & Tzeng, 2004; Jose et al., 2016; Terrell & Batra, 1982).  In China and Japan, it is cultivated as a commercial food crop (Jose et al., 2016).  Furthermore, in Taiwan, and southern China, the production of galls occurs during the season of tropical storms and provides an alternate food source to consumers when cultivation of other vegetables is negatively affected.  Therefore, the fungus is considered highly beneficial and economically important (Chung & Tzeng, 2004).   Hennings (1895) originally discovered the pathogen, Ustilago esculenta in its infected host, Zizania latifolia, in China.

In the USA, Manchurian wild rice, Zizania latifolia, is prohibited entry into the country due to the smut fungus, Ustilago esculenta, that it carries (USDA, 2017).  Native species of wild rice may be at risk of infection and loss of production particularly since the fungus prevents development of inflorescences, thereby, affecting seed production (Terrell & Batra, 1982; Yamaguchi, 1990).

In 1991, an illegal 0.05-ha planting of Manchurian wild rice infected with Ustilago esculenta was discovered in a field near Modesto, California and marked the first report of the disease in a field situation in North America.  The plants had been brought into the USA in violation of federal quarantines and were eradicated (Watson et al., 1991).   In 1999, the host and pathogen were discovered in two small grower’s plots (approximately 2-ha total) in Baton Rouge, Louisiana.  The plants were eradicated in 2000 (NPAG, 2001).

Disease Development: Ustilago esculenta spends its entire life cycle in the host plant.  The fungus grows within and between plant cells in the stem tissues, particularly near the apical meristem.  However, the fungus is not systemically distributed throughout the entire plant and does not invade leaf and root tissue (Chen & Tzang, 1999, Jose et al., 2016).  Chen and Tzang (1999), using PCR technology, found the fungal DNA in the growth tip of Manchurian wild rice plants and not in leaves and healthy plant tissue.  They also detected the fungus in the sheath of infected plants even when there were no outward signs of its presence.  The fungus prevents production of inflorescence and galls develop at the internode region beneath the apical meristem.  Galls are formed within 10-15 days even though the plants may have been planted in the soil for over 8 months. Internally, gall formation involves hypertrophy (increase in cell size), hyperplasia (increase in cell numbers), and presence of mucilaginous cavities (Chan & Thrower, 1980).  At this developmental stage, the inner tissue of a gall appears white and filled with fungal hyphae which later develop to form dark teliospores (sexual spores) within the gall.  Teliospore formation is favored at temperatures greater than 28°C (Chung & Tzeng, 2004). In China, the edible galled plants are harvested for consumption prior to the production of teliospores.  With time, black longitudinal streaks appear, and eventually, the entire stem turns black and deteriorates.  Furthermore, a lack of nutrients in a plant or low water level in a field initiate earlier production of the reproductive stage of the fungus, thereby, reducing quality and yield of the plants (Yamaguchi, 1990).  The optimum temperature for fungal growth is 20-28°C and the optimum pH range is 4-7. The fungus may overwinter as mycelium and teliospores in the grass rhizomes and be transmitted into new shoots through asexual propagation of the plant.  Alternatively, teliospores from decomposed galls, may survive in soil (Chung & Tzeng, 2004).  Jose et al., (2016) detected spores and fragmented hyphae in the rhizomes throughout the year, including the month of January during which the above ground culms degenerated, thereby, suggesting that it may serve as inoculum for infection.

Dispersal and spread: Plant rhizomes, galled stems, and soil (Jose et al., 2016; Chung & Tzeng, 2004).

Hosts: Zizania spp. in the family Poaceae: Z. aquatica, Z. latifolia (syn. Z. caduciflora), and Zizania sp.

Symptoms: Ustilago esculenta stimulates the swelling of the culms of its host grass plants resulting in the formation of edible galls at the internodal region beneath the apical meristem (stem base).  The galls are about 3-4 cm in width and 15-20 cm in length (Chung & Tzeng, 2004).  Infected plants do not show any typical disease symptoms despite the internal presence of the fungus (Jose et al., 2016). Experimentally, plant infected with U. esculenta showed a decrease in height, but significant increase in above-ground biomass and higher chlorophyll content (Yan et al., 2013).

Damage Potential: Ustilago esculenta prevents the production of inflorescences in host plants thereby, significantly reducing seed production and resulting in great yield loss (Terrell & Batra, 1982; Chen & Tzeng, 1999).  Production of wild rice, including near relatives of Zizania latifolia, in California may be significantly reduced by the fungus.

Worldwide Distribution: Asia: Cambodia, China, Hong Kong, India, Japan, Laos, Malaysia, Myanmar, (east and south Asia), Taiwan, Thailand, (former) USSR, Vietnam; North America: USA (District of Columbia) (Farr & Rossman, 2017).

Official Control:  Ustilago esculenta, with its host plant, Zizania spp., are prohibited from being imported or offered for entry into the United States by the USDA, and are on the Prohibited Articles List under Federal Regulations 7CFR 319.37-2 (USDA, 2017).

California Distribution: Ustilago esculenta is not established in California.

California Interceptions In 1998, there was one interception of Manchurian wild rice infested with Ustilago esculenta destined to a private business in San Bernardino County.  The shipment was destroyed.

In 1991, a foreign-sourced, illegal planting of Manchurian wild rice infected with Ustilago esculenta was detected in a field near Modesto.  The plants were eradicated.

The risk Ustilago esculenta would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Ustilago esculenta is likely to establish wherever wild rice, Zizania, is cultivated in California.  California wild rice is grown under warm, dry, clear days, and a long growing season; mostly on fine-textured, poorly-drained soils (Farrar, 2000).   Since the fungus is limited to Zizania spp., and is likely to establish wherever native species of wild rice are grown in California, its potential distribution is considered widespread and a ‘High” rating is given to this category.

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 host range is limited to Zizania

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: The fungus is biotrophic and is dependent on the spread infested galled plants for long distance spread.  It is also transmitted in propagative rhizomes and soil.

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: Ustilago esculenta prevents the production of inflorescences in host plants thereby, drastically reducing seed production and resulting in great yield loss.  The fungus and its vectoring host, Zizania latifolia, are prohibited entry in the USA , and would be a threat to native species of wild rice that are grown in California

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

Economic Impact: A, B, C, D, E

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: Ustilago esculenta, either through the establishment of infected Zizania latifolia or its direct impact on the stand and cultivation of California native wild rice species, can result in reducing native stands of wild rice by reducing seed production, thereby, disrupting aquatic plant and animal communities, critical habitats, and lowering biodiversity.  This could result in additional official treatment programs. A “High” rating is given to this category.

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

Environmental Impact: A, C, D

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 Ustilago esculenta: High (13)

Add up the total score and include it here.

-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 Low.  Ustilago esculenta 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:   

None.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Ustilago esculenta is A.


References:

Chan, Y-S., and L. B. Thrower.  1980.  The host-parasite relationship between Zizania caduciflora Turcz. and Ustilago esculenta P. Henn. 1. Structure and development of the host and host-parasite combination.  New Phytopathology 85: 201-207.

Chen, R-S., and D. D-S. Tzeng.  1999.  PCR-mediated detection of Ustilago esculenta in water oat (Zizania latifolia) by ribosomal internal transcribed spacer sequences.  Plant Pathology Bulletin 8: 149-156.

Chung, K., and D. D. Tzeng.  2004.  Nutritional Requirements of the Edible Gall-producing Fungus Ustilago esculenta. Journal of Biological Sciences, 4(2), 246-252.

Farr, D. F., and A. Y. Rossman.  2017.  Ustilago esculenta.  Fungal databases, U.S. National Fungus Collections, ARS, USDA. Retrieved November 28, 2017, from https://nt.ars-grin.gov/fungaldatabases/

Farrar, K.  2000.  Crop profile for wild rice in California. California Pesticide Impact Assessment Program, University of California, Davis, CA. http://www.ipmcenters.org/CropProfiles/docs/cawildrice.pdf

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).

Jose, R. C., S. Goyari, B. Louis, S. D. Waikhom, P. J. Handique, and N. C. Talukdar.  2016.  Investigation on the biotrophic interaction of Ustilago esculenta on Zizania latifolia found in the Indo-Burma biodiversity hotspot.  Microbial Pathogenesis 98: 6-15.

NPAG.  2001.  NPAG report sent to Trillium.  20. Ustilago esculenta (Basidiomycota: Ustilaginomycetes: Ustilaginaceae) wild rice smut.  New Pest Advisory Group Plant Epidemiology and Risk Analysis Laboratory, Center for Plant Health Science & Technology.

Terrell, E. E., and L. R. Batra.  1982.  Zizania latifolia and Ustilago esculenta, a grass-fungus association. Economic Botany 36: 274-285.

USDA.  2017.  Plants for plant manual. United States Department of Agriculture.  First edition March 2017.

Watson, T., T. E. Tidwell, and D. G. Fogle.  1991.  Smut of Manchurian wild rice caused by Ustilago esculenta in California.  Plant Disease 95: 1075. DOI: 10.1094/PD-75-1075D.

Yamaguchi, M. (1990). Asian vegetables. In J. Janick & J. E. Simon (Eds.), Advances in new crops, 387-390. Timber Press, Portland, OR.

Yan, N., X-Q. Wang, X-F. Xu, D-P. Guo, Z-D. Wang, J-Z. Zhang, K. D. Hyde, and H-L. Liu.  2013.  Plant growth and photosynthetic performance of Zizania latifolia are altered by endophytic Ustilago esculenta infection. https://doi.org/10.1016/j.pmpp.2013.05.005


Responsible Party:

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

12/01/17 – 1/15/18


*NOTE:

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PEST RATING: A


Posted by ls

Colletotrichum aracearum

California Pest Rating for
Colletotrichum aracearum L. W. Hou & L. Cai 2016
PEST RATING: B

 


PEST RATING PROFILE
Initiating Event:  

On July 28, 2017, diseased Cymbidium sp. plants exhibiting leaf spots, were detected by the CDFA Dog Team, in a shipment of plants that had originated in and was destined to a private resident in San Diego County.  Symptomatic leaves were sent to the CDFA Plant Pest Diagnostics Branch for diagnosis.  On August 21, 2017, Suzanne Latham, CDFA plant pathologist, detected the fungal pathogen, Colletotrichum aracearum, in culture from the leaf spots.  The identity of the pathogen was also confirmed by the USDA APHIS National Identification Services at Beltsville, Maryland (Kennedy, 2017).  Currently, C. aracearum has a temporary ‘Q’ rating.  The risk of introduction and establishment of C. aracearum in California is assessed and a permanent rating is proposed herein.

History & Status:

Background Colletotrichum aracearum causes anthracnose disease in its host plants. The recently described species (Hou et al., 2016) has only been reported from China, until its detection in California, USA.   In California, prior to the July 28, 2017 detection of Colletotrichum aracearum (see ‘Initiating Event’), there had been several detections of the pathogen which was then identified as Colletotrichum cf. cliviae (‘cf’ in biological terminology means ‘a significant resemblance to’).  However, those detections were recently shown to be C. aracearum (Kennedy, 2017; Latham, 2017).   The first detection of C. aracearum (then identified as Colletotrichum cf. cliviae) was made on April 28, 2015, from diseased Dieffenbachia sp. plants exhibiting leaf spots and detected in a nursery in San Diego County during regulatory nursery inspections by the San Diego County Agricultural officials. This marked a probable new U.S. record by the USDA National Identification Services at Beltsville, Maryland. Several detections followed from different nurseries within San Diego County.  On June 11, 2015 and August 19, 2015, the same pathogen was detected in Chinese evergreen (Aglaonema sp.) leaves from cuttings that were shipped from Guatemala and intercepted by San Diego County, and from diseased Aglaonema sp. plants detected during regulatory nursery inspections.  On December 3, 2015 and April 20, 2016, infected Aglaonema sp. were intercepted in plant shipments from Costa Rica, and on April 29, 2016, during  regulatory nursery inspections, the pathogen was detected in Cymbidium sp. orchid plants showing leaf spots.   In all these cases, subsequent to the detection of the pathogen, infected plant shipments/nursery stock were either destroyed or rejected from entering California. The presence and status of anthracnose disease caused by C. aracearum in Guatemala and Costa Rica have not been reported.

Hosts: Aglaonema sp. (Chinese evergreen), Cymbidium sp. (orchid), Dieffenbachia sp. (CDFA detection records 2015-2017), Monstera deliciosa (Swiss cheese plant/tarovine/windowleaf), Philodendron selloum (cut-leaf philodendron) (Farr & Rossman, 2016; Hou et al., 2016).

Symptoms:  Generally, Colletotrichum-infected host plants exhibit symptoms of anthracnose which include dark brown leaf, stem, and fruit spots or lesions, fruit rot, and wilting of leaves which often result in dieback and reduction in plant quality.

Damage Potential:  Anthracnose disease caused by Colletotrichum aracearum can result in reduced plant quality and growth, fruit production and marketability.   Estimates of yield/crop loss due to this pathogen have not been reported. However, in California, nursery and greenhouse production of orchids, Chinese evergreen, dieffenbachia, and other host plants are particularly at risk as nursery conditions are often conducive to infection by Colletotrichum species.  In California’s cultivated fields, disease development may be sporadic as it is affected by levels of pathogen inoculum and environmental conditions.

Disease Cycle:  It is likely that Colletotrichum aracearum has a similar life cycle to that of other Colletotrichum species and survives between crops during winter as mycelium on plant residue in soil, on infected plants, and on seeds.  During active growth, the pathogen produces masses of hyphae (stromata) which bear conidiophores, on the plant surface. Conidia (spores) are produced at the tips of the conidiophores and disseminated by wind, rain, cultivation tools, equipment, and field workers.   Conidia are transmitted to host plants.  Humid, wet, rainy weather is necessary for infection to occur.  These requirements in particular may limit the occurrence of the pathogen in California fields and subsequently, the pathogen may be more of a problem under controlled environments of greenhouses.  Conidia germinate, penetrate host tissue by means of specialized hyphae (appresoria) and invade host tissue.

Transmission:  Wind, wind-driven rain, cultivation tools, and human contact.

Worldwide Distribution: Asia: China; North America: USA (Farr & Rossman, 2017; Hou et al., 2016).  Currently, in the USA, C. aracearum has only been reported from California.

Official Control In California C. aracearum is an actionable, Q-rated pathogen, and infected plant material is subject to destruction or rejection.  Colletotrichum aracearum is reportable to the USDA.

California Distribution: San Diego County (see “Background”).

California Interceptions During 2015-17, four shipments of Colletotrichum aracearum-infected Aglaonema sp. (Chinese evergreen) cuttings and one of Cymbidium sp. were intercepted in California.  The shipments had originated Guatemala, Costa Rica, and China (see ‘Background’ and ‘Initiating Event’.).

The risk Colletotrichum aracearum would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Similar to other species of Colletotrichum, aracearum requires humid, wet, rainy weather for conidia to infect host plants. This environmental requirement may limit the ability of the pathogen to fully establish and spread under dry field conditions in California

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: Presently, the host range of Colletotrichum aracearum is limited to few nursery ornamental plant species belonging to the family Araceae.

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:  The pathogen has high reproductive potential and conidia are produced successively.  They are transmitted by wind, wind-driven rain, cultivation tools, and human contact however conidial germination and plant infection require long, wet periods.

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: Under suitable, wet climates, the pathogen could lower plant growth, fruit production and value and trigger the loss of markets. Nursery-grown orchids and other ornamental host plants could be negatively affected.

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: The pathogen could significantly impact cultural practices or home garden plantings.

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 Colletotrichum aracearum: Medium (11)

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 Colletotrichum aracearum 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) Colletotrichum aracearum was detected in a nursery in San Diego 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 = 10.

Uncertainty:

The host range of Colletotrichum aracearum is presently limited to few plants in Araceae.  Further host range studies are needed.  Also, results of detection surveys for C. aracearum in nursery, commercial, and natural environments within California may alter its proposed rating.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for the anthracnose pathogen, Colletotrichum aracearum is B.


References:

Farr, D. F., & A. Y. Rossman.  2016.  Fungal databases, systematic mycology and microbiology laboratory, ARS, USDA. Retrieved April 3, 2016, from

http://nt.ars-grin.gov/fungaldatabases/

Hou, L.W., F. Liu, W. J. Duan, and L. Cai. 2016. Colletotrichum aracearum and C. camelliae-japonicae, two holomorphic new species from China and Japan. Mycosphere 7(8): 1111-1123.

Kennedy, A.  2017.  Email from A. H. Kennedy, Molecular Biologist, National Identification Services, USDA APHIS PPQ PM to John Chitambar, CDFA, sent: August 29, 2017, 12:54 pm.

Latham, S.  2017.  Email from A. H. Kennedy, Molecular Biologist, National Identification Services, USDA APHIS PPQ PM to Suzanne Latham, CDFA, sent: August 18, 2017, 12:11 pm.


Responsible Party:

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

11/29/17 – 1/13/18


*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;

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Pest Rating: B


Posted by ls

Erwinia aphidicola

California Pest Rating for
Erwinia aphidicola
PEST RATING: B

 


PEST RATING PROFILE
Initiating Event:

On September 5, 2017, a melon (Cucumis melo cv. mlada) fruit,   showing symptoms of spotting and scabbing, was collected during a phytosanitary field inspection in Glenn County, by Glenn Agricultural County officials and sent to the CDFA Plant Pathology Laboratory for diagnoses.  Sebastian Albu, CDFA plant pathologist, identified the pathogen, Erwinia aphidicola, by PCR and DNA sequencing, as the cause of the disease on the exterior surface of the melon sample.  As there have been no earlier reports in the USA, the pathogen was sent in culture to the USDA APHIS PPQ CPHST Diagnostic Lab in Beltsville, Maryland, for diagnostic confirmation.  On November 20, 2017, the USDA confirmed the identity of E. aphidicola and marked a new record of the pathogen in the U.S. (USDA, 2017).  The pathogen was assigned a temporary ‘Q’ rating.  The risk of introduction and establishment of this pathogen in California is assessed and a permanent rating is herein proposed.

History & Status:

Background: Erwinia aphidicola (Enterobacteriaceae) was originally discovered as a new species of bacteria that constituted the major flora of the gut of pea aphid, Acyrthosiphon pisum, and caused aphid mortality (Harada et al., 1997).  However, in 2009, E. aphidicola was confirmed as a plant pathogen (Santos et al., 2009) that had caused disease of common bean and pea observed during 2003-2004 in southeastern Spain, and, at that time, was attributed to a different bacterial species, E. persicina (González et al., 2005, 2007; Santos et al., 2009).  Both E. persicina and E. aphidicola are closely related species that show high similarity (99-100%) in 16S rDNA sequence analysis.  However, Santos et al., (2009) confirmed that sequence analysis of 16S rDNA may not provide sufficient resolving power to discriminate these closely related species, but would require a more species-specific set of DNA primers for PCR amplification.  Subsequently, Santos and others were able to molecularly discriminate E. aphidicola from E. persicina and show that E. aphidicola was the cause of the related diseases reported from Spain.

Erwinia aphidicola has not been reported in the USA prior to its recent detection in California.  However, in the USA, a new species of bacteria, E. nulandii was isolated from bean in 1981 in Nebraska, and was shown to be distinct from all other Erwinia species by biochemical, protein, and DNA analytical tests. (Schuster et al., 1981).  In 1994, E. nulandii was determined to be a synonym of E. persicinus (later corrected to E. persicina) – the species that is closely related to E. aphidicola (Brenner et al., 1994). As shown by Santos and others (2009), further sequence analysis of the USA isolate of E. persicina may be necessary to distinguish the possible presence of E. aphidicola.

Hosts:  Presently, Phaseolus vulgaris (bean) and Pisum sativum (pea) are reported as natural hosts for Erwinia aphidicola (Santos et al., 2009).  Experimentally, cucumber, tomato, pepper, and melon were reported as alternative hosts to green bean for the southeastern Spanish isolate of E. persicina (Diánez et al., 2009) which later was identified as E. aphidicola (Marín et al., 2011).  The current detection of E. aphidicola (see ‘Initiating Event’) indicates the infection of melon in a field environment.

Symptoms:  Symptoms of chlorotic and necrotic leaf spots in beans and generalized chlorosis as well as necrosis in leaves and tendrils in peas are exhibited when these plants are infected with Erwinia aphidicola (González et al., 2005, 2007).  In beans, early symptoms of light, interveinal chlorosis in leaves soon turn into yellowish leaves with green veins.   As the disease progresses, necrotic spots develop and completely affected leaves turn brown.  Watery spots and very marked grains appear on infected pods, which take on a curved, hook-like appearance. Rough roots along the entire stem are also produced in diseased plants (Marín et al., 2011).  Marín and other researchers (2011) observed 13 different symptoms in plants grown from commercial bean seeds and 10 different symptoms in plants grown from replanting bean seeds in a controlled environment bioassay study.  Those symptoms included the earlier reported ones in varying intensities, as well as, green wilted and deformed leaves and dwarfed plants.

In experimental trials, tomato, pepper, cucumber, and melon inoculated with E. aphidicola, exhibited symptoms of leaf necrosis, adventitious roots, brown coloration along the stem, interveinal chlorosis, curled, and blistered leaves.  In cucurbits, a distinct lesion in some areas of the stem was also exhibited (Diánez et al., 2009).

In California, symptoms of reticulate scabbing with irregular cracks within scabs, and scattered chlorotic spots were observed on the E. aphidicola-infected melon fruit (see ‘Initiating Event’).  These symptoms covered most of the surface of the fruit and were not apparent in internal tissue (personal communication: Sebastian Albu, CDFA).

Disease development: While there is no information reported on the pathogenesis and epidemiology of disease caused by Erwinia aphidicola in particular, it is likely that the biology of E. aphidicola is similar to its genetically closely related species E. persicina, for which only scant information is available. In greenhouse studies on the life cycle, host range, and environmental effects of E. persicina infecting forage or grain legumes, including bean and pea, Zhang and Nan (2014) determined that the pathogen was transmitted by seeds, water, and soil. It was present both on the surface and within seeds.  Bacteria present on seeds can be internalized within the sprout and become protected from post-harvest sanitation.  Bacteria within seeds can remain alive indefinitely thereby, facilitating long distance transmission of the pathogen via movement of seeds.  The pathogen was capable of surviving in alfalfa soil for more than 3 months and could invade alfalfa plants through natural opening.  Once within a plant, the bacterial pathogen can move from the roots upward to the leaves, inflorescences, and subsequently, the seeds. The pathogen is capable of surviving within a wide range of environmental conditions and can endure arid, saline, and alkaline conditions. The optimum temperature for growth was 28°C within a range of 10-36°C and no growth occurred below 5°C or above 40°C (Zhang & Nan, 2014).

Dispersal and spread: pathogen-infested plants, seeds, soil, and water (Zhang & Nan, 2014).

Damage Potential: In southeastern Spain, Erwinia aphidicola is reported to have caused over 50% decrease in production of commercial beans due to chlorotic and necrotic leaf spotting and deformation of pods (González et al., 2005).  The disease affected approximately 12 ha of field-grown peas (González et al., 2007).   Similar to south eastern Spain, most of California experiences a Mediterranean climate which is usually characterized by rainy winters and dry, warm to hot summers.  Beans and peas are commercially cultivated in such climate in limited regions within the State, and may be at risk of disease caused by E. aphidicola.

Worldwide Distribution: Europe: Spain; North America: USA (California) (Marin et al., 2011).

Official Control:  Presently, Erwinia aphidicola has a temporary Q rating in California.  No official control has reported by any country for E. aphidicola or E. persicina.

California Distribution:  Glenn County (see “Initiating Event”).

California Interceptions:  None reported.

The risk Erwinia aphidicola would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Erwinia aphidicola is likely to establish in limited parts of California wherever its natural hosts, peas and beans are grown. Its current detection in melon fruit indicates the possible inclusion of an additional host in California. It is capable of surviving under a wide range of environmental conditions.

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: Presently, the natural host range is very limited. Peas and beans are the only natural hosts that have been reported.

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: The bacterial pathogen has high reproduction and is spread by artificial means through infected planting stock, seeds, soil, and water.

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: The potential impact of the pathogen on bean and pea production could result in lowered crop yield and value, as well as a loss of marketability of pea and bean pods.

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

Economic Impact: 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:  Evaluate the environmental impact of the pest on California using the criteria below.   No impact to the environment is expected.

Environmental Impact:

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: 1

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 Erwinia aphidicola:

Add up the total score and include it here. 10

-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 ‘Low’.  To date, Erwinia aphidicola has only been detected in a commercial melon field in Glenn County.

Score: (-1).

-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 = 9

Uncertainty:  

The host range of Erwinia aphidicola, its epidemiology, and damage caused to those hosts is not fully known.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Erwinia aphidicola is B.

References:

Brenner, D. J., J. Rodrigues Neto, A. G. Steigerwalt, and C. F. Robbs.  1994.  “Erwinia nulandii” is a subjective synonym of Erwinia persicina.  International Journal of Systematic Bacteriology 44: 282-284.

Diánez, F., Santos, M., Font, I., de Cara, M., & Tello, J. C.  (2009). New host for the enterobacterial phytopathogen Erwinia persicina. In A. Mendez-Vilas (Ed.), Current research topics in applied microbiology and microbial biotechnology (pp. 78–82). Singapore: World Scientific Publishing Co. Pte. Ltd. [Abstract only]

González, A. J., J. C. Tello, and M. de Cara.  2005.  First report of Erwinia persicina from Phaseolus vulgaris in Spain.  Plant Disease 89: 109.

González, A. J., J. C. Tello, and M. R. Rodicio.  2007.  Erwinia persicina causing chlorosis and necrotic spots in leaves and tendrils of Pisum sativum in southeastern Spain.  Plant Disease 91: 460.

Harada, H., H. Oyaizu, Y. Kosaka, and H. Ishikawa.  1997.  Erwinia aphidicola, a new species isolated from pea aphid, Acyrthosiphon pisum.  Journal of General and Applied Microbiology 43: 349-354.

Marín, F., M. Santos, F. Carretero, J. A. Yau, and F. Diánez.  2011.  Erwinia aphidicola isolated from commercial bean seeds (Phaseolus vulgaris).  Phytoparasitica 39: 483-489. https://doi.org/10.1007/s12600-011-0190-4

Schuster, M. L., A. M. Schuster, and D. S. Nuland.  1981.  Erwinia nulandii, a new bacterium pathogenic for beans (Phaseolus vulgaris L.).  Fitopatologia Brasileira 6: 345.

USDA.  2017.  Email from J. H. Bower, USDA APHIS, to S. Brown, CDFA, (and others).  Subject: Fw: Positive: two (2) samples for Erwinia aphidicola from CA (new U.S. record).  Sent: Monday, November 20, 2017, 10:42 am.

Zhang, A., and Z. Nan.  2014.  Erwinia persicina, a possible new necrosis and wilt threat to forage or grain legumes production.  European Journal of Plant Pathology 139: 349-358.


Responsible Party:

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.


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Posted by ls

Phytophthora cactorum (Lebert & Cohn) J. Schröt. 1886

California Pest Rating Proposal for
Phytophthora cactorum (Lebert & Cohn) J. Schröt. 1886
Pest Rating: B

 


PEST RATING PROFILE
Initiating Event:

None.  The current risk and status of Phytophthora cactorum in California are reassessed and a permanent rating is proposed.

History & Status:

Background:  Phytophthora cactorum is an oomycete pathogen that has a very wide host range and can cause a wide range of disease symptoms including, root rot, collar and crown rot, fruit rot, and stem canker, usually in conjunction with other Phytophthora spp. in its hosts.  Phytophthora root and crown rot disease are among the most important soilborne diseases of stone fruits (Brown & Mircetich, 1995).  It is widespread in temperate regions of all continents and occurs in soils of natural forests, agricultural fields and orchards.  It can persist and spread in different environments and is capable of surviving in the soil as a saprophyte and by producing resting spores.

Phytophthora cactorum is widespread in California and has been found in several counties (see: “California Distribution”).  In California, P. cactorum has been found in several hosts: apple, avocado, apricot, American plum, European plum, Japanese plum, Myrobalan plum, sour cherry, sweet cherry, sweet almond, Mabaleb cherry, cherry laurel, peach, nectarine, pear, Southern California walnut, Northern California walnut, English walnut, strawberry, oval kumquat, sweet orange, kiwifruit, peony, rose, rhodendron, tomato, garden rhubarb, lilac, lily, calla lily, Didier’s tulip, tulip, garden snapdragon, western vervain, virbinum, blue blossom ceanothus, million bells, safflower, wild oats, daphne, white fir, Pacific madrone, chamise, manzanita, wild oats, coyote brush, incense cedar, beefwood, deodar cedar, eucalyptus, California buckthorn/coffeeberry, buckthorn, California flannelbush, toyon, common hop, holly, spicebush, carob, savin juniper, juniper, English laurel, redbay, Frasier’s photinia, chokeberry, Ponderosa pine, sticky cinquefoil, Formosa fire thorn, fire thorn, California live oak, valley oak, oak, cork oak, southern live oak, Indian hawthorn, redwood, giant sequoia, yew, and sticky monkey flower (French, 1989, CDFA Pest Damage Records).  The pathogen has also been recovered from various habitats including flowing water, stream and ditch banks, residential and public gardens, recreational areas, orchards, forests, and nurseries (Yakabe et al., 2009; CDFA Pest Damage Records).

Hosts: Phytophthora cactorum has a very wide host range of plants belonging to several families including, Aceraceae, Apocynaceae, Apiaceae, Araliaceae, Cactaceae, Cucurbitaceae, Cornaceae, Ebenaceae, Ericaceae, Fagaceae, Geraniaceae, Grossulariaceae, Hippocastanaceae, Juglandaceae, Lauraceae, Liliaceae, Oleaceae, Pinaceae, Proteaceae, Polygonaceae, Rutaceae, Rosaceae, Salicaceae, Solanaceae, Sterculiaceae, and Violaceae (CABI, 2017).

Farr and Rossman (2017) include 1332 records of hosts for Phytophthora cactorum and its synonyms.  Hosts include: Abies alba (silver fir), A. amabilis (Pacific silver fir), A. balsamea (balsam fir), A. balsamea var. phanerolepsis, A. concolor (white fir), A. firma (momi fir), A. fraseri (Fraser fir), A. magnifica var. shastensis (Shasta red fir), A. procera (noble fir), Abies sp., Acacia sp. (wattles/acacias), Acer spp. (maples), Actinidia chinensis (kiwi), A. deliciosa (fuzzy kiwifruit), Adenostoma fasciculatum (chamise), Aesculus hippocastanum (horse chestnut), Aesculus sp. (buckeye and horse chestnuts), Agonis flexuosa (Jervis Bay Afterdark), Alnus glutinosa (common alder/black alder), A. incana (grey alder/speckled alder), A. oregana (Oregon alder), Amygdalus persica (peach), Ananas comosus (pineapple), Anemone coronaria (poppy anemone/Spanish marigold), Angelica sp. (angelica), Annona cherimola (cherimoya), Antirrhinum sp., A. majus (snapdragon), Aquilegia sp. (columbine), Aralia cordata (spikenard), A. elata (Japanese angelica-tree), Arbutus menziesii (Pacific madrone/madrone), Arctostaphylos spp. (manzanita), Aster spp. (asters), Aucuba japonica (spotted laurel/Japanese laurel), Avena fatua (common wild oat), Baccharis pilularis (coyote brush),  Banksia spp. (banksia), Begonia sp. (begonia), Beta vulgaris var. crassa (beets), Betula lutea (yellow birch), B. pendula (silver birch), Betula sp. (birch), Boehmeria spp. (false nettles), Brassica oleracea var. bullata (Brussel sprouts), Brassica sp. (mustard), Brassolaeliocattleya sp. (orchid), Bryophyllum pinnatum (airplant), Buxus sp. (boxwood), Cactus sp., Calceolaria integrifolia (bush slipperwort), Calceolaria sp. (sweetshrub), Calibrachoa sp. (million bells), Callistephus chinensis (China aster), Calocedrus decurrens (California incense cedar), Calycanthus floridus (eastern sweetshrub), C. occidentalis (spicebush), Calytrix angulata (yellow starflower), Capsicum annuum (cayenne pepper), C. frutescens (chili pepper), Carica papaya (papaya), Carthamus tinctorius (safflower), Carya illinoinensis (pecan), Castanea sativa (sweet chestnut), Castanea sp., Casuarina sp. (beefwood), Catharanthus roseus (Madagascar periwinkle), Ceratonia siliqua (carob), Cereus spp., Cattleya sp. (cattleya orchid), Ceanothus thyrsiflorus (blue blossom ceanothus), Cedrus deodara (deodar cedar), Ceratonia siliqua (carob tree),  Chamaecyparis spp. (false cypress), Chrysalidocarpus lutescens (areca palm/butterfly palm), Chrysanthemum spp., Citrullus lanatus (watermelon; syn. C. vulgaris), Citrus aurantium (bitter orange), C. grandis (pomelo; syn. C. maxima), C. limon (lemon), C. limonia (Mandarin lime), C. sinensis (sweet orange), Citrus sp., Clarkia spp., Cleome spp.,  Cocos nucifera (coconut), Cornus sp. (dogwood), C. sericea (western dogwood), Cucumis  melo var. inodorus (Kolkhoznitsa melon), C. melo var. reticulatus (galia melon), C. sativus (cucumber), C. pepo (field pumpkin), Dahlia sp., Daphne cneorum (rose daphne/garden flower), D. mezereum (February daphne), D. odora (winter daphne), Daphne sp., Dendrobium sp. (dendrobium orchid), Dianthus caryophyllus (carnation), Daucus carota (carrot), Diospyros kaki (persimmon), Diplacus aurantiacus (syn. Mimulus aurantiacus, sticky monkeyflower), Eriobotrya japonica (loquat), Echinochloa crusgalli (barnyardgrass), E. eyriesii, Epidendrum spp. (Epidendrum orchids), Erica hyemalis (cape heath), Eucalyptus spp., Fagus sp. (beeches) F. sylvatica (common beech), Fragaria spp. (strawberry), F. ananassa (strawberry), F. chiloensis (Chilean strawberry), F. vesca (wild strawberry), Frangula californica (coffeeberry/California buckthorn), Fraxinus spp., (ash), Fremontia californica (California flannelbush; syn. Fremontodendron californicum (California flannelbush), Fremontia sp., F. mexicanum (Mexican flannelbush), Fortunella margarita (oval kumquat), Galeandra baueri (orchid), Gladiolus sp., Glycine max (soybean), Hesperocyparis macrocarpa (syn. Cupressus macrocarpa, Monterey cypress), Heteromeles arbutifolia (toyon), Hibiscus spp. (rosemallows), Humulus lupulus (common hop), Ilex sp. (holly), Juglans californica (California black walnut), J. hindsii (Northern California walnut/Hinds’ black walnut), J. nigra (black walnut), J. pyriformis, J. regia (English walnut), Juglans sp., Juniperus procera (African juniper), J. sabina (savin juniper), Juglans. sp., Kalanchoe spp., Lactuca sativa (lettuce), Laeliocattleya sp. (orchid), Lilium spp. (lily), Lycopersicon esculentus (tomato; syn.  Solanum lycopersicum), Malus domestica (apple), Malus sp., M. sylvestris (European crab apple), Mespilus germanica (medlar), Panax quinquefolius (American ginseng), Pelargonium spp. (pelargonium), Paeonia lactiflora (Chinese peony/common garden peony), Paeonia spp. (peony), Panax spp. (ginseng), Persea americana (avocado), P. borbonia (redbay), Photinia spp. (photonia/chokeberry), Picea spp. (spruce), Pinus spp. (pine), Populus alba (silver-leaf poplar), Potentilla glandulosa (syn. Drymocallis glandulosa, sticky cinquefoil), Prunus armeniaca (apricot/American plum), P. avium (sweet cherry), P. cerasus (sour cherry), P. dulcis (almond; syn. P. amygdalus), P. ilicifolia (hollyleaf cherry/evergreen cherry), P. laurocerasus (cherry laurel/English laurel), P. mahaleb (mahaleb cherry), P. mume (Chinese plum/Japanese apricot), P. persica (peach), P. persica var. nucipersica (nectarine), P. salicina (Japanese plum), Prunus sp., Pyracantha coccinea (scarlet firethorn), , P. koidzumii (Formosa firethorn), Pyracantha sp. (fire thorn), Pyrus communis (European pear), Quercus agrifolia (California live oak/coast live oak), Q. falcata (southern red oak), Q. lobata (valley oak), Q. petraea (durmast oak), Q. robur, (English oak), Quercus sp., Q. suber (cork oak), Q. virginiana (live oak), Rhamnus (Frangula) californica (California coffeeberry), Rhaphiolepis indica (Indian hawthorn), Rheum rhaponticum (false rhubarb), Rheum hybridium (rhubarb), Rhododendron spp., (azalea), Ribes spp., (currants), R. lobbii (Lobbs gooseberry), R. uva-crispa (gooseberry), Rosa sp. (rose), Salix sp. ( willow), Sequoiadendron giganteum (giant sequoia), Solanum (nightshade), S. lycopersicum (tomato), Syringa vulgaris (lilac), Syringa sp., Taxus sp. (yew), Theobroma cacao (cocoa), Tulipa sp. (tulip), Tulipa gesneriana (Didier’s tulip), Viola sp. (violet), Vanda sp. (Vanda orchid), Verbena sp., V. lasiostachys (western vervain), Viburnum spp., Vicia faba (fava bean/broad bean), Vicia sp. (vetch), V. unguiculata, Vigna unguiculata (cowpea; syn. V. sinensis), V. cylindrica (catjang), V. sesquipedalis (yardlong bean), Vitis vinifera (grape ), Zea mays (corn), Zantedeschia sp. (calla lily) (CABI, 2017; Farr & Rossman, 2017; French, 1989; CDFA Pest Damage Records).

Symptoms: Phytophthora cactorum attacks a wide range of host plants causing varied symptoms, depending on the host.  Symptoms include root rot, collar and crown rot, fruit rot, stem cankers, leaf blight, wilts and seedling blights.  This pathogen can cause pre- and post-emergence damping-off disease in several plant species.  It has been reported to reduce sprouting and kill seedlings of beech, and cause seedling blight in Pinus spp., Salix scoulerana, and Robinia spp. (CABI, 2017).

On apple, pear and other woody hosts, P. cactorum causes crown, collar and root rot.  Crown rot affects rootstock tissue from the graft union down to the tips of the primary roots, whereas collar rot affects the scion above the graft union or slightly above the soil line.  Root rot refers to symptoms that appear beyond the proximal junction of primary roots to crown tissue (Cox, 2014).   Above ground symptoms are indicative of an impaired root system and include general stunting with reduced terminal growth and small, chlorotic leaves.  Symptom expression depends on the amount of infected crown or root tissue and their rate of destruction.  Young trees are usually killed by the pathogen since their root systems and crown regions are not as developed as those of mature trees.  Generally, crown rots advance rapidly and trees fall and die soon after the first warm spring.  Their leaves wilt, dry, and remain attached to the tree (Adaskaveg et al., 2009; Gubler & Teviotdale, 2009).  Trees with root rot slowly decline and eventually die over several seasons. At early stages of tree decline, removing the bark reveals orange to reddish brown necrotic lesions in cambium tissue.  A thin, dark delineated margin is evident at the junction of healthy tissue and the expanding lesion which, over time, turns dark brown as it gets colonized by secondary fungi and bacteria.  Symptoms can extend through the root system resulting in a lack of fibrous and feeder roots.  Crown lesions can extend to the primary roots and up to the graft union, while collar lesions can extend up to a meter up from the graft union.  On dissection, collar infections may appear striped in the inner phloem tissue and, sometimes, result in weeping though cracked barked tissue (Cox, 2014).   Phytophthora cactorum also causes fruit rot in apple and pear, producing pale olive and dark brown lesions in apple and pear respectively.  Those lesions are diffusely marbled or uniformly colored with softly delineated margins (Covey et al., 2014).

In Rhododendrons affected by Phytophthora root rot, roots become necrotic and leaves turn chlorotic, wilt, roll downwards parallel to the midrib, and eventually turn brown.  In contrast, leaves of infected azalea become chlorotic, and then necrotic, but seldom wilt. Necrotic leaves eventually drop to the ground (Hoitink et al., 2014).

Infected trees may develop cankers on the stem or near the soil line with discoloration of infected bark, sometimes extending into the internal tissues (CABI, 2017).

Phytophthora cactorum can cause crown rot and root rot of strawberries.  Initial symptoms typically include plant stunting and small leaves.  Later, infected plants may collapse rapidly or gradually.  When cut open, brown discoloration of the crown vascular tissue or entire tissue is apparent.  While other Phytophthora species may be involved, P. cactorum is the most common species on strawberry (Koike et al., 2008).  Fruit is also infected by P. cactorum resulting in leather rot disease.  On green fruit, symptoms appear as dark brown areas or green areas with brown margins.  As the rot spreads, the entire fruit turns brown with a rough texture that appears leathery. Infected mature fruit may be slightly discolored or turn brown to dark purple.  Internally, vascular tissue to each seed is darkened, and in later stages of decay mature fruit becomes leathery.  Infected fruit have unpleasant odor and taste.  Under moist conditions, white mycelial growth may be present on the surface of fruit.  Green and mature fruit eventually become shriveled mummies (Ellis & Madden, 1998).

Disease development: P. cactorum can survive for several years, mainly as oospores (sexual spores) in soil and mummified fruit. The pathogen can also survive as chlamydospores (thick-walled asexual spores) (Erwin & Ribeiro, 1996) in orchard soil or mycelium in host tissue (Cox, 2014).  Similar to other Phytophthora spp., P. cactorum lives as a saprophyte in litter and in soil containing dead organic material and is favored by moist and moderate climates. In spring, and in saturated soil, oospores germinate to produce sporangia.  In free water, zoospores are produced within sporangia and liberated into water.  While oospores and chlamydospores form the primary inoculum, sporangia are the principal source of secondary inoculum (CABI, 2017).  Free water is required for infection, however, a high incidence of disease can occur with as little as 2 hours or less of wetness at 17-25°C.  Optimum temperature for infection is 21°C.   The most favorable temperatures for sporangia production are between 15 and 25°C, and optimally at 20°C.  No sporangia are produced at 10 and 30°C (Ellis & Madden, 1998).   Sporangia can germinate directly or indirectly by producing zoospores.  Zoospores allow a population to increase rapidly and disperse widely in films of free water.  Zoospores are expelled from sporangia under suitable temperature and moisture conditions and swim by means of their flagella towards their host in response to root exudates.  Once a zoospore comes in contact with a root it germinates producing a germ tube which penetrates the root directly under waterlogged soil conditions.   More mycelium develops and eventually, oospores (sexual spores) are produced and serve as resting structures that can survive for several years.  (CABI, 2017).

Transmission: Like most Phytophthora species, P. cactorum is soil-borne and water-borne and may be spread to non-infected sites through infected plants, nursery and planting stock, and seedlings, soil, run-off and splash irrigation and rain water, and contaminated cultivation equipment, tools, and boots.  Under high moisture and windy conditions, sporangia may be airborne and important in spread of diseases such as leather rot of strawberry.  The pathogen is not seed-borne but can be spread by infected seedlings and through soil or plant debris containing oospores or chlamydospores contaminating seed samples (CABI, 2017).  Furthermore, irrigation water from canals, rivers, and ponds can be contaminated with Phytophthora spp. (Brown & Mircetich, 1995).

Damage Potential: Specific crop losses caused by Phytophthora cactorum alone may be difficult to assess as more than one species of Phytophthora may cause diseases with symptoms similar to those caused by P. cactorum and may be present in infected hosts. Nevertheless, P. cactorum is a serious pathogen of a wide range of plant species. Infections of 88-97% apple and pear nursery stock material in commercial nurseries has been reported (Jeffers & Aldwinckle, 1988), and P. cactorum has been frequently detected in several ornamental nurseries within California (Yakabe et al., 2009).  Therefore, nurseries may be at risk and need to be monitored for this pathogen to ensure production and planting of disease-free nursery stock.

California’s native vegetation is also at risk of root and crown rot caused by P. cactorum and other Phytophthora spp., many of which are endemic (limited) to California, while some are rare, endangered, or threatened plants, e.g., Ribes spp. (currant/gooseberry), Monterey cypress, and Arctostaphylos spp. (manzanita) (Calflora, 2017; CNPS, 2017).  Introduction of Phytophthora species are a threat to plant health in Bay Area restoration sites, where nursery stock is planted for flood control or to mitigate environmental impacts.   Detections on madrone, toyon, oaks, sticky monkeyflower, and manzanitas in native stands indicate that P. cactorum is capable of becoming established in a variety of native plant habitats under a range of soil and environmental conditions and can have negative impacts on native vegetation.

Worldwide Distribution: Asia: China, India, Indonesia, Iran, Israel, Japan, Korea DPR, Republic of Korea, Laos, Lebanon, Malaysia, Pakistan, Philippines, Taiwan, Turkey, Vietnam; Africa: Egypt, Kenya, Morocco, Senegal, South Africa, Tunisia, Zimbabwe; North America: Bermuda, Canada, Mexico, USA; South America: Argentina, Brazil, Chile, Colombia, Peru, Uruguay, Venezuela; Europe: Austria, Belgium, Bulgaria, Croatia, Czech Republic, (former) Czechoslovakia, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Lithuania, Netherlands, Norway, Poland, Romania, Russian Federation, Russia (European), Serbia, Slovenia, Spain, Sweden, Switzerland, United Kingdom; Oceania: Australia, New Zealand; Central America and Caribbean: Cuba, El Salvador, Trinidad and Tobago (CABI, 2017; EPPO, 2017).

In the USA, Phytophthora cactorum has been reported from California, Florida, Maine, Michigan, Minnesota, New York, North Carolina, Ohio, South Carolina, Tennessee, Virginia, Washington (CABI, 2017; EPPO, 2017).

Official Control:  Presently, Phytophthora cactorum is the “Harmful Organism Lists” for Egypt, French Polynesia, Guatemala, India, Israel, Lebanon, and Nicaragua, while, Phytophthora spp. is on the “Harmful Organism Lists” for Canada, French Polynesia, Mexico, Namibia, Seychelles, South Africa, and the Bolivarian Republic of Venezuela (USDA PCIT, 2017).

California Distribution: Phytophthora cactorum is widely distributed within California.  From 2001-July, 2017, the pathogen was detected in Alameda, Butte, Contra Costa, Imperial, Los Angeles, Marin, Merced, Monterey, Placer, Sacramento, San Diego, San Francisco, San Mateo, Santa Barbara, Santa Clara, Santa Cruz, Siskiyou, Solano, Sonoma, and Stanislaus Counties (CDFA Pest Damage Records).

California Interceptions:  None reported.

The risk Phytophthora cactorum would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Phytophthora cactorum has already established a large distribution under moist and cool to warm climates in California.

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 pathogen has a very wide host range.

Evaluate the host range of the pest.

Score: 3

– 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: Phytophthora cactorum, like other Phytophthora, has high reproductive capability under moist conditions.  It is dependent on moisture for spore dissemination and plant infection.  It is soilborne and may be spread to non-infected sites through infected plants, nursery and planting stock, and seedlings, soil, run-off and splash irrigation and rain water, and contaminated cultivation equipment, tools, boots, rivers, canals, and ponds.  Therefore, it is given a high rating in this category.

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: Damage caused by Phytophthora cactorum alone may be difficult to assess as more than one species of Phytophthora may be associated with root and crown rot of host tree.  Nevertheless, cactorum is a serious pathogen affecting production of several economically important hosts including, apple, pear, stone fruits, strawberry, ornamentals, and California native plants.  Nursery productions could be at risk. Controlling the disease would include soil water management and use of resistant varieties, thereby requiring changes in cultural practices and increase in crop production costs.

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

Economic Impact: A, B, 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: In conjunction with other Phytophthora, P cactorum may be a contributor to root and crown disease of environmental plants. California’s native vegetation is at risk of root and crown rot damage caused by P. cactorum and other Phytophthora spp.  Certain native plants are endemic (limited) to the State, while some are rare, endangered, or threatened.  The pathogen is capable of becoming established in a variety of native plant habitats under a range of soil and environmental conditions and can have negative impacts on native vegetation.  Its association alone and with other Phytophthora spp. in infected forest and native tree and shrub hosts could result in lowered biodiversity, disrupted natural communities, and critical habitats.  Also, it may significantly impact ornamental plantings and home/urban gardening.

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

Environmental Impact: A, B, C, 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 Phytophthora cactorum:

Add up the total score and include it here. 14

-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:

Score: (-3)

-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 = 11

Uncertainty:  

None.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Phytophthora cactorum is B.


References:

Adaskaveg, J. E., J. L. Caprile, W. D. Gubler, B. L. Teviotdale.  2009.  Cherry: Phytophthora root and crown rot, pathogen: Phytophthora spp.  UCIPM Statewide Integrated Pest Management Program, University of California Agriculture & Natural Resources.  http://ipm.ucanr.edu/PMG/r105100711.html

Browne, G. T., and S. M. Mircetich.  1995.  Phytophthora root and crown rots.  In Compendium of Stone Fruit Diseases, Eds: J. M. Ogawa, E. I. Zehr, G. W. Bird, D. F. Ritchie, K. Uriu, and J. K. Uyemoto.  APS Press, The American Phytopathological Society. Pages 38-40.

CABI.  2017.  Phytophthora cactorum (apple collar rot) full datasheet.  Crop Protection Compendium. http://www.cabi.org/cpc/datasheet/40953

Calflora.  2017.  Information on California plants for education, research and conservation. [Web application]. 2017. Berkeley, California. The Calflora Database [a non-profit organization].  http://www.calflora.org/

CNPS.  2017.  Inventory of rare and endangered plants of California (online edition, v8-03 0.38).  California Native Plant Society, Rare Plant Program. Website http://www.rareplants.cnps.org [accessed 10 August 2017].

Covey, R. P. Jr., and D. C. Harris; revised by K. Cox.  2014.  Phytophthora fruit rot.  In Compendium of Apple and Pear Diseases and Pests Second Edition Eds. T. B. Sutton, H. S. Aldwinckle, A. M. Agnello, J. F. Walgenbach.  APS Press, The American Phytopathological Society.  Pages 41-42.

Cox, K.  2014.  Phytophthora collar, crown, and root rots.  In Compendium of Apple and Pear Disease and Pests Second Edition Eds: T. B. Sutton, H. S. Aldwinckle, A. M. Agnello, J. F. Walgenbach.  Pages 63-65.

EPPO.   2017.   Phytophthora cactorum (PHYTCC).  PQR database.  Paris, France: European and Mediterranean Plant Protection Organization.  https://gd.eppo.int/

Ellis, M. A., and L. V. Madden.  1998.  Leather rot.  In Compendium of Strawberry Diseases Second Edition Ed. J. L. Maas.  APS Press, The American Phytopathological Society.  Pages 33-35.

Erwin, D. C., and O. K. Ribeiro.  1996.  Phytophthora Diseases Worldwide. St Paul, Minnesota, USA: American Phytopathological Society Press.

Farr, D. F., and A. Y. Rossman.  2017.  Fungal Databases, U.S. National Fungus Collections, ARS, USDA. Retrieved July 31, 2017, from https://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).

Gubler, W. D., and B. L. Teviotdale.  2009.  Apple, Phytophthora root and crown rot (updated 3/2009).  UCIPM, University of California Agriculture & Natural Resources, Statewide Integrated Pest Management Program.  http://ipm.ucanr.edu/PMG/r4100511.html

Hoitink, D. M. Benson, and A. F. Schmitthenner; revised by D. M. Benson and S. N. Jeffers.  2014.  Phytophthora root rot.  In Compendium of Rhododendron and Azalea Diseases and Pests Second Edition Eds: R. G. Linderman and D. M. Benson.  Pages 5-10.

Jeffers, S. N., and H. S. Aldwinckle.  1988.  Phytophthora crown rot of apple trees: sources of Phytophthora cactorum and P. cambivora as primary inoculum. Phytopathology, 78: 328-335

Mircetich, S. M., and M. E. Matherton.  1976.  Phytophthora root and crown rot of cherry trees.   Phytopathology 66: 549-558.

USDA PCIT.  2017.  USDA Phytosanitary Certificate Issuance & Tracking System. Retrieved June 6, 2017. 11:48:29 am CDT.  https://pcit.aphis.usda.gov/PExD/faces/ReportHarmOrgs.jsp.

Yakabe, L. E., C. L. Blomquist, S. L. Thomas, and J. D. MacDonald.  2009.  Identification and frequency of Phytophthora species associated with foliar diseases in California ornamental nurseries.  Plant Disease, 93: 883-890.


Responsible Party:

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:

August 25, 2017 – October 9, 2017


NOTE:

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 PEST RATING: B


Posted by ls

Uromyces transversalis

California Pest Rating for
Uromyces transversalis (Thüm.) G. Winter
Pest Rating: C

 


PEST RATING PROFILE
Initiating Event:  

None.  The status of Uromyces transversalis in California, is updated and the current rating is reviewed.

History & Status:

Background:  Uromyces transversalis is an autoecious rust pathogen that causes rust disease, commonly known as gladiolus rust, only in members of the family Iridaceae, including Gladiolus, Tritonia, Crocosmia, and Watsonia spp.  Gladiolus is the major host of the pathogen, while the other hosts are of lesser economic importance.  Of six rust pathogens that can infect gladiolus, U. transversalis is the most economically damaging one.

Uromyces transversalis is indigenous to eastern and southern Africa, where it was first detected on leaves of Tritonia securigera in 1876.  Almost a century later, the pathogen spread to the Mediterranean region and southern Europe.  During the 1960-70s it was reported from France, Italy, and Morocco, and from England by 1996 (USDA APHIS PPQ, 2007).

Gladiolus rust was first detected and confirmed in the United States in April 2006, from a gladiolus production farm in Manatee County, Florida, and later, in another commercial gladiolus farm in Hendry County, Florida (USDA APHIS PPQ, 2007).  Then, in May 2006, gladiolus rust was detected on hybrid gladiolus plants in a home garden in San Diego, California.  Consequently, an intensive 23 square mile survey was conducted and the rust pathogen was detected at one commercial nursery and two other residential sites (Blomquist et al., 2007).  Since 2006, the pathogen has been repeatedly detected in Florida and California.  The source of introduction of Uromyces transversalis into the USA is unknown.  The pathogen is known to occur in Mexico and has been intercepted in numerous shipments of cut flowers from Mexico dating back to 2004.  The initial detection in Florida was the result of trace-back investigations following an interception of rust-infected flowers in Hawaii that originated in Florida.  Infected Florida-produced gladiolus flowers were intercepted in Minnesota in 2008, which had, likewise, originated from one of the original infected Florida gladiolus producers (Preston, 2009).

In California, to date, the disease has been detected in over 680 samples submitted to the CDFA Plant Pest Diagnostics Laboratory.  Samples have come primarily from landscapes associated with residences, businesses, and municipalities from no fewer than twelve California counties, ranging from Solano County and San Francisco County in the northern region to San Diego County in the southern region where it was originally detected.  Samples have come from no fewer than 38 different California cities (CDFA Pest Detection Reports).  The wide distribution indicates that Gladiolus Rust is well beyond the possibility of eradication in California, and is, instead, a management issue.

In August 2006, the gladiolus rust pathogen, Uromyces transversalis, was deemed as actionable and reportable by the USDA.  In 2007, federal and state action was taken in accordance with the USDA APHIS’ ‘Gladiolus Rust National Eradication and Management Plan’ (USDA, 2007), whenever the pathogen was detected in commercial growing areas, domestic commerce, and residential areas.  The decision to go that route was made when the pathogen was still believed to be limited in distribution in Florida and California and eradication was thought to be feasible.    However, on May 15, 2015, APHIS revised the domestic response requirements for U. transversalis to no longer take domestic action or require others to take action when gladiolus rust is found in commercial growing areas, domestic commerce, and residential areas.  This revision was made because the pathogen has spread to the limit of its natural range, based on its current distribution, known biology, and plant hardiness zones in the United States.  However, APHIS will continue to regulate other gladiolus rust pathogens that are known to occur in the United States (USDA, 2015).

Transmission:  The primary pathways for introduction of the pathogen are by shipments of infected plants and cut flowers. Interceptions from commercial shipments and passenger baggage at ports-of-entry in Arizona, California, and Texas confirmed that cut flowers are the major pathway of gladiolus rust from other countries (USDA APHIS, 2007). A significant anecdotal observation of the close proximity of residential infections with cemeteries also comes as no surprise, considering the propensity of the public to use gladiolus cut flowers to decorate grave sites.  Long distance and local spread is by wind-blown spores. These airborne spores are easily dispersed by lightly brushing a symptomatic plant and can be spread by surface-contaminated clothing, equipment, corms, rhizomes, and flowers (USDA APHIS PPQ, 2007).

Symptoms: Symptoms are typical for a rust disease, with yellowish-brown (uredinia) or blackish-brown (telia) pustules on the leaves, either solitary or aggregated.  Uredinia develop first and produce urediniospores, followed by development of the telia, which produce teliospores.  Initial symptoms of gladiolus rust are the appearance of small, yellowish spots.  Later, the epidermis bursts open exposing pustules full of yellowish- orange spores.  Over time, pustules coalesce to form large lesions.  Rust pustules normally form on foliage, on both sides, but under heavy disease pressure, can also form on flower spikes. Severely infected plants fail to even flower or produce mature corms. The pustules are formed in lines that run “transversely” across the leaf veins (as opposed to round or amorphous pustules, as is normally the case with most rust fungi on monocots whose sori run longitudinally along the vein of the leaf).  These unique transverse pustules are useful for making field identifications of the rust (USDA, 2007; USDA APHIS PPQ, 2007).

Hosts:  All hosts belong to the family Iridaceae.  The primary/major host is Gladiolus hybrids (sword lily/gladiolus). Minor hosts include, Crocosmia aurea (falling stars), Freesia refracta (common freesia), Tritonia sp. (flame freesia), T. lineata, T. securigera, T. squalida, Watsonia sp. (bugle lily), W. angusta, W. densiflora, W. meriana, and W. borbonica (CABI, 2017; EPPO, 2017; Farr & Rossman, 2017).

Damage Potential:  Gladiolus rust is a serious disease in nurseries and, if left uncontrolled, can completely destroy commercial gladiolus crops.  Severely damaged plants do not flower and/or their corms do not ripen (USDA APHIS PPQ, 2007).  There are efficacious fungicides available that can control the pathogen, however the frequent treatments necessary to protect the product can be costly for producers (Schwartzburg, 2006).  Furthermore, gladiolus rust can be controlled with best management practices (USDA, 2015).

The pathogen has only rarely been found in commercial settings in California, possibly because production managers have taken pro-active measures to protect their crops against the pathogen by frequent scouting and preventive fungicide treatments.  An example of this is a large gladiolus cut flower producer in Santa Barbara County that is virtually surrounded by infected residences. The nursery staff routinely inspect and fungicide-treats the crop which is grown from new imported corms each year.  As further protection, a host-free period at the production grounds follows the harvest of the year’s crop (Scheck, 2012).

Worldwide Distribution: Africa: Kenya, Malawi, Mauritius, South Africa, Tanzania, Uganda, Zambia, Zimbabwe; North America: Mexico, USA (California, Florida); Central America and Caribbean: Costa Rica, Cuba, Martinique; South America: Argentina, Brazil; Europe: France, Italy, Malta, Spain; Oceania: Australia, New Zealand (CABI, 2017; EPPO, 2017; Farr & Rossman, 2017).

Official Control: Uromyces transversalis is on the ‘Harmful Organism Lists’ for the following countries:  Australia, Chile, China, Colombia, Ecuador, French Polynesia, India, Israel, Republic of Korea, Madagascar, Nauru, New Caledonia, Peru, Tunisia (USDA PCIT, 2017).

California Distribution Alameda, Contra Costa, Los Angeles, Orange, San Diego, San Francisco, San Mateo, Santa Barbara, Santa Clara, Santa Cruz, Solano, and Ventura Counties.

California Interceptions None reported.

The risk Uromyces transversalis would pose to California is evaluated below.

Consequences of Introduction: 

 1) Climate/Host Interaction: The ability for Uromyces transversalis to have suitable hosts and climate in order to establish in California is already illustrated by its state-wide distribution over the past eleven years.

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: Gladiolus is the only major host for Uromyces transversalis.

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: Uromyces transversalis has high reproduction and dispersal potential.

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: Gladiolus Rust is known to lower yields, could increase costs due to fungicide treatments for commercial producers, and could result in quarantines by other states or countries.

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

Economic Impact: 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: Gladiolus rust could impact home/urban garden plantings.

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 Gladiolus Rust:

Add up the total score and include it here. 12

-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 ‘High’. Gladiolus Rust has spread to at least 12 California counties since its first detection in 2006. 

Score (-3)

-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 = 9.

Uncertainty:

None.

Conclusion and Rating Justification:

Based on the evidence provided above the rating for the gladiolus rust pathogen, Uromyces transversalis, is proposed to continue as C.


References:

Blomquist, C. L., S. L. Thomas, J. M. Mckemy, P. A. Nolan, and M. Luque-Williams.  2007.  First report of Uromyces transversalis, causal agent of gladiolus rust, in San Diego County, California.  Plant Disease, 91: 1202.  http://dx.doi.org/10.1094/PDIS-91-9-1202C

CABI.  2017.  Uromyces transversalis (gladiolus rust) full datasheet.  Crop Protection Compendium.  http://www.cabi.org/cpc/datasheet/55868

EPPO.  2017.  Uromyces transversalis (UROMTV).  PQR database.  Paris, France: European and Mediterranean Plant Protection Organization.  https://gd.eppo.int/

Farr, D. F., and A. Y. Rossman. Fungal Databases, U.S. National Fungus Collections, ARS, USDA. Retrieved August 1, 2017, from https://nt.ars-grin.gov/fungaldatabases/

Preston, Catherine (2009) USDA Presentation: Gladiolus Rust, Balancing Eradication Efforts and Growers’ Needs through Regulation. http://dpm.ifas.ufl.edu/plant_pest_risk_assessment/ALS6921%20Presentations/PPQ_GR%20presentation.pdf

Scheck, H.  2012. Communication to Timothy Tidwell, Plant Pathologist, CDFA, from Heather Scheck, Plant Pathologist, Santa Barbara County Department of Agriculture (in 2012).

Schwartzburg, K. 2006. NPAG Report Uromyces transversalis (Thüm.) G. Winter 1884: Gladiolus Rust.

USDA, 2007. Gladiolus Rust (Uromyces transversalis): A National Management Plan for Exclusion and Eradication.  GR Plan Original, February 28, 2007.

USDA.  2015.  APHIS revives response to domestic detections of gladiolus rust caused by Uromyces transversalis.  DA-2015-20, dated May 13, 2015 to State and Territory Agricultural Regulatory Officials.

USDA APHIS PPQ.  2007.  Pest Alert.  Gladiolus rust: a new threat.  United States Department of Agriculture Animal and Plant Health Inspection Service Plant Protection and Quarantine.  APHIS 81-35-011.

USDA PCIT.  2017.  USDA Phytosanitary Certificate Issuance & Tracking System. August 1, 2017, 4:03:49 pm CDT.  https://pcit.aphis.usda.gov/PExD/faces/ReportHarmOrgs.jsp.


Responsible Party:

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

8/14/ 2017 – 9/28/ 2017


Pest Rating: C


Posted by ls

Septoria protearum Viljoen & Crous 1998

California Pest Rating for
Septoria protearum Viljoen & Crous 1998
Pest Rating: B

 


PEST RATING PROFILE
Initiating Event:

On March 29, 2017, lavender (Lavendula sp.) plants showing symptoms of leaf spots were detected in a nursery in San Luis Obispo County by County Agricultural officials.  A sample of diseased leaves was sent to the CDFA Plant Pathology Laboratory for diagnosis.  On May 8, 2017, Suzanne Latham, CDFA plant pathologist, identified the fungal pathogen, Septoria protearum associated with the diseased leaf tissue.  The pathogen was assigned a temporary Q rating.  Subsequently, the consequences of introduction and establishment of S. protearum in California are assessed and a permanent rating is proposed herein.

History & Status:

Background:   Septoria protearum is a fungal pathogen that causes leaf spot disease in host plants.  Septoria protearum is the asexual (anamorph) stage, for which the sexual stage or teleomorph is not known.  Verkley et al., (2013) included the pathogen S. pistaciae as a synonym of S. protearum since it could not be robustly distinguished based on a seven-gene phylogenetic analysis.  Crous et al., (2013) stated that further study and inoculation trials are needed to confirm synonymy of the two species.  Also based on DNA evidence, Verkley et al., (2013) reported multiple host family associations for S. protearum, which is unusual for other species of the genus.  Farr & Rossman (2017) included hosts of S. protearum in genera belonging to nine families. The current CDFA detection of the pathogen in lavender, increases the number of represented families to ten.  Septoria pistaciae (syn. S. protearum according to Verkley et al., 2013) was previously reported from a pistachio orchard in California (Farr et al., 1989; Michailides, 2005).

Disease development: While there is no specific information on the disease development of Septoria protearum (Michailides, 2005), it is likely to be similar to that of other species in the genus.  Generally, Septoria spp. overwinter as mycelium and as conidia (asexual spores) within pycnidia (asexual fruiting structures) on or in seed and on diseased plant debris left in the field.  Infected seeds produce infected seedlings that may result in damping-off or provide inoculum for subsequent infections.  When pycnidia in infected plant debris become wet, they swell and conidia are exuded in long tendrils and thereafter, spread by splashing rain, irrigation water, as well as contaminated tools and animals.    Septoria species usually require high moisture for infection and severe disease development, however, they can cause disease under a wide range of temperatures (10-27°C) (Agrios, 2005).  The teleomorph (sexual) stage of S. protearum is unknown.

Dispersal and spread: Infected plants and nursery stock, splashing rain, irrigation water, plant leaf debris, contact with cultivation tools and animals (Agrios, 2005).

Hosts:  Presently, all reported hosts of Septoria protearum are included in several families, viz. Aspleniaceae, Proteaceae, Rutaceae, Rosaceae, Oleaceae, Boraginaceae, Davalliaceae, Anacardiaceae, Aracaceae, and Lamiaceae.  Hosts include: Asplenium ruta-muraria (walrue fern), Boronia denticulata (mauve Boronia), Gerbera jamesonii (Gerber daisy), Geum sp. (Geum), Gevuina avellana (Avellano/Chilean hazelnut), Hedera helix (common ivy/English ivy), Ligustrum vulgare (common privet/ European privet), Masdevallia sp. (Masdevallia), Myosotis sp. (mouse’s ear), Nephrolepis sp. (fern), Pistacia vera (pistachio), Protea cynaroides (king protea), Protea sp. (protea), Skimmia sp. (Skimmia), Zantesdeschia aethiopica (calla lily) (Crous et al., 2008; Farr & Rossman, 2017; Verkley et al., 2013).  In addition, the pathogen was recently detected in Lavendula sp. (lavender; Lamiaceae) (see: ‘Initiating Event’).

Symptoms:  Leaf spots are produced in plants infected by Septoria species.  Leaf spots usually start on the lower leaves and progress upwards,  initiating as small yellowish specks that later enlarge, turn pale brown or yellowish gray, and finally dark brown.  They are usually surrounded by a narrow yellow region and may be circular to irregular.  Affected leaves may turn yellow and eventually die. Numerous small black pycnidia are aggregated and appear as dots within the leaf spots (Agrios, 2005). In pistachio, Septoria protearum produces numerous, subcuticular brown spots, 0.5-1.5 mm on both sides of the leaf, with numerous black pycnidia clustered within the spots.  In California, in pistachio fruit, the pathogen causes distinct grayish to light-brown fruit lesions, 1-4 mm in diameter, surrounded by a bright, distinctly reddish halo and usually located near the peduncle.  Leaf infections have not been observed (Michailides, 2005).

Damage Potential: Quantitative losses due to Septoria protearum have not been reported.  Photosynthetic area can be reduced due to leaf spotting.  In severe infections, leaf wilt, premature leaf drop, and reduced tree vigor may result. Leaf and fruit spots are produced in pistachio.  Leaf spot damage caused by S. protearum may significantly impact production and marketing of nursery ornamental plants.

Worldwide Distribution: Africa: South Africa; Europe: France, Germany, Italy, Netherlands, Spain, Canary Islands; North America: USA (California); Oceania:  New Zealand (Farr & Rossman, 2017).

Official Control:  No official control for Septoria protearum has been reported.  However, currently Septoria spp. is on the ‘Harmful Organism’ list for the Bolivarian Republic of Venezuela (USDA-PCIT, 2017).

California Distribution:  Previous to its current detection, Septoria protearum was reported from a pistachio orchard in California.  Its recent detection was in a nursery in San Luis Obispo County (see “Initiating Event’).

California Interceptions:  None.

The risk Septoria protearum would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Septoria protearum has a diverse range of hosts which largely include several ornamental plant species. While the pathogen may be able to cause disease under cool and warm temperatures, it is dependent on high moisture for infection and severe disease development.  Therefore, it is likely that the pathogen may be able to establish in a larger but limited area of California.

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: Presently, the pathogen has a moderate and diverse range of hosts inclusive of species in ten plant families.

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: Septoria protearum has high reproductive potential however, dispersal of conidia from pycnidia are dependent on wet conditions from splashing rain, dew, and irrigation water. Further artificial spread is caused by use of contaminated tools, animals, etc.  Therefore, a Medium rating is given to this category.

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: Septoria protearum causes leaf and fruit spot in host plants.  In California, it has been found in pistachio.  Other hosts include several nursery-grown ornamental plant species.  While there is no information on quantitative crop loss caused by this pathogen, leaf spot disease could lower crop value and cause loss of markets.  Use of preventive chemical sprays and other control measures could increase production costs.  Avoidance of overhead irrigations would require changes in cultural practices of irrigating plants.

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

Economic Impact: B, C, D

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 pathogen could significantly impact ornamental plantings in home/ urban, public gardens and other recreational environments.

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 Septoria protearum:  Medium (11)

Add up the total score and include it here.

-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 Low.  The pathogen was originally recorded in one pistachio orchard in California (county unknown) and since then has also been found in a nursery in San Luis Obispo.  It is therefore, considered to have a localized distribution within the State.

Score: -1

-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 = 10

Uncertainty:  

Distribution of Septoria protearum in California is not fully known.  Treatments with suppressive fungicides may have kept its spread in check.  Also, a need for further research on taxonomic studies of the species has been mentioned in published literature.  This information, when available, may alter the proposed rating for this pathogen.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Septoria protearum is B.

References:

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

Crous, P. W., B. A. Summerell, L. Mostert, and J. Z. Groenewald. 2008.  Host specificity and speciation of Mycosphaerella and Teratosphaeria species associated with leaf spots of Proteaceae. Persoonia 20: 59-86.

Farr, D. F., and A. Y. Rossman.  2017.  Fungal Databases, U. S. National Fungus Collections, ARS, USDA. Retrieved May 12, 2017, from http://nt.ars-grin.gov/fungaldatabases/

Farr, D. F., G. F. Bills, G. P. Chamuris, and A. Y. Rossman. 1989.  Fungi on Plants and Plant Products in the United States. APS Press. St. Paul, Minnesota.

Michailides, T. J.  2005.  Pest, disease, and physiological disorders management: above ground fungal diseases. In: Pistachio Production Manual, Eds. Beede, R. H., M. W. Freeman, D. R. Haviland, B. A. Holtz, and C. E. Kallsen, Davis, CA. Fruit and Nut Research and Information Center, Department of Plant Sciences, University of California Davis. 214–232 pp.

USDA PCIT.  2017.  USDA Phytosanitary Certificate Issuance & Tracking System. May 12, 2017, 1:43:31 pm CDT.  https://pcit.aphis.usda.gov/PExD/faces/ReportHarmOrgs.jsp.

Verkley, G. J. M., W. Quaedvlieg, H. D. Shin, and P. W. Crous.  2013.  A new approach to species delimitation in Septoria. Studies in Mycology 75: 213-305.

Responsible Party:

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

5/30/2017 – 7/14/2017

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Pest Rating: B


Posted by ls