Tag Archives: fungi

Fungi, Plant Pathogens

Calonectria pteridis Crous, M. J. Wingf. & Alfenas, 1993

California Pest Rating for
Calonectria pteridis Crous, M. J. Wingf. & Alfenas, 1993
Pest Rating: B
PEST RATING PROFILE
Initiating Event:

On April 19, 2016, diseased Ravenea rivularis (majesty palm) plants exhibiting leaf spots were intercepted by San Luis Obispo County Agricultural officials. The shipment of plants had originated in Florida and was destined to a nursery in San Luis Obispo County.  Symptomatic leaves were sent to the CDFA Plant Pest Diagnostics Branch for diagnosis.  Suzanne Latham, CDFA plant pathologist, identified the associated pathogen as Calonectria pteridis.  Then on May 23, 2016, C. pteridis was detected again in a different shipment of majesty palm plants destined to the same nursery in San Luis Obispo.  In both detections, 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. pteridis in California is evaluated and a permanent rating is proposed here.

History & Status:

Background:  Calonectria pteridis is the sexual (telemorph) stage of the fungal pathogen, while its asexual (anamorph) stage is Cylindrocladium pteridis.  Calonectria pteridis causes leaf spot and blight, stalk and root rot diseases in various hosts.  In the continental United States, Calonectria pteridis primarily causes symptoms of leaf spots and blights in palm.  Symptoms are indistinguishable from those caused by three other species in the genus (Yu & Elliot, 2013).  In Brazil, C. pteridis is one of the most common species associated with eucalyptus trees causing Calonectria leaf blight disease (Alfenas et al., 2013). In China, C. pteridis caused serious damage to Serenoa repens – an important medicinal and ornamental garden plant (Yang, et al., 2014).  In the USA, C. pteridis has been found on several hosts including palm from Tennessee, Georgia, Florida, and Hawaii (Uchida, 2004; Farr & Rossman, 2016). Recently, the pathogen was detected in infested majesty palm plants shipped from Florida to California.  The pathogen is widespread especially in subtropical and tropical regions.

Disease cycle:  The disease cycle generally involves the pathogen’s anamorphic or asexual stage resulting in the production of conidia (spores) and telemorphic or sexual stage resulting in perithecia (fruiting structure) and ascospores. Conidia, produced on infected plants are dispersed by insects, tools, gloves, plant handling, wind and splashing water, while ascospores are discharged from fruiting bodies by air currents and splashing water.  Discharged spores land on plant host tissue and germinate and penetrate tissue when leaves are wet or under high relative humidity.  The pathogen grows within the host and after about one week produces conidiophores and conidia.  Perithecia and ascospores are formed on infected tissue (Uchida, 2004; Yu & Elliot, 2013).

Hosts: Calonectria pteridis can attack a number of hosts including ornamentals, forest and environmental trees and shrubs, and few agricultural crops.  In the USA, palms have been reported as the main host attacked by the pathogen.  Hosts include: Arachis hypogaea (peanut), Arachnoides adiantiformis  (syn. Rumohra adiantiformis, Polystichum adiantiformis; leatherleaf fern), Arecastrum romanzoffianum (syn. Sygarus romanzoffiana; queen palm); Asparagus plumosus (asparagus fern), Callistemon citrinus (crimson bottlebrush), C, rigidus (erect bottlebrush), Chamaedorea elegans (syn. Collinia elegans; neanthe bella palm/parlor palm), C. cataractarum (cat palm), Chrysalidocarpus sp. (syn. Dypsis sp.; palm); Cissus rhombifolia (grape ivy), Cocos nucifera (coconut), Crassula sp., C. argentea (jade plant), Dictyosperma album (princess palm), Dracaena marginata (Marginate Dracaena), Drosera sp. (sundews), Dryopteris sp. (woodfern), Elaeis guineensis (African oil palm), Eucalyptus spp.,(eucalyptus), Guzmania wittmackii (bromeliad/Guzmanea), Heliconia bihai (macawflower), Howeia belmoreana, H. forsteriana (kentia palm/curly palm), Laccospadix australasica (Atherton palm), Leucadendron sp., Livistona chinensis (Chinese fan palm), Lupinus sp., (lupine), Mauritia flexuosa (moriche palm), Melaleuca leucadendra (weeping paperback), M. quinquenervia (broad-leaved paperback), Musa sp. (banana), Nephrolepis sp., Nephrolepis exaltata (sword fern), Phoenix canariensis (Canary Island date palm), Pinus sp., P. caribaea (Caribbean pine), P. caribbaea var. hondurensis,  P. oocarpa (Mexican yellow pine), Pouteria dulcifica (syn. Synsepalum dulcificum; miracle fruit/sweet berry), Ravenea rivularis (majesty palm), Rhapis humilis (slender lady palm), Rhododendron obtusum (Hiryu azalea/Kurume azalea), Serenoa repens (saw palmetto), Scolopendrium sp., Solanum tuberosum (potato), Strelitzia reginae (bird of paradise), Tillandsia wagneriana (bromeliad), Washingtonia sp., W. filifera (California or desert fan palm), W. robusta (Mexican fan palm) (Crous et al., 1993; Crous & Wingfield, 1993; Farr & Rossman, 2016; Yu & Elliot, 2013).

Symptoms:  Symptoms caused by Calonectria pteridis in palm begin as flecks of small, water-soaked lesions that develop to irregular shades of gray, yellow, reddish brown, brown, or black.  Newly formed lesions are circular or elliptical, 3-5 mm long, and on enlarging develop a tan or gray center surrounded by a brownish halo. The rachis and petiole may become infected with small flecks and eventually leaves and leaflets dry as the disease progresses and lesions coalesce.  Leaf spots may appear on leaves of all ages, although mature leaves are most susceptible (Yu & Elliot, 2013).

Spread:   Conidia are readily spread by insects, pruning tools, plant handling, air currents, rain or splashing irrigation water, while ascospores can be released from their fruiting bodies and spread by air currents and splashing water (Uchida, 2004; Yu & Elliot, 2013).

Damage Potential:  Leaf spot and blight disease caused by Calonectria pteridis can result in reduced plant growth, quality, and marketablility.  Estimates of yield/crop loss due to this pathogen have not been reported.  However, under nursery controlled environments, production of palms, ferns, eucalyptus, and other ornamental host plants may be at heightened risk for pathogen infection and reduced plant production. Seedling and immature palms without trunks are likely to be most susceptible to this leaf spot disease (Yu & Elliot, 2013).  Infection of outdoor growths of palm and eucalyptus trees require warm and humid to wet climate for disease development.  In Brazil, C. pteridis is one of the most important causal agents of Calonectria leaf blight disease of Eucalyptus spp. and has significantly reduced eucalyptus growth (Alfenas, et al., 2013).  In China, up to 100% incidence of leaf spot disease in Serenoa repens, medicinal plant, often lead to plant death (Yang, et al., 2014).

Worldwide Distribution: Asia: China, India, Malaysia, Singapore; Africa: Cameroon, Ivory Coast, Mauritius, South Africa; Europe: Spain, North America: USA (Florida, Hawaii), West Indies; South America: Brazil, Costa Rica, Martinique, Venezuela (Crous & Wingfield, 1993; Farr & Rossman, 2016).

Official Control: None reported.  Currently, Calonectria pteridis is a quarantine, actionable pathogen with a Q rating in California.

California Distribution: Calonectria pteridis is not known to be established in California.  Diseased plants detected in a San Luis Obispo nursery were destroyed (see “Initiating Event).

California Interceptions:  There have been two interceptions of Calonectria pteridis- infested Ravenea rivularis (majesty palm) plants that originated in Florida (see ‘Initiating Event’).

The risk Calonectria pteridis 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):  Calonectria pteridis requires humid, wet, rainy and warm climates to infect plants and develop.  Therefore, the pathogen may only be able to establish in limited parts of California.

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 High (3): Calonectria pteridis has a very wide host range and can attack a number of diverse hosts including ornamentals, forest and environmental trees and shrubs, and few agricultural crops.  In the USA, palms have been reported as the main host attacked by the pathogen.

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.  Conidia and ascospores are transmitted by wind, wind-driven rain and splashing irrigation water, cultivation tools, and plant handling.  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): Infections of Calonectria pteridis could lower crop value and cause loss of markets.  Under controlled wet and warm environments, nursery productions of palms and other ornamental host plants may be at particular risk for pathogen infection and reduced plant production.

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):  Under conducive climate for development, the pathogen could significantly impact cultural practices or home garden plantings.  Its overall impact on California’s environment is assessed as ‘medium’. 

Consequences of Introduction to California for Calonectria pteridis:

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 Calonectria pteridis to California = (12).

6) Post Entry Distribution and Survey Information: Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included. (Score)

–Not established (0) Pest never detected in California, or known only from incursions.

-Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).

-Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.

-High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Evaluation is Not established (0):  Interceptions of Calonectria pteridis-infected nursery plants were destroyed and therefore, the pathogen is not considered 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 = 12.

Uncertainty:  

Periodic surveys and/or subsequent detection may confirm the presence/absence of C. pteridis 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 Calonectria pteridis is B.

References:

Alfenas, R. F., O. L. Pereira, R. G. Frietas, C. S. Freitas, M. A. D. Dita, and A. C. Alfenas.  2013.  Mass spore production and inoculations of Calonectria pteridis on Eucalyptus spp. under different environmental conditions.   Tropical Plant Pathology, 38:406-413.

Crous, P. W., M. J. Wingfield, and A. C. Alfenas.  1993. Additions to Calonectria.  Mycotaxon 46:217-234.

Crous, P. W., and M. J. Wingfield. 1993.  Calonectria pteridis.  IMI Descriptions of Fungi and Bacteria. No. 116 pp. Sheet 1153.

Farr, D.F., & A. Y. Rossman.  Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA.  Retrieved January 28, 2016, from http://nt.ars-grin.gov/fungaldatabases/.

Uchida, J. Y.  2004.  Calonectria leaf spot (Cylindrocladium leaf spot).  In ‘Compendium of Ornamental Palm Disease and Disorders’ Eds. M. L. Elliott, T. K. Broschat, J. Y. Uchida, and G. W. Simone.  The American Phytopathological Society, pgs. 12-14.

USDA PCIT.  2016.  USDA Phytosanitary Certificate Issuance & Tracking System.  https://pcit.aphis.usda.gov/PExD/faces/ReportHarmOrgs.jsp.

Yang, W., L. Zheng, C. Wang, and C. -P. Xie.  2014.  The first report of Calonectria pteridis causing a leaf spot disease on Serenoa repens in China. Plant Disease. 986: 854.

Yu, J. and M. L. Elliott.  2013.  Calonectria (Cylindrocladium) leaf spot of palm.  University of Florida Institute of Food and Agricultural Sciences.  http://edis.ifas.ufl.edu/PP302.

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: B

Posting by ls

Fungi, Plant Pathogens

Colletotrichum fructicola Prihastuti, L. Cai & K. D. Hyde, 2009

California Pest Rating for
Colletotrichum fructicola Prihastuti, L. Cai & K. D. Hyde, 2009
Pest Rating:  B
PEST RATING PROFILE
Initiating Event:

On March 29, 2016, a shipment of Chinese evergreen (Aglaonema sp.)  cuttings showing leaf spotting symptoms and destined to a nursery in San Luis Obispo County, was intercepted and sampled by San Luis Obispo 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 anthracnose and fruit rot pathogen, Colletotrichum fructicola, as the cause for the disease.  This species was first detected within California on August 26, 2015, in mango fruit shipped from Puerto Rico and intercepted by the California Dog Team.  The fruit shipment was destined to a private citizen in Sacramento County.  The identity of the fungal pathogen was confirmed on August 18, 2015, by the USDA National Identification Services at Beltsville, Maryland.  Several detections of C. fructicola followed the initial find: on August 14, 2015, in Cymbidium orchid leaves from a nursery in San Diego County; on August 19, 2015, on mango fruit from Florida and destined for Stanislaus County; on November 9, 2015, in Dracaena massangeana cuttings from Costa Rica and destined to a nursery in San Diego County; on March 15, 2016, in black sapote fruit from Florida and destined to a private citizen in Los Angeles County.  In all these cases, subsequent to the detection of C. fructicola, all fruit and plant shipments/nursery stock were either destroyed or rejected from entering California.  Currently, C. fructicola 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 fructicola was originally reported to be associated with coffee berries (Coffea arabica) in northern Thailand (Prihastuti et al., 2009) and as a leaf endophyte from Central America (as C. ignotum). Since then, C. fructicola has been found on several tropical and subtropical hosts from diverse geographical regions. In the USA, C. fructicola was reported in 2012 from Florida and North Carolina on strawberry crown and apple fruit respectively (Weir et al., 2012). During 2015-16, the pathogen was also detected in California associated with several quarantine nursery plant/fruit shipments and regulatory nursery samples.

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 by gene sequencing.  However, C. ignotum and Glomerella cingulata var. minor are synonyms of C. fructicola (Prihastuti et al., 2009; Rojas et al., 2010; Weir et al, 2012).

Hosts: Aglaonema sp. (Chinese evergreen), Annona reticulata (custard apple), A. squamosa (sugar apples), Artocarpus heterophyllus (jackfruit), Coffea arabica (coffee), Coffea sp., Camellia japonica (Japanese camellia), Camellia sinensis (tea), Camellia sp., Capsicum frutescens (chili pepper), Carica papaya (papaya), Cestrum parqui (green cestrum), Citrullus vulgaris (watermelon), Citrus limon (lemon), C. reticulata (Mandarin orange), C. sinensis (sweet orange), Citrus x paradisi, Crinum asiaticum (spider lily), Cucumis sativus (cucumber), Cymbidium sp. (orchid), Dendrobium sp. (orchid), Dioscorea alata (purple yam), D. rotundata (white yam), Diospyros nigra (black sapote), Dracaena massangeana (corn plant/cornstalk Dracaena), Epidendrum sp. (orchid), Ficus carica (common fig), F. edulis (fig), F. pumila (creeping fig), Fortunella margarita (oval kumquat) Fragaria ananassa (strawberry), Limonium sinuatum (statice), Limonium sp., Lobularia maritima (sweet alyssum), Lupinus angustifolius (blue lupine), Lycopersicon esculentum (tomato), Lycium chinensis (boxthorn), Malus domestica (apple), M. sylvestris (crab apple), Mangifera indica (mango), Matthiola incana (stock), Medicago polymorpha (burclover), Musa acuminata (edible banana), Nerium oleander (oleander), Nicotiana tabacum (tobacco), Passiflora edulis (passion fruit), Persea americana (avocado), Phalaenopsis sp. (moth orchid), Phormium tenax (flax), Portulaca oleracea (little hogweed/common purslane), Psidium guajava (guava), Pyrus bretschneideri (Chinese white pear), P. pyrifolia (pear), Saccolabium sp. (orchid), Tetragastris panamensis, Theobroma cacao (cocoa), Vanda sp. (orchid) (Farr & Rossman, 2016; Li et al., 2014; Prihastuti et al., 2009; Wang et al., 2016, Weir et al., 2012; Zhang et al., 2015).

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.  In China, early stages of the disease in pear was characterized by the presence of black spots on young fruit which was always followed by severe bitter rot in matured fruit, and less than 1 mm black spots on leaves resulting in severe defoliation and loss of fruit (Jiang et al., 2014; Zhang et al., 2015). Anthracnose symptoms on tobacco leaves initiate as discrete, yellow-green spots which coalesce into larger lesions with white centers and dark brown margins (Wang et al., 2016).

Damage Potential:  Anthracnose disease caused by Colletotrichum fructicola can result in reduced plant quality and growth, fruit production and marketability.   In China, sudden outbreaks of the disease resulted in severe defoliation and a loss of pear fruit quality and yield resulting in fresh market losses ranging from 60-90% which, in 2008, were estimated at US$150 million. (Li, et al., 2013; Zhang, et al., 2015).  In 2014, also in China, 90% of tobacco leaves on ~2% plants in a 3-ha commercial tobacco field were infected with C. fructicola (Wang, et al., 2016).  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 fructicola 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, Israel, Japan, Korea, Thailand; Africa: Angola, Nigeria; Europe: United Kingdom; North America: Canada, Panama, USA (California, Florida, North Carolina); Australia (Farr & Rossman, 2016; Li et al., 2014; Prihastuti et al., 2009; Wang et al., 2016, Weir et al., 2012; Zhang et al., 2015).

Official Control:  In California C. fructicola is an actionable, Q-rated pathogen, and infected plant material is subject to destruction or rejection.

California Distribution: Colletotrichum fructicola was detected in a nursery in San Diego County (see “Initiating Event”).

California Interceptions:  During 2015-16, Colletotrichum fructicola has been intercepted several times mainly in shipments of mango and black sapote fruits, Dracaena and Chinese evergreen cuttings that originated in Costa Rica, Puerto Rico, and Florida (see ‘Initiating event’).

The risk Colletotrichum fructicola 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. fructicola 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.

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 High (3) – The host range of Colletotrichum fructicola is relatively wide and diverse and includes several tropical and subtropical plants, as well as agricultural and ornamental crops grown in 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 High (3) –Under suitable, wet 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.

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

The pest could directly affect threatened or endangered species.

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

The pest could trigger additional official or private treatment programs.

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 fructicola:

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 fructicola to California = (13).

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 fructicola 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 = 12.

Uncertainty:

Periodic surveys need to be conducted to confirm the presence/absence of C. fructicola 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 fructicola is B.

References:

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/

J. Jiang, Zhai, H. Li, Z. Wang, Y. Chen, N. Hong, G. Wang, G. N. Chofong, and W. Xu. 2014. Identification and characterization of Colletotrichum fructicola causing black spots on young fruits related to bitter rot of pear (Pyrus bretschneideri Rehd.) in China.  Crop Protection 58:41-48.

Li, H.N., Jiang, J.J., Hong, N., Wang, G.-P., and Xu, W.X. 2013. First Report of Colletotrichum fructicola Causing Bitter Rot of Pear (Pyrus bretschneideri) in China. Plant Disease 97:1000. http://dx.doi.org/10.1094/PDIS-01-13-0084-PDN.

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.

Wang, H. C., Y. F. Huang, Q. Chen, M. S. Wang, H. Q. Xia, S. H. Shang, and C. Q. Zhang.  2016.  Anthracnose caused by Colletotrichum fructicola on tobacco (Nicotiana tabacum) in China.  Plant Disease (posted on line March 8, 2016). http://dx.doi.org/10.1094/PDIS-06-15-0724-PDN.

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.

P. F. Zhang, L. F. Zhai, X. K. Zhang, X. Z. Huang, N. Hong, W. Xu, and G. Wang. Characterization of Colletotrichum fructicola, a new causal agent of leaf black spot disease of sandy pear (Pyrus pyrifolia).  European Journal of Plant Pathology 143:651-662.

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 Format:

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

Example Comment: 

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

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

♦  Comments may not be posted if they:

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

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

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

Violates agency regulations prohibiting workplace violence, including threats.

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

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

Pest Rating:  B

Posted by ls

Fungi, Plant Pathogens

Ascochyta aquilegiae (Rabenh.) Boerema, Fruyter & Noorder, 1997

California Pest Rating for
Ascochyta fungi (photo source: forestryimages.org)
Ascochyta fungi; Ascochyta spp. Lib.
Ascochyta aquilegiae (Rabenh.) Boerema, Fruyter & Noorder, 1997
Pest Rating:  C
PEST RATING PROFILE
Initiating Event:

On March 28, 2016, a sample of diseased Aquilegia sp. (columbine) plants showing symptoms of dieback, was voluntarily submitted by a nursery in Contra Costa County to the CDFA Plant Pathology Laboratory for disease diagnosis.  Suzanne Latham, CDFA plant pathologist, identified the associated fungus plant pathogen, Ascochyta aquilegiae, as the cause for the disease.  The pathogen was assigned a temporary “Z” rating as it has been reported earlier in California and is considered widely distributed.  That rating is reassessed here and a permanent rating is proposed.

History & Status:

Background:  Ascochyta aquilegiae causes dark leaf spots, stem lesions, and crown rots in plants belonging to the family Ranunculaceae, including several species in the genera Aquilegia and Delphinium.  The fungal species has undergone several name changes in fungal taxonomy and is known by several synonyms including, Stagonosporopsis aquilegiae, Actinonema aquilegiae, Ascochyta laskarisii, Diplodina delphinii, Phoma aquilegiicola, Phyllosticta aquilegiae, and Phyllosticta aquilegicola (Farr & Rossman, 2016).

Disease development and spread:  Ascochyta aquilegiae attack primarily plant leaves by means of spores (conidia) and, following infection, produce numerous condia that are spread to other plants by wind, wind-blown rain, water, and insects.  Conditions that favor prolonged leaf-wetness in warm climates often favor development of the pathogen. The pathogen is also transmitted to non-infected sites through the movement of infected plant materials and debris. The fungus overwinters primarily in fallen leaves or infected leaf debris, or as mycelium in infected tissues of perennial plants (Agrios, 2005; Pscheidt & Ocamb, 2016a, 2016b).

Hosts: Aquilegia spp. (columbine), Aconitum spp. (aconite/wolf’s bane), Clematis sp. (clematis), Consolida spp. (larkspur), Coptis chinensis (goldthread), Delphinium spp. (delphinium/larkspur) (Farr & Rossman, 2016; French, 1989; Garibaldi et al., 2011; Yu et al., 2014).

Symptoms and damage potential: Ascochyta aquilegiae causes leaf spots, stem cankers and crown rots.  Leaf lesions of infected Aquilegia and Coptis plants are extensive, usually beginning at the leaf margin and extending to the central leaf blade eventually coalescing to cover entire leaf, irregular, brown to black, necrotic, slightly sunken with a well-defined border and surrounded by a violet-brown halo.   As the disease progresses, stems are also affected causing death of the apical part of the plant (Garibaldi et al., 2011; Yu et al., 2014). In Delphinium spp., petioles develop brown water-soaked lesions near the base of succulent plants.  Less vigorous plants show black local lesions on the petiole.  Inflorescences and seed pods develop a blackish decay.  Generally, crown rot may be found in plants two years or older (Pscheidt & Ocamb, 2016a, 2016b).  Small, dark brown to black fungal fruiting bodies (pycnidia) may be present in the lesions.

Damage Potential:  While information on the economic importance of the disease caused by Ascochyta aquilegiae is limited, the development of leaf spots, stem cankers and crown rots in infected plants may result in reduced plant production, yield, and marketability of columbine and other host plants used in residential gardens and commercial landscapes.  Plants are particularly at risk of pathogen infection in warm and moist natural climates of California, and in nursery-controlled productions.  In China, A. aquilegiae caused yield losses of 15-75% in gold thread, an important herbaceous plant used in traditional Chinese medicine (Yu et al., 2014).

Worldwide Distribution:  Asia:  Armenia, China, Japan, Russia; Africa: South Africa, Zimbabwe, Europe: Bulgaria, Czechoslovakia, Germany, Italy, Netherlands, Poland, Scotland, United Kingdom; North America: Canada, USA; Oceania: New Zealand.  It is widespread within the USA in Alaska, California, Connecticut, Iowa, Idaho, Maryland, New Jersey, New York, Oregon, Pennsylvania, Texas, Washington, Wisconsin (Farr & Rossman, 2016; Garibaldi et al., 2011; Pscheidt & Ocamb, 2016a, 2016b; Yu et al., 2014).

Official Control: None reported. Currently, the pathogen has a temporary ‘Z’ rating in California, which indicates that it is a previously unrated organism of known economic and/or environmental detriment but generally distributed in the state.

California Distribution: Ascochyta aquilegiae has been detected in California’s northern and southern coastal counties which include: Del Norte, Humboldt, Mendocino, Sonoma, Marin, San Francisco, San Mateo, Santa Cruz, Alameda, Santa Clara, San Benito, Monterey, San Luis Obispo, Santa Barbara, Ventura, Los Angeles, Orange, and San Diego Counties (French, 1989).

California Interceptions: None reported.

The risk Ascochyta aquilegiae 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): Conditions that favor prolonged leaf-wetness in warm climates often favor development of Ascochyta aquilegiae.  The pathogen is already known to be present in northern and southern coastal counties in California.

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): Presently, the host range is limited to few species within Ranunculaceae. 

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 Medium (2): Ascochyta aquilegiae produces numerous condia the infect plants, however, to spread to other plants, they are dependent on wind, wind-blown rain, water, and insects.  Furthermore, prolonged leaf-wetness in warm climates is needed to favor development of the pathogen in plants. The pathogen is also transmitted to non-infected sites through the movement of infected plant materials and debris.

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): While information on the economic importance of the disease caused by Ascochyta aquilegiae is limited, the development of leaf spots, stem cankers and crown rots in infected plants may result in reduced plant production value and marketability of columbine and other host plants used in residential gardens and commercial landscapes.  Plants are particularly at risk of pathogen infection in warm and moist natural climates of California, and in nursery-controlled productions

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 High (3): Commercial landscape and home garden plantings could be negatively impacted if infected by Ascochyta aquilegiae under favorable moist climate conditions.  The pathogen could directly affect certain species of larkspur, namely, Delphinium bakeri (Baker’s larkspur), D. hesperium ssp. cuyamacae (Cuyanaca larkspur), D. luteum (golden larkspur), and D. variegatum ssp. kinkiense (San Clemente Island larkspur) included in the ‘State and Federally Listed Endangered, Threatened, and Rare Plants of California, July 2015’ thereby, potentially lowering biodiversity, natural communities or ecosystem processes.

Consequences of Introduction to California for Ascochyta aquilegiae:

Add up the total score and include it here. (Score)

-Low = 5-8 points

–Medium = 9-12 points

-High = 13-15 points

Total points obtained on evaluation of consequences of introduction to California = 10

6) Post Entry Distribution and Survey Information: Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included. (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 Medium (-2): Presently, Ascochyta aquilegiae is known to be present in northern and southern coastal counties 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 = 8.

Uncertainty:   

The impact and spread of this pathogen to other intrastate regions where host species are grown, is not known.  Future reports of the detection of P. digitalidis in California could lower the overall score for the pathogen although it is unlikely to affect its final rating.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Ascochyta aquilegiae is C.

References:

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

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

Garibaldi, A., D. Bertetti, M. T. Amatulli, and M. L. Gullino.  2011.  First report of leaf spot of fan columbine (Aquilegia flabellata) caused by Phoma aquilegiicola in Italy.  Plant Disease 95:880.  http://dx.doi.org/10.1094/PDIS-05-10-0391.

Pscheidt, J.W., and Ocamb, C.M.  2016a. Columbine (Aquilegia spp.) leaf spots.  Pacific Northwest Plant Disease Management Handbook. © Oregon State University. pnwhandbooks.org/plantdisease/node/3020. http://pnwhandbooks.org/plantdisease/columbine-aquile.

Pscheidt, J.W., and Ocamb, C.M.  2016b. Delphinium – leaf spot and crown rot.  Pacific Northwest Plant Disease Management Handbook. © Oregon State University. pnwhandbooks.org/plantdisease/node/3118.  http://pnwhandbooks.org/plantdisease/delphinium-leaf-spot-and-crown-rot.

Yu, Y., Z. C. Su, W. Z. Tan, and C. W. Bi.  2014.  First report of a leaf spot on goldthread (Coptis chinensis) caused by Phoma aquilegiicola in China. Plant Disease 98:1428. http://dx.doi.org/10.1094/PDIS-01-14-0010-PDN.

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 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

Fungi, Plant Pathogens

Puccinia kuehnii (W. Krűger) E. J. Butler 1914

California Pest Rating for
Puccinia rusts. Photo credit: Cesar Calderon, USDA APHIS PPQ. Bugwood.org
Puccinia rusts. Photo credit: Cesar Calderon, USDA APHIS PPQ. Bugwood.org
Puccinia kuehnii (W. Krűger) E. J. Butler 1914
Pest Rating:  C
PEST RATING PROFILE
Initiating Event:

On February 9, 2016, USDA’s Animal and Plant Health Inspection Service (APHIS) notified the CDFA that the rust pathogen, Puccinia kuehnii was added on February 2, 2016, to their ‘List of Pests no Longer Regulated at U.S. Ports of Entry’ under the Federally Recognized State Managed Phytosanitary (FRSMP) program (USDA APHIS 2016).  Consequently, USDA APHIS will no longer take regulatory action against this pathogen at ports of entry.  Therefore, and at the request of Stephen Brown, Assistant Director, CDFA, the risk of infestation for P. kuehnii is assessed here and a permanent rating is proposed.

History & Status:

Background:  Puccinia kuehnii is one of two major rust fungi on sugarcane and causes orange rust.  The other rust fungi known as P. melanocephala, causes brown rust and is relatively common.  The orange rust of sugarcane pathogen, P kuehnii, most likely originated in Asia-Oceania regions where Saccharum spp. are native.  In other countries where the pathogen occurs, such as Indonesia and the South Pacific, sugarcane has existed for several centuries and it is assumed that P. kuehnii was likewise introduced and also existed in those countries for the same period of time.  The pathogen is now wide spread in Asia and Australia and was recently discovered in West Africa and the Western Hemisphere and from sugarcane-growing regions in the southeastern United States, Central and South America, and the Caribbean Basin (Dixon & Castlebury, 2016). It is likely that the pathogen was introduced to Australia along with sugarcane that was introduced about 150 years ago as there are no known native hosts present in that region (CABI, 2016).  In the USA, P. kuehnii was first reported from Florida having been detected in infected, brown rust-resistant, sugarcane cultivars. The disease appears to be distributed widely in the South Florida sugarcane-growing region (Comstock et al., 2008).  In 2013, orange rust was also reported from the southern region of Louisiana’s sugarcane production area (Grisham, et al., 2013).  Puccinia kuehnii has not been reported from California nor is sugarcane a major production crop of the State.

Disease cycle:  Puccinia kuehnii completes its life cycle on the same host and has an incomplete lifecycle. Spermagonia and aecia spore states are unknown.    Urediniospores are produced abundantly under natural conditions, but the production of teliospores and basidiospores are comparatively less common.    Under favorable conditions of humidity and temperature, urediniospores present on host germinate to penetrate the tissue.  As the fungus grows, uredinia (fruiting structures) are formed and urediniospores are produced in abundance.   Urediniospores are produced between 10°C and 34°C and optimally at 15-25°C for urediniospores and 26°C for teliospores.  Relative humidity above 97% favors urediniospore germination (Hsieh & Fang, 1983; CABI, 2016).

Dispersal and spread: The main risk for natural dispersal of spores over long distances (over 2000 km) is by wind and wind-blown rain.  Other potential means for spread are the movement of infected leaves and spore-contaminated clothing (CABI, 2016).

Hosts:  Saccharum officinarum (sugarcane) is the main host.  Other hosts include few weeds and ornamental grasses belonging to Saccharum spp. within Poaceae: Saccharum arundinaceum, S. barberi, S. bengalense, S. edule, S. munja, S. narenga, S. rufipilum, S. sinense, S. spontaneum; S. ravennae (syn. Erianthus ravennae); Sclerostachya fusca (Afshan & Khalid, 2013; CABI, 2016; Dixon & Castlebury, 2013; EPPO, 2016; Farr & Rossman, 2016 )

Symptoms:  Orange rust disease is characterized by the development of lesion that initiate as small (0.5 mm diameter) spots on leaves and enlarge into elongated brown lesions (2-8 mm x 0.5-2 mm wide).  As the lesions enlarge, fungal mycelium protrudes through the leaf surface, usually on its underside, producing abundant urediniospores. These pustules usually occur in patches or groups, but cover entire leaf surfaces in severe infections. Severely infected leaf tissue becomes necrotic leading to early senescence. Affected crops appear brown with very little green tissue remaining at all. Symptom development may take 3-4 weeks from infection, depending on weather conditions (CABI, 2016).

Disease Potential:  Orange rust of sugarcane is considered a disease of low economic impact that has rarely caused significant economic losses.  The only severe economic loss was reported in Australia in 2000 on the introduced, highly susceptible Q124 sugarcane variety that was subsequently replaced (CABI, 2016).  The potential for establishment and spread of the pathogen in California is reasonably low as sugarcane, the main host, is grown in limited acreage in dry climates of the Imperial Valley.

Worldwide Distribution: Africa: Cameroon, Cote d’Ivore; Asia: China, India, Indonesia, Japan, Malaysia, Myanmar, Nepal, Pakistan, Philippines, Singapore, Sri Lanka, Taiwan, Thailand, Vietnam; Central America and Caribbean:  Costa Rica, Cuba, Dominican Republic, Guatemala, Jamaica, Nicaragua, Panama; North America: USA, Mexico; South America: Brazil, Colombia, Ecuador; Oceania: American Samoa, Australia, Cook Islands, Fiji, French Polynesia, Guam, Micronesia, New Caledonia, Papua New Guinea, Samoa, Solomon Islands (CABI, 2015; Dixon & Castlebury, 2013; EPPO, 2016; Farr & Rossman).

In the USA it has been reported from Florida and Louisiana (Comstock et al., 2008; Grisham et al., 2013).

Official Control: Puccinia kuehnii is on the “Harmful Organisms Lists” for Brazil, Costa Rica, Egypt, Honduras, and Morocco (PCIT, 2016). Currently, the pathogen has not been rated for California.

California Distribution:  Puccinia kuehnii is not established in California.

California Interceptions: None reported.

The risk Orange Rust of Sugarcane 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):   The potential for establishment and spread of the orange rust pathogen in California is likely to be low as sugarcane, the main host, is grown in limited acreage under dry climates of the Imperial Valley.  Spore germination and plant infection are not expected to be favored under climates of low relative humidity common to that region.

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):  Sugarcane is the main host of P. kuehnii.  The pathogen is largely limited to Saccharum spp. and the related species Sclerostachya fusca.    

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): Puccinia kuehnii has high reproduction and dispersal potential via its windblown spores that are primarily transmitted by strong winds over distances of several hundred kilometers.  Also, they may be spread over long distances via infected plant leaves and spore-contaminated human clothing. 

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 Low (1): The economic impact of Puccinia kuehnii to California is considered low as the potential for establishment and spread of the pathogen is reasonably minimal within a state where sugarcane is not a majorly cultivated crop and requires high relative humidity for pathogen infection.  Potential incidents of the disease occurring under conducive climates could lower crop yield.  

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):  Puccinia kuehnii infections could affect production of ornamental grasses belonging to Saccharum spp. and grown in private and/or public commercial environments.    

Consequences of Introduction to California for Myrtle Rust:

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 = 8 (Low).

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).  Puccinia kuehnii 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 = 8 (Low).

Uncertainty:

None.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Puccinia kuehnii is C.

References:

Afshan, N.S., and A. N. Khalid.  2013.  Checklist of the rust fungi on Poaceae in Pakistan. Mycotaxon 125: 1-17.

Comstock, J. C., S. G. Sood, N.C. Glynn, J. M. Shine Jr., J. M. McKemy, and L. A. Castlebury.  2008.  First report of Puccinia kuehnii, causal agent of orange rust of sugarcane, in the United States and Western Hemisphere. Plant Disease, 92(1):175. http://www.apsnet.org.

Dixon, L. and L. Castlebury.  2016.  Systematic Mycology and Microbiology Laboratory, ARS, USDA. . Invasive Fungi. Orange rust of sugarcane – Puccinia kuehnii. Retrieved March 10, 2016, from /sbmlweb/fungi/index.cfm.

EPPO.   2016.  Puccinia kuehnii (PUCCKU).  PQR database.  Paris, France: European and Mediterranean Plant Protection Organization.  http://www.newpqr.eppo.int.

Farr, D. F. and A. Y. Rossman.  2016.   Fungal databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA.  Retrieved August 24, 2016 from http://nt.ars-grin.gov/fungaldatabases/.

Grisham, M. P., J. W. Hoy, J. S. Haudenshield, and G. L. Hartman.  2013.  First report of orange rust caused by Puccinia kuehnii in sugarcane in Louisiana. Plant Disease, 97(3):426-427. http://apsjournals.apsnet.org/loi/pdis.

Hsieh, W. H., and F. G. Fang.  1983.  The uredospore production of Puccinia melanocephala and Puccinia kuehnii in sugarcanes. Plant Protection Bulletin, Taiwan, 25(4):239-244.

USDA-PCIT.  2016.  United States Department of Agriculture, Phytosanitary Certificate Issuance & Tracking System (PCIT). https://pcit.aphis.usda.gov/PExD/faces/ViewPExD.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 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

Fungi, Plant Pathogens

Peronospora digitalidis Gäum, 1923

California Pest Rating for
Foxglove, Downy Mildew Plant Symptoms
Downy mildew does occur in the landscape in Washington. Note lesions with angular margins. ~ Photo Credit: Jenny Glass, 2011.
Peronospora digitalidis Gäum, 1923
Pest Rating: C
PEST RATING PROFILE
Initiating Event:

On February 9, 2016, USDA’s Animal and Plant Health Inspection Service (APHIS) notified the CDFA that the downy mildew pathogen, Peronospora digitalidis, was added on February 2, 2016, to their ‘List of Pests no Longer Regulated at U.S. Ports of Entry’ under the Federally Recognized State Managed Phytosanitary (FRSMP) program (USDA APHIS 2016).  Consequently, USDA APHIS will no longer take regulatory action this pathogen at ports of entry.  Therefore, and at the request of Stephen Brown, Assistant Director, CDFA, the risk of infestation and the current rating for P. digitalidis is re-assessed here.

History & Status:

Background:  Peronospora digitalidis is an oomycete in the order Peronosporales, which causes downy mildew disease of foxglove (Digitalis spp.).  The pathogen has been reported in Europe, Asia, and New Zealand, and was first reported from the United States, in 2002, on potted common foxglove plants in commercial nurseries in Santa Cruz County, California (Tjosvold & Koike, 2002).  It is likely that all affected nursery plants were destroyed, however, following its initial detection, in 2003, the pathogen continued to be found in several nurseries in California coastal counties and most recently in 2015 (CDFA Pest and Damage Records).

Disease cycle:  Peronospora digitalidis is an oomycete belonging to the family Peronosporaceae.  Generally, downy mildews overwinter as thick-walled resting spores called oospores that are produced through the fertilization of two mating types.  However, no oospores have so far been reported for this pathogen.  It is likely that the pathogen survives as mycelium and/or condia (spores) in infected plant buds, plant debris, leaf tissue and shoots.  Downy mildews are severe in cool or warm (but not hot), high humid climates and when a film of water is present on plant tissue.  They primarily cause foliar blights and rapidly spread in young green leaf, twig and fruit tissues.  Under favorable weather conditions, condia are carried by wind or water to wet leaves near the ground where they infect through stomata of the lower leaf surface.  A conidium germinates via a germ tube that grows through leaf stomata into intercellular spaces within the leaf tissue and eventually penetrates plant cells through special structures called haustoria.  Developing hypha that spreads intercellularly forms a cushion of mycelia just below the stomata.  From this cushion, conidophores arise and emerge through stomata.  At their tips, conidia (sporangia/spores) are produced simultaneously and are carried by wind and rain to new infection sites of the same or different plant.

Dispersal and spread:  The pathogen can spread through contaminated plant cuttings, transplants, fresh leaves and within seeds.  Also, it produces airborne conidia (spores) can disperse and be carried by moist winds.  It can also be present in soil associated with host and non-host plants and therefore, can spread by any means that aids in the movement of soil and/or water from infected plants to non-infected ones.

Hosts: Digitalis spp. (foxglove): D. purpurea, D. grandiflora, D. lutea, and Digitalis sp. (Farr & Rossman, 2016). Foxy hybrids are very susceptible and D. grandiflora was symptomless when grown in a heavily diseased region (Tjosvold & Koike, 2002).

Symptoms and damage potential: On leaves, initial symptoms consist of light green, rectangular areas that are delimited by veins.  Later, these spots become chlorotic, coalesce and turn necrotic and purplish-gray sporulation of the pathogen develops primarily on the underside of leaves and sometimes on upper surfaces of leaves (Pscheidt & Ocamb, 2016).

Damage Potential: While estimates of crop losses caused in particular by Peronospora digitalidis have not been reported, downy mildews can cause rapid and severe losses of young plants in seedbeds and in the field. Nursery stock producers and landscape growers of foxglove species may be at risk of damages caused by this downy mildew pathogen.

Worldwide Distribution: Europe: Czech Republic, Poland, Germany, Italy, United Kingdom, Scotland, Wales; North America: USA (California, Oregon, Washington) (Farr & Rossman, 2016; Garibaldi et al., 2013; Tjosvold & Koike, 2002; Pscheidt & Ocamb, 2016).

Official Control: Since 2002, Peronospora digitalidis has been on the North American Plant Protection Organization (NAPPO) “Alert List” (EPPO, 2016).  Since February 2, 2016, it has not been regulated by the USDA (see ‘Initiating event’). Currently, it has a “C” rating in California.

California Distribution: Orange, San Diego, San Luis Obispo, Santa Barbara, and Santa Cruz (CDFA Pest and Damage Records).

California Interceptions:  Peronospora digitalidis was detected in two nursery foxglove shipments imported to California in 2003.

The risk Downy mildew of foxglove 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):  Peronospora digitalidis is likely to establish in cool to warm and very humid to wet climates where foxglove grows in California.  According to the California Invasive Plant Council (2006-2016), foxglove is found along the coast northward from Santa Barbara, infesting moist meadows and roadsides and also in the northern Sierra Nevada foothills.

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): Presently, the host range is limited to few reported species of Digitalis. 

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): Conidia are easily produced simultaneously and in abundance.  The pathogen is transmitted via infected plant material; conidia are dispersed by winds, water and associated soil.   

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): While estimates of crop losses caused by Peronospora digitalidis have not been reported, presence of the pathogen in open fields/landscapes and/or in nursery stock produced in greenhouse environments are expected to cause severe damage under cool or warm and humid climates resulting in significantly lower crop value and yield.  Infected, symptomatic nursery stock plants are not marketable resulting in total loss in recovery of production costs.  Markets for crop sale are directly affected.  Normal cultivation practices, including delivery and supply of irrigation water, would need to be altered to prevent spread of the pathogen.

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): Commercial landscape and home garden plantings of foxglove can be significantly impacted if infected by the downy mildew pathogen.  Under favorable climate conditions, disruption of natural communities and changes in ecosystem could occur with severe and widespread infestations of downy mildew. 

Consequences of Introduction to California for Downy mildew of foxglove:

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 = 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 Medium (-2): Presently, the downy mildew pathogen, Peronospora digitalidis, has been reported from at least five coastal counties.

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 impact and spread of this pathogen to other intrastate regions where Digitalis spp. is grown, is not known.  Future reports of the detection of P. digitalidis in California could lower the overall score for the pathogen although it is unlikely to affect its final rating.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Peronospora digitalidis is C.

References:

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

California Invasive Plant Council.  2006-2016. Invasive Plants of California’s Wildland Digitalis purpurea: http://www.cal-ipc.org/ip/management/ipcw/pages/detailreport.cfm@usernumber=42&surveynumber=182.php?print=y .

EPPO.  2016.  Peronospora digitalidis (PERODG).  New PQR database.  Paris, France: European and Mediterranean Plant Protection Organization.  http://newpqr.eppo.int.

Farr, D.F., & A. Y. Rossman.  Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA.  Retrieved January 28, 2016, from http://nt.ars-grin.gov/fungaldatabases/.

Garibaldi, A., D. Bertetti, A. Poli, and M. L. Gullino.  2013.  Outbreak of downy mildew caused by Peronospora digitalidis on common foxglove (Digitalis purpurea) in Italy.  Journal of Plant Pathology 95:659-668. doi: 10.4454/JPP.V95I3.021.

Pscheidt, J. W., and C. M. Ocamb (Senior Eds.).  2016.  Foxglove (Digitalis spp.) downy mildew.  PNW Plant Disease Management Handbook: http://pnwhandbooks.org/plantdisease/foxglove-digitalis-spp-downy-mildew.

USDA APHIS.  2016.  FRSMP: Pests no longer regulation at U. S. ports of entry.  United States Department of Agriculture Animal and Plant Health Inspection Service.  https://www.aphis.usda.gov/aphis/ourfocus/planthealth/plant-pest-and-disease-programs/frsmp/ct_non-reg-pests.

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 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.]

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Pest Rating: C

Posted by ls

Fungi, Plant Pathogens

Greeneria uvicola (Berk. & M. A. Curtis) Punith. 1974

California Pest Rating Proposal for
Greeneria uvicola (Berk. & M. A. Curtis) Punith. 1974
Pest Rating: B
PEST RATING PROFILE
Initiating Event:  

On December 16, 2015, a shipment of grape leaves from Texas, destined to a retail store in California, was intercepted by the Los Angeles County officials.  The leaves had symptoms of leaf spots and a sample was collected and sent to the CDFA Plant Pathology Laboratory for disease diagnosis.  The fungal pathogen, Greeneria uvicola, was identified as the cause for the leaf spots, by Suzanne Rooney Latham, CDFA plant pathologist.  The pathogen was given a Q rating and subsequently the shipment of grape leaves was destroyed.  The risk of infestation of Greeneria uvicola in California is evaluated and a permanent rating is herein proposed. 

History & Status:

Background:  Greeneria uvicola is the cause of ‘Bitter Rot’ of grapes. The disease is cosmopolitan and common in the southern eastern United States, while being an occasional problem in the northern region as far as Long Island and New England states.  Greeneria uvicola is an asexually reproducing fungus with no known sexual state. Taxonomically, the pathogen is also known by several synonyms (including, Greenaria fuliginea, Melanconium fuligineum, and Phoma uvicola) and based on molecular data was placed in Ascomycetes, Diaporthales (Farr et al., 2001; Sutton, 2015).

Hosts: Grapevine (Vitis spp.).

Symptoms:  The pathogen infects all above ground vegetative plant parts including stem, leaves, tendrils and fruits.  Leaf symptoms, which are more common on muscadine grapes than on bunch grapes, appear as tiny, sunken, reddish-brown flecks with yellow halos.  Stem and petiole infects result in round to elliptical, reddish brown to black lesions which may be slightly raised or sunken.  Flecking of sepals and blighting of flower buds may also occur.  The fungus initially invades the berry from the berry stem (pedicel) at the onset of ripening. Infected light-skinned berries turn brown and form multiple, prominent fungal asexual fruiting bodies (acervuli) once the berries reach their full size.  As the rot progresses through the infected berries, the acervuli form in concentric rings, but are more uniformly distributed once the fruit is completely rotted.  These symptoms are less visible on dark-skinned berries which rough-skinned and iridescent.  Eventually, infected berries soften, shrivel, may be completely covered with acervuli, and may abscise or become mummified and remain attached (Sutton, 2015).

Damage Potential:  Infected fruit becomes rotted and as rotted fruit begins to soften they have a distinct bitter taste which is carried through the winemaking process resulting in a finished wine with an unpleasant, burnt or bitter taste.  Therefore, the marketability of diseased fruit for table or wine use is reduced.

Disease Cycle: The pathogen overwinters as a saprophyte on fallen fruit, cold-damaged shoot tips, and necrotic bark of the trunk and cordons.  In spring, gelatinous masses of spores (conidia) are produced from acervuli and washed by rain to green vegetative parts including the pedicels.  Disease development requires long and warm rains in spring, followed by warm, humid summers.  Infections occur during wet periods at 12-30°C, and optimally at 22.4-24.6°C, with 6-12 hrs wetness.  The fungus invades the pedicel and remains latent until fruit mature.  At that time the pathogen actively grows from the infected pedicel into the maturing fruit resulting in berry rot.  Conidia are produced in infected berries and rain splashed onto other ripening fruit causing secondary infections.  Infections usually occur in fruit wounded by insects, birds, hail, heavy rainstorms, or mechanically.  Berries are most susceptible at the onset of ripening however they may be infected by conidia anytime between bloom and harvest (Sutton, 2015).

Transmission:   The pathogen is spread through infected above ground vegetative plant materials and dead plant debris (leaves, stems, tendrils, and mummied fruits), rain/water splash.

Worldwide Distribution: Greeneria uvicola is distributed worldwide and reported from Asia: India, China, Taiwan, Thailand; Africa: South Africa; Europe: Bulgaria, Poland, Ukraine; North America: USA, Mexico; South America: Brazil, Costa Rica; Uruguay; Australia (Farr & Rossman, 2016; Samuelian, et al., 2013; ChaoYu et al., 2015).  Greece, Japan, and New Zealand have also been reported (Sutton, 2015).

In the USA, Greeneria uvicola has been reported mainly from the south eastern states.  Its distribution includes Florida, Georgia, Missouri, Mississippi, Ohio, Oklahoma, North Carolina, South Carolina, and West Virginia (Farr & Rossman, 2016).

Official Control:  Greeneria uvicola is on the ‘Harmful Organism List’ for China (PCIT, 2015).  Presently, G. uvicola has a temporary (Q) rating as a quarantine, actionable pathogen by the CDFA.

California Distribution:  Greeneria uvicola is not reported from California.

California Interceptions: There has been only one interception of Greeneria uvicola-infected grape leaves in California (see ‘Initiating Event”).

The risk Greeneria uvicola 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) – The requirements for a suitable climate of long periods of warm rains in spring, followed by warm, humid summers would not likely favor or greatly limit the establishment of Greenaria uvicola in California where grape is usually cultivated under warm and dry conditions.

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) – Grape (Vitis spp.) is the only host.  Although the host range is very limited, in California grape is a major crop that is cultivated over significant acreage.

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 Medium (2) – Greeneria uvicola is highly reproductive, producing gelatinous masses of conidia for primary and secondary infections.  Dispersal of conidia is dependent on rain splash for delivery to, and infection of non-infected above ground parts of the grapevine.

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) – Bitter rot diseased fruit is rotted and has a bitter taste that results in finished wine with an unpleasant bitter or burnt flavor.  Therefore, Greeneria uvicola-infected fruit could lower crop yield of healthy fruit bunches, lower crop value, and trigger loss of markets of table and wine grapes.   

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) – Home gardens cultivated with table and/or wine grapes could be significantly impacted if infected with the bitter rot pathogen.

Consequences of Introduction to California for Greeneria uvicola:

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 Greeneria uvicola 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 in California (0). 

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 bitter rot pathogen, Greeneria uvicola is B .  

References:

ChaoYu, Cui, Jiang JunXi, Ouyang Hui, Li Cheng, Liu DengQuan, and Huang Ting.  2015.  First report of Greeneria uvicola causing bitter rot of grape in China.  Journal of Phytopathology, 163:780-782.

http://www.eppo.int/DATABASES/pqr/pqr.htm .

Farr, D. F., and A. Y. Rossman.  2015.  Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved January 12, 2016, from http://nt.ars-grin.gov/fungaldatabases/

Farr. D. F., L. A. Castlebury, A. Rossman, and O. Erincik.  2001.  Greeneria uvicola, cause of bitter rot of grapes, belongs in Diaporthales.  Sydowia-Horn, 53:185-199.

PCIT.  2015.  USDA Phytosanitary Certificate Issuance & Tracking System. July 21, 2015.  https://pcit.aphis.usda.gov/PExD/faces/ReportHarmOrgs.jsp .

Samuelian, S. K., L. A. Greer, K. Cowan, M. Priest, T. B. Sutton, S. Savocchia, and C. C. Steel.  2013.  Phylogenetic relationships, pathogenicity and fungicide sensitivity of Greeneria uvicola isolates from Vitis vinifera and Muscadinia rotundifolia.  Plant Pathology, 62: 829-841.

Sutton, T. B.  2015.  Diseases caused by biotic factors, diseases caused by fungi and Oomycetes: Bitter Rot.  Compendium of Grape Disease, Second Edition.APS Press, The American Phytopathological Society, pg. 24-26.

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 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

Fungi, Plant Pathogens

Erysiphe aquilegiae DC. 1815

California Pest Rating for
Erysiphe aquilegiae DC. 1815
Pest Rating:  C
PEST RATING PROFILE
Initiating Event:  

None.

History & Status:

Background:  The fungal pathogen, Erysiphe aquilegiae, originally named, Ischnochaeta aquilegiae (DC.) Sawada 1959 is the cause of powdery mildew disease that infects several species of plant hosts, including Aquilegia sp. (columbine), mainly in the family Ranunculaceae.

The pathogen is also known by other scientific names, including, E. aquilegiae var. aquilegiae, E. aquilegiae var. ranunculi, and E. ranunculi.  According to Uwe Braun (Professor, Martin-Luther-Universitӓt, Institut für Biologie, Halle, Germany: personal communication to Cheryl Blomquist, CDFA plant pathologist, email dated October 29, 2015), as currently circumscribed, E. aquilegiae is a complex of species that have yet to be clearly distinguished genetically.

During October, 2013, CDFA plant pathologist, Cheryl Blomquist, detected the powdery mildew, Erysiphe aquilegiae on Ranunculus sp. nursery stock that was grown in fields in San Luis Obispo County.  Additionally, there is an earlier report of the asexual (anamorph) stage of Erysiphe, namely, Oidium sp. on Aquilegia sp. from southern coastal counties in California (A. M. French, 1987, California Plant Disease Host Index 2nd edition) that indicates that this powdery mildew pathogen is widely distributed within the State.

Hosts:  Erysiphe aquilegiae comprises numerous ornamental and weed hosts of several genera of the family Ranunculaceae: Aconitum, Actaea, Anemone, Aquilegia, Caltha, Clematis (=Atragene), Consolida, Coptis, Delphinium, Nigella, Ranunculus, Thalictrum, and Trollius (Farr & Rossman, 2015).

Other hosts in different families have been reported based only on morphological analysis of the pathogen.  These records have not been genetically proven and therefore, are doubtful (Braun-Blomquist: personal communication, 2015).  They include Alnus japonica and A. pendula (Betulaceae), Breea setosa and Cirsium spp. (Asteraceae), Magnolia liliiflora (Magnolioideae), Paeonia lactiflora (Paeoniaceae), Quercus crispula and M. mongolica var. grosseserrata (Fagaceae), Swertia spp. (Gentianaceae), Urena lobata and U. lobata var. tomentosa (Malvaceae), and Catharanthus roseus (Apocynaceae) (Bolay, 2005; Farr & Rossman, 2015; Liberato & Cunnington, 2006).

Symptoms:  White to grayish powdery, mildew grows in spots or patches on young plant tissue or covers entire leaves and other plant organs. Mildew growth is most common on upper side of leaves, but may also be found on the underside of leaves, young shoots and stems, buds, flowers and young fruit. Pinhead-sized spherical chasmothecia (completely closed fungal fruiting bodies containing spores), initially white to yellow brown later turning black in color, develop singly or in clusters on older mildew.

Damage Potential:  In general, powdery mildews seldom kill their hosts however they reduce photosynthesis, utilize plant nutrients, increase respiration and transpiration, impair plant growth and reduce crop yields up to 40% (Agrios, 2005).

Disease Cycle:  Erysiphe aquilegiae is an obligate parasite that produces mycelium on the surface of plant tissues without invading it.  The pathogen obtains nutrients from the plant by producing haustoria (specialized absorbing organs) that grow into the epidermal cells of the plant. On the plant surface, the mycelium produces short conidiophores which in turn produce numerous chains of conidia that appear as white powdery coating.  These conidia are easily dispersed by air currents to cause new infections of host plants.  When conditions are unfavorable, the pathogen may produce chasmothecia containing ascospores.  The disease is common in cool or warm humid regions, but can also be common in warm and dry climates since their spores only require high relative humidity and not free-standing water to be released, germinate and cause infections (Agrios, 2005).  Once a plant is infected, mycelium continues to spread on a leaf surface regardless of the level of atmospheric moisture.

Worldwide Distribution: Erysiphe aquilegiae is circumglobally distributed.  Africa: South Africa; Asia: Armenia, China, Iran, Taiwan, Japan, Korea, Israel, USSR; Africa: South Africa; Europe: Lithuania, Ukraine, Romania, Estonia, Belarus, Switzerland, Austria, Czechoslovakia, Denmark, Finland, France, Germany, Hungary, Italy, Norway, Poland, Sweden, USSR, Yugoslavia, United Kingdom, Bulgaria, the Netherlands, Montenegro;  North America: Canada,  Mexico, USA (including Alaska, California); South America: Argentina; Oceania: Australia, New Zealand (Bolay, 2005; Braun, 1987; Farr & Rossman, 2015).

Official Control: No official control has been reported specifically for Erysiphe aquilegiae.  However, the order Erysiphales and Erysiphe spp. are included in the ‘Harmful Organism Lists’ for Australia and Nauru (Erysiphales) and Dominica, Grenada and Saint Lucia (Erysiphe spp., specifically for Mangifera spp. which is not a reported host for E. aquilegiae) (USDA-PCIT, 2015).  In California, the current rating for E. aquilegiae is ‘Z’ (which is given to a previously unrated organism of known economic and or environmental detriment but generally distributed within the state).

California Distribution:  Southern coastal counties: San Benito, Monterey, San Luis Obispo, Santa Barbara, Ventura, Los Angeles, Orange, and San Diego Counties.

California Interceptions: None reported.

The risk Erysiphe aquilegiae 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): Powdery mildew disease is common in cool or warm humid regions, but can also be common in warm and dry climates since the fungal spores only require high relative humidity and not free-standing water to be released, germinate and cause infections.  Once a plant is infected, mycelium continues to spread on a leaf surface regardless of the level of atmospheric moisture.

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 High (3):  Hosts comprise ornamental and weed plants.  Most hosts of Erysiphe aquilegiae are in Ranunculaceae. Other doubtful hosts have also been reported in at least six other plant families.

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 powdery mildew pathogen has high reproduction and, under conducive environmental conditions of high relative humidity and wind currents, has high dispersal potential.

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): In particular, nursery grown ornamental plants infected with the powdery mildew pathogen Erysiphe aquilegiae could result in lowered crop production and loss in sales.

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): Powdery mildew infection may significantly impact home/urban and ornamental plantings.  Endangered plant species are not affected.  Although five species of the thistle plant Cirsium spp. (Crystal Springs fountain thistle, San Luis Obispo thistle, Ashland thistle, Suisun thistle, and Surf thistle) and four species of larkspur Delphinium spp. (Baker’s larkspur, Cuyamaca larkspur, Golden larkspur, and San Clemente Island larkspur) are listed as endangered plants in California, these species are not reported hosts of E. aquilegiae.

Consequences of Introduction to California for Erysiphe aquilegiae:

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 = 12 (Medium).

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 Medium (-3): Erysiphe aquilegiae has been detected in several southern coastal counties extending from San Benito to San Diego.  Given its high reproduction capability and suitable environmental conditions for its spread and infection, it is possible that the distribution of this powdery mildew extends further than currently reported.

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 Erysiphe aquilegiae is C.

References:

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

Bolay, A.  2005.  Les Oïdiums de Suisse (Erysiphacées).  Cryptogamica Helvetica, 20:38-40.

Braun U.  1987.  A monograph of the Erysiphales (powdery mildews).  Beihefte zur Nova Hedwigia, Heft 89, J. Cramer Berlin-Stuttgart 1987. Pgs 208-209.

Farr, D. F., and A. Y. Rossman.  2015.  Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved October 22, 2015, from http://nt.ars-grin.gov/fungaldatabases/

Liberato, J. R., and J. H. Cunnington.  2006.  First record of Erysiphe aquilegiae on a host outside the Ranunculaceae.  Australasian Plant Pathology, 35:291-292.

USDA-PCIT.  2015.  United States Department of Agriculture, Phytosanitary Certificate Issuance & Tracking System (PCIT). https://pcit.aphis.usda.gov/PExD/faces/ViewPExD.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.

Pest Rating:  C

Posted by ls

Fungi, Plant Pathogens

Colletotrichum theobromicola Declr. 1905

California Pest Rating for
Colletotrichum theobromicola Declr. 1905
Pest Rating:  B
PEST RATING PROFILE
Initiating Event:  

On September 8, 2015 diseased Coleonema sp. (breath of heaven) seedlings exhibiting blight symptoms were collected from a nursery in Sacramento by Sacramento County Agricultural officials, and sent to the CDFA Plant Diagnostics Branch for diagnosis.  Suzanne Latham, CDFA plant pathologist identified the fungal fruit spot and anthracnose pathogen, Colletotrichum theobromicola as the cause for the disease. Subsequently, on September 14 and October 8, 2015, C. theobromicola was detected from Annona squamosa (sugar apple) fruit intercepted in shipments destined to private citizens and intercepted at the United States Postal Service by County officials in San Joaquin and Santa Clara Counties respectively.  Both shipments originated in Florida.  Consequently, all infected plant material was destroyed.  The risk of infestation of C. theobromicola in California is evaluated and a permanent rating is proposed.

History & Status:

Background:  Colletotrichum theobromicola 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. The species: C. fragariae, C. gloeosporioides f. stylosanthis, C. gloeosporioides f. stylosanthis “f. sp. stylosanthis”, and C. gloeosporioides f. stylosanthis “f. sp. guianensis’ are genetically similar to, and synonyms of C. theobromicola (Weir et al, 2012).

Colletotrichum fragariae (synonym of C. theobromicola) has been previously reported from strawberry plants in California (Gunnell & Gubler, 1992), however, that report was based only on morphological analysis of the species.  So, while there is the possibility that C. theobromicola may have been present in California prior to the CDFA detections mentioned above, its presence cannot be assumed or confirmed without genetic analysis. The recent detections of the C. theobromicola by CDFA constitute its first official State record in California.

Hosts: Colletotrichum theobromicola has been reported on different hosts from different countries:  Acca sellowiana (pineapple guava), Annona diversifolia (Ilama fruit), Annona squamosa (sugar/custard apple), Buxus microphylla var. japonica (Japanese boxwood), Cassia obtusifolia (sicklepod), coffea arabica (Arabian coffee), Coffea sp., Coleonema sp. (breath of heaven)( CDFA detection), Cyclamens persicum (Persian cyclamen), Fragaria ananassa (strawberry), Fragaria sp., F. chiloensis (coastal strawberry), F. vesca (wild strawberry), F. virginiana (woodland strawberry), Limonium sp. (statice), Olea europaea (olive), Potentilla canadensis (dwarf cinquefoil), Punica granatum (pomegranate),  Quercus sp. (oak), Stylosanthes guianensis (stylo, Brazilian lucerne), S. viscosa (poorman’s friend), Theobroma cacao (cacao, cocoa tree) (Farr & Rossman, 2015; Weir et al., 2012).

Symptoms:  Colletotrichum theobromicola 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.  The pathogen causes anthracnose disease of strawberry with symptoms that include crown rot, fruit rot and stolon lesions (Gunnell & Gubler, 1992).

Damage Potential:  Anthracnose disease caused by Colletotrichum theobromicola 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 theobromicola 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:  Colletototrichum theobromicola is widely distributed in tropical and subtropical region worldwide.  Africa: Nigeria; Asia: India, Israel, Japan; North America: Mexico, USA (California, Florida, Indiana, Louisiana, Michigan, Mississippi, New York, North Carolina, South Carolina, Virginia), Cuba, Panama; South America: Brazil, Uruguay; Australia; New Zealand (CABI, 2015; Farr & Rossman, 2015; Gunnell & Gubler, 1992; Weir et al., 2012).

Official Control:  In California C. theobromicola is an actionable, Q-rated pathogen, and infected plant material is subject to destruction or rejection.

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

California Interceptions: Two interceptions of Colletotrichum theobromicola-infected sugar apple fruit (see ‘Initiating event’).

The risk Colletotrichum theobromicola 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. theobromicola 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.

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 Moderate (2) – Colletotrichum theobromicola has a moderate range of diverse hosts generally common in tropical and sub tropical regions. Of those hosts,strawberry, certain ornamentals, olive and oak are among the economically important hosts in 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 High (3) – Productions of strawberry fruit and nursery grown ornamental plants, in particular, can be limited by their 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 theobromicola:

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 theobromicola to California = (12).

6) Post Entry Distribution and Survey Information: Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included. (Score)

-Not established (0) Pest never detected in California, or known only from incursions.

-Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).

-Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.

-High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Evaluation is not established (0).  Colletotrichum theobromicola 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 = 12.

Uncertainty:

None.

Conclusion and Rating Justification:

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

References:

CABI.  2015.  Colletotrichum fragariae (anthracnose of strawberry) full 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/

Gunnell, P. S., and W. D. Gubler.  1992.  Taxonomy and morphology of Colletotrichum species pathogenic to strawberry.  Mycologia 84:157-165.

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

Fungi, Plant Pathogens

Colletotrichum queenslandicum B. Weir & P. R. Johnst. 2012

California Pest Rating for
Colletotrichum queenslandicum B. Weir & P. R. Johnst. 2012
 Pest Rating:  B
PEST RATING PROFILE
Initiating Event:  

On October 29, 2015 California Dog Teams intercepted Persea americana (avocado) fruit at parcel distribution facilities in Los Angeles and Santa Clara Counties.  The shipments had originated in Florida and Puerto Rico and were destined to private citizens in Los Angeles and Santa Clara Counties accordingly.  Diseased avocado fruit with necrotic spots were collected by County Agricultural officials, and sent to the CDFA Plant Diagnostics Branch for diagnosis.  Suzanne Latham, CDFA plant pathologist identified the fungal fruit spot and anthracnose pathogen, Colletotrichum queenslandicum as the cause for the disease. The identity of the associated pathogen was later confirmed by USDA National Identification Services at Beltsville, Maryland, and marked the first detection of C. queenslandicum in continental USA.  [According to USDA APHIS, the first US domestic detection of C. queenslandicum was reported from Hawaii on October 19, 2015.]  Consequent to the California detection, all infected plant materials were destroyed. The risk of infestation of C. queenslandicum in California is evaluated and a permanent rating is proposed.

History & Status:

Background:  Colletotrichum queenslandicum 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).  The species was originally described in 1965 as C. gloeosporioides var. minus Simmonds from Carica papaya (papaya) in Queensland, Australia.  The new name, C. queenslandicum was proposed by Weir and Johnston in 2012.

Hosts: Colletotrichum queenslandicum is known from few different hosts in different countries: Carica papaya, Carica sp. Persea americana, and Passiflora edulis (Australia); Coffea sp. (Fiji) (Farr & Rossman, 2015; James et al., 2014; Vieira et al., 2014; Simmonds, 1965).

Symptoms:  Colletotrichum queenslandicum 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:  Anthracnose disease caused by Colletotrichum queenslandicum 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 papaya and avocado 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 queenslandicum 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 queenslandicum is distributed in Australia and Fiji (Farr & Rossman, 2015; James et al., 2014; Vieira et al., 2014; Simmonds, 1965).

Official Control:  In California C. queenslandicum is an actionable, Q-rated pathogen, and infected plant material is subject to destruction or rejection.

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

California Interceptions: There have been two reported interceptions of Colletotrichum queenslandicum-infected avocado fruit. (see ‘Initiating event’).

The risk Colletotrichum queenslandicum 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 queenslandicum requires humid, wet, rainy weather for conidia to infect host plants. This environmental requirement and narrow host range may limit the ability of the pathogen to fully establish and spread under dry field conditions in mainly in southern California.

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 queenslandicum has a limited host range comprising mainly of avocado, papaya, coffee and purple Granadilla (Passiflora edulis).  The Latter two hosts are not grown in California and avocado and papaya have limited productions mainly in the southern regions of the State.

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 papaya and avocado fruit may result in lower crop value and market loss.  Its 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 backyard productions of papaya and avocado wherever grown in California.

Consequences of Introduction to California for Colletotrichum queenslandicum:

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 queenslandicum to California = (10).

6) Post Entry Distribution and Survey Information: Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included. (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 queenslandicum 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 = 10.

Uncertainty:

None.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for the anthracnose pathogen, Colletotrichum queenslandicum 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/

James, R.S., J.  Ray, Y. P. Tan and R. G. Shivas.  2014.  Colletotrichum siamense, C. theobromicola, and C. queenslandicum from several plant species and the identification of C. asianum in the Northern Territory, Australia. Australasian Plant Disease Notes : 1-6.

Simmonds, J. H.  1965.  A study of the species of Colletotrichum causing ripe fruit rots in Queensland.  Queensland Journal of Agricultural and Animal Sciences 22: 437-459.

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. Fung. 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

Fungi, Plant Pathogens

Geosmithia pallida (G. Sm.) M. Kolarík, Kubátová & Paotová

California Pest Rating for
Geosmithia pallida (G. Sm.) M. Kolarík, Kubátová & Paotová
 Pest Rating:  C
PEST RATING PROFILE
Initiating Event:

During August 2014, The CDFA Pathology Laboratory received official samples of diseased oak trees exhibiting symptoms of foaming cankers, collected from residential and commercial landscape sites in Marin and Napa counties.  The fungal pathogen Geosmithia pallida, causing foamy bark canker disease, was identified by Suzanne Latham, CDFA Plant Pathologist.  Within a few weeks of this detection, G. pallida was also detected in official oak samples collected in Santa Clara and El Dorado counties.  Prior to these official reports, the foamy bark canker disease has been known to exist throughout southern California extending to Monterey County.   The pathogen has not been previously rated and therefore, the need for a definite rating is necessitated and proposed.

History & Status:

Background:  Researchers at the Department of Plant Pathology, University of California, Riverside, have observed since 2012 decline of coast live oak (Quercus agrifolia) throughout urban landscapes in southern California (Lynch, et al., 2014). The fungus Geosmithia pallida was determined to be the cause of the observed symptoms which were successfully reproduced in pathogenicity tests on detached coast live oak shoots and in 2014, Lynch et al. provided the first report of G. pallida causing foamy bark canker on coast live oak in California and the USA.  They recovered the fungal species from symptomatic plant tissues associated with the western oak bark beetle Pseudopityophthorus pubipennis.  The western oak bark beetle is native to California and common as a secondary agent that readily attacks stressed plants.  It has not been previously associated with disease; however, cryptic species may be common among bark and ambrosia beetles (Lynch et al., 2014). The beetle burrows through the tree bark forming shallow tunnels below the bark and across the grain of the wood.  Eggs are laid within the tunnels and on hatching, the developing larvae form tunnels at right angles to their main tunnel and mostly within the inner bark or phloem close to the surface.  The fungus is dry-spored and occurs in the tunnels or galleries built by the beetles. Once insect larvae develop, they carry fungal spores and fly to other uninfected trees thereby spreading the fungus.

The fungal pathogen was originally placed in the genus Penicillium as the species, P. palladium which was later considered a synonym of Geosmithia putterillii (Pitt, 1979).  The latter species is a complex group of species comprising three genetically isolated cryptic species with worldwide distribution (Kolařík et al., 2004). Several isolates have been acquired from wood or subcorticolous insects.  In 2004, based on molecular and morphological analyses, Kolařík and others separated G. pallida from the G. putterillii species complex.

Hosts: Quercus agrifolia (coast live oak), Q. rubra (northern red oak), Q. wislizenii (interior live oak).

Symptoms:  Symptoms of G. pallida infection occur on the trunk and primary branches of trees and include wet discoloration seeping through entry holes caused by the western oak bark beetle.  Necrotic phloem and xylem tissue is apparent beneath the outer bark.  Multiple beetle entry holes may also be apparent on a single tree.  As the disease advances, a cream to reddish sap may ooze from the entry hole, followed by a prolific foamy liquid which may run down the trunk for about 2 feet.  The symptoms may be confused with those caused by Fusarium dieback/Polyphagous Shot Hole Borer; however, the size of the entry hole associated with foamy canker is smaller than those made by the Polyphagous Shot Hole Borer (Lynch et al., 2014).  In Europe, in laboratory plant growth culture tests using garden cress plants, G. pallida inhibited root growth by 25% whereas stem growth was almost unimpaired (Čižková et al., 2005).

Damage Potential:  Symptom associated with foamy bark canker disease on coast live oak result in branch dieback and tree death.

Transmission:  The fungal pathogen is associated with the western oak bark beetle and transmitted from infected to non-infected trees during movement and feeding by the beetle.  The fungus is also spread to uninfected sites through the movement of infected wood, such as firewood, and contaminated pruning and cutting equipment.

Worldwide Distribution:  Geosmithia pallida has a worldwide distribution (Kolařík et al., 2004).

Official Control:  There are no reports of official control of the fungal pathogen.

California Distribution: Los Angeles, Orange, Riverside, Santa Barbara, Ventura and Monterey counties (Lynch et al., 2014).  CDFA official samples collected from El Dorado, Napa, Marin and Santa Clara counties were positive for Geosmithia pallida (see ‘Initiating Event’).

California Interceptions:  Geosmithia pallida has not been intercepted in imported official shipments to California.

The risk Geosmithia pallida 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 High (3). Geosmithia pallida is already established in ten counties.

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).   Presently the pathogen has been observed causing decline and death of coast live oak in association with the western oak bark beetle.  In California, coast live oak occurs in the coastal ranges from north central to southern counties. So, even though Geosmithia pallida has been found affecting one host, the latter as well as other host species of oak are relatively wide spread throughout the State.

 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 fungal pathogen is artificially spread by movement of its associated insect vector and infected wood. The western oak bark beetle vector is native to California and is capable of moving and finding habitation throughout the State.

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).  Foamy bark canker disease caused by Geosmithia pallida could result in tree decline and death of coast live oak trees.  Currently, there are no known control measures against this pathogen. Early detection is noted as being crucial and could lead to pruning back infected branches, and other cultural treatments.  Regulations against movement of oak firewood could be necessary and this could directly trigger loss of markets. Plus the pathogen is easily vectored by the native western oak bark beetle.   

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 High (3).  The decline of infected oak trees could have significant environmental impact by disrupting natural communities, critical habitats or changing the ecosystem process. The potential loss of coast live oak could seriously threaten the conservation of the host plant thereby negatively impacting the 2001 California Oak Woodlands Conservation Act approved by California State Legislature.

Consequences of Introduction to California for Geosmithia pallida:

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 Geosmithia pallida to California = (13).

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 High (-3). The pathogen has been reported in more than two contiguous or non-contiguous counties with suitable host and climate.

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 pathogen is capable of spreading throughout California wherever suitable host and climate are present.  Since its detection in the southern counties it has spread to the central coastal region.  With the widespread distribution of the host plant and the associated western oak bark beetle vector, there is the possibility for the foamy bark canker disease to continue to spread statewide.  Further statewide survey and reports would be necessary to confirm this probability.  With further spread of the pathogen, the numeric score assessed here is not expected to change by much, thereby, strengthening its proposed ‘C’ rating.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for the Foamy Bark Canker Disease pathogen, Geosmithia pallida is C.

References:

Čížková, D., P. Šrůtka, M. Kolařík, A. Kubátová and S. Pažoutová.  2005.  Assessing the pathogenic effect of Fusarium, Geosmithia and Ophiostoma fungi from broad-leaved trees.  Folia Microbiologica, 50:59-62.

Kolařík, M., A. Kubátová, S. Pažoutová and Petr Šrůtka.  2004.  Morphological and molecular characterization of Geosmithia putterillii, G. pallida comb. nov. and G. flava sp. nov., associated with subcorticolous insects.  Mycological Research 108: 1053-1069.

Lynch, S. C., D. H. Wang, J. S. Mayorquin, P. Rugman-Jones, R. Southamer and A. Eskalen.  2004.  First report of Geosmithia pallida causing foamy bark canker, a new disease on coast live oak (Quercus agrifolia) in association with Pseudopityophthorus pubipenis (western oak bark beetle, Coleoptera: Curculionidae: Scolytinae) in California.  Plant Disease “First Look” paper posted 05/21/2014: http://dx.doi.org/10.1094/PDIS-03-14-0273-PDN.

Lynch, S. P., R. Rugman-Jones, R. Southamer and A. Eskalen.  (Not dated).  Pest Alert:  Geosmithia pallida and Western Oak Bark Beetle (Pseudopityophthorus pubipenis) causing foamy bark canker disease on coast live oak (Quercus agrifolia) in California.  University of California, Riverside.

Pitt, J. I. (1979) Geosmithia gen. nov. for Penicillium lavendulum and related species. Canadian Journal of Botany 57: 2021–2030.

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:  C

Posted by ls

Fungi, Plant Pathogens

Didymella bryoniae (Auersw.) Rehm [teleomorph] (Auersw.) Rehm

California Pest Rating for
Didymella bryoniae (Auersw.) Rehm [teleomorph] (Auersw.) Rehm
Pest Rating:  B
PEST RATING PROFILE
Initiating Event:

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

History & Status:

Background:  Didymella bryoniae is the fungal pathogen that causes gummy stem blight of cucurbits disease affecting members of the family Cucurbitaceae.  Gummy stem blight was first reported in 1891 in France, Italy and the United States and affects the leaves, stems, fruits and seeds of all cucurbits.   The disease is most common in subtropical and tropical regions globally but also found in temperate regions, especially on winter squash and pumpkin and greenhouse grown cucumber (Sitterly & Keinath, 1996).  The disease is most common in the southern United States, and in California, gummy stem blight was first reported in greenhouse-produced transplants of watermelon in the Salinas Valley (Koike, 1997).  Since 1997, there have not been any further reports of the pathogen in California.

Didymella bryoniae is the sexual (teleomorph) stage of the fungus that produces ascospores, while Phoma cucurbitacearum represents the asexual stage (anamorph) that produces conidia.  Didymella bryoniae was originally described as Sphaeria bryoniae, but since then has undergone several classifications that resulted in synonymizations of many different species.

Hosts: Members of the family Cucurbitaceae including wax gourd (Benincasa hispida), watermelon (Citrullus lanatus), melon (Cucumis melo), cucumber (C. sativus), pumpkin (Cucurbita sp.), giant pumpkin (C. maxima), ornamental gourd (C. pepo), buffalo gourd (C. foetidissima), bottle gourd (Lagenaria siceraria), bitter gourd (Momordica charantia), loofah (Luffa cylindrica), white bryony (Bryonia alba), red bryony (B. dioica), chayote (Sechium edule), and burcucumber (Sicyos angulatus) Occasionally, the pathogen has been found in members of Solanaceae, Caricaceae, and Primulaceae (CABI, 2015; Farr & Rossman, 2015).

Symptoms:  Didymella bryoniae invades the leaves and stems of watermelon, cucumber, and muskmelon (cantaloupe) and gummy stem blight diseased plants may exhibit a variety of symptoms which are referred to as leaf spot, stem canker, vine wilt and black fruit rot (Ferreira & Boley, 1992).  Initial spots on leaves, petioles and stems usually become pale brown or gray. On stems, spots usually start at the joints, frequently elongate into streaks and exude an amber-colored gummy liquid.  Lesions on leaves and fruit initiate as spreading water-soaked areas which in leaves may have a chorotic halo, become light brown and irregular in outline, and necrotic.  Leaves wilt and collapse; affected plants wilt and eventually die. On fruit, faded and irregular spots first form on the surface and eventually turn dark and may have a hardened droplet of exudates in the center; cracked sunken lesions form with internal rotting – especially in storage fruit.  In certain kinds of squash, lesions are superficial and spread almost over the entire fruit surface.  When seed-transmitted, the pathogen causes damping-off thereby, killing seedlings.  In the field, initial symptoms include plant collapse with sunken girdling cankers that result in total loss of plants.  Vine cankers are common near the crown of the plant.  (Agrios, 2005; CABI, 2015; Ferreira & Boley, 1992; Koike, 1997; Sitterly & Keinath, 1996.)

The main diagnostic symptoms are the gummy exudates on stem and fruit lesions, and the presence of abundant closely spaced groups of pale-colored pycnidia (asexual fruiting body) and dark brown to black-colored perithecia (sexual fruiting body) on fruit, stem or leaves.  During rainy seasons lesions can become water-soaked and spread resulting in severe defoliation.  Gummy substances may exude from cracks, and severe infections can result in death of plants (CABI, 2015).

Damage Potential: Didymella bryoniae has the potential of damaging plant growth causing reductions in plant growth, death of infected plants, fruit rot, and seedling death resulting in significant crop losses.

Disease Cycle:   The pathogen usually overwinters in diseased plant debris as chlamydospores and possibly in or on seeds.  Subsequently, spores or infected seed result in primary infection of plants. Cucurbit plants are predisposed to infection by wounds and bruises although uninjured plants have also been shown to become infected when exogenous nutrients are present (Ferreira & Boley, 1992).  The disease thrives in cool moist climates with an optimum temperature of 20-28 C for development.  Moisture, especially extended periods of wetness, is necessary for infection (at least 1 hour) and disease development.  Leaves are penetrated directly through the cuticle or through intercellular spaces around the bases of trichomes. Stems are penetrated through wounds and fruit are penetrated through wounds or flower scars at the time of pollination.  Fruit rot initiates approximately 3 days following infection.  Following penetration and development, the fungus produces numerous pycnidia and perithecia.  Pycnidia are filled with conidia (spores) that protrude from the fruiting body in a gelatinous substance appearing as long cream to pink tendrils.  Water dissolves this gelatinous substance and the conidia are dispersed usually by wind and rain.  Perithecia are also produced along with pycnidia and filled with ascospores. Both types of spores serve as inoculum for infection.  Neither type survives long after dispersal (Agrios, 2005; Ferreira & Boley, 1992; Sitterly & Keinath, 1996).

Transmission:  Infected planting material (transplants), infected fruit, plant debris, weeds, and soil.  In addition, conidia can be transmitted by air transport and water splashing (Ferreira & Boley, 1992).  Seed transmission has only been demonstrated experimentally (Brown et al., 1970; CABI, 2015; Lee et al., 1984).  Reports of seed transmission are conflicting and there is no evidence that seed transmission occurs naturally although fruiting bodies (pycnidia and perithecia) of the pathogen have been found on naturally infected cucumber and pumpkin seeds (CABI, 2015).  The striped cucumber beetles (Diabrotica undecimpunctata howardii and Acalymma vittatum) are believed to transmit D. bryoniae in a nonpersistent manner by providing wounds in plants as avenues for fungal infections. It has also been shown experimentally that cucumber plants infested with melon aphids were susceptible to D. bryoniae and powdery mildew (Ferreira & Boley, 1992).

Worldwide Distribution:  Didymella bryoniae is distributed worldwide in several countries in Asia, Africa, North America, Central America and Caribbean, South America, Europe, and Oceania (CABI, 2015).

In the USA, it has been reported from Florida, Georgia, New York, North Carolina, and South Carolina.

Official Control:  Didymella bryoniae is included on the ‘Harmful Organism Lists’ for nine countries namely: Bangladesh, Ecuador, Egypt, Indonesia, Iran, Israel, Panama, Syrian Arab Republic and Timor-Leste (PCIT, 20115).  It is a quarantine pest in Jordan (EPPO, 2015).   Currently, it is an actionable, temporary ‘Q’-rated pathogen in California.

California Distribution: Didymella bryoniae has only been reported once in 1997 in Salinas in greenhouse watermelon transplants.  The diseased plants would have been destroyed following detection.  The pathogen has not been reported since then and is not known to be established in California.

California Interceptions:  None reported.

The risk Didymella bryoniae 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) – Didymella bryoniae requires cool and moist conditions to infect cucurbit hosts and cause gummy stem blight disease.  At least 1 hour of wetness is required for infection and extended periods for disease development.  This may limit the establishment of the disease in cucurbit productions in California and may also be why this disease has not been observed outside greenhouse production in California since the early 1990s.  Therefore, a ‘medium’ rating is given to this category.

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 Medium (2) – The host range is mainly limited to various species of the Cucurbitaceae family.  Nevertheless, Cucurbitaceous hosts, including watermelon, melon, squash and cucumber, are widely grown commercially within 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) – Under favorable environmental conditions Didymella bryoniae has a high reproductive rate and depends on wind and moisture or rain for its short distance dispersal.  Infected planting material, infected fruit, plant residues, weeds, soil, and possibly seed provide the means for long distance dispersal, also in fields and greenhouses. In addition, the striped cucumber beetles are believed to transmit D. bryoniae in a nonpersistent manner by providing wounds in plants as avenues for fungal infections.  

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) –  The cucurbit gummy stem blight pathogen could lower crop value and yield, cause increases in production costs for disease management, and negatively change normal cultural practices to mitigate potential damages.  There is also the possibility for the pathogen to be vectored by pestiferous striped cucumber beetles.  Therefore, a ‘high’ rating is given to this category.   

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) – Cucurbitaceous plants grown in home/urban gardens could be negatively impacted if infected with Didymella bryoniae.

Consequences of Introduction to California for Didymella bryoniae:

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 Didymella bryoniae to California = Medium (12).

6) Post Entry Distribution and Survey Information: Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included. (Score)

–Not established (0) Pest never detected in California, or known only from incursions.

-Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).

-Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.

-High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Evaluation is not established in California (0). 

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 =12 (Medium).

Uncertainty:

Infested seeds and transplants are a ready source of introduction of the pathogen to CA fields.  The future status of Didymella bryoniae, gummy stem blight of cucurbits disease, can be known through periodic surveys, diligent monitoring and testing of seed/plants in greenhouses and will be necessary in order to mitigate risk of field introduction and potential establishment of the pathogen in California soils.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for the anthracnose pathogen, Didymella bryoniae is B.  

References:

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

Brown, M. E., E. M. Howard, and B. C. Knight. 1970. Seedborne Mycosphaerella melonis on cucumber. Plant Pathology, 19:198.

CABI.  2015.  Didymella bryoniae (gummy stem blight of cucurbits) datasheet (full) report.  Crop Protection Compendium.  www.cabi.org/cpc/

EPPO.  2015.  Stagonosporopsis cucurbitacearum (DIDYBR).  European and Mediterranean Plant Protection Organization PQR database.  http://www.eppo.int/DATABASES/pqr/pqr.htm .

Farr, D. F., and A. Y. Rossman.  2015.  Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved July 14, 2015, from http://nt.ars-grin.gov/fungaldatabases/

Ferreira, S. A., and R. A. Boley.  1992.  Didymella bryoniae Gummy stem blight, black rot, canker (Plant Disease Pathogen).  http://www.extento.hawaii.edu/kbase/crop/Type/d_bryon.htm

Koike, S. T.  1997.  First report of gummy stem blight, caused by Didymella bryoniae, on watermelon transplants in California.  Plant Disease, 81:1331. http://dx.doi.org/10.1094/PDIS.1997.81.11.1331B.

Lee, D. H., S. B. Mathur, and P. Neergaard. 1984. Detection and location of seed-borne inoculum of Didymella bryoniae and its transmission in seedlings of cucumber and pumpkin. Phytopathologische Zeitschrift, 109(4):301-308.

PCIT.  2015.  USDA Phytosanitary Certificate Issuance & Tracking System. July 21, 2015.  https://pcit.aphis.usda.gov/PExD/faces/ReportHarmOrgs.jsp .

Sitterly, W. R., and A. P. Keinath.  Gummy stem blight.  1996.  In, Compendium of cucurbit diseases.  Compendium of cucurbit diseases ed. T. A. Zitter, D. L. Hopkins, and C. E.  Thomas, APS Press  pg 27-28. http://www.apsnet.org/publications/apsnetfeatures/Pages/GummyStemBlight.aspx .

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

Fungi, Plant Pathogens

Colletotrichum spaethianum (Allesch.) Damm, P. F. Cannon & Crous, 2009

California Pest Rating for
Colletotrichum spaethianum (Allesch.) Damm, P. F. Cannon & Crous, 2009
Pest Rating:  B
PEST RATING PROFILE
Initiating Event:  

On March 27, 2015, a mail shipment containing Iris sp. plants with leaf spots was intercepted by the CDFA Dog Team, at the United States Postal Service Center in West Sacramento, Yolo County.   The plants had been shipped by a private owner in Gowen, Oklahoma.  Samples collected were submitted to the CDFA Plant Pathology Laboratory and the fungal pathogen, Colletotrichum spaethianum, was isolated from the diseased plants and identified by Suzanne Latham, CDFA plant pathologist.  The species identity was confirmed on August 18, 2015, by the USDA PPQ National Mycology Laboratory.  This detection was considered a new US record and reportable by the USDA. Consequently, the shipment of Iris sp. plants was destroyed.  The risk of infestation of C. spaethianum in California is evaluated and a permanent rating is proposed.     

History & Status:

Background:  The fungal pathogen Colletotrichum spaethianum was originally described in 1895 under the name Vermicularia spaethiana from dead stems of Funkia univittata (synonym Hosta sieboldiana) in Berlin, Germany.  A living strain of the original material of pathogen is no longer available however, as a result of taxonomic and phylogenetic studies, Damm et al., (2009) combined V. spaethiana to the genus Colletotrichum becoming C. spaethianum and designated an epitype (representative specimen in place of the non-available original specimen) from the same host in the same city as the original fungal species.

Hosts: Hosta sieboldiana, Hemerocallis sp.(daylily), H. flava, H. fulva, H. citrine, Hymenocallis americana (northern spider lily), Lilium sp. (Lily), Peucedanum praeruptorum (Qian Hu), Allium fistulosum (Welsh onion), (Damm et al., 2009, 2012; Yang et al., 2009; Yang et al., 2014; Guo et al., 2013; Vieria et al., 2014; Farr & Rossman, 2015). The CDFA detection of Colletotrichum spaethianum in Iris sp. is a new host record.

Symptoms:  Colletotrichum spaethianum infected host plants exhibit symptoms of anthracnose which include reddish brown to dark brown leaf and stem necrotic spots and wilting of leaves which often result in dieback and reduction in plant quality.

Damage Potential:  Anthracnose disease caused by Colletotrichum spaethianum 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 spaethianum 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:  Europe: Germany; Asia:  South Korea; North America: Florida, South America: Oceania: New Zealand (Cai, et al., 2009; Damm et al., 2009; Farr & Rossman, 2015; Yang, et al., 2009; Yang et al., 2014).

Official Control:  In California C. spaethianum is an actionable, Q-rated pathogen, and infected plant material is subject to destruction or rejection.   The species is considered ‘reportable’ by the USDA.

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

California Interceptions:  There has been one interception of Colletotrichum spaethianum –infected (Iris) plants that originated in Oklahoma (see ‘Initiating event’).

The risk Colletotrichum spaethianum 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. spaethianum requires humid, wet, rainy weather for conidia to infect host plants. This environmental requirement may limit the ability of the pathogen to establish and spread in less conducive climates. Also confining is the limited host range comprising primarily of lily and iris ornamental plants which are cultivated in nurseries, residential and commercial community environments such as parks and gardens.  The pathogen could establish within these limited regions when grown under favorable moist conditions.

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) – Presently, the host range of Colletotrichum spaethianum is limited to hosta, daylilies, northern spider lily, lily, iris, Qian Hu (Chinese medicinal plant), and Welsh onion.

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) – In particular, nursery and private productions of lily, hosta, and iris ornamental plants can be limited by their susceptibility to anthracnose under wet conditions. Therefore, under suitable climates, the pathogen could lower plant growth, 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 High (3) – The pathogen could significantly impact cultural practices or home/urban garden plantings. Also, the pathogen could impact endangered lily plants in California, namely: western lily (Lilium occidentale) and Pitkin Marsh lily (Lilium pardalinum ssp. Pitkinense) (State and federally listed endangered, threatened and rare plants of California, California Natural Diversity Database, California Department of Fish and Wildlife, July 2015).

Consequences of Introduction to California for Colletotrichum spaethianum:

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 spaethianum 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 spaethianum is not established in California.  The intercepted C. spaethianum-infected iris 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:

None.

Conclusion and Rating Justification:

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

References:

Cai, L., Hyde, K.D., Taylor, P.W.J., Weir, B.S., Waller, J.M., Abang, M.M., Zhang, J.Z., Yang, Y.L., Phoulivong, S., Liu, Z.Y., Prihastuti, H., Shivas, R.G., McKenzie, E.H.C., and Johnston, P.R. 2009. A polyphasic approach for studying Colletotrichum. Fungal Diversity 39: 183-204.

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/

Guo, M., Y. M. Pan, Y. L. Dai, and Z. M. Gao.  2013.  First report of leaf spot caused by Colletotrichum spaethianum on Peucedanum praeruptorum in China.  Plant Disease, 97:1380.

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.

Santana, K. F. A., C. B. Garcia, K. S. Matos, R. E. Hanada, N. R. Sousa, G. F. and Da Silva.  2015. First report of anthracnose caused by Colletotrichum spaethianum on Allium fistulosum in Brazil.  Plant Disease (Accepted for publication) posted on line on 3Aug 2015, First Look.  http://dx.doi.org/10.1094/PDIS-07-15-0737-PDN.

Vieira, W. A. S., S. J. Michereff, A. C. Oliveira, A. Santos and M. P. S. Câmara.  2014.  First report of anthracnose caused by Colletotrichum spaethianum on Hemerocallis flava in Brazil.  Plant Disease, 98:997.  http://dx.doi.org/10.1094/PDIS-10-13-1026-PDN

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

Yang, H. C., J. S. Haudenshield and G. L. Hartman. 2014. Colletotrichum incanum sp. nov., a curved-conidial species causing soybean anthracnose in USA. Mycologia 106: 32-42.

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