Tag Archives: fungus

Fungi, Plant Pathogens

Cercospora ruscicola

California Pest Rating for
Cercospora ruscicola V. G. Rao & A. S. Patil 1972
Pest Rating: B
PEST RATING PROFILE
Initiating Event:

On April 28, 2017, a shipment of Ruscus (Ruscus sp.) plants with symptoms of leaf spots and destined to a private resident in Contra Costa County, was intercepted by Contra Costa County officials.  The shipment had originated in Florida.  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, Cercospora ruscicola associated with the diseased leaf tissue. As there have not been any earlier reports of this pathogen in California, it was given a temporary ‘Q’ rating.  Subsequently, the consequences of introduction and establishment of C. ruscicola in California is assessed and a permanent rating is proposed herein.

History & Status:

Background:   The fungal pathogen, Cercospora ruscicola was originally identified from necrotic lesions on “leaves” (actually, ‘cladodes’ which are leaf-like modified stems) of several Ruscus plants at Poona, India (Rao & Patil, 1972).   There have not been any further reports of the global spread of this species, however, Cercospora spp., including C. ruscicola have been detected in federally intercepted samples of Ruscus plants, according to USDA’s National Mycologist (personal communications: S. Latham, CDFA plant pathologist).  Cercospora ruscicola is not known to be present in California.  The recent detection of this species in intercepted plants from Florida marked a first record.   Cercospora ruscicola is also known by its teleomorph (sexual) stage, Mycosphaerella ruscicola A. Pande 1980.

Disease development: 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:  Ruscus aculeatus (butcher’s broom), Ruscus sp. (Farr & Rossman, 2017; Rao & Patil, 1972; CDFA Pest and Damage Record, May 8, 2017).

Symptoms:  Similar to most other Cercospora diseases, symptoms caused by C. ruscicola are leaf spots.  Spots may be irregularly circular to angular, with or without a distinct border, and usually coalesce to form extensive blighted regions.  Rao and Patil (1972) observed extensive, irregular necrotic regions on leaves of Ruscus plants.

Damage Potential:  Quantitative losses due to Cercospora ruscicola have not been reported.  Photosynthetic area can be reduced due to leaf spotting.  In severe infections, leaf wilt and drop may be expected.  Rao and Patil (1972) stated that the “severe’ disease ultimately resulted in defoliation and blight of Ruscus plants in India.  Generally, the damage potential due to this pathogen is likely to be similar to other Cercospora diseases which is usually low (Agrios, 2005).

Ruscus spp. are evergreen, perennial plants that are uncommon and not grown commercially in California, even though they are able to tolerate a wide range of temperatures, except freezing, and grow in shade under wet and dry conditions (Stamp, 2001).  In California, they may be found in ornamental nurseries, and residential and public gardens where they may be at risk of infection and damage by Cercospora ruscicola.  Furthermore, Ruscus stems and berries are used in dried or fresh floral arrangements.  Damage caused by C. ruscicola may significantly impact commercial and private florist businesses.

Worldwide Distribution:  Asia: India (Farr & Rossman, 2017; Rao & Patil, 1972).

Official Control:  Presently, Cercospora ruscicola is on the ‘Harmful Organism’ list for Paraguay (USDA-PCIT, 2017).

California Distribution:  Cercospora ruscicola is not known to be established in California.

California Interceptions:  Cercospora ruscicola was detected in a single shipment of Ruscus sp. intercepted by Contra Costa County officials in April 2017 (see: ‘Initiating Event’).

The risk Cercospora ruscicola would pose to California is evaluated below.

Consequences of Introduction:   

1) Climate/Host Interaction: Ruscus are not commonly grown in California. However, they are able to grow in shade under wet and dry conditions and can tolerate a wide range of temperature (except freezing). These conditions enable the plants to grow in several areas in California and, if introduced, Cercospora ruscicola would be able to establish wherever its host plant is grown under high relative humidity/moisture and warm climate.  However, as the plants are not commercially cultivated and are uncommonly grown in residential and public gardens and ornamental nurseries, the pathogen is given a low score in this category.

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

Score: 1

– 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 is only limited to Ruscus and R. aculeatus in the family Ruscaceae.

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

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: Diseased Ruscus plants exhibiting leaf spot symptoms could result in lowered value of plants and loss of markets to nurseries and florist businesses. Increased costs of production can be expected with the necessary use of appropriate fungicides and other disease management strategies.

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

Economic Impact: 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:  2

– 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:  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 Cercospora ruscicola: Medium (9)

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 established’.

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: 9)

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 ruscicola is B.

References:

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

Farr, D. F., and A. Y. Rossman.  2017.  Fungal Databases, U. S. National Fungus Collections, ARS, USDA. Retrieved May 10, 2017, from http://nt.ars-grin.gov/fungaldatabases/

Rao, V. G., and A. S. Patil.  1972.  Cercospora ruscicola sp. nov. from India.  Transactions British Mycological Society, 58: 522.

Stamp, R. H.  2001.  Florida/Holland/Israeli Ruscus production and use.  University of Florida Extension, IFAS. Circular 1268 (ENH844).

USDA PCIT.  2017.  USDA Phytosanitary Certificate Issuance & Tracking System. May 10, 2017, 12:21:55 pm CDT.  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 Format:

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

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

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

♦  Comments may not be posted if they:

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

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

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

Violates agency regulations prohibiting workplace violence, including threats.

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

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

Pest Rating: B

Posted by ls 

Fungi, Plant Pathogens

Ganoderma adspersum (Schulzer) Donk

 California Pest Rating for
Ganoderma adspersum (Schulzer) Donk
Pest Rating: B
PEST RATING PROFILE
Initiating Event:

On January 25, 2017, Dr. David Rizzo, Professor, Department of Plant Pathology, University of California, Davis, notified CDFA of his detection of Ganoderma adspersum in almond orchards in the San Joaquin Valley, during surveys which initiated during fall 2015, of almond trees for wood decay fungi. The fungus was noted to be very aggressive and had killed relatively young almond trees in some orchards.  Consequently, CDFA will collect official samples of the fungus for analysis at the CDFA Plant Pathology Laboratory, and for official record.  Ganoderma adspersum has not been reported earlier from California or North America (Rizzo, 2017a).  The potential risk of infestation of G. adspersum is assessed here and a permanent rating is proposed for the species.

History & Status:

Background:   Ganoderma adspersum is a wood-decaying fungus that occurs in a very wide range of tree species including deciduous trees and conifers throughout the world. The species has more frequently been detected in trees growing near human habitations, gardens, parks, and planted sites (Papp & Szabo, 2013; De Simone & Annesi, 2012).   Ganoderma adspersum is a pathogen of roots and butts of living trees causing white rot, and can continue to grow saprophytically on nonliving tissue such as, stumps of felled trees (De Simone & Annesi, 2012).  Ganoderma species often kill their hosts and frequently, a diseased tree breaks or is wind-thrown while still alive as a result of decay in the butt and base of the trunk (Sinclair & Lyon, 2005). Unlike other closely related species, G. adspersum is an aggressive species that is able to penetrate and break through intact reaction zones of infected wood causing progressive and extensive decay over a relatively short period of time (De Simone & Annesi, 2012).   In Italy, G. adspersum-infected pine stands were felled within two years of infection (De Simone & Annesi, 2012).

Ganoderma adspersum has been known by several names.  The fungus was originally found growing on Carpinus betulus (European hornbeam) in Croatia, and published by Schulzer 1878 as Polyporus adspersus, and later as P. linhartii Kalchbr. 1884, Ganoderma linhartii (Kalchbr.) Z. Igmándy 1968, and G. europaeum Steyaert 1961.  After studying all specimens under the different species names, in 1969, Donk concluded the correct name for the fungus, G. adspersum (Tortic, 1971). In European polypore monographs, G. adspersum was found under the name, G. australe (Fr.) Pat. 1889.  However, through molecular analysis, the European taxon (G. adspersum) was differentiated from the Australian taxon (G. australe).  Ganoderma adspersum is the name of the European species (Papp & Szabó, 2013).  Differentiation of species of Ganoderma is confusing and problematic with only seven species, including G. adspersum, being accepted in the European polypore monographs (Papp & Szabó, 2013).  Taxonomically, G. adspersum is a distinct species belonging to the G. applanatum – australe complex (Papp & Szabó, 2013).

The species was first reported from Europe and is primarily found in that continent. However, it has also been found in Argentina, Brazil, American Samoa, and recently in the USA (California) (see: ‘Worldwide Distribution’).

In California, Ganoderma adspersum was detected in nine and ten year old almond orchards trees in Kings County during surveys of almonds for wood decay fungi in February 2016 (Rizzo, 2017a)  Over a three-year period, the orchard had experienced almost 20% tree loss, resulting in its removal by the end of 2016.  This detection marked a first for the fungus in California and North America.  Another detection was made in August 2016, in a twelve-year old almond orchard in Fresno County, and in 2017, additional infections were detected in Tulare, Kern, and Madera Counties (Rizzo, 2017b).  Presently, in California, the fungus has been found only in almond, prune and peach. All surveyed almond trees were planted on peach rootstock (Rizzo, 2017b).

Disease development:  Generally, most infections are initiated by airborne basidiospores that enter wounds on roots and trunk bases.  Basidiocarps (fruiting bodies or conks containing numerous spore producing structures or basidia) usually grow from the vicinity of old wounds.  Basidiospores are produced in great numbers during evening hours when the air is humid.  Experimentally, infection by root contact with previously colonized wood is also possible, although tree-to-tree spread has not been indicated by field observations (Sinclair & Lyon, 2005).

Dispersal and spread: Primarily by airborne basidiospores (De Simone & Annesi, 2012).

Hosts: Abies sp. (fir), A. alba (silver fir), Acer saccharinum (silver maple), Aesculus hippocastanum (horse chestnut), Betula pendula (European white birch), Broussonetia papyrifera (paper mulberry), Carpinus betulus (European hornbeam), Cedrus deodara (deodar cedar), Celtis occidentalis (common hackberry), Cercis siliquastrum (Judas tree), Fagus sylvatica (European/common beech), Fraximus sp. (ash), F. angustifolia subsp. danubialis (narrow-leafed ash), F. ornus (manna ash), Gleditschia triacanthos (honeylocust), Gymnocladus dioicus (Kentucky coffeetree), Juglans nigra (black walnut), Laurus nobilis (bay laurel), Picea abies (Norway spruce), Pinus sp. (pine), P. pinea (Italian stone pine), Platanus sp. (sycamore/plane trees), Populus alba (white poplar), P. nigra (black poplar), Prunus avium (wild cherry), P. padus (European bird cherry), P. cerasus (sour cherry), P. domestica (European plum), P. dulcis (almond), P. persica (peach), Prunus sp. (plum), Robinia sp. (locusts), R. pseudoacacia (black locust),  Quercus sp. (oak), Q. cerris (Turkey oak), Q. petraea (sessile oak), Q. pubescens (downy oak ), Q. robur (English oak), Q. ilex (holly oak), Morus sp. (mulberry), Salix sp. (willow), Tilia sp. (basswood), T. cordata (littleleaf linden), Ulmus laevis (European white elm), Zelkova serrata (Japanese zelkova) (De Simone & Annesi, 2012; Farr & Rossman, 2017; Gottlieb et al., 1998; Papp, 2013; Rizzo, 2017b; Tortic, 1970);

Symptoms:  In general, trees affected by Ganoderma develop widespread decay of sapwood in the butt and major roots.  Other symptoms include loss of vigor, undersized and sometimes yellowing or wilting leaves, thin crowns, and dead branches.  Some infected trees may die while others are weakened and fall by windstorms as a result of decay.  In advanced stages of decay, wood is light colored and stringy or spongy.  Large, reddish brown basidiocarps of G. adspersum grow from roots or butts (Sinclair & Lyon, 2005).  Progression of decay may be favored by predisposing conditions such as wounds, excessive stem density, or water stress (De Simone & Annesi, 2012).

Damage Potential:  Ganoderma adspersum causes wood decay and root rot thereby decreasing structural strength, growth and stand of infected trees.  In California, Rizzo (2017b) reported 50% to 70% infection rates in almond and prune orchards, with tree loss being exponential over time. Very high infection levels were observed in 9-12 years old almond orchards.  The life span of a typical almond orchard is about 25 years.  However, extensive infections may be terminal for almond orchards.  Few orchards were removed entirely due to high infections of Ganoderma adspersum.

Worldwide Distribution: Europe: Belgium, England, Germany, Hungary, Italy, Yugoslavia; North America: USA (California); South America: Argentina; Brazil; Oceania: American Samoa (CABI, 2017; De Simone & Annesi, 2012; Farr & Rossman, 2017; Gottlieb et al., 1998; Tortic, 1971)

Official Control: No official controls are reported for Ganoderma adspersum.  However, Ganoderma spp. is on the “Harmful Organism Lists” for Colombia and Jamaica.  Shipments of Ganoderma spp.-free Phoenix dactylifera, (date palm) plants is required by Colombia (USDA PCIT, 2017).

California Distribution: Ganoderma adspersum has been found in almond and prune orchards in Fresno, Kings, Tulare, Kern, and Madera Counties (Rizzo, 2017b).

California Interceptions: None reported.

The risk Ganoderma adspersum would pose to California is evaluated below. 

Consequences of Introduction: 

1) Climate/Host Interaction: Presently, Ganoderma adspersum has been found in almond and prune orchards within the San Joaquin Valley.  It has therefore demonstrated its capability to establish under suitable climates for those hosts within the State.

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

Score: 3

– 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: Ganoderma adspersum has a wide host range which includes deciduous and confer trees reported worldwide.  However, in California, the fungus has presently been detected in almond, prune and peach (almond on peach root stock) (Rizzo, 2017b). Those fruit hosts are cultivated in significant acreage in California.

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: Numerous basidiospores are produced by the fungus but are dependent on wind currents for dispersal and spread to non-infected trees. Therefore, a Medium rating is given for high reproductive potential.

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: Rizzo (2017b) reported 50% to 70% infection rates in almond and prune orchards in California, with tree loss being exponential over time.  Ganoderma adspersum causes wood decay and root rot resulting in decreased structural strength, growth and stand of infected trees.  Few orchards were removed entirely due to high infections.

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

Economic Impact: A, B, C

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

Economic Impact Score: 3

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

– Medium (2) causes 2 of these impacts.

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

5) Environmental Impact: Ganoderma adspersum has been reported on several hosts that are found in California environments.  Internationally, the fungus has more frequently been detected in trees growing near human habitations, gardens, parks, and planted sites.  However, in California, the fungus has only been detected in cultivated almond and prune. Other hosts may be threatened if the almond isolate in California is able to infect them.  However, as presently this is not known, the fungus is given a Medium score for potentially impacting urban gardens and 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.

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 Ganoderma adspersum: 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 Medium (-2).  Ganoderma adspersum has been reported (Rizzo, 2017a, 2017b) from Fresno, Kings, Tulare, Kern, and Madera Counties.

Score: (-2)

-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:  

Presently, in California, Ganoderma adspersum has only been found in almond, prune, and almond on peach rootstock.  The fungus has a wide host range, but it is not known if other hosts, in particular those in natural environments of California, have been infected or will be infected by the almond isolate of the fungus.  Future information on its distribution may alter the numerical score but less likely, the proposed rating.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Ganoderma adspersum is B.

References:

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

De Simone, D., and T. Annesi.  2012. Occurrence of Ganoderma adspersum on Pinus pinea.  Phytopathologia Mediterranea 51: 374-382.

CABI.  2017.   Ganoderma adspersum basic datasheet. http://www.cabi.org/cpc/datasheet/24922

Farr, D. F., and A. Y. Rossman.  2017.  Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved March 8, 2017, from http://nt.ars-grin.gov/fungaldatabases/

Gottlieb A. M., B. O Saidman, and J. E. Wright, 1998. Isoenzymes of Ganoderma species from southern South America. Mycological Research 102, 415‒426.

Papp, V. and I. Szabó.  2013.  Distribution and host preferences of poroid Basidiomycete in Hungary I. – Ganoderma.  Acta Silv. Lingn. Hung. 9: 71-83.  DOI: 10.2478/aslh-2013-0006

Rizzo, D.  2017a. Email from David Rizzo, University of California, Davis, to Cheryl Blomquist, CDFA, sent Wednesday, January 25, 2017 6:09 am, forwarded to John Chitambar, CDFA, Wednesday, January 25, 2017 8:03:08 am.

Rizzo, D.  2017b. Email from David Rizzo, University of California, Davis to John Chitambar, CDFA, Tuesday, March 7, 2017 12:33 pm.

Sinclair, W. A., and H. H. Lyon.  2005.  Diseases of trees and shrubs second edition.  Comstock Publishing Associates, a division of Cornell University Press, Ithaca and London.  660 p.

Tortic, M.  1971.  Ganoderma adspersum (s. Schulz.) Donk (Ganoderma europaeum Steyaert) and its distribution in Yugoslavia.  Acta Botanica Croatica. 30: 113-118.

USDA PCIT.  2017.  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 Format:

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

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

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

♦  Comments may not be posted if they:

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

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

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

Violates agency regulations prohibiting workplace violence, including threats.

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

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

Pest Rating: B

Posted by ls

Fungi, Plant Pathogens

Diaporthe pseudomangiferae

 California Pest Rating for
Diaporthe pseudomangiferae R. R. Gomes, C. Glienke & Crous
Pest Rating: C
PEST RATING PROFILE
Initiating Event:

On December 15, 2016, a shipment of Cacao seed pods with symptoms of necrotic spotting and rot and destined to a private citizen in Contra Costa County, was intercepted by the CDFA Dog Team at the United States Postal Service in Oakland, Alameda County.  The shipment was confiscated and destroyed and a sample of symptomatic seed pods was sent to the CDFA Plant Diagnostics Branch for disease diagnosis.  Suzanne Latham, CDFA plant pathologist identified the fungal pathogen, Diaporthe pseudomangiferae, as the cause for the disease and marked the first detection of D. pseudomangiferae in California.  The current status and rating of D. pseudomangiferae in California is assessed and a permanent rating is proposed.

History & Status:

Background:  Diaporthe pseudomangiferae is a fungal plant pathogen belonging to the order Diaporthales.  The species was named after its morphological similarity to the Phomopsis mangiferae, which was originally isolated from dead leaves of Mangifera indica in Pakistan, however, later reported to differ morphologically from P. mangiferae (Gomes et al., 2013).  Presently, D. pseudomangiferae has only been reported from the Dominican Republic, Puerto Rico, and Mexico (Farr & Rossman, 2017).

Diaporthe pseudomangiferae is not reported from the USA.  The pathogen is not established in California but was detected in a mail shipment of Cacao seed pods which was intercepted in California and subsequently, confiscated, bagged, frozen, and disposed.  However, its detection in Cacao marks a new host for the pathogen, which until now, has only been reported from mango (Gomes et al., 2013).

Disease development:  While specific information is lacking, it is likely that plant infection and disease development caused by Diaporthe pseudomangiferae are similar to those caused by other species of Diaporthe occurring as plant pathogens, endophytes or saprobes.  The fungus produces ascospores (sexual spores) in perithecia (sexual fruiting bodies) and conidia (asexual spores) in pycnidia on dead twigs and leaves.  Conidia are the main inoculum causing primary and secondary infections and are spread to host plants by splashing rains.  Ascospores may be involved in long distance dispersal of the pathogen.  The fungus is likely to overwinter as mycelium and/or as conidia within pycnidia (Agrios, 2005).

Dispersal and spread: Windblown/splashing rain and irrigation water, pruning tools, possibly insects, and animals can spread fungal spores to non-infected plants.

Hosts: Mangifera indica (mango) (Farr & Rossman, 2017; Gomes et al., 2013; Serrato-Diaz et al., 2014); Cacao sp. (CDFA Pest and Damage Record, 2016).

Symptoms:  In mango, Diaporthe pseudomangiferae causes inflorescence rot, rachis canker, and flower abortion.  Symptoms are characterized by blackening of plant tissue with soft rot lesions and sunken lesions on the rachis respectively.  In pathogenicity tests, initially white mycelia developed on inflorescences which later turned brown and flowers aborted (Serrato-Diaz et al., 2014).

Damage Potential:  Quantitative losses caused by Diaporthe pseudomangiferae have not been reported.  During a two-year disease survey in Puerto Rico, Serrato-Diaz et al., (2014) found 50% of mango symptomatic inflorescences to be infected with D. pseudomangiferae. The pathogen causes inflorescence rot, rachis canker, and flower abortion of mango. Therefore, if left uncontrolled, infections may result in reduced fruit production and marketability.  In California, nurseries and other growers of mango plants may be at risk of damage caused by this pathogen.

Worldwide Distribution: Caribbean: Dominican Republic, Puerto Rico; North America: Mexico (Farr & Rossman, 2016; Gomes et al., 2013; Serrato-Diaz et al., 2014).

Official Control: None reported.  In California, currently Diaporthe pseudomangiferae is a quarantine actionable pathogen with a temporary Q rating.

California Distribution: Diaporthe pseudomangiferae is not known to be established in California.

California Interceptions: There has been only one interception.  On December 15, 2016, the fungal pathogen was detected in a shipment of Cacao seed pods that originated in Puerto Rico and was intercepted at a United States Postal Service in Alameda County (see: ‘Initiating Event’).

The risk Diaporthe pseudomangiferae would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Mango is the only known host in California.  Diaporthe pseudomangiferae may be able to infect its host under wet conditions and is therefore, only likely to establish in very limited regions of the State where mango is grown mainly in the Coachella valley and foothill regions of southern California.

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

Score: 1

– 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 the pathogen is presently limited to Mangifera indica and Cacao

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: Diaporthe pseudomangiferae has high reproductive potential with an abundant production of spores, however, the spores are dependent on splashing water for dispersal.

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: Under favorable wet conditions for spread and disease development, Diaporthe pseudomangiferae has been found to cause inflorescence rot, rachis canker, and aborted flowers in mango, thereby possibly resulting in lowered fruit production, value, and loss of markets.

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

Economic Impact: A, B, C

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

Economic Impact Score: 3

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

– Medium (2) causes 2 of these impacts.

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

5) Environmental Impact: Mango and cacao are the only known hosts, therefore no significant impact on the environment is expected.

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

Environmental Impact:  None

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: 1

– 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 Diaporthe pseudomangiferae: Low (8)

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 established’ (0).

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 = 8.

Uncertainty: 

None.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Diaporthe pseudomangiferae is C.

References:

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

Anon.  1996. Mango Mangifera indica L. California Rare Fruit Growers, Inc.  http://www.crfg.org/pubs/ff/mango.html

Farr, D. F., and A. Y. Rossman.  2017.  Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved January 18, 2017, from http://nt.ars-grin.gov/fungaldatabases/

Gomes, R.R., C. Glienke, S. I. R. Videira, L. Lombard, J. Z. Groenewald, and P. W. Crous.  2013.  Diaporthe: a genus of endophytic, saprobic and plant pathogenic fungi. Persoonia 31: 1-41.

Serrato-Diaz, L.M., L. I. Rivera-Vargas, and R. D. French-Monar.  2014.  First report of Diaporthe pseudomangiferae causing inflorescence rot, rachis canker, and flower abortion of mango. Plant Disease 98(7): 1004

Responsible Party:

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

Comment Format:

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

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

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♦  Comments may not be posted if they:

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Pest Rating: C

Posted by ls

Fungi, Plant Pathogens

Calonectria pseudonaviculata (Crous, J. Z. Groenew. & C. F. Hill) L. Lombard, M. J. Wingf. & Crous, 2010

California Pest Rating for
Calonectria pseudonaviculata (Crous, J. Z. Groenew. & C. F. Hill) L. Lombard, M. J. Wingf. & Crous, 2010
Pest Rating: B
PEST RATING PROFILE
Initiating Event:

On November 22, 2016, non-official samples of diseased boxwood plants collected by a landscaper from a private property in Hillsborough, San Mateo County, were sent through the San Mateo County Agricultural Commissioner’s office to the CDFA Plant Pathology Lab for diagnosis.  The samples were examined by Kathy Kosta CDFA plant pathologist, and the associated pathogen was cultured and identified by Cheryl Blomquist CDFA plant pathologist, as Calonectria pseudonaviculata (Kosta, 2016).  Subsequently, on November 29, 2016, official samples were collected from the same private property by Kathy Kosta (CDFA) and Fred Crowder (San Mateo County) and processed at the CDFA Plant Pathology Lab for pathogen diagnosis.  The official identification of Calonectria pseudonaviculata was made by Cheryl Blomquist on December 7, 2016.  This detection marked a first record of the pathogen in California.  Consequently, the pathogen was assigned a temporary ‘Q’ rating.   The risk of introduction and establishment of the pathogen is assessed here and a permanent rating is proposed.

History & Status:

Background:  Calonectria pseudonaviculata is the fungal pathogen that causes boxwood blight or box blight disease.  The pathogen is also known by its asexual (anamorph) stage as Cylindrocladium pseudonaviculatum.  The disease was first reported in the United Kingdom in the early to mid-1990s and the pathogen was given the name Cylindrocladium buxicola.  The origin of C. pseudonaviculatum is not known.  The pathogen was considered an exotic species that had been introduced to the UK and by 1998, it had spread to Europe and New Zealand.  (CABI, 2016; Crous et al., 2002; Dart et al., 2012).  While most published literature refers to the fungus as C. buxicola, this pathogen was not formally reported in the literature until 2002 as Cylindrocladium pseudonaviculatum which later became synonymous with Calonectria pseudonaviculata, the sexual (teleomorph) stage of the fungus (Lombard et al., 2010).  The current scientific name of the pathogen is Calonectria pseudonaviculata (CABI, 2016; Crous et al., 2002; Ivors & LeBude, 2011).

Disease cycle:  The pathogen infects host plants rapidly in warm (18-25°C) and humid conditions and has a life cycle that is completed in one week (Henricot, 2006; Henricot et al., 2008).  The primary inoculum of spores are sticky and therefore, are best transmitted to healthy host plants by water-splash or carried by insects, birds or infested plants.  Spores germinate three hours after inoculation and penetrate leaves in as little as five hours (Henricot, 2006).  Hyphae penetrate through stomata on lower surface of leaves, or directly through the cuticle on upper surface of leaves without appressorium formation (specialized attachment and penetration structure).  The fungus continues to grow intercellularly in the mesophyll layers of the plant (Henricot, 2006).  Two to three days after infection, the fungus produces conidiophores and conidia (asexual spores) through stomata and after seven days, these cover the lower surface of the leaf.  Leaves are eventually killed (Henricot, 2006).   The fungus can form resting structures (microsclerotia) which can survive on leaf material and in the soil in the absence of a susceptible host (Henricot, 2006).  However, in a 5-year study on the survival of the fungus on decomposing plant material, Henricot et al., (2008) did not detect the presence of microsclerotia.  Apparently, the pathogen is able to survive as mycelium within decomposing plant tissue.   No sexual stage structures have been observed in nature or in culture (CABI, 2016).

C. pseudonaviculata is a low temperature fungus that can grow below 10°C but is inhibited at 30°C and killed at 33°C (Henricot, 2006).

Dispersal and spread: The pathogen is spread by wind-driven rain and splashing water over short distances.  Long distance spread occurs by movement of infected plants/nursery stock, infested plant debris, soil, contaminated tools and equipment, insects or birds.  The pathogen can survive in leaf debris on or beneath the soil surface for up to 5 years (Dart et al., 2012; Henricot, 2006; Henricot et al., 2008).  The disease may also be spread is through the movement of asymptomatic (or with very limited outward symptoms) boxwood plants or plants treated with fungicides that suppress but do not kill or eliminate the inhabiting pathogen (Douglas, 2011).

Hosts: Buxaceae: Buxus microphylla (little-leaf box), B. microphylla var. japonica, B. sempervirens (syn. B. colchica; common boxwood), B. sinica (Chinese box), B. sinica var. insularis (Korean boxwood), Buxus sp. (box), Pachysandra procumbens, P. terminalis (Japanese spurge), Sarcococca sp. (sweet box) (CABI, 2016; EPPO, 2016; Farr & Rossman, 2016).

The full host range of this pathogen is not currently known however, none of the Buxus species are immune to boxwood blight and susceptibility to the pathogen may vary among cultivars (Henricot et al., 2008).  Sarcococca sp. (sweet box) and Pachysandra terminalis (Japanese spurge) are experimental hosts (Henricot et al., 2008; LaMondia et al., 2012).

Symptoms:  Infections by Calonectria pseudonaviculata result in the production of dark brown or lighter brown leaf spots surrounded by a dark border.  Stems are also infected exhibiting characteristic black streaks.  Eventually severe defoliation and dieback occur.  The fungus does not infect the roots.  Entire foliage typically becomes blighted causing the leaves to turn ‘straw’ to light brown in color and defoliate.  Stems of blighted plants may remain green under the outer bark until infected by secondary or opportunistic pathogens and diseases resulting in decline and eventual death of entire plants.  Young seedlings can be killed by this pathogen (Henricot, 2006; Henricot et al., 2008; USDA-NCSU).

Damage Potential:   The disease has been described as ‘devastating’ to boxwood plants (Henricot et al., 2008). Foliage of infected plant is eventually killed and blighted plants are predisposed to infections by secondary pathogens also resulting in their eventual death.  At particular risk are boxwood plants grown in nurseries, commercial landscapes, parks and gardens, and at private residences under warm and wet climates conducive for the development and spread of the pathogen.  Rapid and widespread infection including over 10,000 American boxwood plants and 150,000 plants in production nurseries in North Carolina and Connecticut were reported (Ivors et al., 2012).  Buxus spp. (boxwood) are not native to the United States, and are widely cultivated as ornamental plants.  In California, depending on plant species and cultivar, boxwood is commonly grown throughout the State except in cold, mountainous regions, and are likely to prefer cooler climates in the State (Sunset Western Garden Book, 1992).  Three main species are grown as ornamentals in the USA, B. sempervirens, B. microphylla, and B. sinica var. insularis, all which are known hosts of C. pseudonaviculata (USDA-NCSU).

Worldwide Distribution: Asia: Iran, Republic of Georgia, Turkey; North America: Canada (restricted distribution in British Columbia, few occurrences in Ontario and Quebec), USA; Europe: Austria, Belgium, Croatia, Czech Republic, Denmark, France, Germany, Ireland, Italy, Netherlands, Norway, Slovenia, Spain, Sweden, Switzerland, United Kingdom; Oceania: New Zealand (CABI, 2016; EPPO, 2016; Farr & Rossman, 2016).

In the USA, C. pseudonaviculata has been reported from Alabama, Connecticut, Delaware, Kentucky, Maryland, Massachusetts, New Jersey, New York, North Carolina, Ohio, Oregon, Pennsylvania, Rhode Island, Virginia (CABI, 2016; EPPO, 2016; Farr & Rossman, 2016), and by this report from California.

Official Control:  Cylindrocladium buxicola (synonym C. pseudonaviculata) is on the ‘Harmful Organism Lists’ for the Republic of Korea (USDA PCIT, 2016).  Presently, it has a temporary Q rating in California.

California Distribution:   San Mateo County.

California Interceptions:  None reported.

The risk Calonectria pseudonaviculata would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: The boxwood blight pathogen, Calonectria pseudonaviculata rapidly infests host plants under humid and warm (18-25°C) climates – being inhibited at 30°C and killed at 33°C. Spores are transmitted to healthy host tissue under wet conditions, requiring wind-driven rains and water splash from overhead irrigation systems. Depending on species and cultivar selection, Buxus are grown throughout California, except in mountainous regions, and are likely to do best in cool climates, such as coastal regions of the State.  Plants grown in warm and humid climates are at possible risk of infection by the pathogen.  The pathogen may be able to establish in a larger but limited region in the State, suitable also to the growth of its host plants.  Therefore a ‘medium’ rating is given to this category.

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 Calonectria pseudonaviculata is currently limited to few Buxus species (boxwood) and several cultivars, as well as Sarcococca (sweet box) and Pachysandra spp. (Japanese spurge).

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: Calonectria pseudonaviculata has high reproductive potential.  Although its dispersal and spread over short distances to non-infected plants depends on wind-driven rain and water-splash, long distance spread occurs by movement of infected plants/nursery stock, infested plant debris, soil, contaminated tools and equipment, insects or birds. The disease may also be spread through the movement of asymptomatic (or with very limited outward symptoms) boxwood plants or plants treated with fungicides that suppress but do not kill or eliminate the inhabiting pathogen.  These modes of spread, plus the ability of the pathogen to survive in leaf debris on or beneath the soil surface for up to 5 years, places it as a ‘high risk’ in this category.

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: Boxwood blight disease could result in lower crop value, loss of foliage and plants, increased production costs, loss of markets, and changes in delivery of irrigation water so to avoid water splash and wetness of foliage.  Also, insects and birds could aid in spread of the pathogen to non-infected plants.  Therefore, economic impact, caused by the boxwood blight pathogen, is given a ‘High’ score.

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

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

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: Infections of Calonectria pseudonaviculata could significantly affect private and commercial plantings of boxwood plants commonly used as hedge and shrub ornamentals and result in additional treatments against the pathogen.  Therefore, risk on environmental impact is scored as ‘High’.

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

Environmental Impact: 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: 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 Calonectria pseudonaviculata: 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: Presently, the boxwood blight pathogen has only been officially reported from one region, namely, San Mateo 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 = Medium (10)

Uncertainty:  

None.                              

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Calonectria pseudonaviculata is B.

References:

CABI, 2016.  Calonectria pseudonaviculata (buxus blight) full datasheet. http://www.cabi.org/cpc/datasheet/17414.

Crous, P.W., J. Z. Groenewald, and C. F. Hill.  2002.  Cylindrocladium pseudonaviculatum sp. nov. from New Zealand, and new Cylindrocladium records from Vietnam. Sydowia 54: 23-34.

Dart, N., M. A. Hansen, E. Bush, and C. Hong.  2012.  Boxwood blight: a new disease of boxwood found in the eastern U.S.  Virginia Cooperative Extension, Virginia State University Publications and Educational Resources PPWS-4.  http://pubs.ext.vt.edu/PPWS/PPWS-4/PPWS-4.html

Douglas, S. M.  2011.  Boxwood blight – a new disease for Connecticut and the U. S.  The Connecticut Agricultural Experiment Station.  www.ct.gov/caes .

Farr, D.F., and A. Y. Rossman.  2016.  Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA.  Retrieved December 1, 2016, from http://nt.ars-grin.gov/fungaldatabases/.

Henricot, B., C. Gorton, G. Denton, and J. Denton. 2008. Studies on the control of Cylindrocladium buxicola using fungicides and host resistance. Plant Disease, 92(9):1273-1279.  http://www.apsnet.org

Ivors, K. and A. LeBude.  2011.  A new pest to the U. S. ornamental industry: the “box blight” pathogen Cylindrocladium pseudonaviculatum = Cylindrocladium buxicola.  NC Pest Alert. http://plant-clinic.bpp.oregonstate.edu/files/plant_clinic/webfm/NC_pest_alert_box_blight1-1.pdf

Ivors, K. L., L. W. Lacey, D. C. Milks, S. M. Douglas, M. K. Inman, R. E. Marra, and J. A. LaMondia.  2012.  First report of boxwood blight caused by Cylindrocladium pseudonaviculatum in the United States.  Plant Disease.  96: 1070. http://dx.doi.org/10.1094/PDIS-03-12-0247-PDN.

Kosta, K.  2016.  Personal communication to J. Chitambar, CDFA Primary Plant Pathologist/Nematologist via email on November 30, 2016, 5:03:15 pm.

LaMondia, J. A., D. W. Li, R. E. Marra, and S. M. Douglas.  2012.  First report of Cylindrocladium pseudonaviculatum causing leaf spot of Pachysandra terminalis.  Plant Disease 96: 1069. http://dx.doi.org/10.1094/PDIS-03-12-0235-PDN.

Lombard, L., P. W. Crous, B. D. Wingfield, and M. J. Wingfield.  2010.  Phylogeny and systematics of the genus Calonectria.  Studies in Mycology. 66: 31-69.  www.studiesinmycology.org , doi:10.3114/sim.2010.66.03

USDA-NCSU.  (Date not known).  The ‘box blight’ pathogen: Cylindrocladium pseudonaviculatum = Cylindrocladium buxicola (Teleo.  Calonectria pseudonaviculata).  Datasheet developed by USDA-APHI-PPQ-CPHST and NCSU Department of Plant Pathology, Mountain Horticultural Crops Research and Extension Center (MHCREC) staff. caps.ceris.purdue.edu/dmm/1603

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 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;

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

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

Pest Rating: B

Posted by ls

Fungi, Plant Pathogens

Coleophoma empetri (Rostr,) Petr. 1929

California Pest Rating for
Coleophoma empetri (Rostr,) Petr. 1929
Pest Rating: B
PEST RATING PROFILE
Initiating Event:

On April 27, 2016 a mail shipment containing cut foliage of Galax sp. was intercepted by the Santa Barbara County Dog Team, at the FedEx Service Center in Goleta, Santa Barbara County.  The shipment had originated in Florida and was destined to a nursery in Carpinteria, Santa Barbara County.  Samples of diseased leaves exhibiting leaf spots were collected by the County and sent to the CDFA Plant Pathology Laboratory for disease diagnosis.  On April 29, 2016 Suzanne Latham, CDFA plant pathologist, identified the fungal pathogen, Coleophoma empetri, 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 the County resulted in the destruction of the intercepted shipment of Galax sp. foliage (CDFA, 2016). The risk of infestation of Coleophoma empetri in California is evaluated and a permanent rating is herein proposed.

History & Status:

Background: Originally described as Septoria empetri, the fungal pathogen Coleophoma empetri is also known by other synonyms, Rhabdostromina empetri, Sporonema oxycocci, and Coleophoma rhododendri, and Coleophoma ericae.  The pathogen is widely distributed and found on living and dead leaves and fruit of many different plant species (Farr & Rossman, 2016; Sutton, 1980).

Disease cycle:   There is a paucity of specific information on Coleophoma empetri.  However, it is likely that the development of disease caused by the pathogen would be similar to other pycnidia-forming fungal pathogens.   The pathogen overwinters as mycelium or immature pycnidia in infected fruit and diseased plant debris. Under high moisture and cool temperature conditions, pycnidia swell and release conidia which are spread by splashing rain, irrigation, water, and so on.  Seed transmission is not known for C. empetri.  Infection of host plants and severity of disease development is likely to require high moisture and cool temperatures.  In the development of fruit rot of berries, conidia initiate infection during bloom and early berry development.  As infected fruit mature, hyphae continue to invade the fruit and rot symptoms do not develop until the late growing season and mostly in storage (Kusek, 1995).

Dispersal and spread: Splashing rain and irrigation water, air currents, infected plants, infected plant debris, cultivation tools, animals, and contaminated clothing.

Hosts:  Archontophoenix alexandrae (Alexander palm), Arctostaphylos sp. (Manzanita), A. uva-ursi, Arctous alpine (bearberries), Betula sp. (birch), Camellia sp., Cajanus cajan (pigeon pea), Canavalia ensiformis (Jack bean), Capsicum annuum (bell peppers), Croton sp., Diapensia sp., D. obovata (pincushion plant), Elaeagnus sp. (oleaster), E. macrophylla, Empetrum sp., E. nigrum (black browberry), Erica carnea (winter heath), Eucalyptus sp. E. tereticornis (forest red gum), Ficus sp., Fraxinus sp. (ash), Galax aphylla (beetleweed/coltsfoot), Gaultheria shallon (shallon), Gaylussacia brachycera (box huckleberry), Juniperus sp. (juniper), Kalmia angustifolia (sheep laurel), Laurus sp., L. nobilis (sweet bay), Leucothoe sp., Loiseleuria sp., L. procumbens, Lonicera sp. (honeysuckle), L. periclymenum, Malus sylvestris (European crab apple), Paxistima canbyi (Canby’s mountain-lover), Plea europaea, Prunus laruocerasus (cherry laurel), P. ponticum, Rhododendron sp., R. maximum, Solanum tuberosum (potato), Stransvaesia sp., Taxus baccata (English yew), Vaccinium sp. (blueberry), V. macrocarpon (American cranberry), V. ovatum (California huckleberry), V. oxycoccos (bog cranberry), V. vitis-idaea (lingonberry) (Farr & Rossman, 2016; Kusek, 1995; Sutton, 1980).

Symptoms:  Coleophoma empetri causes leaf spot, fruit rot and tuber skin spot disease on numerous hosts in numerous families.  Symptoms of ripe rot on cranberry fruit initially appear as a small soft area which expands over the entire fruit.  Diseased fruit appear off-red or reddish orange, and internally watery, squirting a watery fluid when squeezed.  However, as not all watery-soft fruit is caused by the pathogen, the latter must be isolated from the diseased fruit to confirm an association with the symptoms (Kusek, 1995).

Disease Potential:  Specific information on quantitative crop losses caused by Coleophoma empetri has not been reported. Photosynthetic area can be reduced due to leaf spotting.  In severe infections, leaf wilt and drop may be expected. Symptomatic host plants infected with the pathogen 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 plants including ornamental and landscape plants such as Manzanita, Camellia, Rhododendron, and Eucalyptus. The pathogen causes fruit rot that is apparent during late growing season and mainly in storage.

Worldwide Distribution: Coleophoma empetri is globally widely distributed.  Asia: India, USSR; Europe: Finland, Lithuania, Poland, USSR, United Kingdom, Ukraine, Scotland, Germany; North America: Alaska, Maryland, Massachusetts, Maine, Michigan, New Jersey, Oregon, Tennessee, Virginia, Washington, Wisconsin, and Northwestern states (Farr & Rossman, 2016).

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

California Distribution:  is not established in California.

California Interceptions: A single shipment of Coleophoma empetri-infected Galax sp. foliage was intercepted on April 27, 2016 at the FedEx Service Center in Goleta, Santa Barbara County (see ‘Initiating Event’).

The risk Coleophoma empetri 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: 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.

Risk is Medium (2): Coleophoma empetri may be able to establish on suitable host plants growing in high moisture and cool to warm climate conditions.  These conditions would likely limit natural establishment to northern coastal regions of California.

2) Known Pest Host Range: 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.

Risk is Medium (2):  Coleophoma empetri has a moderate host range that includes many host species in different plant families.  Most hosts grow under cool and wet climates.  In California, main hosts include ornamental, landscape, and fruit berry plants such as, Manzanita, Camellia, Rhododendron, Eucalyptus, blueberry, and cranberry.

3) Pest Dispersal Potential: 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.

Risk is High (2): Coleophoma empetri has high reproduction and dispersal potential.  The pathogen can be spread over short and long distance by splashing rain and irrigation water, air currents, infected plants, infected plant debris, cultivation tools, animals, and contaminated clothing.

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

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.

Score: 2

– 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):  The pathogen 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 plants including ornamental and landscape plants.  Also, the pathogen may cause fruit rot that is apparent during late growing season and mainly in storage.

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: 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.

 Risk is High (3): Severe infections caused of Coleophoma empetri could impact ornamental plantings.  Under suitable conditions that result in severe disease, threatened or endangered plant species, namely, manzanita (Arctostaphylos spp.) could be affected and disrupt critical habitats.  

Consequences of Introduction to California for Coleophoma empetri:

Add up the total score and include it here:

-Low = 5-8 points

–Medium = 9-12 points

        -High = 13-15 points

Total points obtained on evaluation of consequences of introduction to California = 11 (Medium).

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

Score: 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.

Evaluation is Not Established (0).  Coleophoma empetri 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 = 11 (Medium).

Uncertainty:

None.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Coleophoma empetri is B.

References:

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

CDFA.  2016.  Santa Barbara County Dog Team Interception.  CDFA AQW Pest Report No. 18-2016, weekly AQW report: for the week of April 28 to May 04, 2016.

Duan, J. X., W. P. Wu, and X. Z. Liu.  2007.  Reinstatement of Coleonaema for Coleophoma oleae and notes on Coleophoma.  Fungal Diversity 26: 187-204.

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/.

Kusek, C. C.  1995.  Cranberry Ripe Rot.  In Compendium of Blueberry and Cranberry Diseases Edited by F. L. Caruso and D. C. Ramsdell.  APS Press, The American Phytopathological Society, page 43.

Sutton, B. C. 1980. The Coelomycetes. Fungi Imperfecti with pycnidia, acervuli and stromata. Commonwealth Mycological Institute, Kew, Surrey, England, 696 pages

Responsible Party:

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

Comment Format:

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

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

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

♦  Comments may not be posted if they:

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Pest Rating: B

Posted by ls

Fungi, Plant Pathogens, Ratings

Pseudocercospora purpurea (Cooke) Deighton 1976

California Pest Rating for
Pseudocercospora purpurea (Cooke) Deighton 1976
Pest Rating: B
PEST RATING PROFILE
Initiating Event:

On November 17, 2016, USDA APHIS PPQ inquired if CDFA had conducted a pest risk assessment of the fungal pathogen, Pseudocercospora purpurea on avocados in California.  Subsequently, the risk of infestation of P. purpurea in California is evaluated and a permanent rating is herein proposed.

History & Status:

Background:  Pseudocercospora purpurea is a fungal plant pathogen that causes Pseudocercospora (Cercospora) spot (blotch) disease exhibiting leaf and fruit spot symptoms in Persea spp., including avocado (P. americana) plants. The pathogen was originally known as Cercospora purpurea. In South Africa, the disease is known as black spot or Cercospora spot and is the most serious pre-harvest disease affecting all cultivars of avocado, particularly, cv. Fuerte (Crous et al., 2000; Pohronezny et al., 1994).  The disease occurs in warm, humid and rainy climates and is found in southeastern USA, South America, northern Australia, Asia, Africa, and the Caribbean (CABI, 2016; Menge & Ploetz, 2003).  The pathogen has not been reported from California.

Disease cycle:  Initial inoculum of conidia (asexual spores) mostly comes from infected leaves.  New shoot tissues are infected wherever this disease occurs.  The pathogen penetrates host tissue either directly or through wounds. 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.  In South Africa, the pathogen remains latent for about 3 months after penetration.  Infected plants produce conidiophores (specialized hypha) that arise from the plant surface in clusters through stomata and form conidia successively.  Substomatal stroma (compact mycelial structure) may form from which conidiophores develop.  Fruit are susceptible when developed to a quarter to three-quarter of their full size.  Very small fruit (< 4 cm diameter) and those at or near maturity are almost immune.  Disease development is severe during warm, rainy weather when fruit are about a quarter size (Agrios, 2005; Menge & Ploetz, 2003; Pohronezny et al., 1994).  High relative humidity is necessary for conidial germination and plant infection.  The pathogen can overwinter as mycelium (stromata) in old infected leaves (Agrios, 2005).  

Dispersal and spread: Wind, rain, irrigation water, infected nursery plants, infected leaves, insects (Menge & Ploetz, 2003).

Hosts: Avocado is the main host; Persea spp. in the family Lauraceae, namely, P. americana (syn. P. gratissima, avocado), P. borbonia (redbay), P. drymifolia (Mexican avocado), P. palustris (swamp bay), and Persea sp. (Farr & Rossman, 2016).

Symptoms: Symptoms occur on leaves, stems, and fruit (Pohronezny et al., 1994).  On leaves, lesions initially appear as small (1-5 mm) angular, purple to purplish brown flecks or spots near leaf margins.  Over time, chlorotic halos surround older spots and are visible on both leaf surfaces.  The fungus sporulates under high humid conditions, appearing as gray, felty mycelial growths in the center of lesions. Individual lesions may coalesce forming larger regions of necrotic tissue.  Leaves become curled, deformed and may fall.

On fruit, lesions initiate as small flecks which later become slightly sunken, expand or coalesce becoming somewhat circular, and turn brown to brownish black in color.  Fissures or cracks usually develop in fruit lesions and serve as avenues for infection by other pathogens.  In certain cases, if the disease is temporarily arrested, the lesions appear as minute, raised, shiny, black specks associated with the corking of lenticels.  While blotch is usually confined to the rind of fruit, in advanced cases, the flesh may be invaded.  Once defoliation occurs, fruit may turn chlorotic, shrivel and drop.  Dark brown to black, 2-10 mm lesions may also form on green twigs and fruit pedicels (Pohronezny et al., 1994; Menge & Ploetz, 2003).

Damage Potential:  Pseudocercospora spot (blotch) is one of the most common diseases of avocado in Florida (Pohronezny et al., 1994).  Losses in avocado production may be severe and have been reported to be up to 69% in non-sprayed orchards in South Africa (Pohronezny et al., 1994; Menge & Ploetz, 2003).  Photosynthetic area can be reduced due to leaf spotting.  In severe infections, leaf wilt and drop may be expected.  In California, avocado production is a major industry producing 75% and 92% of the nation’s avocado fruit supplies (Lazicki et al., 2016).  Therefore, losses due to this pathogen is of particular concern.

Worldwide Distribution: Pseudocercospora purpurea is widespread in subtropical and tropical regions.  Asia:  India, Japan, Philippines; Africa: Cameroon, Democratic Republic of Congo, Côte d’Ivoire, Guinea, Kenya, South Africa; North America: Bermuda, Mexico, USA; Central America and Caribbean: Dominica, El Salvador, Honduras, Jamaica, Nicaragua, Panama, Puerto Rico, Trinidad and Tobago, United States Virgin Islands; South America: Argentina, Bolivia, Brazil, Chile, Guyana, Peru, Venezuela; Oceania: Australia, Palau (CABI, 2016; Farr & Rossman, 2016).

In the USA, the pathogen has been found in the states of Florida, Georgia, and Mississippi (CABI, 2016).

Official Control:  Presently, Cercospora purpurea (syn. Pseudocercospora purpurea) is on the ‘Harmful Organism Lists’ for Namibia and South Africa and P. purpurea is on the ‘Harmful Organism Lists’ for French Polynesia and New Caledonia (USDA PCIT, 2016).

California Distribution: Pseudocercospora purpurea has not been reported from California.  The pathogen is not known to be established in California.

California Interceptions:  None reported.

The risk Pseudocercospora purpurea 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: 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.

Risk is Medium (2): In California, Pseudocercospora purpurea may be able to establish on avocado, under high moisture and warm climate conditions.  In the State, avocados are grown mostly along the southern coast (Lazicki et al., 2016).

2) Known Pest Host Range: 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.

Risk is Low (1):  The host range for Pseudocercospora purpurea is limited to Persea spp. with avocado being the main host.

3) Pest Dispersal Potential: 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.

Risk is High (3):  Pseudocercospora purpurea has high reproductive potential resulting in the successive production of conidia which are mainly dependent on wind, rain, and infected plants for dispersal and spread.

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

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.

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.

Risk is High (3):  Infected host plants with leaf and fruit spot symptoms caused by Pseudocercospora spot (blotch) disease could lower value and yield of commercially produced avocado plants as well as affect nursery productions resulting in 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: 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.

Risk is Medium (2):  The pathogen could significantly impact avocado plants grown for fruit and aesthetic value in private residential and public environments.

Consequences of Introduction to California for Pseudocercospora purpurea:

Add up the total score and include it here:

-Low = 5-8 point

–Medium = 9-12 point

-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: 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.

Evaluation is not established (0):  Pseudocercospora purpurea 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:

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 Pseudocercospora purpurea is B.

References:

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

CABI.  2016.  Pseudocercospora purpurea (spot blotch) (basic) datasheet.  Crop Protection Compendium.  http://www.cabi.org/cpc/datasheet/12266 .

Crous, P.W., A. J. L. Phillips, A. P. and Baxter.  2000.  Phytopathogenic fungi from South Africa. University of Stellenbosch, Department of Plant Pathology Press, 358 pages (referenced by Farr & Rossman, 2016).

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

Lazicki, P., D. Geisseler, and W. R. Horwath.  2016.  Avocado production in California. https://apps1.cdfa.ca.gov/FertilizerResearch/docs/Avocado_Production_CA.pdf. (Last updated April, 2016.)

Menge, J. A., and R. C. Ploetz.  2003.  Disease of Avocado.  In Diseases of Tropical Fruit Crops, Edited by R. C. Ploetz, CABI Publishing, CAB International, UK, USA, 527 p.

Pohronezny, K. L., G. W. Simone, and J. Kotzé.  1994.  Pseudocercospora spot (blotch).  In Compendium of Tropical Fruit Diseases, Edited by R. C. Ploetz, G. A. Zentmeyer, W. T. Nishijima, K. G. Rohrbach, and H. D. Ohr, APS Press, The American Phytopathological Society, 79-80 p.

Responsible Party:

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

Comment Format:

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

Example Comment: 

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

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

♦  Comments may not be posted if they:

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

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

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

Violates agency regulations prohibiting workplace violence, including threats.

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

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

Pest Rating: B

Posted by ls

Fungi, Plant Pathogens

Neofusicoccum mangiferae (Syd. & P. Syd.) Crous, Slippers & A. J. L. Phillips, 2006

California Pest Rating for
Neofusicoccum mangiferae (Syd. & P. Syd.) Crous, Slippers & A. J. L. Phillips, 2006
Pest Rating: C
PEST RATING PROFILE
Initiating Event:

The current status and rating of Neofusicoccum mangiferae in California is reassessed and a permanent rating is proposed.

History & Status:

Background:  Neofusicoccum mangiferae is a fungal plant pathogen belonging to the family Botryosphaeriaceae.  The species was originally named Dothiorella mangiferae but since then has undergone several taxonomic revisions and is also been known as Nattrassia mangiferae, Fusicoccum mangiferae, and Hendersonula cypria (Crous et al., 2006; Farr & Rossman, 2016).

In California, Neofusicoccum mangiferae is widespread and has been found in different hosts including walnut and fig causing branch wilt and limb dieback (Michailides et al., 2007), in citrus causing branch and trunk canker (Eskalen et al., 2011) and Indian leaf-laurel fig causing ‘Sooty Canker’ disease (as syn. Nattrassia mangiferae) which severely damaged street plantings of Indian leaf-laurel fig in southern California (Hodel, et al., 2009; Mayorquin et al., 2012).  In addition, during 2015-16, CDFA plant pathologists identified the pathogen from diseased mango and avocado fruit that were intercepted in shipments from Florida to California. In natural infestations, the pathogen is often found in combination with other fungal species.

Disease development:  In Indian laurel-leaf fig and other host plants, Hodel et al., (2009) reported that the pathogen enters the tree primarily through bark wounds produced by mechanical damage, pruning, freezing weather, sunburn, insects, or other diseases.  Smooth, thin-barked trees or those stressed from insufficient water and other factors are especially susceptible to the disease.  The fungus and disease develops most rapidly in warm temperatures (85-105°F) under high humidity. Slightly sunken cankers develop at the wound and point of infection on branches and may expand as the disease progresses.  Once the disease expands to the trunk, the tree dies.  Small, black, pencil-point size fungal fruiting bodies are formed on the cankers while the underlying infected sapwood inside the bark is stained grey to black and sharply demarcated from adjacent light-colored, healthy tissue.   Masses of dark spores are produced by the fruiting bodies and dispersed by wind, rain splash, pruning tools, and insects.

Dispersal and spread: Wind, rain, water-splash, pruning tools, insects, and animals can spread fungal spores to non-infected plants.

Hosts: Agathis spp. (kauri; Araucariaceae), Castanea sativa (European chestnut; Fagaceae), Dioscorea rotundata (white yam; Dioscoreaceae), Eucalyptus grandis (flooded/rose gum; Myrtaceae), Mangifera indica (mango; Anacardiaceae), Manihot esculenta (cassava; Euphorbiaceae), Persea americana (avocado; Lauraceae), Prunus armeniaca (ansu apricot; Rosaceae), Phoenix dactylifera (date palm; Arecaceae), Cupressus (cypress; Cupressaceae), Robina pseudoacacia (black locust; Fabaceae), Tibouchina urvilleana (glory bush/purple glory tree; Melastomataceae), Ficus microcarpa (Indian laurel-leaf fig; Moraceae)) F. carica (edible fig: Moraceae), Juglans regia (English walnut; Juglandaceae), Citrus sp. (citrus; Rutaceae) (El-Trafi, 2010; Farr & Rossman, 2016; French, 1989; Heath et al., 2011; Mayorquin et al., 2012; Michailides et al., 2007; Nazerian et al., 2015).  Vitis vinifera (grape: Vitaceae) was reported as a host of Neofusicoccum mangiferae in China (Dissanayake et al., 2015).

Symptoms: Neofusicoccum mangiferae causes blight of inflorescences, rachis, and branches of infected host plants.  Symptoms include branch and trunk cankers, branch wilt and dieback, lesions and rot of fruit, rachis and flower discoloration and necrosis.

The pathogen has been reported to be associated with rachis necrosis and inflorescence blight in mango in Puerto Rico (Serrato-Diaz et al., 2014), lesions and progressive rot in mango and avocado fruit in Taiwan (Ni et al., 2009, 2010), Walnut branch wilt, fig branch dieback, citrus branch and/or trunk cankers, branch dieback and tree death symptoms of sooty canker disease in Indian laurel-leaf fig trees in California (Eskalen et al., 2011; Michailides et al., 2007; Hodel et al., 2009). In China, symptoms associated with grapevine dieback were characterized by partial or total death of affected cordons, with brown U-shaped necrotic sectors and brownish-black spot in cross-sections of affected trunks and arms (Dissanayake et al., 2015).

Damage Potential: In mango, disease incidences of 20-100% have been reported (Serrato-Diaz et al., 2014; El-Trafi, 2009) as well as 30-72% rot disease in stored mango fruit (Ni et al., 2010).  In several cities in Los Angeles County, California, the pathogen has devastated landscape plantings of Indian laurel-leaf fig tree by causing severe damage and death (Hodel et al., 2009).  Branch and trunk canker of citrus and other tree hosts may lead to decline or death of branches and whole plants (Eskalen et al., 2011; Michailides et al., 2007).

Worldwide Distribution: Asia: India, Iran, Myanmar, Pakistan, Taiwan; Africa: Benin, Nigeria, South Africa, Sudan; Europe: Cyprus; North America: Arizona, California, Hawaii, Washington, West Virginia; South America: Uruguay; Caribbean: Puerto Rico; Australia (CABI, 2016; USDA ARS, 2016; Farr & Rossman, 2016).

Official Control: None reported.

California Distribution: Neofusicoccum mangiferae is widespread in California in northern and southern coastal and valley counties including, Fresno, Los Angeles, Riverside, San Diego, San Luis Obispo, Tulare, and Ventura Counties (Eskalen et al., 2011; French, 1989; Hodel et al., 2009; Mayorquin et al., 2012).

California Interceptions:  From June 2014 to August 2016, Neofusicoccum mangiferae has been detected in eight shipments of mango and one shipment of avocado fruit imported to California (CDFA Pest and Damage Records).

The risk Neofusicoccum mangiferae 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):  Neofusicoccum mangiferae is able to establish in California under warm to hot and very humid climates.  Already, it is distributed within the State in certain southern and northern coastal and valley counties.

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

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

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

Risk is Medium (2):  Neofusicoccum mangiferae has a moderate and diverse host range. In California it has been found in Indian laurel-leaf fig tree, edible fig, citrus, avocado, and chestnut.  It has been detected in intercepted shipments of mango and avocado fruit.

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): Numerous numbers of spores are produced by this pathogen due to its high reproduction.  However, spore dispersal to non-infested hosts is dependent on external factor such as wind, water-splash, rain, infected pruning tools, insects, and animals. Therefore, it is given a Medium score.

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): Neofusicoccum mangiferae could lower crop yield, value, increase production costs, require changes in normal pruning practices, and can be spread by insects and animals, thereby, qualifying it for a high score for economic impact.

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

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

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

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

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

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

Score the pest for Environmental Impact. Score:

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

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

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

Risk is High (3): Infections of tree hosts used as commercial landscape, ornamental and private gardens plantings could result in disrupting natural communities in those environments, subsequently requiring official or private treatments.

Consequences of Introduction to California for Neofusicoccum mangiferae:

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 = 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): Neofusicoccum mangiferae has been reported from certain southern and northern coastal and valley counties.

Final Score:

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

Final Score:  Score of Consequences of Introduction – Score of Post Entry Distribution and Survey Information = 9.

Uncertainty:  

None.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Neofusicoccum mangiferae is C.

References:

CABI.  2016.  Neofusicoccum mangiferae datasheet (basic).  http://www.cabi.org/cpc/datasheet/115758 .

Crous, P. W., B. Slippers, M. J. Wingfield, J. Rheeder, W. F. O. Warasas, A. J. L. Philips, A. Alves, T. Burgess, P. Barber, and J. Z. Groenewald.  2006.  Phylogenetic lineages in the Botryosphaeriaceae.  Studies in Mycology 55: 235-253.

Dissanayake, A. J., W. Jhang, X. Li, Y. Zhou, T. Chethana, E. Hukeatirote, K. D. Hyde, J. Yan, G. Zhang, and W. Zhao.  2015.  First report of Neofusicoccum mangiferae associated with grape dieback in China.  Phytopathologia Mediterranea temp25-30.  DOI: 10.14601/Phytopathol_Mediterr-15159.

El-Trafi, M. A.  2010.  Studies on mango branch wilt disease caused by Neofusicoccum mangiferae.  FAO Agris Records.  http://agris.fao.org/openagris/search.do?recordID=SD2010000222 .

Eskalen, A., A. Adesemoye, and D. Wang.  2011.  Identification of different species causing Botryosphaeriaceae canker in citrus reveal Neofusicoccum mangiferae with Scytalidium-like synanomorph.  Phytopathology, 101: S49.

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

French, A.M. 1989. California Plant Disease Host Index. California Department of Food and Agriculture, Sacramento, 394 pages.

Heath, R.N., J. Roux, B. Slippers, A. Drenth, S. R. Pennycook, B. D. Wingfield, and M. J. Wingfield.  2011.  Occurrence and pathogenicity of Neofusicoccum parvum and N. mangiferae on ornamental Tibouchina species. Forest Pathology, 41: 48-51.

Hodel, D. R., A. J. Downer, and D. M. Mathews.  2009.  Sooty canker, a devastating disease of Indian laurel-leaf fig trees.  Western Arborist 35: 28-32.

Mayorquin, J. S., A. Eskalen, A. J. Downer, D. R. Hodel, and A. Liu.  2012.  First report of multiple species of the Botryosphaeriaceae causing bot canker disease of Indian laurel-leaf fig in California.  Plant Disease, 96:459. http://dx.doi.org/10.1094/PDIS-08-11-0714.

Michailides, T. J., D. P. Morgan, D. Felts, and H. Reyes.  2007.  Emerging fungal diseases in fruit and nut crops in California.  Phytopathology, 97: S170.

Nazerian, E., H. R. Naji, H. Abdul-Hamid, and M. Moradi.  2015.  Phenotypic and molecular characterization of Neofusicoccum mangiferae, the causal agent of black locust decline.  Journal of Plant Pathology and Microbiology, 6: 1. http://dx.doi.org/10.4172/2157-7471.1000250 .

Ni, H. F., R. F. Liou, T., H. Hung, R. S. Chen, and H. R. Yang.  2010. First report of fruit rot disease of mango caused by Botryosphaeria dothidea and Neofusicoccum mangiferae in Taiwan.  Plant Disease 94: 128. http://dx.doi.org/10.1094/PDIS-94-1-0128C

Ni, H. F., R. F. Liou, T., H. Hung, R. S. Chen, and H. R. Yang.  2009.  First report of a fruit rot disease of avocado caused by Neofusicoccum mangiferae.  Plant Disease 93: 760. http://dx.doi.org/10.1094/PDIS-93-7-0760B

Serrato-Diaz, L. M., L. I. Rivera-Vargas, and R. D. French-Monar.  2014.  First report of Neofusicoccum mangiferae causing necrosis and inflorescence blight of Mango (Mangifera indica) in Puerto Rico.  Plant Disease 98: 570. http://dx.doi.org/10.1094/PDIS-08-13-0878-PDN

USDA ARS.  2016.  Fungi on Mango in India, but not found in the U.S.A.  U.S. Department of Agriculture, Agricultural Research Service, Systematic Mycology and Microbiology Laboratory – Nomenclature Fact Sheets.  July 7, 2016. http://nt.ars-grin.gov/sbmlweb/onlineresources/nomenfactsheets/rptBuildFactSheet_onLine.cfm?thisName=Fungi%20on%20Mango%20in%20India&currentDS=specimens .

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.

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Pest Rating: C

Posted by ls

Fungi, Plant Pathogens

Fusarium brachygibbosum Padwick 1945

California Pest Rating for
Fusarium brachygibbosum Padwick 1945
Pest Rating: C  
PEST RATING PROFILE
Initiating Event: 

On July 18, 2016, CDFA plant pathologists were notified by Dr. R. Bostock, Professor, Department of Plant Pathology, University of California, Davis, of a fungal pathogen, Fusarium brachygibbosum, detected in cold-stored, bare-root nursery almond trees in California. This detection marked a first report of the pathogen in California.  Therefore, a risk analysis of F. brachygibbosum to California agriculture and environment was conducted and a permanent rating is proposed here for the otherwise non-rated pathogen.

History & Status:

Background: In California, Seidle et al. (2016) reported the first detection of Fusarium brachygibbosum from asymptomatic, cold-stored, bare-root propagated almond (Prunus dulcis) trees.  Samples had been collected in fall 2013, from a nursery in Sutter County.

In 2011, that same nursery had experienced the re-emergence of a canker disease that occurred in the late 1900s.  During the winter of 1997-98, a severe canker disease developed during cold storage of dormant almond trees and other fruit tree species in several nurseries in California.  Fusarium acuminatum and F. avenaceum were identified as the primary causal agents of the disease.  The predominant symptoms were necrosis of the inner bark, cambium, and sapwood, which in severe cases, resulted in girdling and death of trees. However, in the absence of external symptoms, internal necrosis was not readily evident in dark-bark trees, but detectable in light-bark trees.  Notably, the canker phase of Fusarium-infected young trees did not become apparent unless predisposed by some physiological stresses.  Consequently, infected trees were distributed to growers and the disease that developed under abiotic stress factors, including desiccation and variable cold storage temperatures, resulted in loss of thousands of trees, newly planted orchards, and millions of dollars (Marek et al., 2013). Fusarium acuminatum and F. avenaceum were also detected along with F. brachygibbosum in the 2013 almond samples reported by Seidle et al. (2016).  The ability to detect F. brachygibbosum during the last few years than earlier was likely due to the availability of molecular tools for distinguishing this pathogen from other Fusarium species associated with nursery trees and storage/processing facilities and fields (Personal communication: Dr. R. M. Bostock, Professor, Department of Plant Pathology, University of California, Davis).

Fusarium brachygibbosum has been found on diverse host species within five plant families and reported from few countries in Asia, Africa, and North America (see ‘Worldwide Distribution’).

Hosts: Citrullus lanatus (watermelon; Cucurbitaceae), Euphorbia larica (spurge; Euphorbiaceae), Sorghum vulgare (broom corn; Poaceae), Triticum spp.  (wheat; Triticeae), Prunus dulcis (syn. P. amygdalus, almond; Rosaceae) (Al-Mahmooli et al., 2013; Farr & Rossman, 2016; Mirhosseini et al., 2014; Renteria-Martinez et al., 2015; Seidle et al., 2016; Van Coller et al., 2016).

Symptoms:  Fusarium brachygibbosum is associated with symptoms of wilting, dieback, and cankers and has often been found infecting plants with a complex of fungi species.  Therefore, symptoms particular to the species have only been demonstrated experimentally through pathogenicity tests.  In pathogenicity tests using almond branches inoculated with F. brachygibbosum and incubated at 15°C for two weeks, Siedle et al. (2016) found that canker lesions (area: 26.7 mm2 to 83.0 mm2) developed, comparable to those produced by F. acuminatum and F. avenaceum. Additionally, F. brachygibbosum was found in asymptomatic almond rootstock.  Experimentally in watermelon, F. brachygibbosum produced variable sized light brown colored lesion at neck and root causing wilting of leaves or whole plants (Renteria-Martinez et al., 2015). The pathogen produced dark brown to black, circular to elliptical leaf spots in oleander (Mirhosseini et al., 2014).  In South Africa, F. brachygibbosum was isolated along with several other Fusarium species from kernels of field-grown wheat exhibiting symptoms of Fusarium head blight disease (Van Coller et al., 2013).

Disease cycle: While the disease cycle has not been reported specifically for Fusarium brachygibbosum, it is likely that it is similar to other Fusarium species causing canker and wilt disease.  Generally, Fusarium species inhabit soils and plants.  They can exist saprophytically, but can also act as opportunistic pathogens.  On hosts predisposed by stress, as in cold storage temperatures, or in combination with other pathogens, symptoms may become severe.  The pathogen overwinters as mycelium or spores in infested crop residues and seed, or as chlamydospores (thick walled asexual spores) in soil, and produces asexual spores (microconidia and macroconidia) which are dispersed to plants and other plant debris by wind or rain-splash. Generally, under warm and humid conditions, sexual spores are produced which are forcibly discharged into the air and transmitted by wind currents to susceptible plants where infection and further development of the pathogen occur.

Damage Potential: Precise losses due to Fusarium brachygibbosum have not been reported.  More than one Fusarium species and/or other fungal species may be present in cold-stored canker diseased nursery stock (Marek et al., 2013).  Fusarium brachygibbosum may remain cryptic and asymptomatic within the host, and the canker phase does not become apparent unless young trees are subjected to some physiological stress. Asymptomatic, infected nursery trees may result in the development of the disease and losses in production in the field.

Transmission: Infected plants, roots, stems, leaves, seeds (Van Coller et al., 2016), plant debris, soil, air currents, rainwater splash, and contaminated equipment.

Worldwide Distribution: Asia: India, Iran, Oman; Africa: South Africa; North America: Mexico, USA (California) (Al-Mahmooli et al., 2013; Farr & Rossman, 2016; Mirhosseini et al., 2014; Renteria-Martinez et al., 2015; Seidle et al., 2016; Van Coller et al., 2016).

Official Control: None reported.

California Distribution: Sutter and Stanislaus Counties (Seidle et al., 2016). However, suspected to be widespread in California (R. M. Bostock, Professor, Department of Plant Pathology, University of California, Davis: personal communication).

California Interceptions:  None reported.

The risk Fusarium brachygibbosum 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) – In California, Fusarium brachygibbosum was detected in young almond nursery rooting predisposed to cold storage temperatures.  It was also isolated from soil under almond production (Seidle et al., 2016), and is suspected to be widespread within California.  The disease is likely to establish primarily in nurseries with bare-root propagative almond plants predisposed to abiotic stresses – including temperature variations in cold storage, and in almond production fields within California.  Watermelon is a reported host of the pathogen (although not reported from California) and may also be affected by the disease.

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 known host range of Fusarium brachygibbosum is limited to watermelon, almond, wheat, spurge, and broom corn.

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) – Fusarium brachygibbosum has high reproduction and dispersal potential through infected plants, roots, stems, leaves, seeds, soil, plant debris, air currents, rainwater splash, and contaminated equipment.

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) – Quantitative estimates of losses in crop yield have not been reported, however, based on losses caused by the complex of other Fusarium species also detected in cold-stored almond tree seedlings in California (Marek et al., 2013), significant loss in crop production, value and yield is possible. However, development of the pathogen and production of visible disease symptoms in young trees is subject to predisposing physiological stresses.

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 has not been reported to significantly impact the environment.  However, leaf spots caused by the pathogen in infected ornamental oleander have been reported (but not from California). 

Consequences of Introduction to California for Fusarium brachygibbosum:

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 Fusarium brachygibbosum to California = (10).

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

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

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

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

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

Evaluation is Medium (-2).  Fusarium brachygibbosum has been detected in cold-stored young almond rootings in Sutter and Stanislaus Counties, however, the pathogen is suspected to be widespread in California.

Final Score:

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

Final Score:  Score of Consequences of Introduction – Score of Post Entry Distribution and Survey Information = 8

Uncertainty:

The full distribution of Fusarium brachygibbosum in California needs to be confirmed.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Fusarium brachygibbosum is C.

References:

Al-Mahmooli, I. H., Y. S. Al-Bahri, A. M. Al-Sadi, and M. L. Deadman.  2013.  First report of Euphorbia larica dieback caused by Fusarium brachygibbosum in Oman. Plant Disease, 97(5):687. http://apsjournals.apsnet.org/loi/pdis.

CABI.  2016.  Fusarium brachygibbosum basic datasheet.  Crop Protection Compendium. http://www.cabi.org/cpc/datasheet/119707.

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/.

Marek, S. M., M. A. Yaghmour, and R. M. Bostock.  2013.  Fusarium spp., Cylindrocarpon spp., and environmental stress in the etiology of a canker disease of cold-stored fruit and nut tree seedlings in California.  Plant Disease 97: 259-270.  http://dx.doi.org/10.1094/PDIS-04-12-0355-RE .

Mirhosseini, H. A., V. Babaeizad, and L. Hashemi.  2014.  First report of Fusarium brachygibbosum causing leaf spot on oleander in Iran. Journal of Plant Pathology, 96(2):431. http://www.sipav.org/main/jpp/.

Renteria-Martinez, M. E., A. Meza-Moller, M. A. Guerra-Camacho, F. Romo-Tamayo, A. Ochoa-Meza, S. F. Moreno-Salazar.  2015.  First report of watermelon wilting caused by Fusarium brachygibbosum in Sonora, Mexico. Plant Disease, 99(5):729. http://apsjournals.apsnet.org/loi/pdis.

Seidle, A. J., M. A. Yaghmour, S. C. Kirkpatrick, T. R. Gordon, and R. M. Bostock.  2016.  First report of Fusarium brachygibbosum causing cankers in cold-stored, bare-root propagated almond trees in California.  (Submitted for publication: Plant Disease, shared with J. Chitambar, CDFA, August, 2016).

Van Coller, G. J., A. -L. Boutigny, L. Rose, T. J. Ward, S. C. Lamprecht, and A. Viljoen.  2013.  Head blight of wheat in South Africa is associated with numerous Fusarium species and chemotypes.  Conference paper: 12th European Fusarium Seminar, at Palais de la Bourse, Bordeaux, France, May 2013.  https://www.researchgate.net/publication/269700231_Head_blight_of_wheat_in_South_Africa_is_associated_with_numerous_Fusarium_species_and_chemotypes

Responsible Party:

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

Pest Rating: C

Posted by ls 

Fungi, Plant Pathogens

Pseudocercospora smilacicola U. Braun, 2014

California Pest Rating for
Pseudocercospora smilacicola U. Braun, 2014
Pest Rating: B
PEST RATING PROFILE
Initiating Event:

On July 21, 2016, a shipment of lance leaf greenbrier (Smilax sp.) plants from Texas, destined to a wholesale plant company in Santa Barbara, was intercepted by the Santa Barbara County officials.  Diseased plants exhibiting leaf spot symptoms were collected and sent the CDFA Plant Pathology Laboratory for disease diagnosis.  The fungal pathogen, Pseudocercospora smilacicola, was identified as the cause for the leaf spots, by Cheryl Blomquist, CDFA plant pathologist.  This pathogen was also detected on March 23, 2016 and September 30, 2015, from Smilax sp. plant shipments that had originated in Texas and were destined for wholesale plant companies in Santa Barbara and Riverside Counties respectively.  The pathogen was given a temporary Q rating.  The risk of infestation of P. smilacicola in California is evaluated and a permanent rating is herein proposed.

History & Status:

Background:  Pseudocercospora smilacicola 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 has previously been referred to as Ceracospora petersii and C. (or Pseudocercospora) mississippiensis, which are synonym species of Exosporium petersii which is morphologically distinguished from P. smilacicola (Braun et al., 2014; Farr & Rossman, 2016).  However, Braun et al., (2014) reported that Pseudocercospora mississippiensis on Smilax riparia from Korea is morphologically indistinguishable from the Cuban and North American collections of P. smilacicola.

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.  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.

Hosts: Smilax auriculata (earleaf greenbrier), S. laurifolia (laurel greenbrier), S. pseudochina (bamboo vine), S. riparia, S. rotundifolia (roundleaf greenbrier), Smilax sp. (Braun et al., 2014).

Symptoms:  Infected host plants exhibit leaf spots on both leaf surfaces and are sub-circular to angular or irregular, 1-10 mm in diameter, initially pale then turn dark brown and later develop a paler center, brownish to greyish brown, occasionally somewhat zonate with darker brown to black margin.  Lesions or spots may be slightly raised and occasionally surrounded by a diffuse lighter halo (Braun et al., 2014).

Damage Potential: Specific losses due to Pseudocercospora smilacicola 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, Smilax californica and S. jamesii grow indigenously in the northern mountain and valley regions (Calflora, 2016).  Smilax sp. vines and foliage are used in floral decorations and therefore, diseased plants could be of concern to greenbrier floral/ornamental production nurseries.

Worldwide Distribution: Asia: Japan, Korea; North America: USA, Cuba. (Braun et al., 2014).  In the USA, Pseudocercospora smilacicola has been found in Georgia, Florida, Louisiana Mississippi, and Pennsylvania (Braun et al., 2014).

Official Control: None reported.

California Distribution: Pseudocercospora smilacicola has not been reported from California.  The pathogen is not known to be established in California.

California Interceptions:  Pseudocercospora smilacicola was detected shipments of Smilax sp. plants intercepted thrice from September 2015 to July 2016 (see ‘Initiating Event’).

The risk Pseudocercospora smilacicola 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): In California, host plants (Smilax spp.) grow indigenously in warm and humid conditions in northern mountain and valley regions.  If introduced, the pathogen could establish in those limited areas.    

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 Pseudocercospora smilacicola is limited to Smilax 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 High (3):  Pseudocercospora smilacicola 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 Low (1):  Infected host plants with leaf spot symptoms could lower value of nursery-produced Smilax plants used in floral/ornamental decorations.

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

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

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

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

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

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

Score the pest for Environmental Impact. Score:

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

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

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

Risk is High (3):  Two plant species, namely, Smilax californica and S. jamesii, are native to California and grow under warm, humid conditions in northern mountain and valley regions of the State.  The plants grow as under story plants in pine and mixed evergreen forest communities and provide food for wild animals and birds. Climate conditions may be conducive for the development of the pathogen if introduced.  In severe infections, available food could be reduced for wildlife.  Smilax jamesii is included in the California Native Plant Society Inventory of Rare and Endangered Plants on List 1B.3 7th/8th edition.  Also, the pathogen could significantly impact nursery production of ornamental greenbrier foliage and vines.

Consequences of Introduction to California for Pseudocercospora smilacicola:

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

-Low = 5-8 points

–Medium = 9-12 points

-High = 13-15 points

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

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

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

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

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

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

Evaluation is not established (0):  Pseudocercospora smilacicola is not established in California and has only detected in intercepted plant shipments 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 = 10

Uncertainty:  

None.

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Pseudocercospora smilacicola is B.

References:

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

Braun, U., Crous, P.W., and Nakashima, C. 2014. Cercosporoid fungi (Mycosphaerellaceae) 2. Species on monocots (Acoraceae to Xyridaceae, excluding Poaceae). IMA Fungus 5: 203-390.

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/

Farr, D.F., & A. Y. Rossman.  2016.  Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA.  Retrieved August 1, 2016, from http://nt.ars-grin.gov/fungaldatabases/.

Responsible Party:

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

Comment Format:

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

Example Comment: 

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

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

♦  Comments may not be posted if they:

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

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

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

Violates agency regulations prohibiting workplace violence, including threats.

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

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

 Pest Rating: B

Posted by ls

Fungi, Plant Pathogens

Phytophthora quercina T. Jung 1999

California Pest Rating for
Phytophthora quercina T. Jung 1999
Pest Rating: B 
PEST RATING PROFILE
Initiating Event: 

On April 25, 2016, two soil samples with roots of valley oak (Quercus lobata) trees that showed symptoms of stunting in a restoration site in Santa Clara County, were collected by Santa Clara County Agricultural officials and sent to the CDFA Plant Pathology Laboratory, for diagnosis.  DNA was extracted from soil baits and determined to be 100% similar to the pathogen, Phytophthora quercina, by Suzanne Rooney-Latham, CDFA plant pathologist.   DNA samples were sent by CDFA to the USDA APHIS PPQ CPHST Laboratory in Beltsville, Maryland, and on June 10, 2016, USDA confirmed the identity of P. quercina.  This detection marked the first confirmed presence and new record of the pathogen in the United States (USDA APHIS PPQ, 2016).  Currently, P. quercina has a temporary ‘Q’ rating in California.  The risk of introduction and establishment of this pathogen in California is assessed and a permanent rating is proposed herein.

History & Status:

Background: Oak decline is a serious and frequently recurring disease in Europe since the beginning of the twentieth century (Jung et al., 1999).  During the early 1990s, several Phytophthora spp. including a newly described P. quercina were found to be associated with oak decline and root rot in central and southern Europe.  In pathogenicity tests on oak, Quercus robur, P. quercina was found to be most pathogenic in comparison to the other associated Phytophthora species (Jung et al., 1999).  Subsequent reports associated P. quercina with oak decline from Turkey, Austria, and Italy (Balcý & Halmschlager, 2002a, 2002b; Vettraino et al., 2002).  Phytophthora quercina is an oomycete, and Cooke et al, (1999) provided molecular evidence that verified P. quercina as a distinct species.

Phytophthora quercina was recently detected in soil samples obtained from the root zone area of diseased valley oak trees grown at a California restoration site.  The USDA marked this detection as the first known confirmation of the pathogen in the United States.  Details are given above in “Initiating Event”.   The species was reported in 2007 on being detected in a soil bait around a declining oak tree in Central Missouri (Schwingle et al., 2007), however, the identification was not confirmed by USDA APHIS and there have not been any further publications on the species in the USA (USDA APHIS PPQ, 2016).

Hosts: Quercus spp. (oak): Q. cerris, Q. hartwissiana, Q. frainetto, Q. ilex, Q. robur, Q. petraea, Q. pubescens, Q. suber, and Q. vulcanica (Balcý & Halmschlager, 2002a, 2002b; EPPO, 2016; Farr & Rossman, 2016; NPRG, 2010).

Symptoms:  Phytophthora quercina, along with several other Phytophthora species, occur in oak decline stands in Europe (Balcý & Halmschlager, 2002; Jung et al., 2008).  Above ground symptoms of oak decline include dieback of branches and parts of the crown, formation of epicormic shoots, high transparency of the crown, yellowing and wilting of leaves and tarry exudates from the bark.  These symptoms are indicative of water stress and poor nutrition (Jung et al., 2008).  Below ground symptoms in declining European oak species resulted in deterioration of oak fine roots, including a progressive destruction of the fine root system, dieback of long roots, and necrotic lesions on suberized and non-suberized roots.  Although these symptoms occur in both healthy and declining oaks, the damage is generally more severe in declining oaks (Jung, et al., 2008).  The pathogen also causes abnormal root branching, and produces elicitins, viz. toxic substances that induce wilting and yellowing and leaf necrosis in declining oaks (NPRG, 2010).   In pathogenicity test, P. quercina-infected Quercus robur (oak) seedlings with severe root rot showed wilting and necrosis of leaves, root necrosis and dieback of the shoot. Under natural conditions, mature Q. robur trees showed reductions in fine root length (Jung et al., 1999).

Damage Potential:  The extent of damage caused by Phytophthora quercina has not been reported.  Several Phytophthora species including P. quercina are associated with oak decline disease.  However, P. quercina has been shown to be pathogenic to some European Quercus species, such as Q. robur (Jung et al., 1999), and to be one of the most aggressive and most common species found in reported surveys in Europe (Jung et al., 1999, 2008; Balcý and Halmschlager 2002a, 2002b).  In Italy, P. quercina was the only species significantly associated with declining oak trees (Vettraino et al., 2002).

Disease Cycle: Although present in roots and rhizosphere soil of oaks exhibiting symptoms of oak decline, the precise role of Phytophthora quercina in this disease is not known and very little is known about its biology.  Jung et al. (2008), reported that at least two different complex diseases are referred to as ‘oak decline’.  On sites with a mean soil pH 3.5 or greater and sandy-loam to clayey soil texture, Phytophthora species were commonly isolated from rhizosphere soil, and highly significant correlations existed between crown transparency and various root parameters.  However, in sites with a mean soil pH less than 3.9 and sandy to sandy-loam soils, Phytophthora species were not found. Biotic and abiotic stress factors such as drought and frost, may often act synergistically and accelerate Phytophthora-mediated decline of oaks.

Generally, species of Phytophthora that cause root and stem rots survive cold winters or hot and dry summers as thick-walled, resting spores (oospores and chlamydospores) or mycelium in infected roots, stems or soil.  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). Phytophthora quercina is homothallic.  Optimum growth in culture is at 20°C and 25°C, however, it is able to grow at temperatures as high as 27.5°C (Jung et al., 1999; Barzanti et al., 2001).

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

Worldwide Distribution: Asia: Turkey; Europe: Austria, Belgium, France, Germany, Hungary, Italy, Luxemberg, Montenegro, Serbia, Spain, Sweden, Scotland, United Kingdom: North America: USA (California) (Balcý & Halmschlager, 2002a, 2002b; EPPO, 2016; Farr & Rossman, 2016; Jung et al., 1999; NPRG, 2010).

Official Control: Phytophthora quercina is listed as an exotic forest pathogen in USDA APHIS PPQ Federal New Pest Response Guidelines for Phytophthora species (NPRG, 2010).  The species has been on the North American Plant Protection Organization (NAPPO) alert list since 2002.  Currently, P. quercina has a temporary ‘Q’ rating in California.

California Distribution: Phytophthora quercina has been detected in a California native plant restoration site in a Santa Clara County.

California Interceptions: None.

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

Consequences of Introduction:

1) Climate/Host Interaction: Evaluate and score the pest for suitability of hosts and climate to establish in California.  Score:

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

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

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

Risk is High (3) – Although Phytophthora quercina has been reported to be associated primarily with European oak species in Europe, its recent detection in valley oak rhizosphere soil extends the capability of this pathogen to be associated with California native oaks.  Valley oak is endemic to California and present throughout the State.  Thereby, making it likely for the pathogen to establish a widespread distribution in California.  It is not yet known, but probable that other California native oaks may be affected by P. quercina.

2) Pest Host Range: Evaluate and score the pest as it pertains to host range.  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) – Phytophthora quercina has a host range limited to Quercus spp. that includes Q. cerris, Q. hartwissiana, Q. frainetto, Q. ilex, Q. robur, Q. petraea, Q. pubescens, Q. suber, and Q. vulcanica.  In California, it was found to be associated with Q. lobata.

3) Pest Dispersal Potential: Evaluate and score the pest for dispersal potential using these criteria.  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) – Phytophthora quercina is soil-borne and water-borne and therefore, primarily spread artificially via infested soils, plants, nursery and planting stock, seedlings, run-off and splash irrigation water, cultivation equipment and tools, and boots that may spread contaminated soil and plant materials to non-infected sites.

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) – The extent of damage caused by Phytophthora quercina has not been reported.  Several Phytophthora species including P. quercina are associated with oak decline disease. In Europe, P. quercina was most commonly associated with the disease than were other Phytophthora species.  The pathogen could impact nursery-produced oaks thereby triggering possible loss of markets and requiring changes in normal cultural practices to avoid spread of the soil and water-borne pathogen.  

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

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 could significantly impact cultural practices, home/urban gardening or ornamental plantings.

Score the pest for Environmental Impact:

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

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

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

 Risk is High (3) – Phytophthora quercina is listed as an exotic forest pathogen in USDA APHIS PPQ Federal New Pest Response Guidelines for Phytophthora species (NPRG, 2010).  The species has been on the North American Plant Protection Organization (NAPPO) alert list since 2002.  Although the extent of damage potentially caused by this pathogen is not yet known, its spread within California could cause serious impact on native oaks, disrupt critical habitats by killing critical species necessary for species diversity and soil stability, necessitate official or private treatment programs to preserve critical, rare, or endangered species, and significantly impact cultural practices, home/urban and/or ornamental plantings.

Consequences of Introduction to California for Phytophthora quercina:

Add up the total score and include it here

Low = 5-8 points

Medium = 9-12 points

High = 13-17 points

Total points obtained on evaluation of consequences of introduction of Phytophthora quercina to California = (12).

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

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

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

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

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

Evaluation is Low (-1).

Final Score

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.

Uncertainties:

The extent of economic damage caused by Phytophthora quercina is not known. Also not known is the exact role of the pathogen in oak decline disease, and details of the biology of the pathogen species.

Conclusion and Rating Justification:

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

References:

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

Balcý, Y. and E. Halmschlager.  2002a. First confirmation of Phytophthora quercina on oaks in Asia.  Plant Disease 86:442. http://dx.doi.org/10.1094/PDIS.2002.86.4.442C

Balcý, Y. and E. Halmschlager.  2002b. First report of Phytophthora quercina in Austria.  New Disease Reports volume 6, August 2002-January 2003. http://www.bspp.org.uk/ndr/jan2003/2002-28.htm

Barzanti, G. P., P. Capretti, and A. Ragazzi. 2001. Characteristics of some Phytophthora

species isolated from oak forest soils in central and northern Italy.

Phytopathologia Mediterranea 40(2): 149-156.

Cooke, D.E.L., T. Jung, N. A. Williams, R. Schubert, G. Bahnweg, W. Oswald, and J. M. Duncan.  1999.  Molecular evidence supports Phytophthora quercina as a distinct species. Mycological Research, 103:799-804.

EPPO.  2016.  Phytophthora quercina (PHYTQU).  New PQR database.  Paris, France:  European and Mediterranean Plant Protection Organization.  http://newpqr.eppo.int

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

Jung, T., D. E. L. Cooke, H. Blaschke, J. M. Duncan, and W. Oswald. 1999.  Phytophthora quercina sp. nov., causing root rot of European oaks. Mycol. Res. 103: 785-798.

Jung, T., H. Blaschke and W. Oßwald.  2008.  Involvement of soilborne Phytophthora species in Central European oak decline and the effect of site factors on the disease.  Plant Pathology, 49:706-718. DOI: 10.1046/j.1365-3059.2000.00521.x

Schwingle, B. W., J. Juzqik, J. Eggers, and B. Moltzan.  2007.  Phytophthora species in soils associated with declining and nondeclining oaks in Missouri Forests.  Plant Disease 91:633. http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-91-5-0633A

NPRG.  2010.  New Pest Response Guidelines: Phytophthora species in the Environment and Nursery Settings. USDA MRP APHIS PPQ Cooperating State Departments of Agriculture, July 09 2010. 229 pages.

USDA APHIS PPQ.  2016.  Email from J. H. Bowers, National Survey Coordinator National Policy Manager, Cooperative Agricultural Pest Survey, USDA, APHIS, PPQ, PHP, to Nick Condos, Director, CDFA, sent Friday, June 10, 2016, 11:56 am.

Vetrraino, A. M., G. P. Barzanti, M. C. Bianco, A. Ragazzi, P. Capretti, E. Paoletti, N. Luisi, N. Anselmi, and A. Vannini.  2002.  Occurrence of Phytophthora species in oak stands in Italy and their association with declining oak trees.  Forest Pathology, 32:19-28.  DOI: 10.1046/j.1439-0329.2002.00264.x

Responsible Party:

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

Comment Format:

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

Example Comment: 

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

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

♦  Comments may not be posted if they:

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

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

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

Violates agency regulations prohibiting workplace violence, including threats.

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

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

Pest Rating: B 

Posted by ls

Fungi, Plant Pathogens

Phytophthora tentaculata Kröber & Marwitz 1993

California Pest Rating Proposal for
Phytophthora tentaculata Kröber & Marwitz 1993
Pest Rating: B
PEST RATING PROFILE
Initiating Event: 

During January 2016, samples of two diseased Diplacus hybrids (monkey flower hybrid varieties) and one of diseased Artemisia palmeri (Palmer sagewort) were collected by Kathleen Kosta, CDFA, from a nursery in Santa Clara County.  The samples were processed and analyzed at the CDFA Plant Pathology Laboratory and Phytophthora tentaculata was tentatively identified as the associated pathogen by Suzanne Rooney-Latham, CDFA plant pathologist.  The identity of the pathogen was later confirmed by the USDA APHIS PPQ CPHST Laboratory in Beltsville, Maryland.  The three afore mentioned plant varieties are new hosts records for P. tentaculata.  Several detections of this pathogen have been made in California during the past few years.  Therefore, the current rating for P. tentaculata is reassessed here.

History & Status:

Background: In 1993, Phytophthora tentaculata was first isolated from roots and stems of greenhouse-grown Argyranthemum frutescens (syn. Chrysanthemum frutescens), Leucanthemum vulgare  (syn. C. leucanthemum), Delphinium ajacis, and Verbena sp. in nurseries in the Netherlands and Germany in 1993 (Kröber & Marwitz, 1993).  Later, the pathogen was also reported from Spain (Moralejo et al., 2004; Álvarez et al., 2006), Italy (Cristinzio et al., 2006; Martini et al., 2009) and China (Meng & Wang, 2006; Wang and Zhao, 2014) after detection in nursery-potted and field-grown plants.  In 2012, P. tentaculata was first detected in North America, in sticky monkey flower, Diplacus aurantiacus (syn. Mimulus aurantiacus) growing in a native plant nursery in Monterey County, California.  Plant samples collected by Monterey County and CDFA staff were submitted to CDFA for analysis and the pathogen P. tentaculata was identified by Suzanne Rooney-Latham and Cheryl Blomquist, CDFA plant pathologists (Rooney-Latham & Blomquist, 2014), and later confirmed by the USDA APHIS National Identification Services. The source of the Diplacus (Mimulus) plants was traced back to plants that were grown from seed and cuttings from a historical site in Monterey County.  No Diplacus (Mimulus) plants had been shipped from the native plant nursery prior to the initial detection.  Consequently, all positive Diplacus (Mimulus) plants and materials were destroyed.  The California detection marked the first detection on a native host, albeit in a native plant restoration nursery and a host that has a wide geographical native range in California.  Since its initial Monterey County find, P. tentaculata has also been detected in native plant nurseries in Placer, Butte, Santa Cruz, San Mateo, Orange, and Santa Clara Counties, and in out-planted nursery stock in habitat restoration sites in Alameda, Monterey, and Santa Clara Counties. The pathogen was detected and reported from several new hosts that are listed below (see ‘Hosts’) and include Artemisia douglasiana, A. californica, A. dranunculus, A. palmeri, Diplacus x “Apricot”, Diplacus x “Red brick”, Monardella villosa, and Salvia sp.  Several of these detections were made during a 2014-2015 survey of California native plant nurseries and restoration sites conducted by the collaborative efforts of CDFA, USDA and a private research company.  The survey resulted in the detection of P. tentaculata in 8 out of 16 counties.  The origin of P. tentaculata is unknown.  Presently in California, Phytophthora tentaculata has only been detected in nursery-grown plants that were out-planted in the environment.  The pathogen has persisted on those plants in the field for at least 4.5 years. Therefore, it is likely that in California, the pathway of pathogen spread is from infected nurseries to restoration field sites, and that the pathogen has been spread between and within nurseries by the use of infested pots and plants (Rooney-Latham, et al., 2015).

Hosts: The currently known hosts are included in the plant families Asteraceae, Lamiaceae, Phrymaceae,  Ranunculaceae, Rhamnaceae, Rosaceae, and Verbenaceae.  The host range includes the following plants, diseases and geographical locations:

Apium graveolens (celery); stem and root rot; China (Wang & Zhao, 2014).

Argyranthemum frutescens (syn. Chrysanthemum frutescens) (marguerite daisy); root and stem base rot; Germany & the Netherlands; Root, collar & stalk rot (Kröber & Marwitz 1993).

Artemisia douglasiana (California mugwort); root rot; California, USA (Rooney-Latham, et al., 2015).

Artemisia dracunculus (tarragon); root rot; California, USA (Rooney-Latham et al., 2015). Artemisia californica (California sagebrush); root rot; California, USA (Rooney-Latham et al., 2015).

Artemesia palmeri (Palmer sagewort); root rot; California, USA (see “Initiating Event”).

Aucklandia lappa (rhizomatous medicinal herb); China; stalk rot & wilt (Meng & Wang 2008).

Calendula arvensis (field marigold) (Li et al., 2011).

Ceanothus cuneatus (buckbrush); root rot; California, USA (Rooney-Latham et al., 2015).

Cichorium intybus (chicory, endive); Italy; collar and root rot (Garibaldi et al. 2006).

Delphinium ajacis (nursery stock); Germany & the Netherlands; root, collar & stalk rot (Kröber & Marwitz 1993).

Diplacus aurantiacus (syn Mimulus aurantiacus) (sticky monkey-flower); California, USA.  root and collar rot (Rooney-Latham & Blomquist, 2014).

Diplacus x “Apricot” (Diplacus hybrid variety); root and collar rot; California, USA (see “Initiating Event”).

Diplacus x “Red brick” (Diplacus hybrid variety); root and collar rot; California, USA (see “Initiating Event”).

Frangula californica (syn. Rhamnus californica) (coffeeberry); California; root and collar rot (Frankel et al., 2015; NPAG, 2014).

Gerbera jamesonii (African daisy); Italy; Crown & stem rot (Cristinzio et al. 2006).

Heteromeles arbutifolia (toyon) California, USA (Frankel et al., 2015; NPAG, 2014).

Leucanthemum vulgare (syn. Chrysanthemum leucanthemum) Germany & the Netherlands; Root, collar & stalk rot (Kröber & Marwitz 1993).

Monardella villosa (coyote mint); California, USA (Rooney-Latham et al., 2015).

Origanum vulgare (oregano); Italy.  Leaf russeting & chlorosis, wilt, defoliation, twig dieback,basal stem rot, root rot, entire plant collapse (Martini et al. 2009).

Salvia spp. (sage) California, USA (Frankel et al., 2015; NPAG, 2014).

Santolina chamaecyparissus (lavender cotton); Spain; Root rot (Alvarez et al. 2004).

Verbena sp. (nursery stock); Germany, Netherlands; nursery potted plant in Spain; root, collar & stalk rot (Moralejo et al. 2004).

Symptoms:  Depending on the host species, Phytophthora tentaculata causes moderate to severe root and crown rot, and death in highly infected plants. The symptoms are not unique to P. tentaculata by similar to infections caused by other Phytophthora species, root and stem pathogens and drought.   According to Rooney-Latham et al (2015) symptoms can vary in field-planted nursery stock.  Infected sticky monkey flower plants are stunted, with dull yellowish leaves that turn red as the disease progresses.  Roots and stem collars have necrotic, sunken lesions with few feeder roots and discolored leaves. In some cases, plants may exhibit poor growth and eventually collapse within their first season, while some plants may grow for a year or more before exhibiting severe dieback during hot summers. Transplanted infected Artemisia douglasiana plants did not show dieback, but exhibited stunting and chlorosis more that 4.5 years after being out-planted (Rooney-Latham et al., 2015; Frankel et al., 2015; Kröber & Marwitz 1993).

Damage Potential:  Phytophthora tentaculata causes moderate to severe root and crown rot on woody and semi-woody hosts.  Introduction of P. tentaculata-infected native plants to restoration sites could negatively impact native plants in their natural environment.

Disease Cycle: Generally, species of Phytophthora that cause root and stem rots survive cold winters or hot and dry summers as thick-walled, resting spores (oospores and chlamydospores) or mycelium in infected roots, stems or soil.  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). Little information is known about the life cycle or biology of Phytophthora tentaculata other than what was provided by the original species description by Kröber and Marwitz. The temperature range of the pathogen is 7°C to 32°C, the optimum temperature being 15°C to 25°C.

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

Worldwide Distribution: Asia: China; Europe: Italy, Germany, the Netherlands, Spain; North America: USA (California).

Official Control: USDA lists Phytophthora tentaculata in the top 5 Phytophthora species of concern and threat to nurseries and forests in Federal New Pest Response Guidelines (USDA APHIS, 2010).  USDA APHIS New Pest Advisory Group determined that P. tentatculata is “actionable and reportable.

California Distribution: Phytophthora tentaculata has been detected in native plant nurseries in Monterey, Placer, Butte, Santa Cruz, San Mateo, Orange, and Santa Clara Counties, and in out-planted nursery stock in habitat restoration sites in Alameda, Monterey, and Santa Clara Counties.

California Interceptions: None.

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

Consequences of Introduction:

1) Climate/Host Interaction: Evaluate and score the pest for suitability of hosts and climate to establish in California.  Score:

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

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

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

Risk is High (3) – To date, Phytophthora tentaculata has been detected in native plant nurseries in eight counties and in habitat restoration sites (in out-planted nursery stock) in three of those eight counties.  Several native plant hosts are widespread in California.  Since the pathogen is known to attack many plants in the nursery trade, it is possible that the pathogen could appear and survive wherever nurseries, including native plant nurseries, are present in California.  Therefore, there is the potential for this pathogen to establish a widespread distribution in California.

2) Pest Host Range: Evaluate and score the pest as it pertains to host range.  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) – Presently, 23 plant hosts belonging to 7 families have been reported.  Of these, almost half the number of hosts have been reported from California, and are native to the State.  While several new hosts have been reported after the initial detection of the pathogen in Monterey County, based on the present known host range, the risk of the pathogen is evaluated as medium.

3)   Pest Dispersal Potential: Evaluate and score the pest for dispersal potential using these criteria.  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) – Phytophthora tentaculata is soil-borne and water-borne and therefore, primarily spread 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.

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 presence of Phytophthora tentaculata could cause severe economic impacts in nursery trade, impacting a number of nursery-produced native and ornamental plants that are commonly used in California landscapes as well as some of which play a significant role in the State’s florist trade.  In addition to lowered crop yields and lowered crop values due to increased need for protective treatments, the management of infestations of a soil- and water-borne pathogen such as Phytophthora spp. in a commercial nursery may be a laborious and expensive problem that would involve alterations in the normal cultural practices such as choice of sites to grow susceptible hosts, and water and growth medium management practices to ensure pathogen propagule-free irrigation water and growth media.

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

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 could significantly impact cultural practices, home/urban gardening or ornamental plantings.

Score the pest for Environmental Impact:

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

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

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

 Risk is High (3) – The USDA APHIS lists Phytophthora tentaculata in the top 5 Phytophthora species of concern and threat to nurseries and forests in Federal New Pest Response Guidelines (USDA APHIS, 2010).  The presence of P. tentaculata could cause serious impact on native plants, threatened or endangered species, disrupt critical habitats by killing critical species necessary for species diversity and soil stability, necessitate official or private treatment programs to preserve critical, rare, or endangered species, and significantly impact cultural practices, home/urban and/or ornamental plantings.

Consequences of Introduction to California for Phytophthora tentaculata:

Add up the total score and include it here

– Low = 5-8 points

– Medium = 9-12 points

– High = 13-17 points

Total points obtained on evaluation of consequences of introduction of Phytophthora tentaculata to California = (14).

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

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

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

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

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

Evaluation is Medium (-2). To date, Phytophthora tentaculata has been detected in native plant nurseries in Monterey, Placer, Butte, Santa Cruz, San Mateo, Orange, and Santa Clara Counties, and in out-planted nursery stock in habitat restoration sites in Alameda, Monterey, and Santa Clara Counties in California.

Final Score: 

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

Final Score:  Score of Consequences of Introduction – Score of Post Entry Distribution and Survey Information = 12.

Uncertainties:

While more is known about the presence of Phythophthora tentaculata in California since its original detection in Monterey County, more researched information is needed on the distribution, behavior and threat of Phytophthora tentaculata in California’s natural soils and plant communities under diverse climatic environments.  

Conclusion and Rating Justification:

Based on the evidence provided above the proposed rating for Phytophthora tentaculata remains B.

References:

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

Álvarez, L. A., A. Pérez-Sierra, M. León, J. Armengol, and J. García-Jiménez.  2006.  Lavender cotton root rot: a new host of Phytophthora tentaculata found in Spain. Plant Disease 90:523. http://dx.doi.org/10.1094/pd-90-0523A

Cristinzio, G., I. Camele and C. Marcone.  2006.  Phytophthora tentaculata su gerbera in Italia.  First report of Phytophthora tentaculata on gerbera in Italy.  Informatore Fitopatologico 56:23-25. http://www.cabdirect.org/abstracts/20063066005.html;jsessionid=C23F9F14D93FF641EEE94948EFEB99D5.

Frankel, S., S. Rooney-Latham, C. L. Blomquist, and E. Bernhardt.  2015.  Pest Alert: Phytophthora tentaculata.  Technical Report, February 2015, United States Department of Agriculture. http://www.suddenoakdeath.org/wp-content/uploads/2015/02/P.tentaculata.

Garibaldi A., G. Gilardi, M. L. Gullino.  2010. First report of collar and root rot caused by Phytophthora tentaculata on witloof chicory (Cichorium intybus) in Italy. Plant Disease 94:1504.

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]

Martini, P., A. Pane, F. Raudino, A. Chimento, S. Scibetta, and S. O. Cacciola.  2009.  First report of Phytophthora tentaculata causing root and stem rot of oregano in Italy. 93:843. http://dx.doi.org/10.1094/PDIS-93-8-0843B.

Meng, J., and Y. C. Wang.  2008.  First Report of Stalk Rot Caused by Phytophthora tentaculata on Aucklandia lappa in China. Plant Disease 92 (9): 1365.

doi:10.1094/PDIS-92-9-1365B. http://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-92-9-1365B.

Moralejo, E., M. Puig, and W. A. Man in’t Veld.  2004.  First report of Phytophthora tentaculata on Verbena sp. in Spain. The British Society for Plant Pathology.

http://www.bspp.org.uk/publications/new-disease-reports/ndr.php?id=009038. May 31, 2009.

USDA APHIS.  2010.  New Pest Response Guidelines: Phytophthora species in the Environment and Nursery Settings. 229 pages.

Rooney-Latham, S., and C. L. Blomquist.  2014. First report of root and stem rot caused by Phytophthora tentaculata on Mimulus aurantiacus in North America. Plant Disease 98(7):996.

Rooney-Latham, S., C. L. Blomquist, T. Swiecki, and E. Bernhardt.  2015.  Phytophthora tentaculata.  Forest Phytophthoras 5(1):  doi:10.5399/osu/fp.5.1.3727.

Schwartzburg, K., H. Hartzog, C. Landry, J. Rogers, and B. Randall-Schadel.  2009. Prioritization of Phytophthora of Concern to the United States. USDA APHIS PPQ CPHST PERAL (Plant Epidemiology and Risk Analysis Laboratory), Raleigh, NC. 61 pages.

Wang, T. and W. Zhao.  2014.  First report of Phytophthora tentaculata causing stem and root rot on celery in China. http://dx.doi.org/10.1094/PDIS-06-13-0592-PDN.

Responsible Party:

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

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Pest Rating: B

Posted by ls

Fungi, Plant Pathogens

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

California Pest Rating Proposal for
Colletotrichum cordylinicola Phoulivong, L. Cai & K. D. Hyde, 2011
Pest Rating: B
PEST RATING PROFILE
Initiating Event:  

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

History & Status:

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

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

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

Damage Potential:  In general, anthracnose disease of fruits and leaves caused by Colletotrichum spp., can result in reduction in yield quantity and quality of agricultural crops and fruit trees (Phoulivong et al., 2010).  It is, therefore, highly likely that Colletotrichum cordylinicola can result in reduced plant quality and growth, fruit production and marketability.  Estimates of yield/crop loss due to this pathogen have not been reported.  Nursery productions of ornamental cordyline and wax jambu plants are particularly at risk as nursery conditions are often conducive to infection by Colletotrichum species.  In open fields, disease development may be sporadic as it is affected by levels of pathogen inoculum and environmental conditions.

Disease Cycle:  It is likely that Colletotrichum cordylinicola has a similar life cycle to that of other Colletotrichum species and survives between crops during winter as mycelium on plant residue in soil, on infected plants, and on seeds.  During active growth, the pathogen produces masses of hyphae (stromata) which bear conidiophores, on the plant surface. Conidia (spores) are produced at the tips of the conidiophores and disseminated by wind, rain, cultivation tools, equipment, and field workers.   Conidia are transmitted to host plants.  Humid, wet, rainy weather is necessary for infection to occur.  These requirements in particular may limit the occurrence of the pathogen in California fields and subsequently, the pathogen may be more of a problem under controlled environments of greenhouses.  Conidia germinate, penetrate host tissue by means of specialized hyphae (appresoria) and invade host tissue.

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

Worldwide Distribution:  Colletotrichum cylindricola is distributed in Thailand, Laos, and New Zealand (Farr & Rossman, 2015; Phoulivong et al., 2010; Weir et al., 2012).

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

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

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

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

Consequences of Introduction: 

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

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

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

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

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

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

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

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

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

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

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

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

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

Risk is High (3) – The pathogen has high reproductive potential and conidia are produced successively.  They are transmitted by wind, wind-driven rain, cultivation tools, and human contact however conidial germination and plant infection require long, wet periods.

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

A.  The pest could lower crop yield.

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

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

D.  The pest could negatively change normal cultural practices.

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

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

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

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

– Medium (2) causes 2 of these impacts.

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

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

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

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

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

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

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

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

Score the pest for Environmental Impact. Score:

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

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

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

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

Consequences of Introduction to California for Colletotrichum cordylinicola:

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

-Low = 5-8 points

–Medium = 9-12 points

-High = 13-15 points

Total points obtained on evaluation of consequences of introduction of Colletotrichum cordylinicola to California = (9).

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

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

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

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

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

Evaluation is not established (0).  Colletotrichum cordylinicola is not established in California. 

Final Score:

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

Final Score:  Score of Consequences of Introduction – Score of Post Entry Distribution and Survey Information = 9.

Uncertainty:

None.

Conclusion and Rating Justification:

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

References:

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

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

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

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

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

Responsible Party:

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

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

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Pest Rating: B

Posted by ls