Colletotrichum sansevieriae M. Nakamura & M. Ohzono 2006

California Pest Rating for

Colletotrichum sansevieriae M. Nakamura & M. Ohzono 2006

Pest Rating: B

PEST RATING PROFILE

Initiating Event:

On November 11, 2016, diseased Sansevieria sp. plants exhibiting leaf spot symptoms, were intercepted by San Diego County Agricultural officials. The plants had originated in Florida and were destined to a nursery in San Diego County. A sample of diseased leaves was collected and sent by the County to the CDFA Plant Pathology Lab for diagnosis. On December 7, 2016, Suzanne Latham, CDFA plant pathologist, detected Colletotrichum sansevieriae in culture from leaf spots and confirmed the identification by morphological and sequence analyses. Then, on December 19, 2016, C. sansevieriae was detected once again in a shipment of Sansevieria trifasciata plants that had originated in Florida but were destined to a different nursery in San Diego County. The samples submitted to the CDFA Lab had been collected on November 22, 2016 by San Diego County. Consequently, the infested greenhouse-contained, potted Sansevieria plants were treated with fungicidal sprays and continue to be periodically monitored for detection of the pathogen (personal communication: Pat Nolan, plant pathologist, San Diego County). Currently, C. sansevieriae 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 sansevieriae is a fungal pathogen that causes anthracnose disease only in Sansevieria spp. plants (Nakamura et al., 2006). The pathogen was first detected in Sansevieria plants in Japan and soon after reported from Australia (Aldaoud et al., 2010), India (Gautam et al., 2012), USA (Florida; Palmateer et al., 2012), and Korea (Park et al., 2013). Its recent find in a California nursery marked its first detection in for the State.

Hosts: Sansevieria sp. (snake plant), S. trifasciata (mother-in-law’s tongue) (Farr & Rossman, 2016; CABI, 2016).

Symptoms: Initially, round, water-soaked lesions are formed on leaves. Lesions form on young and mature leaves and rapidly enlarge and coalesce resulting in foliage blight. In mature lesions, numerous brownish-black and crustose cankers or acervuli (fungal fruiting bodies) in concentric rings are produced characteristic of anthracnose. Abundant conidia are produced on these cankers (Makamura et al., 2006; Palmateer et al., 2012).

Damage Potential: Anthracnose disease caused by Colletotrichum sansevieria can result in reduced plant quality and growth, and marketability. In California, 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 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 sansevieria 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. The optimum temperature for growth of C. sansevieria ranges from 25° to 28°C Nakamura et al., 2006). In greenhouse tests, anthracnose disease developed within 10 days of inoculation of Sanseviera plants at 29°C with 70-85% relative humidity (Palmateer et al., 2012), or 6 days after inoculation in a humid chamber at 27°C under 12h fluorescent light/12 h darkness (Nakamura et al., 2006).

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

Worldwide Distribution: Asia: India, Japan, Korea; North America: USA (Florida); Oceania: Australia (Farr & Rossman, 2016; CABI, 2016; Gautam et al., 2012).

Official Control: In California C. sansevieriae is a quarantine actionable, Q-rated pathogen.

California Distribution: Colletotrichum sansevieriae was detected in two nursery greenhouses in San Diego. Conseq ently, infected plants were treated and continue to be monitored periodically for detection of the pathogen (see “Initiating Event”). As the infected plants were contained in pots in greenhouses, the pathogen is not considered to be established in California.

California Interceptions: Colletotrichum sansevieria has been intercepted twice in 2016, in shipments of Sansevieria plants that originated in Florida (see ‘Initiating event’).

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

Consequences of Introduction:

1) Climate/Host Interaction: Similar to other species of Colletotrichum, sansevieriae 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: The host range of Colletotrichum sansevieriae is limited to Sansevieria

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, value, and trigger the loss of markets.

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: 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.

Score the pest for Environmental Impact.

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 sansevieriae: 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: Colletotrichum sansevieriae was detected in an incursion of plants held at a nursery in San Diego County and is not considered to be established within 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 = 11

Uncertainty:

None.

Conclusion and Rating Justification:

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

References:

Aldaoud, R., S. de Alwis, S. Salib, J. H. Cunnington, and S. Doughty. 2011. First record of Colletotrichum sansevieriae on Sansevieria sp. (mother-in-law’s tongue) in Australia. Australasian Plant Disease Notes 6: 60-61

CABI. 2016. Colletotrichum fructicola 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 3, 2016, from http://nt.ars-grin.gov/fungaldatabases/

Gautam, A. K., S. Avasthi, and R. Bhadauria. 2012. Colletotrichum sansevieriae on Sansevieria trifasciata – a report form Madhya Pradesh, India. Plant Pathology & Quarantine 2: 190-192. doi 10.5943/ppq/2/2/12

Nakamura, M., M. Ohzono, H. Iwai, and K. Arai. 2006. Anthracnose of Sansevieria trifasciata caused by Colletotrichum sansevieriae sp. nov. Journal of General Plant Pathology 72: 253-256.

Palmateer, A. J., T. L. B. Tarnowski, and P. Lopez. 2012. First Report of Colletotrichum sansevieriae Causing Anthracnose of Sansevieria trifasciata in Florida. Plant Disease 96: 293.

Park, J. H., K. S. Han, J. Y. Kim, and H. D. Shin. 2013. First Report of Anthracnose Caused by Colletotrichum sansevieriae on Sansvieria in Korea. Plant Disease 97: 1510

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.

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