California Pest Rating for
Colletotrichum asianum Prihastuti, L. Cai & K. D. Hyde, 2009
Pest Rating: B
PEST RATING PROFILE
Initiating Event:
During July, 2014, mango fruit exhibiting spots or lesions were intercepted by the CDFA Dog Team in Santa Clara County and samples of symptomatic fruit were sent to the CDFA Plant Pathology Laboratory for diagnosis. The associated anthracnose fungal pathogen, Colletotrichum asianum, was identified by Suzanne Latham, CDFA plant pathologist and later confirmed by USDA. Subsequently, the fruit was destroyed and the shipment was traced back by the USDA to Florida and C. asianum was detected in fruit still on the tree. This detection marked the first report of the pathogen in the USA (USDA, 2015). Since its first detection and during April and June 2015, C. asianum continued to be detected in mango fruit shipments destined for Alameda, Butte, Los Angeles, Merced, Riverside, Sacramento, San Joaquin, and Santa Clara Counties. The shipments were intercepted at USPS distribution facilities by Dog Teams. On July 7, 2015, C. asianum was found to be associated with necrotic spots in mango leaves of plants in a nursery in Imperial County. This was the first detection of the pathogen from leaves. In all cases of interceptions mentioned afore, subsequent to the detection of C. asianum, all fruit and plant shipments were received from Florida and either destroyed or rejected from entering California. Currently, C. asianum has a temporary ‘Q’ rating. The risk of introduction and establishment of this pathogen in California is assessed and a permanent rating is proposed herein.
History & Status:
Background: Colletotrichum asianum was first reported to be associated with coffee berries (Coffea arabica) in northern Thailand (Prihastuti et al., 2009). The pathogen is a distinct fungus species belonging to the vastly morphological and physiological variable C. gloeosporioides complex and is generally identified from other species of the complex only with DNA sequences (Prihastuti et al., 2009; Weir et al, 2012).
Hosts: Mangifera indica (mango) and Coffea arabica (coffee) (Prihastuti et al., 2009; Weir et al., 21012).
Symptoms: Initially, small, dark brown circular spots are produced on mango fruit and leaves infected with Colletotrichum asianum. These spots increase rapidly in size and coalesce to form dark depressed anthracnose lesions in ripened fruit (Krishnapillai & Wilson Wijeratnam, 2014). 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: Anthracnose disease caused by Colletotrichum asianum 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 production of potted host plants or in greenhouses are particularly at risk as nursery conditions are often conducive to infection by Colletotrichum species. In 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 asianum 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: Africa: South Africa; Asia: Japan, Sri Lanka, Thailand, Philippines; South America: Brazil, Colombia, Panama; Australia; North America: Florida (Farr & Rossman, 2015; Krishnapillai & Wilson Wijeratnam, 2014; Lima et al., 2013; Prihastuti et al., 2009; Sharma et al., 2013; USDA, 2015; Vieira et al., 2014; Weir et al., 2012).
Official Control: In California C. asianum is an actionable, Q-rated pathogen, and infected plant material is subject to destruction or rejection.
California Distribution: Colletotrichum asianum is not established in California (see “Initiating Event”).
California Interceptions: During 2015, Colletotrichum asianum has been intercepted several times mainly in shipments of mango fruit and less frequently in mango plants (leaves) that originated in Florida (see ‘Initiating event’).
The risk Colletotrichum asianum 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 Medium (2) – Similar to other species of Colletotrichum, C. asianum 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. Also limiting is the very narrow host range of C. asianum comprising mango and coffee. Coffee is not cultivated in California and mango has limited production in the foothills of southern California or warm locations in the Coachella Valley. It is also grown in residential backyards and few nurseries, either as fruit or nursery stock. The pathogen could establish within these limited regions under conducive climates.
2) Known Pest Host Range: Evaluate the host range of the pest. Score:
– Low (1) has a very limited host range.
– Medium (2) has a moderate host range.
– High (3) has a wide host range.
Risk is Low (1) – The host range of Colletotrichum asianum is limited to mango and coffee.
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 High (3) – Mango fruit production, in particular, can be limited by its susceptibility to anthracnose under wet conditions. Therefore, under suitable climates, the pathogen could lower plant growth, fruit production and value and trigger the loss of markets.
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 cultural practices or home garden plantings.
Consequences of Introduction to California for Colletotrichum asianum:
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 karstii 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 (0). Colletotrichum asianum is not established in California. All instances of interception of C. asianum-infected mango fruit and plants were either rejected or destroyed.
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:
Periodic surveys need to be conducted to confirm the presence/absence of C. asianum in commercial and private production regions within California. Subsequent results may alter the herein proposed rating for the pathogen.
Conclusion and Rating Justification:
Based on the evidence provided above the proposed rating for the anthracnose pathogen, Colletotrichum asianum is B.
References:
CABI. 2015. Colletotrichum asianum basic datasheet report. Crop Protection Compendium. www.cabi.org/cpc/
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/
Kitterly, W. R., and A. P. Keinath. 1996. Fungal disease of aerial parts: Anthracnose. In ‘Compendium of Cucurbit Diseases’. Edited by T. A. Zitter, D. L. Hopkins, and C. E. Thomas, APS Press The American Phytopathological Society Minnesota, USA, p. 24-25.
Krishnapillai, N., and R. S. Wilson Wijeratnam. 2014. First report of Colletotrichum asianum causing anthracnose on Willard mangoes in Sri Lanka. New Disease Reports, 29:1. http://dx.doi.org/10.5197/j.2044-0588.2014.029.001 .
Prihastuti, H., L. Cai, H. Chen, E. H. C. McKenzie, and K. D. Hyde. 2009. Characterization of Colletotrichum species associated with coffee berries in northern Thailand. Fungal Diversity 39: 89-109.
Sharma, G., M. Gryzenhout, K. D. Hyde, A. K. Pinnaka, and B. D. Shenoy. 2015. First report of Colletotrichum asianum causing mango anthracnose in South Africa. Plant Disease, 99:725. http://dx.doi.org/10.1094/PDIS-08-13-0837-PDN .
USDA. 2015. Email from John H. Bower, USDA ,APHIS, PPQ, PHP to Nick Condos, CDFA, subject: Colletotrichum asianum on mango from CA and from the source tree in FL (first records for Continental US), dated April 30, 2015 6:26 am.
Vieira, W. A. S., S. J. Michereff, M. A. de Morais Jr., K. D. Hyde, and M. P. S. Câmara. 2014. Endophytic species of Colletotrichum associated with mango in northeastern Brazil. Fungal diversity, 67:181-202.
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.
PEST RATING: B
Posted by ls
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