Tag Archives: fungi

Cronartium quercuum (Berk.) Miyabe ex Shirai 1899


California Pest Rating Proposal for

Cronartium quercuum (Berk.) Miyabe ex Shirai 1899
Current Rating: Z
Proposed Rating: C

Comment Period: 8/29/2019 through 10/13/2019



Responsible Party:

Heather J. Scheck, CDFA Primary Plant Pathologist/Nematologist. 204 West Oak Ave, Lompoc, CA
93463. 805-736-8050. plant.health[@]cdfa.ca.gov.

*NOTE:

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Posted by ka

Septoria protearum Viljoen & Crous 1998

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

 


PEST RATING PROFILE
Initiating Event:

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

History & Status:

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

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

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

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

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

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

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

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

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

California Interceptions:  None.

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

Consequences of Introduction: 

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

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

Score: 2

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

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

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

2) Known Pest Host Range: Presently, the pathogen has a moderate and diverse range of hosts inclusive of species in ten plant families.

Evaluate the host range of the pest.

Score: 2

– Low (1) has a very limited host range.

Medium (2) has a moderate host range.

– High (3) has a wide host range.

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

Evaluate the natural and artificial dispersal potential of the pest.

Score: 2

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

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

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

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

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

Economic Impact: B, C, D

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

Economic Impact Score:  3

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

– Medium (2) causes 2 of these impacts.

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

5) Environmental Impact:  The pathogen could significantly impact ornamental plantings in home/ urban, public gardens and other recreational environments.

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

Environmental Impact: E

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

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

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

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

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

Environmental Impact Score: 2

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

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

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

Consequences of Introduction to California for Septoria protearum:  Medium (11)

Add up the total score and include it here.

-Low = 5-8 points

Medium = 9-12 points

-High = 13-15 points

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

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

Score: -1

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

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

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

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

Final Score:

7) The final score is the consequences of introduction score minus the post entry distribution and survey information score: (Score)

Final Score:  Score of Consequences of Introduction – Score of Post Entry Distribution and Survey Information = 10

Uncertainty:  

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

Conclusion and Rating Justification:

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

References:

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

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

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

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

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

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

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

Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-262-1110, plant.health[@]cdfa.ca.gov.


Comment Period: CLOSED

5/30/2017 – 7/14/2017

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

Stemphylium solani G. F. Weber 1930

California Pest Rating for
Stemphylium solani G. F. Weber 1930
Pest Rating: A

 


PEST RATING PROFILE
Initiating Event:

On March 31, 2017, the CDFA Permits and Regulations Program requested a rating for Stemphylium solani.  Therefore, the associated risk and current status of S. solani in California are assessed here and a permanent rating is proposed.

History & Status:

Background:   Stemphylium solani is a fungal pathogen that causes Gray leaf spot disease in tomato, and Stemphylium leaf blight disease in cotton, garlic, and other hosts.  Gray leaf spot in tomato is actually caused by three species of Stemphylium, one being S. solani and the other two species: S. lycopersici (Enjoji) W. Yaman (syn. S. floridanum Hannon & G. F. Weber) and S. botryosum Wallr. f. sp. lycopersici Rotem, Y. Cohen, & I. Wahl.  Gray leaf spot is regarded one of the most destructive diseases of tomato in the southeastern United States and throughout the world wherever warm and humid conditions prevail (Jones & Pernezny, 2014).

Gray leaf spot disease has been reported from several countries worldwide including the United States (see ‘Worldwide Distribution’). In the United States, the disease was first observed in 1924 and by 1928 had spread throughout Florida causing widespread defoliation. Since then, the pathogen has been reported from several states but has never been reported from California.

Disease development:  The disease begins in infested seedbeds and transplant houses or field-transplanted seedlings, usually when the plants are in the first true-leaf stage of growth.  Cotyledons are not severely infected.   The pathogen is spread when infected seedlings are transplanted to fields.  Conidia (asexual spores) can be spread over extensive distances by wind. The teleomorph or sexual stage of S. solani is not known.  The disease is favored by warm temperatures (24-27°C) and high humidity. Spore germination and infection of plant are dependent on the presence of free moisture (dew or rain) (Jones & Pernezny, 2014).  Leaf wetness is considered more important than temperature in establishment of infection (Cerkauskas, 2005).  Stemphylium solani survives as a saprophyte on infected plant debris or on volunteer tomato, pepper, gladiolus, blue lupine, and other wild solanaceous plants.  In the southern state climates, the pathogen remains viable on tomato plants which are grown throughout the year (Jones & Pernezny, 2014).  The pathogen can be seedborne (Koike et al., 2007).

Dispersal and spread: Infected plants, seedlings, and plant debris.  Conidia may be wind-blown over extensive areas or by splashing water (Jones & Pernezny, 2014).

Hosts: Hosts of Stemphylium solani are included primarily in the plant family Solanaceae.  Numerous other plant families are also included with their associated hosts, including Amaryllidaceae (Allium sp.), Asteraceae (Lactuca sp.), and Malvaceae (Gossypium hirsutum).  Hosts include, Aegiceras corniculatum (black mangrove), Allium sativum (garlic), Aster sp. (aster), Basella rubra (Malabar spinach), Capsicum annuum (bell pepper), C. annuum var. annuum (cayenne pepper), C. frutescens (chili pepper), Carthamus sp. (distaff thistles), Cirsium sp. (thistle), Citrus sp. (citrus), Convolvulus arvensis (field bindweed), Cucumis sativus (cucumber), Dactylis glomerata (orchardgrass), Dianthus caryophyllus (carnation), Gossypium hirsutum (upland cotton), Ipomoea reptans (synonym: I. aquatica, swamp morning-glory), Kalanchoe blossfeldiana (flaming katy), Lactuca sativa (lettuce), Lupinus angustifolius (narrowleaf lupine), Lupinus sp. (lupine), Lycopersicon esculentum (synonym: L. lycopersicum, tomato), Lycopersicon sp., Pelargonium zonale (horse-shoe pelargonium), Physalis pubescens (husk tomato), Physalis sp. (groundcherry), Solanum gilo (gilo), S. lycocarpum (wolf apple), S. lycopersicum (garden tomato), S. melongena (aubergine/eggplant), S. melongena var. esculentum, S. pseudocapsicum (Jerusalem cherry), S. tuberosum (potato), Vicia faba (fava bean), Vigna sinensis (synonym: V. unguiculata, cowpea) (CABI, 2017; Farr & Rossman, 2017).

Symptoms:  Gray leaf spots or lesions are almost entirely limited to the leaf blades, but under favorable conditions, lesions may develop on petioles and on the more tender parts of growing stems.  Lesions on stems are linear and parallel to the stem.  Fruit symptoms have not been observed.  In infected tomatoes, symptoms of gray leaf spot are first exhibited as minute brownish-black specks on the lower leaves.  Randomly scattered circular to oblong spots develop on adaxial and abaxial leaf surfaces without being restricted by leaf veins.  The spots may be surrounded by a narrow yellow halo and enlarge to about 2.1 mm in diameter while individual spots on the base of leaves may enlarge to twice that size or more in diameter and occasionally coalesce, thereby, killing large portions of the leaf blade. As the spots enlarge, the centers turn gray, eventually dry, crack, and fall out.  Frequently, at this stage entire leaves conspicuously turn yellow, especially if the infection is severe, and die rapidly, turning brown before dropping from the plants.  Seedbed infections result in marked defoliation without conspicuous yellowing (Jones & Pernezny, 2014; Damicone & Brandenberger, 2015).  In garlic, early symptoms of S. solani infection were observed as white spots (1-3 mm), which enlarged to sunken purple lesions, extending until the leaves withered (Zheng et al., 2008).

Damage Potential:  Gray leaf spot almost entirely affects leaves, and defoliation can be severe reducing available photosynthetic areas of infected plants thereby, resulting in reductions in plant development, quality, and fruit yields.  In China, garlic leaf blight caused by Stemphylium solani affected over 7,000 ha of field production and reduced yields up to 70% (Zheng et al., 2010).  During 1994 and 1995, a severe epidemic of leaf blight of cotton in Brazil resulted in yield losses up to 100% in some commercial fields (Mehta, 1998). Gray leaf spot disease limited tomato production in Venezuela and Malaysia (Cadeño & Carrero, 1997; Nasehi et al., 2012).   In California, processing tomatoes are grown in the warm and dry San Joaquin and Sacramento Valleys while fresh-market tomatoes are grown in the San Joaquin Valley, Central Valley, Central and Southern Coastal regions and the Imperial Valley.  It is less likely that S. solani will be able establish under warm and dry regions of the state’s tomato production acreages, as well as under the possible use of resistant varieties, protectant fungicides and cultural management strategies.  However, for tomato and other host plants under wet and warm climates, the pathogen may be able to establish within those regions.

Worldwide Distribution: Asia: Brunei Darussalam, China, Hong, Kong, Taiwan, Thailand, Korea, Malaysia; Africa: Libya, Mauritius, Senegal, Sudan, Tanzania; Europe: Greece, Spain; North America: Canada, USA (Alabama, Florida, Georgia, Indiana, Louisiana, Maryland, Mississippi, North Carolina, New Jersey, South Carolina, Tennessee, Texas, Virginia); South America: Brazil, Honduras, Venezuela; Central America and Caribbean: Cuba; Oceania: American Samoa (CABI, 2017; Cadeño & Carrero, 1997; Farr & Rossman, 2017).

Official Control: Presently, Stemphylium solani is on the Harmful Organisms list for Peru (USDA-PCIT, 2017).

California Distribution: Stemphylium solani has not been reported from California.

California Interceptions: None reported.

The risk Stemphylium solani would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Although Stemphylium solani has a wide host range that includes several economically important agricultural crops in California as well as wild solanaceous plants, the pathogen is dependent on leaf wetness for plant infection and additionally on warm temperatures for disease development.  The disease is most severe under humid and overcast climate conditions that favor wet foliage mainly due to dew or rain.  These conditions would allow the pathogen to establish in a larger but limited part of California.

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

Score: 2

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

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

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

2) Known Pest Host Range: Stemphylium solani has a wide host range of plants included primarily in the family Solanaceae. However, numerous other plant families are also included with their associated hosts.  Economically important crops include tomato, pepper, cotton, citrus, cucumber, lettuce, garlic, eggplant and others.  Several wild solanaceous host plants could allow build-up of fungal inoculum.

Evaluate the host range of the pest.

Score: 3

– Low (1) has a very limited host range.

– Medium (2) has a moderate host range.

High (3) has a wide host range.

3) Pest Dispersal Potential: Conidia are produced in abundance and readily dispersed by wind and splashing water. Also, the pathogen is spread through infected plants, seedlings, plant debris, and seed.

Evaluate the natural and artificial dispersal potential of the pest.

Score: 3

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

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

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

4) Economic Impact: Stemphylium solani causes gray leaf spot in tomato and peppers as well as leaf blight in other hosts. Leaves are almost always entirely affected by the disease and defoliation can be severe reducing available photosynthetic areas of plants thereby, resulting in reductions in plant development, quality, and fruit yields.  If not controlled, significant reductions in crop yield and markets could occur.  Use of fungicides and cultural management practices could increase costs of crop production.

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

Economic Impact: A, B, C, D

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

Economic Impact Score: 3

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

– Medium (2) causes 2 of these impacts.

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

5) Environmental Impact:  The pathogen could significantly affect home/urban gardening of agricultural crops and ornamental hosts.

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

Environmental Impact: E

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

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

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

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

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

Environmental Impact Score: 2

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

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

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

Consequences of Introduction to California for Stemphylium solani: High (13)

Add up the total score and include it here.

-Low = 5-8 points

-Medium = 9-12 points

High = 13-15 points

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

Evaluation is Not establishedin California.

Score: (0)

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

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

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

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

Final Score:

7) The final score is the consequences of introduction score minus the post entry distribution and survey information score: (Score)

Final Score:  Score of Consequences of Introduction – Score of Post Entry Distribution and Survey Information = 13

Uncertainty:  

None.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Stemphylium, solani is A.

References:

CABI, 2017.  Stemphylium solani (gray leaf spot) basic datasheet.  Crop Protection Compendium. http://www.cabi.org/cpc/datasheet/51531

Cerkauskas, R.  2005.  Tomato diseases, Gray leaf spot, Stemphylium solani, S. lycopersici found worldwide in warm climates.  AVRDC – The World Vegetable Center Fact Sheet.  AVRDC Publication 05-634.

Cadeño, L., and C. Carrero.  1997.  First report of tomato gray leaf spot caused by Stemphylium solani in the Andes Region of Venezuela.  Plant Disease 81: 1332. http://dx.doi.org/10.1094/PDIS.1997.81.11.1332B

Damicone, J. P., and L. Brandenberger.  2015.  Common diseases of tomatoes Part 1.  Diseases caused by fungi.  Oklahoma Cooperative Extension Service EPP-7625.

Farr, D. F., and A. Y. Rossman.  2017.  Fungal Databases, U. S. National Fungus Collections, ARS, USDA. Retrieved April 3, 2017, from http://nt.ars-grin.gov/fungaldatabases/

Jones, J. P., and K. L. Pernezny.  2014.  Gray Leaf Spot.  In Compendium of Tomato Disease and Pests Second Edition.  Ed. J. B. Jones, T. A. Zitter, T. M. Momol, and S. A. Miller, APS Press. The American Phytopathological Society.  29-30 p.

Koike, S. T., P. Gladders, and A. O. Paulus.  2007.  Stemphylium solani, S. lycopersici – gray leaf spot.  In Vegetables diseases a color handbook.  Academic Press, an imprint of Elsevier, Burlington, San Diego.  211-212 p.

Mehta, Y. R.  1998.  Severe outbreak of Stemphylium leaf blight, a new disease of cotton in Brazil. Plant Disease, 82: 333-336.

Nasehi, A., J. B. Kadir, M. A. Zainal Abidin, M. Y. Wong, and F. Mahmodi.  First report of tomato gray leaf spot disease caused by Stemphylium solani in Malaysia.  Plant Disease 96: 1226.  http://dx.doi.org/10.1094/PDIS-03-12-0223-PDN

USDA PCIT.  2017.  USDA Phytosanitary Certificate Issuance & Tracking System. April 3, 2017, 1:17:10 pm CDT.  https://pcit.aphis.usda.gov/PExD/faces/ReportHarmOrgs.jsp.

Zheng, L., J. B. HUANG, and T. HSIANG.  2008.  First report of leaf blight of garlic (Allium sativum) caused by Stemphylium solani in China. Plant Pathology 57: 380.

Zheng, L., L. V. Rujing, J. Huang, D. Jiang, X. Liu, and T. Hsiang.  2010.  Integrated control of garlic leaf blight caused by Stemphylium solani in China.  Canadian Journal of Plant Pathology 32: 135-145.


Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-262-1110, plant.health[@]cdfa.ca.gov.


Comment Period: CLOSED

Apr 20, 2017 – June 4, 2017


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: A


Posted by ls

Phytophthora parvispora Scanu & Denman, 2013

California Pest Rating for
Phytophthora parvispora  Scanu & Denman, 2013
Pest Rating: B 

 


PEST RATING PROFILE
Initiating Event: 

On August 19, 2016, non-official samples of pear baits of effluent collected from the bottom of four pots containing diseased Mexican orange blossom (Choisya ternata) plants, were sent by a private company to the CDFA Plant Pathology Lab for identification of the cultured pathogen.  The private company had prepared the pear baits after collection of the effluent drained from the four diseased plants that were contained in a commercial nursery in San Francisco County.  The associated pathogen was identified by Suzanne Latham, CDFA plant pathologist, as Phytophthora parvispora on September 9, 2016.  Subsequently, on September 22, 2016, San Francisco County Agricultural inspectors collected official samples of the same four symptomatic Mexican orange blossom plants originally sampled in San Francisco County.  The diseased plants exhibited root and crown rot symptoms and were sent to the CDFA Plant Pathology Lab for diagnosis.  On November 22, 2016, Suzanne Latham officially identified Phytophthora parvispora after baiting and culturing it from the roots of one of the four Choisya ternata plant samples (Latham, 2016).  This detection marked the first report of P. parvispora in the USA and therefore, a culture of the pathogen was sent from CDFA to the USDA APHIS CPHST in Beltsville for confirmation.  On November 15, 2016, the identity of P. parvispora was confirmed by CPHST.   Consequently, the pathogen was assigned a temporary ‘Q’ rating by CDFA.   The risk of introduction and establishment of this pathogen is assessed here and a permanent rating is proposed.

History & Status:

Background: Phytophthora parvispora was originally recorded from the stem bases of Beaucarnea sp. nursery plants grown in a greenhouse in Germany and was regarded a variety of the polyphagous fungal species, P. cinnamomi based on its morphology and temperature required for growth (Kröber & Marwitz, 1993).  However, Scanu et al., (2014) stated that P. parvispora was apparently isolated from citrus in Taiwan (Ann & Ko, 1985) prior to Kröber & Marwitz’ report and was suggested by several researchers to belong to a distinct species different from P. cinnamomi.   In subsequent years, studies based on molecular and phylogenetic analyses, combined with morphological characters, temperature-growth relations, and pathogenicity experiments, demonstrated that P. cinnamomi var. parvispora significantly differed from P. cinnamomi and therefore, was elevated to species status to become Phytophthora parvispora (Scanu et al., 2014).

Since its first records from Germany and Taiwan, P. parvispora has been also reported from Australia, isolated from potting mixes of nursery plants and an irrigation channel surrounded by cultivated agricultural fields; from South Africa, isolated from Arbutus unedo plants; from Brazil, isolated from the rhizosphere of cowpea; from Italy, isolated from Mandevilla sp. and A. unedo plants; and from Portugal isolated from potted Pinus pinea nursery plants (Scanu et al., 2014).   The current record of its detection in Choisya ternata in California marked its first detection in the USA.  As almost all reports of P. parvispora are associated with trade of plants intended for planting, the latter is considered a major pathway for introduction of the pathogen into ornamental, landscape and natural environments.  Choisya ternata is native to Mexico and not naturalized in the USA (NPGS).  The pathogen has never been recorded from natural environments (Scanu et al., 2014).  The origin of P. parvispora is considered to be south-east Asia as the earliest record came from Taiwan (Ann & Ko, 1985; Scanu et al., 2014).

Hosts: Although few plant hosts have been reported, they belong to six monocot, dicot, and coniferous plant families.  Rutaceae: Agathosma betulina (buchu) and Citrus sp.; Ericaceae: Arbutus unedo (strawberry tree); Asparagaceae: Beaucarnea recurvata (elephants foot, ponytail palm), Beaucarnea sp.; Apocynaceae: Mandevilla sanderi (Brazilian jasmine), M. splendens, Mandevilla sp., Mandevilla x amabilis; Pinaceae: Pinus pinea (Italian stone pine, umberella pine); Fabaceae: Vigna unguiculata (cowpea) (Farr & Rossman, 2016; Scanu et al., 2014).  Choisya ternata (Mexican orange blossom, Rutaceae; CDFA Pest and Damage Record, November 22, 2016) is included here as a newly reported host.

Symptoms:  Host plants infected with Phytophthora parvispora exhibit symptoms of root and collar rot, leaf chlorosis, shoot dieback and plant decline.  Two to three-year-old infected seedlings of Arbutus unedo showed symptoms of shoot tip dieback and root and collar rot (Scanu et al., 2014).

Disease Cycle:  Generally, species of Phytophthora that cause root and stem rots survive cold winters or hot and dry summers as resting spores (oospores and chlamydospores) or mycelium in infected roots, stems or soil.  For P. parvispora, it is suggested that the pathogen survives long terms in moderate dry conditions between consecutive rains as mycelial aggregations and selfed oospores than as chlamydospores as the former structures are produced in solid agar and in water, while chlamydospores are thin-walled and infrequently produced, thereby indicating short-term survival (Jung et al., 2013; Scanu et al., 2014).  During spring, the oospores and chlamydospores germinate to produce motile spores (zoospores) that swim around in soil water and roots of susceptible hosts. The pathogen infects the host at the soil line causing water soaking and darkening of the trunk bark. This infected area enlarges and may encircle the entire stem of small plants which wilt and eventually die.  On large plants, the infected, necrotic area may be on one side of the stem and become a depressed canker below the level of the healthy bark.  Collar rot canker may spread down the root system. Roots are invaded at the crown area or at ground level.   Mycelium and zoospores grow in abundance in cool, wet weather causing damage where the soil is too wet for normal growth of susceptible plants and low temperatures (15-23°C) prevail (Agrios, 2005).   The temperature range for the development P. parvispora in culture is from 10-11°C to 36-37°C, the optimum temperature being 16°C to 32°C (Kröber & Marwitz, 1993).  With high cardinal temperatures for growth, P. parvispora is well adapted to tropical and subtropical climates and greenhouse conditions (Scanu et al., 2014).

Dispersal and spread: Like most Phytophthora species, P. parvispora is soil-borne and water-borne and may be spread to non-infected sites through infected plants, nursery and planting stock, seedlings, pathogen-contaminated soil, run-off and splash irrigation and rain water, and contaminated cultivation equipment and tools.

Damage Potential:  Phytophthora parvispora causes root and crown rot on woody and semi-woody hosts.  At particular risk are nursery-grown plants for plantings in commercial and private garden, landscape, and horticultural environments.

Worldwide Distribution: Asia: Taiwan; Africa: South Africa; Europe: Germany, Italy, Portugal; North America: USA (California); South America: Brazil; Australia (Farr & Rossman, 2016; Scanu et al., 2014).

Official Control:  Presently, Phytophthora parvispora has a temporary, quarantine status and ‘Q’ rating by the CDFA.

California Distribution: San Francisco County.

California Interceptions: None.

The risk that Phytophthora parvispora would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Phytophthora parvispora may be able to establish in cool to warm (10-11°C to 36-37°C, or 16-32°C optimal) and wet climates within California. Its in-state establishment is likely to be large but limited in accordance with the distribution of its hosts under climates favorable for infection.  Its hosts range from ornamentals such as Mandevilla which are grown in cool to warm coastal and inner valley regions, to citrus and stone pine which cover larger regions of the state.  The pathogen is well adapted to tropical and subtropical climates and greenhouse conditions, and requires wet weather for infection.

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

Score: 2

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

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

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

2) Known Pest Host Range: Presently, the host range for Phytophthora parvispora is limited to relatively few, yet diverse hosts which are found in six monocot, dicot and coniferous families. Important hosts for California include mainly ornamentals (Arbutus unedo – strawberry tree, Mandevilla, Choisya ternata – Mexican orange blossom), conifer (Pinus pinea) and few fruit (Citrus sp.).  A low score is ascribed to this category.

Evaluate the host range of the pest.

Score: 1

– Low (1) has a very limited host range.

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

3) Pest Dispersal Potential: Phytophthora parvispora is soil-borne and water-borne and therefore, primarily spreads artificially via infested soils, plants, nursery and planting stock, seedlings, run-off and splash irrigation water, cultivation equipment and tools that may spread contaminated soil and plant materials to non-infected sites.

Evaluate the natural and artificial dispersal potential of the pest.

Score: 3

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

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

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

4) Economic Impact: Although losses caused solely by Phytophthora parvispora have not been quantified, the potential for the pathogen to infect mainly ornamental, conifer, and citrus plants in California could result in root and crown rot, and shoot dieback thereby decreasing healthy stands, causing yield losses, increasing production costs and causing loss of market of nursery stocks. Also, the pathogen’s potential to survive and spread in infected soils and irrigation water could require changes in normal cultivation practices of host plants.  A ‘High’ score is given for this category.

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

Economic Impact: A, B, C, D, G.

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

Economic Impact Score: 3

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

– Medium (2) causes 2 of these impacts.

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

4) Environmental Impact: Phytophthora parvispora may impact conifers and other ornamentals grown in commercial and private gardens and landscape environments.  The pathogen has never been reported from natural environments nevertheless, infected nursery plants provide a pathway for the introduction of the pathogen to outdoor environments, and the possibility of its establishment under favorable conditions. Infestations could trigger additional treatment programs.  Infections of perennial shrub and tree hosts could disrupt natural communities or alter ecosystem processes.

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

Environmental Impact:  A, D, E.

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

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

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

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

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

Score the pest for Environmental Impact.

Environmental Impact Score: 3

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

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

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

Consequences of Introduction to California for Phytophthora parvispora: Medium (12)

Add up the total score and include it here.

-Low = 5-8 points

-Medium = 9-12 points

High = 13-15 points

6) Post Entry Distribution and Survey Information: Presently, Phytophthora parvispora has only been officially reported from one region, namely, San Francisco County. California.

Score: (-1)

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

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

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

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

Final Score:

7) The final score is the consequences of introduction score minus the post entry distribution and survey information score: (Score)

Final Score:  Score of Consequences of Introduction – Score of Post Entry Distribution and Survey Information = 11

Uncertainty:  

None.

Conclusion and Rating Justification:

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


References:

Agrios, G. N.  2005.  Plant Pathology fifth edition.  Elsevier Academic Press, Massachussetts, USA.  922 p.

Ann, P. J., and W. H. Ko.  1985.  Variants of Phytophthora cinnamomi extend the known limits of the species.  Mycologia 77: 946-950.

Farr D.F., & Rossman, A.Y.  2016.  Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved December 7, 2016, from http://nt.ars-grin.gov/fungaldatabases/

Jung, T., I. Colquhoun, G. E. St. J. Hardy.  2013.  New insights into the survival strategy of the invasive soilborne pathogen Phytophthora cinnamomi in different natural ecosystems in Western Australia. Forest Pathology 43: 266-288.  doi:10.1111/efp.12025.

Kröber, H., and R. Marwitz.  1993.  Phytophthora tentaculata sp. nov. und Phytophthora cinnamomi var. parvispora var. nov., zwei neue Pilze von Zierpflanzen in Deutschland. Zeitschrift fur Pflanzenkrankheiten und Pflanzenschutz 100, 250-258. [Original Description].

Latham, S.  2016.  Email to J. Chitambar et al., CDFA, on Monday, November 7, 2016, 10:12:21 am.

NPGS.  (Date unknown).  Taxon: Choisya ternata Kunth.  U. S. National Plant Germplasm System.  https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?315354

Scanu, B., Hunter, G.C., Linaldeddu, B.T., Franceschini, A., Maddau, L., Jung, T., and Denman, S. 2014. A taxonomic re-evaluation reveals that Phytophthora cinnamomi and P. cinnamomi var. parvispora are separate species. Forest Pathology 44: 1-20.


Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: (916) 262-1110, plant.health[@]cdfa.ca.gov.


Comment Period:  CLOSED

1/9/2017 – 2/23/2017

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

 

Colletotrichum sansevieriae M. Nakamura & M. Ohzono 2006

California Pest Rating for
Colletotrichum sansevieriae  M. Nakamura & M. Ohzono 2006 
Pest Rating: B

 


PEST RATING PROFILE
Initiating Event:

On November 11, 2016, diseased Sansevieria sp. plants exhibiting leaf spot symptoms, were intercepted by San Diego County Agricultural officials.  The plants had originated in Florida and were destined to a nursery in San Diego County.  A sample of diseased leaves was collected and sent by the County to the CDFA Plant Pathology Lab for diagnosis.  On December 7, 2016, Suzanne Latham, CDFA plant pathologist, detected Colletotrichum sansevieriae in culture from leaf spots and confirmed the identification by morphological and sequence analyses.  Then, on December 19, 2016, C. sansevieriae was detected once again in a shipment of Sansevieria trifasciata plants that had originated in Florida but were destined to a different nursery in San Diego County.  The samples submitted to the CDFA Lab had been collected on November 22, 2016 by San Diego County.  Consequently, the infested greenhouse-contained, potted Sansevieria plants were treated with fungicidal sprays and continue to be periodically monitored for detection of the pathogen (personal communication: Pat Nolan, plant pathologist, San Diego County).  Currently, C. sansevieriae has a temporary ‘Q’ rating.  The risk of introduction and establishment of this pathogen in California is assessed and a permanent rating is proposed herein.            

History & Status:

Background: Colletotrichum sansevieriae is a fungal pathogen that causes anthracnose disease only in Sansevieria spp. plants (Nakamura et al., 2006).  The pathogen was first detected in Sansevieria plants in Japan and soon after reported from Australia (Aldaoud et al., 2010), India (Gautam et al., 2012), USA (Florida; Palmateer et al., 2012), and Korea (Park et al., 2013).  Its recent find in a California nursery marked its first detection in for the State.

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

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

Damage Potential:  Anthracnose disease caused by Colletotrichum sansevieria can result in reduced plant quality and growth, and marketability.  In California, nursery production of potted host plants or in greenhouses are particularly at risk as nursery conditions are often conducive to infection by Colletotrichum species.  In California’s cultivated fields, disease development may be sporadic as it is affected by levels of pathogen inoculum and environmental conditions.

Disease Cycle:  It is likely that Colletotrichum sansevieria has a similar life cycle to that of other Colletotrichum species and survives between crops during winter as mycelium on plant residue in soil, on infected plants, and on seeds.  During active growth, the pathogen produces masses of hyphae (stromata) which bear conidiophores, on the plant surface. Conidia (spores) are produced at the tips of the conidiophores and disseminated by wind, rain, cultivation tools, equipment, and field workers.   Conidia are transmitted to host plants.  Humid, wet, rainy weather is necessary for infection to occur.  These requirements in particular may limit the occurrence of the pathogen in California fields and subsequently, the pathogen may be more of a problem under controlled environments of greenhouses.  Conidia germinate, penetrate host tissue by means of specialized hyphae (appresoria) and invade host tissue.  The optimum temperature for growth of C. sansevieria ranges from 25° to 28°C Nakamura et al., 2006).   In greenhouse tests, anthracnose disease developed within 10 days of inoculation of Sanseviera plants at 29°C with 70-85% relative humidity (Palmateer et al., 2012), or 6 days after inoculation in a humid chamber at 27°C under 12h fluorescent light/12 h darkness (Nakamura et al., 2006).

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

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

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

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

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

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

Consequences of Introduction: 

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

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

Score: 2

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

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

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

2) Known Pest Host Range: The host range of Colletotrichum sansevieriae is limited to Sansevieria

Evaluate the host range of the pest.

Score: 1

Low (1) has a very limited host range.

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

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

Evaluate the natural and artificial dispersal potential of the pest.

Score: 3

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

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

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

4) Economic Impact: Under suitable, wet climates, the pathogen could lower plant growth, value, and trigger the loss of markets.

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

Economic Impact: A, B, C.

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

 Economic Impact Score: 3

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

– Medium (2) causes 2 of these impacts.

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

5)  Environmental ImpactThe pathogen could significantly impact cultural practices or home garden plantings.

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

Environmental Impact:  E.

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

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

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

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

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

Score the pest for Environmental Impact.

Environmental Impact Score: 2

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

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

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

Consequences of Introduction to California for Colletotrichum sansevieriae: Medium (11)

Add up the total score and include it here.

-Low = 5-8 points

Medium = 9-12 points

-High = 13-15 points

6) Post Entry Distribution and Survey Information: Colletotrichum sansevieriae was detected in an incursion of plants held at a nursery in San Diego County and is not considered to be established within California.

Score: (-0)

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

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

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

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

Final Score:

7) The final score is the consequences of introduction score minus the post entry distribution and survey information score: (Score)

Final Score:  Score of Consequences of Introduction – Score of Post Entry Distribution and Survey Information = 11

Uncertainty:

None.

Conclusion and Rating Justification:

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

References:

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

CABI.  2016.  Colletotrichum fructicola basic datasheet report.  Crop Protection Compendium.  www.cabi.org/cpc/

Farr, D. F., & A. Y. Rossman.  Fungal databases, systematic mycology and microbiology laboratory, ARS, USDA. Retrieved April 3, 2016, from http://nt.ars-grin.gov/fungaldatabases/

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

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

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

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

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


Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-262-1110, plant.health[@]cdfa.ca.gov.


Comment Period:  CLOSED

1/9/2017 – 2/23/2017

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

Phakopsora phyllanthi Dietel 1910

California Pest Rating for
Phakopsora phyllanthi Dietel 1910
Pest Rating: C

 


PEST RATING PROFILE
Initiating Event:

On December 4, 2015, a shipment of cut foliage of an unidentified plant species was intercepted at the USPS West Sacramento Distribution Center by the CDFA Dog Team.  The shipment had originated in Florida and was destined to a private owner in Merced County, California.  A sample of the symptomatic foliage was collected from the shipment and sent to the CDFA Plant Pathology Laboratory for pathogen diagnosis.  On January 20, 2016, Suzanne Latham, CDFA plant pathologist, identified the rust fungal pathogen, Phakopsora phyllanthi associated with the diseased leaves and confirmed the identification by PCR sequencings.  Subsequently, the shipment was destroyed (Martyn, 2016).  On further investigation, USDA APHIS PPQ and Florida Department of Agriculture and Consumer Services communicated to Suzanne Latham, CDFA, that P. phyllanthi had been detected in three locations in Florida on February 18, 2016 (Latham, 2016).  The risk of introduction and establishment of this pathogen in California is assessed and a permanent rating is proposed.

History & Status:

BackgroundPhakopsora phyllanthi is a fungal pathogen that causes rust disease in Phyllanthus spp. (‘gooseberry’).  The pathogen has only been detected on certain species of the plant genus primarily grown in tropical and subtropical regions of the globe.  In 2015, Phakopsora phyllanthi was first reported in the USA from Hawaii (Dietrich & Ko, 2015), and later in 2016, from Florida (Latham, 2016).  The pathogen is not known to be present in California and was detected for the first time in an intercepted shipment of cut foliage from Florida, which was subsequently destroyed (see ‘Initiating Event’).  The plant genus, Phyllanthus (Phyllanthaceae) contains several hundred species, however, only one species, P. caroliniensis subsp. caroliniensis (Carolina leaf-flower) native to the eastern United States, is known to be present in San Diego County as an introduced annual plant (Calflora, 2016).

Disease cycle:  The life cycle of Phakopsora phyllanthi is not fully known.  Teliospores (the sexual, overwintering stage of the fungus), have not been observed nor is it known if the pathogen needs an alternate host to complete its life cycle (Dietrich & Ko, 2015).  It is likely, but not proven, that P. phyllanthi is spread to non-infected hosts via production of urediniospores only.

Dispersal and spread: Urediniospores are spread by wind and splashing rain.  Insects, animals, and humans may also aid in spreading spores to non-infected plants. Infected nursery plants also aid in introducing and spreading the pathogen.

Hosts:  Phyllanthus acidus (synonyms: Cicca acida, P. distichus; Tahitian gooseberry), P.benguetensis, P. emblica (Indian gooseberry), P. niruri (gale of the wind), P. phyllanthi, Phyllanthus sp. (Dietrich & Ko, 2015; Farr & Rossman, 2016).  Some Phyllanthus species such as, P. emblica and P. acidus are cultivated for fruit in warm climates, while other species are pantropical weeds or grown for medicinal uses – but these species are not present in California.

Symptoms:  Rust-infected Phyllanthus acidus (Tahitian gooseberry) trees may exhibit a general unthrifty appearance with thinning canopy, and barren branches or twigs.  Leaves exhibit discolored chlorotic or necrotic spots on upper and lower surfaces.  Small white-brownish raised spots or pustules containing numerous powdery urediniospores are produced on lower leaf surfaces.  Affected leaves eventually drop off.  Rust pustules and lesions are also formed on the surface of fruit (Dietrich & Ko, 2015).

Disease PotentialPhyllanthus species, such as P. acidua (Tahitian gooseberry) and P. emblica (Indian gooseberry) grown for their fruit in tropical climates, are not commercially cultivated in California, but are probably sold by rare fruit nurseries within the State.  Infections of this rust pathogen could negatively impact production and value of plants.  In general, severe infestation of rust can result in defoliation and reduction in plant growth, vigor and stand.  Containment and management of the rust pathogen can be difficult as masses of air-borne spores produced can spread over long distances.  Backyard growers, other small, rare fruit production growers, hobbyists, and rare plant nurseries in warm and wet climates of southern California may be at particular risk.

Worldwide Distribution: Asia: China, India, Indonesia, Malaysia, Philippines, Thailand; North America: USA (Florida, Hawaii); South America: Brazil, Ecuador, French Guyana, Venezuela (Dietrich & Ko, 2015; Farr & Rossman, 2016).

Official Control: None reported.  Presently, Phakopsora phyllanthi has a temporary Q rating in California.

California Distribution The gooseberry rust pathogen, Phakopsora phyllanthi is not established in California.

California Interceptions The pathogen has only been detected once in a single intercepted quarantine shipment of unidentified cut foliage that originated in Florida (see “Initiating Event”).

The risk Phakopsora phyllanthi 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):  Phakopsora phyllanthi may establish in very limited areas within southern California that have warm and wet climates where the tropical host, Phyllanthus spp. is able to grow.  Presently, only one species, Phyllanthus caroliniensis subsp. caroliniensis (Carolina leaf-flower) native to the eastern United States, is known to be present in San Diego County’s coastal region as an introduced annual plant. 

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

Low (1) has a very limited host range.

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

Risk is Low (1):  The host range for the pathogen is very limited and comprises of some species non-native, tropical plants belonging to the genus Phyllanthus.

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): Phakopsora phyllanthi has high reproduction and dispersal potential.  Spores are spread by wind and splashing rain.  Insects, animals, and humans may also aid in spreading spores to non-infected plants. Infected nursery plants also aid in introducing and spreading the pathogen.

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): Reported hosts of the gooseberry rust pathogen are not to be present in California and therefore, no major economic impact of this pathogen is expect within California.  However, if the pathogen was introduced, growers of rare, imported fruit plants, such as backyard growers, hobbyists, and rare plant nurseries in warm and wet climates of southern California may be at particular risk of reduced crop value.  The economic impact is evaluated to be low.

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):  Backyard growers, other small, rare fruit production growers, hobbyists, and rare plant nurseries in warm and wet climates of southern California may be at particular risk, if the pathogen were introduced into the State.

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).  

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:

Details of the pathogen’s complete life cycle including the need of an alternate host to complete its life cycle are not presently knownHowever, it is unlikely that this information will alter the proposed rating for the pathogen.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for gooseberry rust pathogen, Phakopsora phyllanthi is C.

References:

Calflora.  2016.  Calflora: Information on California plants for education, research and conservation [web application].  Berkeley, California: The Calflora Database [a non-profit organization].  http://www.calflora.org/

Dietrich, B., and M. Ko.  2015.  Phyllanthus Rust Phakopsora phyllanthi Dietel.  New Pest Advisory No. 15-02 October 2015, State of Hawaii Department of Agriculture.

Farr, D. F. and A. Y. Rossman.  2016.   Fungal databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA.  Retrieved October 17, 2016 from http://nt.ars-grin.gov/fungaldatabases/.

Khan, S.  2016.  Email from K. Martyn, Yolo County, to S. Khan, CDFA, subject: “RE: Information request for A/Q/W reports”, dated February 11, 2016, forwarded to J. Chitambar, CDFA, by T. Walber, CDFA on October 18, 2016.

Latham, S.  2016.  Email from S. Latham (CDFA) to J. Chitambar (CDFA), subject: “FW: confirmed ID: Positive for gooseberry rust (Phakopsora phyllanthi) from St. Petersburg, Pinellas Co., FL.”, sent October 17, 2016.

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 Period:  CLOSED

Oct 26 – Dec 10, 2016


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

Pseudocercospora myrticola (Speg.) Deighton 1976

California Pest Rating for
Pseudocercospora myrticola (Speg.) Deighton 1976
Pest Rating: B

 


PEST RATING PROFILE
Initiating Event:

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

History & Status:

BackgroundPseudocercospora myrticola is a fungal plant pathogen that belongs to a larger group of Cercospora-like fungi most of which cause leaf spot symptoms in host plants. The pathogen was originally named Cercospora myrticola, and since then has also been known by several synonyms: Cercospora myrti, C. saccardoana, C. amadelpha and Fusariella cladosporioides (Crous et al., 2013; Farr & Rossman, 2016).   The pathogen is widely distributed globally and infects myrtle and several species within the family Myrtaceae, with few in Melastomataceae (Farr & Rossman, 2016). In the USA, P. myrticola has only been reported from myrtle (Myrtus communis).  In 1984, P. myrticola was first reported in the USA from Florida (Alfieri et al., 1984) and from San Diego, California in 2006 (CPPDR, 2007).  On December 4, 2013, the pathogen was detected in a decorative wreath comprising of symptomatic leaves of an unknown plant, most likely to be myrtle that had been shipped from the State of Nevada and intercepted in Sonoma County, California.

Disease cycle: Infected plants produce conidiophores (specialized hypha) that arise from the plant surface in clusters through stomata and form conidia (asexual spores) successively.  Conidia are easily detached and blown by wind often over long distances.  On landing on surfaces of a plant host, conidia require water or heavy dew to germinate and penetrate the host.  Sub-stomatal stroma (compact mycelial structure) may form from which conidiophores develop.  Development of the pathogen is favored by high temperatures and the disease is most destructive during summer months and warmer climates.  High relative humidity is necessary for conidial germination and plant infection.  The pathogen can overwinter in or on seed and as mycelium (stromata) in old infected leaves (Agrios, 2005).  

Dispersal and spread: air-currents, infected nursery plants, infected leaves, seeds.

Hosts: Blepharocalyx divaricatus, Metrosideros excela (New Zealand Christmas tree), M. parkinsonii (Parkinson’s rata), Monochaetum polyneurum, Myrciaria cauliflora (jaboticaba), Myrtus communis (common myrtle), M. communis var. latifolia, M. communis var. laurifolia, M. divaricata, Tristania suaveolens (swamp mahogany) (Farr & Rossman, 2016).

Symptoms:  Infected host plants exhibit irregular to angular, leaf spots on both leaf surfaces.  Spots are 2-4 mm in diameter, rusty-brown, abundant on the lower leaf surface, usually confluent.  Lesions or spots may be surrounded by a diffuse lighter halo (Nakashima et al., 2004).

Damage Potential: Specific losses due to Pseudocercospora myrticola have not been reported.  Photosynthetic area can be reduced due to leaf spotting.  In severe infections, leaf wilt and drop may be expected.  However, damage potential due to this pathogen is likely to be similar to other Cercospora diseases which is usually low (Agrios, 2005).  In California, myrtle is not native to California and is grown in lower coastal and some inner valley regions of the State (Calflora, 2016) in landscapes, commercial and private gardens.  Also, young branches and foliage are used in floral decorations and therefore, diseased plants could be of particular concern to production nurseries.

Worldwide Distribution: Africa: South Africa, Cape Province; Asia:  India, Japan; Europe: Cyprus, England, Republic of Georgia, Germany, Greece, Israel, Italy, Sicily, Scotland, Sweden, Yugoslavia; North America: USA (Florida, California); South America: Brazil, Chile, Paraguay; Oceania: Australia, New Zealand (Crous et al., 2013;  Farr & Rossman, 2016).

Official Control: None reported.  Presently, Pseudocercospora myrticola has a temporary ‘Q’ rating in California.

California Distribution: Pseudocercospora myrticola has been found in San Diego Counties (CDFA Plant Pest and Damage Records).

California Interceptions Pseudocercospora myrticola was detected in 2013 in an intercepted quarantine shipment of a plant wreath that originated in Nevada.

The risk Pseudocercospora myrticola 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): Pseudocercospora myrticola may be able to establish wherever myrtle and other hosts plants are able to grow.  Myrtle is a non-native plant in California and is grown in lower coastal and some inner valley regions in warm and humid climates.

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

– Low (1) has a very limited host range.

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

Risk is Medium (2):  Pseudocercospora myrticola has a moderate host range that comprises common myrtle and other species within Myrtaceae, plus few species in Melastomataceae.

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):  Pseudocercospora myrticola has high reproductive potential resulting in the successive production of conidia which are dependent on air currents and infected plants and seed for dispersal and spread.

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):  Infected host plants with leaf spot symptoms could lower value of nursery-produced plants 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): Pseudocercospora myrticola infections could significantly impact home/urban gardening and aesthetic plantings of myrtle in commercial environments, such as parks and public gardens.

Consequences of Introduction to California for Pseudocercospora myrticola:

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 Low (-1): Pseudocercospora myrticola has been found in San Diego County only.

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 Pseudocercospora myrticola is B.

References:

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

Alfieri Jr., S. A., K. R. Langdon, C. Wehlburg, and J. W. Kimbrough.  1984.  Index of Plant Diseases in Florida (Revised). Florida Department of Agriculture and Consumer Service, Division of Plant Industry Bulletin 11: 1-389.  In [Farr, D. F.  & A. Y. Rossman, 2016. Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA.  Retrieved October 19, 2016, from http://nt.ars-grin.gov/fungaldatabases/ ].

Crous, P.W., U. Braun, G. C. Hunter, M. J. Wingfield, G. J. M. Verkley, H. D. Shin, C. Nakashima, and J. Z. Groenewald.  2013.  Phylogenetic lineages in Pseudocercospora. Studies in Mycology 75: 37-114.

Calflora.  2016.  Information on California plants for education, research and conservation. [Web application].  Berkeley, California: The Calflora Database [a non-profit organization]. http://www.calflora.org/

CPPDR.  2007.  Plant pathology A & Q rated pathogen & hosts detected by county.  California Plant Pest & Disease Report, California Department of Food and Agriculture July 2005 through December 2006 23(1): 113-115.

Farr, D.F., & A. Y. Rossman.  2016.  Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA.  Retrieved October 19, 2016, from http://nt.ars-grin.gov/fungaldatabases/.

Nakashima, C., H. Horie, and T. Kobayashi.  2004.  Addition and reexamination of Japanese species belonging to the genus Cercospora and allied genera.  VI. Four Pseudocercospora species from Ohshima Island, Tokyo.  Mycoscience 45: 49-55.  DOI 10.1007/s10267-003-0151-y

Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-262-1110, plant.health[@]cdfa.ca.gov.


Comment Period:  CLOSED

Oct 26 – Dec 10, 2016


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

Cercospora coniogrammes Crous & R. G. Shivas 2012

California Pest Rating for
Cercospora coniogrammes Crous & R. G. Shivas 2012
Pest Rating: B

 


PEST RATING PROFILE
Initiating Event:

On June 14, 2016, a shipment of silver lady fern (Blechnum gibbum) plants from Florida, destined to a nursery in Nippomo, San Luis Obispo County, was intercepted by San Luis County officials.  Diseased plants exhibiting leaf spot symptoms were collected and sent to the CDFA Plant Pathology Laboratory for disease diagnosis.  Suzanne Latham, CDFA plant pathologist, identified the fungal pathogen, Cercospora coniogrammes, by culturing and multigene sequencing.  On July 19, 2016, the pathogen was detected in another shipment of silver lady fern plants from Florida and destined to the same nursery in San Luis Obispo County. The identity of the pathogen was confirmed on August 19, 2016 by the USDA PPQ PM National Identification Services in Beltsville, Maryland.  This detection marked a new US record and is reportable/actionable by the USDA (Bowers, 2016).    The pathogen was given a temporary Q rating and consequently, the shipment of Blechnum gibbum was placed on hold, treated with fungicides, and is currently undergoing 30-day inspections (Schnabel, 2016).  The risk of infestation of C. coniogrammes in California is evaluated and a permanent rating is herein proposed.

History & Status:

BackgroundCercospora coniogrammes is a fungal pathogen that causes leaf spots on fern.  The pathogen was first reported in 2012 from infected bamboo fern, Coniogramme japonica var. gracilis, in Brisbane, Queensland, Australia (Groenewald et al., 2012), and in 2016 from Brazil (Guatimosim et al., 2016).  The detection of C. coniogrammes in California marked a new record of the pathogen in the USA (Bowers, 2016; see ‘Initiating Event’).  Presently, not much is known about the distribution and ecology of the pathogen.

Disease cycle:  In general, in infected plants, Cercospora species produce conidiophores (specialized hypha) that arise from the plant surface in clusters through stomata and form conidia (asexual spores) successively.  Conidia are easily detached and blown by wind often over long distances.  On landing on surfaces of a plant host, conidia require water or heavy dew to germinate and penetrate the host.  Substomatal stroma (compact mycelial structure) may form from which conidiophores develop.  Development of the pathogen is favored by high temperatures and the disease is most destructive during summer months and warmer climates.  High relative humidity is necessary for conidial germination and plant infection.  The pathogen can overwinter in or on seed and as mycelium (stromata) in old infected leaves (Agrios, 2005).  

Dispersal and spread: air-currents, infected nursery plants, infected leaves, seeds (Agrios, 2005).

Hosts: Fern species, namely, Blechnum gibbum, Coniogramme japonica var. gracilis, Hypolepis mitis, Macrothelypteris torresiana (Groenewald et al., 2012; Guatimosim et al., 2016).

Symptoms: Infected host plants exhibit leaf spots on upper and lower sides of leaves and are sub-circular to angular, 1-3 mm in diameter, grey to pale brown, surrounded by a broad brown margin up to 4 mm in diameter (Groenewald et al., 2012).

Damage Potential: Quantitative losses due to Cercospora coniogrammes have not been reported.  Photosynthetic area can be reduced due to leaf spotting.  In severe infections, leaf wilt and drop may be expected.  However, damage potential due to this pathogen is likely to be similar to other Cercospora diseases which is usually low (Agrios, 2005).

Worldwide Distribution: Australia: Queensland; South America: Brazil; North America: USA (Groenewald et al., 2012; Guatimosim et al., 2016).

Official Control: None reported particularly for Cercospora coniogrammes, however, the following countries have Cercospora spp. on their ‘Harmful Organism Lists’: French Polynesia, Madagascar, South Africa, and Sri Lanka (USDA PCIT, 2016).

California Distribution: Cercospora coniogrammes is not known to be established in California.  Interceptions of infected plants in a San Luis Obispo nursery were placed on hold, treated with fungicide, and is currently undergoing 30-day inspections (see, ‘Initiating event’).

California InterceptionsCercospora coniogrammes was detected in only two shipments of Blechnum gibbum intercepted by San Luis Obispo County officials during June and July 2016.

The risk Cercospora coniogrammes 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):  Cercospora coniogrammes may be able to establish in large but limited regions in California wherever fern plants are able to grow naturally under high humid and cool to warm temperatures. Silver lady fern, Blechnum gibbum, is cultivated indoors and outdoors in coastal 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 Low (1): Presently, the host range for Cercospora coniogrammes is limited to few species of fern, namely, Blechnum gibbum, Coniogramme japonica var. gracilis, Hypolepis mitis, and Macrothelypteris torresiana.

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):  Cercospora coniogrammes has high reproductive potential resulting in the successive production of conidia which are dependent on air currents and infected plants and seed for dispersal and spread.

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):  Infected host plants with leaf spot symptoms could result in lowered value and loss of markets of nursery-produced fern host plants.

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 Low (1): The pathogen could significantly impact ornamental plantings in home/ urban and commercial gardens and recreational environments.

Consequences of Introduction to California for Cercospora coniogrammes:

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 = 9

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

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

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

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

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

Evaluation is not established (0):  Cercospora coniogrammes is not established in California and has only been detected in intercepted shipments of fern to the State. 

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 Cercospora coniogrammes is B.

References:

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

Bowers, J. H.  2016.  Email from J. H. Bowers, USDA, to H. R. Wright, USDA APHIS, forwarded to U. Kodira, CDFA on September 2, 2016.

Farr, D.F., & A. Y. Rossman.  2016.  Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA.  Retrieved September 22, 2016, from http://nt.ars-grin.gov/fungaldatabases/.

Groenewald, J. Z., C. Nakashima, J. Nishikawa, H. D. Shin, J. H. Park, A. N. Jama, M. Groenewald, U. Braun, and P. W. Crous.  2013.  Species concepts in Cercospora: spotting the weeds among the roses. Studies in Mycology 75: 115-170.

Guatimosim, E., P. B. Schwartsburd, R. W. Barreto, and P. W. Crous.  2016.  Novel fungi from an ancient niche: cercosporoid and related sexual morphs on ferns.  Persoonia 37: 106-141.

Schnabel, D. L.  2016.  Email from D. L. Schnabel, CDFA Pest Exclusion, to J. Chitambar, CDFA on September 28, 2016.

USDA PCIT.  2016.  USDA Phytosanitary Certificate Issuance & Tracking System. Sept. 23, 2016.  https://pcit.aphis.usda.gov/PExD/faces/ReportHarmOrgs.jsp


Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-262-1110, plant.health[@]cdfa.ca.gov.


Comment Period:  CLOSED

Oct 3 – Nov 17, 2016


Pest Rating: B


Posted by ls 

Podosphaera xanthii (Castagne) U. Braun & Shishkoff 2000

Watermelon leaf showing an even distribution of powdery mildew (Podosphaera xanthii) over the entire leaf surface. June 1995 Photo by Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org
Watermelon leaf showing an even distribution of powdery mildew (Podosphaera xanthii) over the entire leaf surface. June 1995.  Photo by Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org

California Pest Rating for
Podosphaera xanthii (Castagne) U. Braun & Shishkoff 2000
Pest Rating:  C

 


PEST RATING PROFILE
Initiating Event:

On July 13, 216, diseased leaves of Calibrachoa sp. plants exhibiting powdery mildew symptoms were collected during a regulatory nursery inspection, from a nursery in San Luis Obispo County, by San Luis Obispo County officials and sent to the CDFA Plant Pathology Laboratory for diagnoses.  Suzanne Latham, CDFA plant pathologist, identified the powdery mildew pathogen, Podosphaera xanthii, 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: Podosphaera xanthii causes powdery mildew disease primarily in cucurbits under field and greenhouse conditions.  The pathogen has a wide host range which includes several ornamental plants, including Verbena. There are several pathogenically distinct races of P. xanthii, and plant resistance-breaking races are present in California.  The pathogen is widely distributed throughout the world (see ‘Worldwide Distribution’ below) as well as in California.  Within California, powdery mildew may be common in coastal and desert production areas, but is more common in fall in the San Joaquin Valley and Sacramento Valley (Davis, et al., 2012).

Podosphaera xanthii was previously known by several names including Sphaerotheca fuliginea and S. fusca.  In 2012, P. caricae-papayae was synonymized with the morphologically similar species P. xanthii (Braun & Cook, 2012) however, the synonymy of P. xanthii and P. caricae-papayae is in question given the molecular work of Takamatsu et al., (2010) who also inferred that further molecular and morphological studies would help to determine the correct taxonomic position of P. caricae-papayae within the genus Podosphaera in the family Erysiphaceae of the order Erysiphales.  (The CDFA risk assessment and rating for P. caricae-papayae is published separately.)

Hosts: Podosphaera xanthii has a wide host range which includes agricultural crops, ornamentals, few fruit, and weed plant species within eight or more families. Hosts include, Citrullus lanatus (watermelon), Cucumis melo (melon), C. sativus (cucumber), Cucurbita (pumpkin), C. maxima (giant pumpkin, C. moschata (pumpkin), C. mixta (pumpkin), C. pepo (synonym: C. ovifera; ornamental gourd), C. vulgaris, Lagenaria siceraria (bottle gourd), Luffa acutangula (angled luffa), L. aegyptiaca (loofah), L. cylindrica, Momordica charantia (bitter gourd), M. cochinchinensis (gac), Sechium edule (chayote), Cyamopsis tetragonoloba (guar), Phaseolus aconitifolius (synonym: Vigna aconitifolia; moth bean), P. coccineus (runner bean), P. vulgaris (common bean), Vigna mungo (black gram), V. radiata (mung bean), V. umbellata (rice-bean), V. unguiculata (synonym: V. catjang; cowpea), Cajanus cajan (pigeon pea), Sesamum indicum (sesame), Capsicum frutescens (chili), Solanum melongena (eggplant),  Hibiscus mutabilis (cottonrose), H. syriacus (shrubby althaea), Hoheria lyallii (synonym: H. populnea; lacebark), Malva pusilla (round-leaved mallow), Carica papaya (papaya), Coriaria arborea (tree tutu), Kalanchoe blossfeldiana (flaming katy), Petunia x hybrid, , Verbena bonariensis (purpletop vervain), V. brasilensis (Brazilian verbena), V. canadensis (clump verbena), Verbena x hybrida (synonym: V. hortensis; garden verbena), V. incisa, V. lasiostachys (western vervain), V. litoralis (blue vervain),V. macdougalii (MacDougal verbena), V. officinalis (common verbena), V. phlogiflora, V. rigida rigid verbena), Calendula sp. C. arvensis (field marigold), C. officinalis (pot marigold), C. palaestina (Palestine marigold),  Cosmos bipinnatus (garden cosmos), Calibrachoa sp.,  Cephalotus follicularis (Albany pitcher plant), Farfugium japonicum (leopard plant), Glandularia pulchella (South American mock vervain), Gynostemma pentaphyllum (jiagulan), Gerbera jamesonii (African daisy), Gynura bicolor (Okinawan spinach), Helianthus annuus (sunflower), Heteropogon contortus (black speargrass), Jatropha gossypiifolia (bellyache bush), Ligularia sibirica, Medusagyne oppositifolia (jellyfish tree), Melampyrum nemorosum (wood cow-wheat), Melothria japonica (Japanese wild cucumber), Melothria sp. Parasenecio hastatus subsp. tanakae, Pericallis cruenta (common cineraria), Physalis alkekengi (Chinese lantern), Pisum sativum (pea), Pulicaria dysenterica (meadow false fleabane), Senecio chrysanthemoides , S. grahamii, S. hercynicus, S. nemorensis, Impatiens hawker (New Guinea impatiens), Ageratum conyzoides (billy goat weed), Bidens bipinnata (Spanish needles), B. cernua (nodding beggarticks), B. frondosa (devil’s beggartick), B. pilosa (blackjack), B. tripartita (three-lobe beggarticks), Boehmeria nivea (Chinese grass), Buddleja brasiliensis, B. salviifolia, Xanthium californicum (synonym: X. strumarium var. canadense; Canada cocklebur), Xanthium italicum, X. pensylvanicum, X. spinosum, X. strumarium (common cocklebur), X. spinosum (spiny cocklebur) Zinnia elegans (zinnia), (CABI, 2016; Farr & Rossman, 2016).

Symptoms:  Powdery mildew symptoms on cucurbits: the disease first appears as pale yellow spots on stems, petioles, and leaves.  These spots enlarge as white powdery fungal growth comprising primarily of asexual spores (conidia) develops on upper and under leaf surfaces, petioles, and stems of infected plants, usually developing first on crown leaves, shaded lower leaves, and leaf undersurfaces.  Affected leaves become dull, chlorotic and may wilt and eventually turn brown and papery (Davis et al., 2012).  Older plants are initially infected and infected leaves usually wither and die.  Premature senescence may occur.  Fruit infection occurs rarely in cucumber and watermelon.  Minute dark brown chasmothecia (sexually produced, closed fruiting structures) have been rarely observed in infected cucurbits in the USA and may be easily overlooked. They may develop late in the season, and the sexual spores within the structures are protected from adverse conditions.  Symptoms are less common on cucumber and melon as many commercial cultivars are resistant to the pathogen (McGrath, 2011).

Disease cycle:  Podosphaera xanthii is an obligate parasite.  Primary sources of inoculum include conidia which can be dispersed over long distances and remain viable for 7-8 days.  The fungus grows on the surface of plant tissue and invades by sending feeding organs (haustoria) into the plants epidermal cells only in order to obtain nutrients.  Mycelium produces conidiophores on the plant surface.  Each conidiophore produces chains of conidia (spores) that are dispersed by air currents.  Powdery mildew develops quickly under favorable conditions of dense plant growth and low light intensity.  High relative humidity is favorable for infection and conidial survival, and infection can occur as low as 50% relative humidity.  Dry conditions favor colonization, sporulation, and dispersal, however, rain and free moisture on plant surfaces are unfavorable.  Optimum temperature for disease development is 20-27°C with infection occurring at 10-32°C.  Powdery mildew development is arrested at 38°C and higher temperatures.  As an obligate parasite, P. xanthii requires living host plants for survival, however, it may also survive as chasmothecia which have been reported rarely in the United States (CABI, 2016; McGrath, 2011).

Damage Potential:  Powdery mildew can diminish the photosynthetic regions of cucurbit leaves. Severely infected leaves turn brown and shriveled.  Fruit quality and yield are reduced.  In squash, fruit quality is reduced by sunscald and premature ripening resulting in poor storability, in melon, incomplete ripening and poor flavor occurs, and pumpkin fruit may be shriveled and discolored (CABI, 2016).  Late fruit usually fail to mature and are small and misshapen.  Stress from disease can result in speckling and oedema on fruit rind.  Powdery mildew-infected plants can be weakened and predisposed to other diseases.  Podosphaera xanthii can be a major production problem of cucurbits in field and greenhouse conditions (McGrath, 2011).

Transmission:  Conidia (spores) are airborne and dispersed by wind currents.  Laboratory studies have shown that conidia remain viable for 7-8 days. On cucurbits in greenhouses conidia are released and spread from plant to plant via irrigation or air currents.  Conidia can overwinter on cucurbit plants in a greenhouse and then be dispersed from greenhouse to field crops during spring and summer.  Non-cucurbit hosts are not a major source of inoculum due to pathological specialization (CABI, 2016; McGrath, 2011).

Survival:  During cool weather, conidia production ceases and powdery mildew fungi overwinter as chasmothecia and mycelium in weeds and dormant plant tissue. However, the sexual (teleomorph) stage has only been found in California greenhouses and reported for the first time in greenhouse grown squash and melons in Salinas, California (Ramos et al., 2010-2011).  Constant greenhouse growth conditions could perpetuate the asexual stage of the fungus.

Worldwide Distribution: Asia: Armenia, Azerbaijan, Bangladesh, China, Republic of Georgia, India, Iran, Iraq, Israel, Japan, Republic of Korea, Kyrgyzstan, Lebanon, Myanmar, Oman, Pakistan, Saudi Arabia, Singapore, Taiwan, Turkey, Turkmenistan Uzbekistan, Vietnam; Africa: Egypt, Ethiopia, Libya, Somalia, South Africa, Sudan, Tunisia; North America: Canada, Mexico, USA; Central America and Caribbean: Cuba, Puerto Rico; South America: Argentina, Bolivia, Brazil, Nicaragua, Uruguay, Venezuela; Europe: Austria, Bulgaria, Czech Republic, (former) Czechoslovakia, Denmark, Estonia, Finland, Former USSR, Romania, France, Germany, Greece, Hungary, Ireland, Italy, Lithuania, Netherlands, Norway, Poland, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, United Kingdom, Ukraine, Yugoslavia (Serbia and Montenegro); Oceania: Australia, New Zealand, Samoa (CABI, 2016; Farr & Rossman, 2016).

Official Control: Podosphaera xanthii is on the ‘Harmful Organism List’ for Guatemala (USDA-PCIT, 2016).

California Distribution: San Luis Obispo, Solano, and Yolo (CDFA Pest and Damage Records); San Joaquin Valley and Sacramento Valley counties, coastal and desert cucurbit production areas (Davis, et al., 2012).

California Interceptions None reported.

The risk Podosphaera xanthii 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 of cucurbits Podosphaera xanthii can occur in coastal and desert production regions, and is common in fall in the San Joaquin Valley and Sacramento Valley. Powdery mildew thrives in warm and humid environments. Low light levels, high humidity, and moderate temperature enhance disease development.  Dry conditions favor conidia production and dispersal.  The pathogen is already widely distributed within cucurbit production regions of the state.   

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

– Low (1) has a very limited host range.

– Medium (2) has a moderate host range.

High (3) has a wide host range.

Risk is High (3) – Podosphaera xanthii has a wide host range that includes agricultural crops – primarily cucurbits, ornamentals, few fruit and weed plants.

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 suitable climate conditions, airborne conidia are produced in abundance and readily spread by wind currents to non-infected sites.  Within and outside greenhouse environments, the pathogen is capable of rapidly spreading to non-infested host plants as well as other sites where host plants are grown.

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 pathogen can potentially cause significant losses in plant growth and crop yield. Powdery mildew infections could lower crop yield and value causing significant losses in production – especially with use of protective and eradicative fungicides.  It could result in loss of markets, and change in cultivation practices to prevent the spread of inocula to non-infected, healthy plants.

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 powdery mildew pathogen could significantly impact home/urban gardening and/or ornamental plantings.  

Consequences of Introduction to California for Podosphaera xanthii:

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 P. xanthii 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).  Powdery mildew of cucurbits caused by Podosphaera xanthii is widely distributed 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.

Remark:

The assessment of risk of Podosphaera xanthii distinctly documents its economic importance to California agriculture and environment and its widespread distribution within cucurbit production regions of the State.  Due to its biological capacity for rapid spread and its current widespread instate status, it is highly unlikely that the powdery mildew pathogen of cucurbits can be eradicated from California.  However, control measures, including use of protectant fungicides and resistant varieties, have proven successful in significantly reducing disease intensities and spread (CABI, 2016).  Therefore, a ‘C’ rating is proposed for this pathogen.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Podosphaera xanthii is C.

References:

Braun, U. and R. T. A. Cook.  2012.  Taxonomic manual of the Erysiphales (Powdery Mildews).  Centraalbureau voor Schimmelcultures, vol. 11, 707 p.

CABI.  2016.  Podosphaera xanthii (powdery mildew of cucurbits) full datasheet.  http://www.cabi.org/cpc/datasheet/50922.

Davis, R. M., T. A. Turini, B. J. Aegerter, and J. J. Stapleton.  2012.  Cucurbits powdery mildew pathogens: Sphaerotheca fuliginea (=Podosphaera xanthii) and Erysiphe cichoracearum (=Golovinomyces cichoracearum).  UC IPM Pest Management Guidelines: Cucurbits UC ANR Publication 3445. http://ipm.ucanr.edu/PMG/r116100711.html .

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

McGrath, M. T.  2011.  Vegetables: powdery mildew of cucurbits.  Vegetable MD Online, Cooperative Extension, New York State, Cornell University.  Fact sheet Page: 732.30 Date: June 2011.  http://vegetablemdonline.ppath.cornell.edu/

Ramos, C. B., K. Maruthachalam, J. D. McCreight, and R. S. Garcia Estrada.  2010-2011. Podosphaera xanthii but not Golovinomyces cichoracearum infects cucurbits in a greenhouse at Salinas, California.  Cucurbit Genetics Cooperative Report 33-34: 24-28.

Takamatsu, S., S. Ninomi, M. Harada and M. Havrylenko.  2010.  Molecular phylogenetic analyses reveal a close evolutionary relationship between Podosphaera (Erysiphales: Erysiphaceae) and its rosaceous hosts.  Persoonia, 24, 38-48.

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


Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-262-1110, plant.health[@]cdfa.ca.gov.


Comment Period:  CLOSED

45-day comment period: Aug 17 – Oct 1, 2016


 PEST RATING:  C

Posted by ls

Phyllosticta yuccae Bissett 1986

California Pest Rating for
Phyllosticta yuccae Bissett 1986
Pest Rating: C

 


PEST RATING PROFILE
Initiating Event:

On June 17, 2016 Yucca elephantipes (Adam’s needle) plants exhibiting leaf spot symptoms were intercepted at a nursery in San Diego County by San Diego County officials.  The shipment had originated in Florida.  Samples of symptomatic leaves were collected by the County and sent to the CDFA Plant Pathology Laboratory for disease diagnosis.  On July 17, 2016 Suzanne Latham, CDFA plant pathologist, identified the fungal pathogen, Phyllosticta yuccae, as the cause for the disease.   The pathogen has not been previously reported in California and therefore, was assigned a temporary Q rating.  Subsequent action taken by CDFA resulted in prevention of the shipment from introduction to California. The risk of infestation of Phyllosticta yuccae in California is evaluated and a permanent rating is herein proposed.

History & Status:

BackgroundPhyllosticta yuccae causes leaf blotch disease in Yucca plants.

Disease cycle:  It is likely that Phyllosticta yuccae has a similar life cycle to that of other Phyllosticta species and overwinters as conidia (asexual spores) in pycnidia (asexual fruiting structures) and ascospores (sexual spores) in perithecia (sexual fruiting structures) in infected plant leaf debris. Conidia and ascospores are only released when the fruiting structures become thoroughly wet.  Conidia are exuded from pycnidia in mucoid mass and are washed down or splashed away by rain or overhead irrigation water.  Ascospores are shot out forcibly from perithecia and carried by air currents.  On landing on host leaf surfaces, conidia or ascospores are germinate and infect plant tissue of young leaves.  Pycnidia are produced within lesions and provide conidia for secondary infections of plants (Agrios, 2005).

Dispersal and spread: rain/water splash, air currents, infected plant material and debris.

Hosts:  Yucca sp., Y. aloifolia, Y. elephantipes, Y. filamentosa (Farr & Rossman, 2016).

Symptoms:  Phyllosticta yuccae infections result in production of leaf spots in Yucca plants.  Initial symptoms include dark brown, elliptical, and scattered lesions which later become grey at the center with a reddish brown margin, irregular and coalesced (Silva et al., 2013).

Disease Potential Symptomatic Yucca plants infected with Phyllosticta yuccae may be more of a serious problem for nursery greenhouse productions where favorable wet requirements for disease development and spread are more likely to occur under controlled environments than in open field environments in California.  The disease could negatively impact value and marketability of nursery-grown Yucca plants.

Worldwide Distribution: Asia: Iran; Caribbean: Dominican Republic; North America: Canada, USA (Florida), Guatemala; South America: Brazil; Oceania: New Zealand (Farr & Rossman, 2016; Silva et al., 2013).

Official Control:  Currently, Phyllosticta yuccae has a temporary Q rating in California.

California Distribution:  Phyllosticta yuccae is not established in California.

California Interceptions: Phyllosticta yuccae was detected once in a shipment of Yucca elephantipes plants from Florida and destined to a San Diego nursery.

The risk Phyllosticta yuccae 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): Yucca plants. grow naturally under dry conditions in southern California.  Under those natural conditions, Phyllosticta yuccae may not receive adequate wet conditions for infection and spread.  However, certain species of the host plant may be grown as residential and commercial landscape ornamentals in coastal regions of southern and central California under favorable environments for disease development.     

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

Low (1) has a very limited host range.

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

Risk is Low (1):  The host range is limited to Yucca spp.   

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): Phyllosticta yuccae has high reproductive potential, however, the dispersal of spores from fruiting structures is dependent on wet conditions.

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): Nursery grown Yucca plants infected with Phyllosticta yuccae and exhibiting leaf blotch/spot symptoms could lower crop value and marketability.

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 favorable conditions for disease development, Phyllosticta yuccae may significantly impact ornamental plantings of commercially and home grown Yucca plants.     

Consequences of Introduction to California for Phyllosticta yuccae:

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).  Phyllosticta yuccae 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 Phyllosticta yuccae is C.

References:

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

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/.

Ingram, S.  2008.  Cacti, Agaves and Yuccas of California and Nevada.  Pacific Horticulture, 69 (3): http://www.pacifichorticulture.org/articles/cacti-agaves-and-yuccas-of-california-and-nevada/

Silva, A.D.A., Pinho, D.B., Jr., Hora, B.T., and Pereira, O.L. 2013. First Report of Leaf Spot Caused by Phyllosticta yuccae on Yucca filamentosa in Brazil. Plant Disease 97: 1257.

Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-262-1110, plant.health[@]cdfa.ca.gov.


Comment Period:  CLOSED

45-day comment period:  Aug 17 – Oct 1, 2016.


PEST RATING:  C


Posted by ls

Sclerophthora rayssiae var. zeae Payak & Renfro 1967

California Pest Rating for
Sclerophthora rayssiae var. zeae Payak & Renfro 1967
Pest Rating: C

 


PEST RATING PROFILE
Initiating Event:

Sclerophthora rayssiae var. zeae was recently proposed by the USDA to be removed as a select agent from the 2016 updated Select Agents Registration List and Select Agent Regulations.  Currently, the pathogen is not rated in California.  Therefore, the risk of introduction and establishment of this pathogen in California is assessed and a permanent rating is proposed herein.

History & Status:

Background: Sclerophthora rayssiae var. zeae is an oomycete pathogen that causes brown stripe downy mildew disease of maize.  The disease was first observed in several maize-growing regions of India in 1962, and the pathogen was described by Payak and Renfro in 1967.  Since its initial discovery, the disease has spread through India has also been reported from Mynmar, Nepal, Pakistan, and Thailand (CABI, 2016; Putnam, 2007; EPPO, 2016).

Sclerophthora rayssiae var. zeae has not been reported within the USA (CABI, 2016; USDA, 2013).  In 2002, the USDA designated the pathogen a ‘select agent’ deemed to be very damaging to susceptible maize and sources of resistance, if any, had not been established for U. S. maize varieties (USDA, 2013).  However, on January 14, 2016, after its fourth biannual review, the USDA proposed to remove S. rayssiae from the updated Select Agents Registration List and Select Agent Regulations.  Removal of select agents, by the USDA, was based on either the absence of viable samples present in the U.S., no climate conducive to growth, or the availability of adequate treatments for the agents (USDA, 2016).

Hosts: Zea mays (maize), Z. mays var. indurata; Digitaria sanguinalis (large crabgrass), D. bicornis (CABI, 2016; EPPO, 2016; Farr & Rossman, 2016; Putnam, 2007).

Symptoms: Characteristic symptoms of Sclerophthora rayssiae var. zeae infection are expressed only in leaves as vein-delimited narrow chlorotic or reddish to purple stripes, 3 to 7 mm wide, depending on maize genotype, extending parallel with the leaf veins. Other parts of the plant including leaf sheaths, husk leaves, ears or tassels do not exhibit symptoms even though all the leaves may be symptomatic.  Early infections appear as vein-delimited chlorotic flecks which enlarge and coalesce to form stripes. At first the stripes are chlorotic or yellowish but later turn yellowish-tan to reddish-brown and necrotic.  The disease initially appears on the lowermost leaves which have a high level of striping, and appear pale-brown and burnt.  Severely affected leaves may be shed prematurely.  In comparison, leaves around the ear shoot show a lesser amount of striping and the leaves above show the least.  The veins are not affected, but in severe infections, leaves tear apart near the apices and become tattered.  Greyish-white downy growth develops on the upper and lower surfaces of the stripes on leaves.  The downy growth disappears as the stripes become necrotic.  Sporangia disappear as the lesions become necrotic and oospores are produced only in necrotic tissue.  Unlike other downy mildews of maize, brown stripe downy mildew does not result in malformation of floral and vegetative tissues (CABI, 2016; Putnam, 2007).

Disease cycle:  The disease cycle involves both sexual and asexual reproduction.  Oospores (sexual spores) germinate to produce sporangia (sac-like structures containing spores), which then release zoospores (motile spores) that penetrate leaf tissue.  Moisture is critical for infection.  A twelve-hour wetting period of a free film of moisture on a leaf surface is essential for infection to occur.  Longer wetting periods increase the amount of infection (Singh et al., 1970).   Once primary infection occurs, the disease becomes established and lesions are formed in leaves.  Sporangia are produced and a cyclic chain of secondary infections occur that eventually result in the spread of the disease throughout an entire crop (CABI, 2016). High levels of moisture and warm temperatures are required for disease development and spread.  Asexual reproduction, resulting in the production of sporangia is most abundant at 22 to 25°C.  Sporangia production, germination, and infection require a film of water (Putnam, 2007; CABI, 2016). Oospores are produced in necrotic leaf tissue and form the survival stage of the pathogen in soil or in plant debris.

Dispersal and spread The pathogen survives as oospores in soil or plant debris.  Oospores serve as primary inoculum for infections of plants, where the lower leaves show greater disease intensity than the upper leaves, and can survive in soil or plant debris for several years (CABI, 2016; Fry & Grűnwald, 2010).  Experimentally, oospores were shown to be viable for up to 3 years when powdered infected leaf debris was placed around each seed at the time of sowing, resulting in heavy infection of the emerging seedlings (Singh et al., 1970). Seed transmission may also occur, although the initiation of new infections is less likely through seed transmission than infected leaf debris (Putnam, 2007).  The pathogen may be found on the seed surface and within the embryo (CABI, 2016; Putnam, 2007).  The pathogen is dispersed short distances by wind and rain splash or physical contact with infected plants.  Long distance transmission by wind is unlikely (Singh & Renfro, 1971).

Damage Potential: Brown stripe downy mildew of maize causes severe infections in areas of high rainfall.  In India, 20 to 90% in crop losses are reported.  Losses above 70% occur in highly susceptible maize cultivars grown under disease-favorable conditions (CABI, 2016).  In California, the required warm temperature and long wet periods (heavy rain durations) for disease development and spread are not present.  Therefore, the potential for damage caused by the pathogen to California’s maize production, can be considered to be minimal, if at all.

Worldwide Distribution: Asia: India, Mynmar, Nepal, Pakistan, Thailand (CABI, 2016).

Official Control: Presently, Sclerophthora rayssiae var. zeae is on the ‘Harmful Organism Lists’ of the following countries: Honduras, Namibia, New Zealand, Peru, and South Africa (USDA-PCIT, 2016).  The USDA designated S. rayssiae var. zeae a select agent in 2002, however, on January 14, 2016, the USDA proposed to remove S. rayssiae from the updated Select Agent Registration List and Select Agents Regulations (see ‘Background’.

California Distribution: Sclerophthora rayssiae var. zeae is not present in California.

California Interceptions:  There are no reports of the detection of Sclerophthora rayssiae var. zeae in plant and soil shipments imported to California.

The risk Brown stripe downy mildew of maize 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):   Sclerophthora rayssiae var. zeae is not likely to establish in California as the required warm temperature and long wet periods (12 hours or more) for disease development and spread are not present.

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): Maize and crabgrass are the only reported hosts of 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):  Under favorable wet conditions, Sclerophthora rayssiae var. zeae has high reproductive potential.  The pathogen is dispersed primarily through infected soil, plant debris, and maize seeds.  Short distance spread is by wind and rain splash or physical contact with infected plants.  Long distance transmission by wind is reported to be unlikely.

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):  In California, the required warm temperature and long wet periods (heavy rain durations) for disease development and spread of the pathogen, are not present, thereby, making it most unlikely for the pathogen to establish and cause infections to the State’s maize cultivation. However, within contained and artificially controlled conditions as in greenhouses, it is possible for pathogen infections to occur.  The economic impact is therefore, regarded low.

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 Low (1):  No environmental impacts due to the pathogen are expected to occur in California.

Consequences of Introduction to California for Brown stripe downy mildew of maize:

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 = 7

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):

Final Score:

7) The final score is the consequences of introduction score minus the post entry distribution and survey information score: (Score)

Final Score:  Score of Consequences of Introduction – Score of Post Entry Distribution and Survey Information = 7

Uncertainty:

None.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Sclerophthora rayssiae var. zeae is C.

References:

CABI.  2016.  Sclerophthora rayssiae var. zeae (brown strip downy mildew of maize) full datasheet.  http://www.cabi.org/cpc/datasheet/49244

EPPO.  2016.  Sclerophthora rayssiae var. zeae ().  PQR database.  Paris, France: European and Mediterranean Plant Protection Organization.  http://www.newpqr.eppo.int.

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

Fry, W. E. and N. J. Grűnwald.  2010.  Introduction to Oomycetes.  The Plant Health Instructor.  DOI:10.1094/PHI-I-2010-1207-01

Payak, M. M., and B. L. Renfro.  1967.  A new downy mildew disease of maize.  Phytopathology, 57:394-397.

Putnam, M. L.  2007.  Brown stripe downy mildew (Sclerophthora rayssiae var. zeae) of maize.  Plant Management Network International Plant Health Progress, published 8 November 2007. http://www.plantmanagementnetwork.org/pub/php/diagnosticguide/2007/stripe/

Singh, J. P., and B. L. Renfro.  1971.  Studies on spore dispersal in Sclerophthora rayssiae var. zeae.  Indian Phytopathology, 24:457-461.

Singh, J. P., B. L. Renfro, and M. M. Payak.  1970.  Studies on the epidemiology and control of brown stripe downy mildew of maize (Sclerophthora rayssiae var. zeae).  Indian Phytopathology, 23:194-208.

USDA.  2013.  Recovery plan for Philippine downy mildew and brown stripe downy mildew of corn caused by Peronosclerospora philippinensis and Sclerophthora rayssiae var. zeae, respectively.   http://www.ars.usda.gov/SP2UserFiles/Place/00000000/opmp/Corn%20Downy%20Mildews%20Recovery%20Plan%20Revised%202013.pdf

USDA, 2016.  Stakeholder announcement: USDA proposes updates to select agents registration list and select agent regulations.  USDA APHIS. Published January 14, 2016.

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


Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-262-1110, plant.health[@]cdfa.ca.gov.


Comment Period:  CLOSED

The 45-day comment period opened on Jul 27, 2016 and closed on Sep 10, 2016.


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

Peronosclerospora philippinensis (W. Weston) C. G. Shaw, 1978

peronosclerospora philippinensis | photo by Bob Kemerait, Univ of Georgia, Bugwood.org
California Pest Rating for
Peronosclerospora philippinensis (W. Weston) C. G. Shaw, 1978
Pest Rating: C

 


PEST RATING PROFILE
Initiating Event:

Peronosclerospora philippinensis was recently proposed by the USDA to be removed as a select agent from the 2016 updated Select Agents Registration List and Select Agent Regulations.  Currently, the pathogen is not rated in California.  Therefore, the risk of introduction and establishment of this pathogen in California is assessed and a permanent rating is proposed herein.

History & Status:

Background: Peronosclerospora philippinensis is an oomycete pathogen that causes Philippine downy mildew disease.  The disease is destructive mainly to corn in tropical Asia, endemic to the Philippines, and has also been reported from China, India, Indonesia, Nepal, Pakistan, Taiwan, and Congo, Mauritius, and South Africa (CABI, 2016; EPPO, 2016; Farr & Rossman, 2016).  The pathogen has not been reported within the USA (Farr & Rossman, 2016; USDA, 2013).

In 2002, the USDA designated Peronosclerospora philippinensis a ‘select agent’ deemed to be very damaging to susceptible maize and sources of resistance, if any, had not been established for U. S. maize varieties (USDA, 2013).  However, on January 14, 2016, after its fourth biannual review, the USDA proposed to remove P. philippinensis from the updated Select Agents Registration List and Select Agent Regulations.  Removal of select agents, by the USDA, was based on either the absence of viable samples present in the U.S., no climate conducive to growth, or the availability of adequate treatments for the agents (USDA, 2016).

Hosts: Hosts include species within the family Poaceae.  Zea mays (maize) is the main host.  Other hosts include, Andropogon sorghum (Sorghum bicolor, sorghum), Avenae sativa (oats), Euchlaena luxurians, Saccharum officinarum (sugarcane), S. spontaneum (wild sugarcane), Sorghum halepense (Johnson grass), Zea mays subsp. mexicana (teosinte) (CABI, 2016; EPPO, 2016; Farr & Rossman, 2016).

Symptoms: Systemic symptoms are expressed in the first true leaf stage as stripes or overall yellowing of an entire leaf.  Local symptoms are expressed as long chlorotic streaks with downy growth of conidia (spores) and conidiophores.  This downy growth is the site of spore production and may be present on both upper and lower leaf surfaces, but is more common on the lower surface.  Tassels may be malformed and produce less pollen, and ears may be aborted.  Early infected plants are stunted and may die.  Infected stems do not show external symptoms, but may be stunted (CABI, 2016).  The pathogen invades the stem, and becomes established in the shoot apex producing chlorotic areas, which are initially confined to the base of the lower leaf but later increase in size in succeeding leaves.  The youngest leaf emerging from the whorl becomes completely chlorotic.  The pathogen becomes established within seed, as mycelium in the pericarp layer, and also within the embryo and endosperm.  However, no external symptoms on seed are expressed and seed quality is not affected (CABI, 2016).

Disease cycle:  Although the Philippine downy mildew pathogen was reported to produce oospores (overwintering sexual spores) on corn leaf, there have been no subsequent reports.  Even though the Philippine downy mildew pathogen was reported in 1967 to produce overwintering sexual spores (oospores), on corn leaf, there have not been any subsequent reports since then and therefore, the role of oospores has not been established in the life cycle or disease caused by this pathogen (USDA, 2013). Airborne conidia (spores) released from infected crops or weeds form primary source of inoculum for infection. Germinating conidia produce germ tubes which penetrate stomata of leaves.  The optimum temperature for germination and germ tube growth is 18-30°C.  Penetration is followed by invasion of the mesophyll.  Soon the disease becomes established and lesions are formed in leaves.  Conidia are produced under night temperatures ranging from 21 to 26°C and free moisture.  Moisture is critical for infection.  Secondary infections occur that eventually result in the spread of the disease throughout an entire crop.  Seed transmission can occur at low rates from seeds harvested with higher moisture content (CABI, 2016).

Dispersal and spread Peronosclerospora philippinensis is commonly spread by wind and rain.  Production of conidia requires night temperatures ranging from 21 to 26°C and free moisture.  Disease severity is highest in areas that receive 39-78 inches of rain annually and in tropical climates.  The pathogen is dispersed short distances by wind.  Although the pathogen is present within infected seed, it has been demonstrated that once the seed or grain is dried to below 14% it will not produce an infected plant (Adenle & Cardwell, 2000; USDA 2013).

Damage Potential: Before resistant varieties became widely available in the Philippines, annual yield losses of maize were often 40 to 60%.  Yield losses of sweet corn were 100%. Disease severity is highest in areas that receive 39-78 inches of rain annually and in tropical climates (USDA, 2013).  In California, the required warm temperature and long wet periods (heavy rain durations) for disease development and spread are not present.  Therefore, the potential for damage caused by the pathogen to California’s maize production, can be considered to be minimal, if at all.  Furthermore, the pathogen is seed transmissible, but transmission will not occur once the seed has been dried to the moisture content required for storage.  Seed treatments are available to eradicate the pathogen (CABI, 2016).

Worldwide Distribution: Asia: China, India, Indonesia, Japan, Nepal, Pakistan, Philippines, Taiwan, Thailand; Africa: Mauritius, Congo, South Africa (CABI, 2016; Farr & Rossman, 2016).

Official Control: Presently, Peronosclerospora philippinensis is on the ‘Harmful Organism Lists’ of the following countries: Colombia, French Polynesia, Guatemala, Honduras, Indonesia, Japan, Republic of Korea, Morocco, Namibia, New Caledonia, New Zealand, Peru, South Africa, and Timor-Leste  (USDA-PCIT, 2016).  The USDA designated S. rayssiae var. zeae a select agent in 2002, however, on January 14, 2016, the USDA proposed to remove S. rayssiae from the updated Select Agent Registration List and Select Agents Regulations (see ‘Background’).

California Distribution: Peronosclerospora philippinensis is not present in California.

California Interceptions:  There are no reports of the detection of Peronosclerospora philippinensis in plant and soil shipments imported to California.

The risk Philippine downy mildew disease 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):   Peronosclerospora philippinensis is not likely to establish in California as the required warm temperature and long wet periods (12 hours or more) for disease development and spread are not present.

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

Low (1) has a very limited host range.

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

Risk is Low (1): The host range is limited to include species within the family Poaceae.  Maize is the main host, cultivated sugarcane, oats, sorghum cultivars, and weedy grass species including Euchlaena luxurians, wild sugarcane, Johnson grass, and Zea mays subsp. mexicana (teosinte).

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 wet conditions, Peronosclerospora philippinensis has high reproductive potential.  The pathogen is dispersed primarily through infected soil, plant debris, and maize seeds.  Short distance spread is by wind and rain splash or physical contact with infected plants.  Long distance transmission by wind is reported to be unlikely.

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):  In California, the required warm temperature and long wet periods (heavy rain durations) for disease development and spread of the pathogen, are not present, thereby, making it most unlikely for the pathogen to establish and cause infections to the State’s maize cultivation. However, within contained and artificially controlled conditions as in greenhouses, it is possible for pathogen infections to occur. Seed transmission of the pathogen will not occur once the seed has been dried to the moisture content required for storage and the pathogen can be eradicated from seed through seed treatments. The economic impact is therefore, regarded low.

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 Low (1):  No environmental impacts due to the pathogen are expected to occur in California.

Consequences of Introduction to California for Brown stripe downy mildew of maize:

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 = 7

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):

Final Score:

7) The final score is the consequences of introduction score minus the post entry distribution and survey information score: (Score)

Final Score:  Score of Consequences of Introduction – Score of Post Entry Distribution and Survey Information = 7

Uncertainty:  

None.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Peronosclerospora philippinensis is C.

References: 

Adenle, V. O., and K. F. Cardwell. 2000.  Seed transmission of maize downy mildew (Peronosclerospora sorghi) in Nigeria. Plant Pathology 49:628-634.

CABI.  2016.  Peronosclerospora philippinensis (Philippine downy mildew) full datasheet.  http://www.cabi.org/cpc/datasheet/44646

EPPO.  2016.  Peronosclerospora philippinensis (PRSCPH).  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 January 28, 2016, from http://nt.ars-grin.gov/fungaldatabases/.

Fry, W. E. and N. J. Grűnwald.  2010.  Introduction to Oomycetes.  The Plant Health Instructor.  DOI:10.1094/PHI-I-2010-1207-01

Payak, M. M., and B. L. Renfro.  1967.  A new downy mildew disease of maize.  Phytopathology, 57:394-397.

USDA.  2013.  Recovery plan for Philippine downy mildew and brown stripe downy mildew of corn caused by Peronosclerospora philippinensis and Sclerophthora rayssiae var. zeae, respectively.   http://www.ars.usda.gov/SP2UserFiles/Place/00000000/opmp/Corn%20Downy%20Mildews%20Recovery%20Plan%20Revised%202013.pdf

USDA, 2016.  Stakeholder announcement: USDA proposes updates to select agents registration list and select agent regulations.  USDA APHIS. Published January 14, 2016.

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


Responsible Party:

John J. Chitambar, Primary Plant Pathologist/Nematologist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-262-1110, plant.health[@]cdfa.ca.gov.


Comment Period: CLOSED

The 45-day comment period opened on Jul 27, 2016 and closed on Sep 10, 2016.


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.

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Posted by ls