Colletotrichum cordylinicola Phoulivong, L. Cai & K. D. Hyde, 2011

California Pest Rating Proposal for
Colletotrichum cordylinicola Phoulivong, L. Cai & K. D. Hyde, 2011
Pest Rating: B

 


PEST RATING PROFILE
Initiating Event:  

On October 6, 2015 a shipment of Green Ti plant cuttings (Cordyline glauca) showing leaf blight symptoms and destined to a nursery in San Diego County, was intercepted and sampled by San Diego County Agricultural officials.   The shipment had originated in Costa Rica.  Diseased plant samples were sent to the CDFA Plant Diagnostics Branch for diagnosis.  Suzanne Latham, CDFA plant pathologist identified the leaf spot and anthracnose pathogen, Colletotrichum sp. as the cause for the disease. The identity of the associated pathogen was later confirmed to be C. cordylinicola by USDA National Identification Services at Beltsville, Maryland, and marked the first detection of C. cordylinicola in continental USA.  The pathogen was assigned a temporary Q rating by the CDFA and consequently, all infected plant materials were destroyed. The risk of infestation of C. cordylinicola in California is evaluated and a permanent rating is proposed.

History & Status:

Background:  In 2010, Phoulivong et al. first reported the fungal species, Colletotrichum cordylinicola causing anthracnose disease in Cordyline fruticosa in Thailand and Eugenia javanica in Laos. They noted that the isolate from C. fruticosa was not pathogenic to E. javanica and vice versa, and that both strains may represent different pathotypes.  However, Weir et al. (2012), through further molecular analysis placed both isolates within the same species.  Colletotrichum cordylinicola is a distinct fungus species belonging to the vastly morphological and physiological variable C. gloeosporioides and is genetically identified from other species of the complex (Weir et al, 2012). Colletotrichum cordylinicola has not been reported from the USA.  A reported identification of C. cordylinicola detected on Cordyline fruticosa in Florida (Sharma et al., 2014) is considered inconclusive by the USDA APHIS PPQ National Identification Services.

Hosts: Cordyline (Cordyline fruticosa) in the Asparagaceae family, and wax jambu (Eugenia javanica = syn. Syzygium samarangense) in the Myrtaceae family.

SymptomsColletotrichum cordylinicola causes leaf and fruit spots.  Generally, Colletotrichum-infected host plants exhibit symptoms of anthracnose which include dark brown leaf, stem and fruit spots and wilting of leaves which often result in dieback and reduction in plant quality.

Damage Potential:  In general, anthracnose disease of fruits and leaves caused by Colletotrichum spp., can result in reduction in yield quantity and quality of agricultural crops and fruit trees (Phoulivong et al., 2010).  It is, therefore, highly likely that Colletotrichum cordylinicola 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.  Nursery productions of ornamental cordyline and wax jambu plants are particularly at risk as nursery conditions are often conducive to infection by Colletotrichum species.  In open 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 cordylinicola 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:  Colletotrichum cylindricola is distributed in Thailand, Laos, and New Zealand (Farr & Rossman, 2015; Phoulivong et al., 2010; Weir et al., 2012).

Official Control Presently, in California C. cordylinicola is an actionable, Q-rated pathogen, and infected plant material is subject to destruction or rejection.  The pathogen is categorized as ‘reportable’ by the USDA.

California Distribution: Colletotrichum cylindricola is not established in California (see “Initiating Event”).

California Interceptions: There has been one reported interception of Colletotrichum cordylinicola-infected Cordyline glauca plant cuttings. (see ‘Initiating event’).

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

Consequences of Introduction: 

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

Low (1) Not likely to establish in California; or likely to establish in very limited areas.

– Medium (2) may be able to establish in a larger but limited part of California.

– High (3) likely to establish a widespread distribution in California.

Risk is Low (1) – Similar to other species of Colletotrichum cordylinicola requires humid, wet, rainy weather for conidia to infect host plants. The environmental requirements and narrow host range may limit the ability of the pathogen to fully establish and spread under outdoor dry conditions in the State.

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

Low (1) has a very limited host range.

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

Risk is Low (1) – Colletotrichum cylindricola has a limited host range comprising of cordyline (Cordyline fruticosa) and wax jambu (Eugenia javanica) .  Cordyline is an indoor decorative plant that is commonly produced in nursery greenhouses in California. Outdoor cultivation of this plant is not common.  Wax Jambu (Eugenia javanica) may be grown in limited residential and commercial public regions in Southern California..

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

– Low (1) does not have high reproductive or dispersal potential.

– Medium (2) has either high reproductive or dispersal potential.

High (3) has both high reproduction and dispersal potential.

Risk is High (3) – 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.

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

A.  The pest could lower crop yield.

B.  The pest could lower crop value (includes increasing crop production costs).

C.  The pest could trigger the loss of markets (includes quarantines).

D.  The pest could negatively change normal cultural practices.

E.  The pest can vector, or is vectored, by another pestiferous organism.

F.  The organism is injurious or poisonous to agriculturally important animals.

G.  The organism can interfere with the delivery or supply of water for agricultural uses.

– Low (1) causes 0 or 1 of these impacts.

Medium (2) causes 2 of these impacts.

– High (3) causes 3 or more of these impacts.

Risk is Medium (2) –Anthracnose-infected cordyline and wax jambu plants may result in lower crop value and market loss.  .Nursery production of these hosts is particularly at risk as nursery conditions are often conducive to infection by Colletotrichum speciesIts economic impact is evaluated as a medium risk.   

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

A.  The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes.

B.  The pest could directly affect threatened or endangered species.

C.  The pest could impact threatened or endangered species by disrupting critical habitats.

D.  The pest could trigger additional official or private treatment programs.

E.  The pest significantly impacts cultural practices, home/urban gardening or ornamental plantings.

Score the pest for Environmental Impact. Score:

– Low (1) causes none of the above to occur.

Medium (2) causes one of the above to occur.

– High (3) causes two or more of the above to occur.

 Risk is Medium (2) – The pathogen could significantly impact home/urban gardens and ornamental plantings.

Consequences of Introduction to California for Colletotrichum cordylinicola:

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 cordylinicola to California = (9).

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).  Colletotrichum cordylinicola is not established in California. 

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 proposed rating for the anthracnose pathogen, Colletotrichum cordylinicola is B.

References:

Farr, D. F., & A. Y. Rossman.  Fungal databases, systematic mycology and microbiology laboratory, ARS, USDA. Retrieved April 7, 2015, from

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

Phoulivong S., L. Cai, N. Parinn, H. Chen, K. A. Abd-Elsalam, E. Chukeatirote, and K. D. Hyde.  2010.  A new species of Colletotrichum from Cordyline fruticosa and Eugenia javanica causing anthracnose disease.  Mycotaxon 114:247-257.

Sharma K., E. Goss, and Ariena H. C. van Bruggen.  2014.  Isolation and identification of the fungus Colletotrichum cordylinicola causing anthracnose disease on Cordyline fruticosa in Florida.  HortScience 49:911-916.

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.

 


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

The 45-day comment period opened on Wednesday, January 20, 2016 and closed on March 7, 2016.


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

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Pest Rating: B


Posted by ls