All posts by Dean Kelch

Graceful Spurge | Euphobia hypericifolia

California Pest Rating  for
Graceful spurge | Euphorbia hypericifolia L.
Malpighiales: Euphorbiaceae
Pest Rating: A | Proposed Seed rating: N/A

 


PEST RATING PROFILE
Initiating Event:

This plant given a Q rating as a potential invasive weed on 11/2/2017 (PDR 19TPO6465546).

History & Status:

Graceful spurge (Euphorbia hypericifolia, synonym Chamaesyce hypericifolia) is an upright perennial herb with arching, openly branched flowering stems to 60 cm tall, but often low when mowed. The leaves are opposite, ovate, with small teeth. The flowers are small, even by spurge standards (0.5 – 1 mm) and are borne in dense heads in the axils of the upper leaves. Seeds are expelled forcefully from capsules up to 4 meters away. Cattle avoid foraging on spurge when possible, but goats and sheep are generally immune to its irritant properties and may develop a preference for it. It grows in disturbed areas, in evergreen woodland and in crop fields. It is also found in nurseries as a weed. The common horticultural container plant Euphorbia ‘Diamond Frost’ is sometimes attributed to Euphorbia hypericifolia. Nevertheless, it is not closely related to this species, nor is it weedy. Therefore, this attribution is in error and should not be used for regulatory action, regardless of labelling.

Official Control: Graceful spurge was just recently detected in recently imported nursery stock, and, although weedy, it is native to the southeastern U.S. So, there is no official control.

California Distribution:  It is not yet fully established in California, although it has been detected in weedy situations several times.

California Interceptions: Vouchered specimens are known from San Diego County as weeds.

United States: It is native to the Southeastern U.S.

International: Graceful spurge is native to the New World as a tropical to subtropical weed. It is introduced in warmer areas of the Old World.

This risk Carnation spurge would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: The plant has adapted to warm, well-watered areas throughout the world, so it could spread widely as a nursery weed, but is not otherwise likely to spread except to irrigated situations. Graceful spurge receives a Low (1) in this category.

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.

2) Host Range: Risk is High (3) as weeds do not require any one host, but grow wherever ecological conditions are favorable.

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.

3) Pest Dispersal Potential: Graceful spurge produces via numerous seeds that are able to spread via nursery stock and other means. The seed bank is moderately persistent. Graceful spurge receives a Medium (2) in this category.

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.

4) Economic Impact: Graceful spurge can lower nursery productivity, and require more intensive weed control activities in nurseries. If is escapes into horse paddocks and other irrigated pastures, it could poison livestock. Graceful spurge receives a High (3) in this category.

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

Economic Impact: A, B, D, F

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: Graceful spurge is not likely to spread widely beyond disturbed, human-mediated landscapes, as California is too dry to favor its growth. Graceful spurge receives a Low (1) in this category.

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

Environmental Impact:

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 Graceful spurge: Medium (10)

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: Graceful spurge has been found in in several counties in California, but does not seem to be well established. It receives a Low (-1) in this category.

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.

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

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (10)

Uncertainty:

Graceful spurge has not yet widely established in California due to the paucity of appropriate habitat. Nevertheless, it has shown its ability to spread and thrive in similar climates to those it is found in in Florida as a nursery or garden weed. It could almost certainly do the same in California.

Conclusion and Rating Justification:

Graceful spurge is a significant nursery weed. It deserves an A rating as the nursery industry in California would be harmed by the establishment of this weed; its rarity in California raises the possibility of excluding it by timely regulation.


References:

Brunel S, G. Schrader, G. Brundu & G. Fried. 2010. Emerging invasive alien plants for the Mediterranean Basin. Bull OEPP/EPPO Bull. 40:219–238.

Consortium of California Herbaria  (ucjeps.berkeley.edu/consortium/).

Flora of North America Editorial Committee, eds.  1993+.  Flora of North America North of Mexico.  16+ vols.  New York and Oxford.

Gregor T. & L. Meierott. 2013. Report 72. Euphorbia hypericifolia L. – P. 277. In: Vladimirov V., Dane F., Stevanovič V., & Tan K, eds. New floristic records in the Balkans: 22. Phytol Balcan.19: 267-303.

S. Sciandrello, S., G. Giusso del Galdo & P. Minissale. 2016. Euphorbia hypericifoliaL. (Euphorbiaceae), a new Alien Species for Italy. Webbia 71: 163-168.


Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6650;  plant.health[@]cdfa.ca.gov.


Comment Period:* CLOSED

1/5/18 – 2/19/18


*NOTE:

You must be registered and logged in to post a comment.  If you have registered and have not received the registration confirmation, please contact us at 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: A | Proposed Seed rating: N/A

 


Posted by ls

Manchurian Wild Rice | Zizania latifolia

California Pest Rating  for
Machurian Wild Rice. Photo credit: National Institute of Water & Atmospheric Research (NIWA), New Zealand
Click on image for photo citation
Manchurian Wild Rice | Zizania latifolia
Pest Rating: A | Proposed Seed Rating: R

 


PEST RATING PROFILE

Initiating Event:

This plant was been detected in California in 2017.

History & Status:

Zizania latifolia is a large perennial grass growing to 3.5 m.  It is hardy in warm temperate and subtropical areas. It flowers from July to September, and the seeds ripen soon thereafter. The flowers are bisexual. It is adaptable to many soil types and can even grow in shallow water once established. Z latifolia typically grows in dense, long-lived stands on land and water margins, overtopping other riparian species. It is extremely tolerant of damage, grazing, cold or heat, wind, fire, different soil types, moderate shade and moderate salinity.

Although Z. latifolia was once grown in China as a grain crop, it is now almost exclusively grown as a vegetable. The swollen stem bases, infected with the smut fungus Ustilago esculenta, are eaten as a vegetable by the Chinese. They must be harvested before the fungus starts to produce spores, as the stems deteriorate once the smut reaches reproductive maturity.

Official Control: Z. latifolia has been eradicated in California and other states as it serves as a host to a fungus that could infect North American native wild rice species (e.g., Z. aquatica). Importation of the stems to the United States is prohibited in order to protect the North American Zizania from the fungus. A small plot of smut-infested Z. latifolia was discovered growing near Modesto, CA in 1991; it was destroyed to prevent the spread of the smut.

California Distribution:  Z. latifolia is not known to be naturalized in California, but it is being cultivated in Riverside County.

California Interceptions: Z. latifolia was recently submitted to CDFA from a cultivated field in Riverside County.

Worldwide Distribution: Z. latifolia is native to China, Northeastern India, Japan, Korea, Myanmar, and southern Russia where is grown as a vegetable. It is cultivated in Southeast Asia as well. It is naturalized in several other areas. It is unknown whether it is not invasive in these areas despite naturalization, or its invasiveness is ignored due to its long cultivation. Z. latifolia was accidentally introduced into New Zealand where it has become a serious wetland weed in the coastal zone of the North Island. It was also introduced into Hawaii, where it may not have persisted.

Consequences of Introduction: 

1) Climate/Host Interaction: Evaluate if the pest would have suitable hosts and climate to establish in California. The risk is Medium (2), as the plant could occur in wetlands in warmer areas. Areas such as the Delta as well as irrigation canals and watering ponds might be potential habitat for this plant in California.

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: Evaluate the host range of the pest. Score: 3 The risk is High (3) as weeds do not require any one host, but grow wherever ecological conditions are favorable.

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: Risk is High (3). The plant spreads vegetatively via rhizomes and produces numerous seeds. Under the right conditions it can spread rapidly in water. The seeds can spread on boats and equipment. Birds may also spread the seed.

Evaluate the natural and artificial dispersal potential of the pest:

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: If it invaded wet meadows (as in New Zealand) or rice fields, it could lower yields and choke out desired plants. It can grow in irrigation ditches and reduce water delivery and access. The swollen stem bases, infected with the smut fungus Ustilago esculenta, are eaten as a vegetable by the Chinese. There is concern that esculenta could spread from Z. latifolia to native North American species of Zizania (e.g., Z. aquatica) that produce commercial wild rice. Z. aquatica is not native to California, but over 16,000 acres of wild rice was grown in California in 2006, making it the largest producer of wild rice in the world.

Economic Impact 4: A, D, E, & G.

Evaluate the likely economic impacts 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.

The potential Economic Impact is High (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: Under favorable circumstances, latifolia forms permanent stands along water margins and moist meadows of nothing but Zizania latifolia, replacing all other species. It can increase siltation, altering water systems, increase the impact of flooding and destroying habitat for aquatic fauna and flora. The impact is potentially High (3).

Environmental Impact 3: A, C, & D

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.

Environmental Impact Score: 3

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

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

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

Consequences of Introduction to California for Zizania latifolia:

Add up the total score and include it here. High (14)

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.
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

The final score is the consequences of introduction score minus the post entry distribution and survey information score: High (14)

Uncertainty:

There is moderate uncertainty, as the plant has established and become invasive in New Zealand, but similar conditions occur in limited areas of California. It is native to eastern Asia and widely naturalized beyond its natural range, yet it is not cited as a weed of rice paddies despite being seemingly well adapted to these conditions.

Conclusion and Rating Justification:

A potentially significant weed in CA of both natural wetlands, wet crop lands and irrigation canals. It is also a carrier of a fungus that could attack and seriously reduce productivity of wild rice. Despite some uncertainty, an A rating is justified given the potential risks.


References:

Baldwin, B. G., D. H. Goldman, D. J. Keil, R. Patterson, T. J. Rosatti, and D. H. Wilken, editors. 2012. The Jepson manual: vascular plants of California, second edition. University of California Press, Berkeley.

CDFA Pest Damage Report 331PO6200067 dated 10/19/2017.

CDFA Pest Damage Report 331PO6200069 dated 10/20/2017.

Chen, S., Li, D., Zhu, G., Wu, Z., Lu, S., Liu, L., et al. 2006. Zizania in Flora of China, Vol. 22. Z. Y. Wu & P. H. Raven eds. Beijing; St. Louis, MO: Science Press, Missouri Botanical Garden Press. Pp. 186–187.

Duke, J. A. 1983. Handbook of Energy Crops: Zizania aquatica L. Accessed online 11/9/2017: https://www.hort.purdue.edu/newcrop/duke_energy/Zizania_aquatica.html

Larkcom J. Oriental Vegetables John Murray 1991 ISBN 0-7195-4781-4

Global Invasive Species Database. Species profile: Zizania latifolia. Accessed on on 11/8/2017:  http://www.iucngisd.org/gisd/species.php?sc=866

Ohwi, J. 1984. Flora of Japan. F. G. Meyer & E. G. Walker, eds. Smithsonian Institution Press. Washington, D.C.

Tanaka. T. Tanaka’s Cyclopaedia of Edible Plants of the World. Keigaku Publishing 1976

Terrell, E. E. & L. R. Batra. 1982.  Zizania latifolia and Ustilago esculenta, a grass-fungus association. Economic Botany 36: 274–85.

Wagner, W. L. D. R Herbst and S. H. Sohmer. 1999. Manual of the Flowering Plants of Hawai`i, Volume 1. University of Hawai’i and Bishop Museum Press. Honolulu, HI.

Weedbusters Plant Profile: Manchurian Wild Rice. Accessed 11/8/2017: http://www.weedbusters.org.nz/weed-information/zizania-latifolia/59/

Photo credit: National Institute of Water & Atmospheric Research (NIWA), New Zealand


Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6650;  plant.health[@]cdfa.ca.gov.


Comment Period:* CLOSED

1/5/18 – 2/19/18


*NOTE:

You must be registered and logged in to post a comment.  If you have registered and have not received the registration confirmation, please contact us at 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: A | Proposed Seed Rating: R

 


Posted by ls

Banded Wood Snail | Cepaea nemoralis

California Pest Rating for
Banded Wood Snail  |  Cepaea nemoralis
Gastropoda: Helicidae  
Pest Rating: A

 


PEST RATING PROFILE
Initiating Event:

Cepaea nemoralis is frequently intercepted by CDFA. A pest rating proposal is required to support its permanent pest rating.

History & Status:

Background: Cepaea nemoralis, known as the banded wood snail, is the most common species of land snail in Europe and has been introduced to North America. This snail is commonly found in urban areas, where it inhabits gardens and abandoned lots. They feed on dead and living plant material, carrion, fungi, moss, and insects1.

          Cepaea nemoralis has a yellow, pink, or brown shell. The shell contains five dark bands. Banded wood snails are hermaphrodites, but cross fertilization occurs (each snail fertilizes the other). They often mate multiple times prior to egg-laying and can store sperm for up to 15 months. Eggs are buried in moist soil, hatching after about three weeks. The snails reach maturity in four years and may live as  long as five to nine years 1, 4.

Worldwide Distribution: Banded wood snails are distributed throughout much of Europe, extending to Poland.  This snail was introduced into North America during the nineteenth century, and it is currently found in Virginia, New York, Ontario, and Massachusetts1, 2.

Official Control: Banded wood snail is listed as a harmful organism in Canada, Israel, Japan, and Taiwan6.

California Distribution: Banded wood snails have never been found in the environment of California.

California Interceptions: Between January 2000 and August 2017, banded wood snails have been intercepted 20 times.  These interceptions include border station inspections and high risk pest exclusion activities.

The risk Cepaea nemoralis (Banded wood snail) would pose to California is evaluated below.

Consequences of Introduction:
  1. Climate/Host Interaction: Banded wood snails can feed on a variety of live and dead plants and dead animals and insects, including remains of ants, beetles, spiders, mites, springtails, and aphids. Banded wood snails may establish in larger, but limited, warm agricultural and metropolitan areas of California. It receives a Medium (2) in this category.

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

  • 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: Banded wood snails are highly polyphagous and are known to feed on a wide variety of live and dead plants and animals. It receives a High (3) in this category.

Evaluate the host range of the pest.

  • 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: Banded wood snails are obligately outcrossing hermaphrodites, with both individuals exchanging sperm during mating, and both individuals able to lay eggs afterward. On average, they lay 30-80 eggs that hatch in 15-20 days. Breeding takes place from April through October. The snail’s foot is used to create a cavity in the soil where the eggs are deposited1, 4. It receives a High (3) in this category.

Evaluate the natural and artificial dispersal potential of the pest.

  • 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: The banded wood snail is not expected to lower crop yields. It could reduce the value of nursery stock by disfiguring plants with its presence and increase crop production costs in nurseries and orchards. The banded wood snail is a potential vector of Angiostrongylus vasorum, the French heartworm (a disease of wild and domestic canids) 3. It receives a High (3) in this category. Economic Impact: B, C, E: Environmental Score: 3

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.

  • 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: If introduced, the banded wood snail is not expected to lower biodiversity, disrupt natural communities, or change ecosystem processes. It might trigger new chemical treatments in orchards and nurseries and by residents who find infested plants unsightly. It is not expected to significantly impact cultural practices, home/urban gardening, or ornamental plantings. It receives a Medium (2) in this category.

Environmental Impact: A, D:  Environmental Impact: Score: 2

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.

  • 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 Cepaea nemoralis(Banded wood snails): High (13) 
  • Low = 5-8 points
  • Medium = 9-12 points
  • High = 13-15 points

Post Entry Distribution and Survey Information: The banded wood snail has never been found in the environment in California and receives a Not Established (0) in this category

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.

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:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (13)

Uncertainty:

Banded wood snails are commonly intercepted. There have been no formal surveys for this snail in the state. It is therefore possible that it could be present in some locations in California. 

Conclusion and Rating Justification:

Banded wood snail is not known to occur in California and might cause significant economic and environmental impacts if it were to become established here. Currently, an “A” rating is justified.

References:
  1. Animal Diversity Web. Accessed September 7, 2017. http://animaldiversity.org/accounts/Cepaea_nemoralis/

2. Encyclopedia of Life. Accessed September 7, 2017.
http://eol.org/pages/449909/details#overview

3. G.A. Conboy. 2000. Canine Angiostrongylosis (French Heartworm). Accessed September 7, 2017.
http://www.ivis.org/advances/Parasit_Bowman/conboy_angiostrongylosis/ivis.pdf

4. Maggie Whitson. 2005. Journal of the Kentucky Academy of Science, 66(2):82-88. Accessed September 7, 2017. 
http://stoppinginvasives.com/dotAsset/e2bbc1b0-81c5-42b1-b9e4-8123952c6c02.pdf

5. Pest and Damage Record Database, California Department of Food and   Agriculture, Plant Health and Pest Prevention Services.
http://phpps.cdfa.ca.gov/user/frmLogon2.asp

6. USDA phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). Accessed September 7, 2017.
https://pcit.aphis.usda.gov/pcit/


Author:

Javaid Iqbal,  California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6695; plant.health[@]cdfa.ca.gov.

Responsible Party:

Jason Leathers; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-1211; plant.health[@]cdfa.ca.gov.


Comment Period:*CLOSED

11/7/17 – 12/22/17


Pest Rating: A


Posted by dk

Giant Reed | Arundo donax

California Pest Rating for
Giant Reed | Arundo donax
Family: Poaceae
Pest Rating: B  | Proposed Seed Rating: R

 


PEST RATING PROFILE
Initiating Event:

There have been queries about growing tracts of giant reed in CA for use in biofuel production.

History & Status:

Background: Arundo donax is a tall, erect, perennial cane or bamboo-like grass, 2 to 8 meters high. It is one of the largest of the herbaceous grasses. The fleshy, almost bulbous, creeping root stocks form compact masses from which arise tough, fibrous roots that penetrate deeply into the soil. The culms reach a diameter of 1 to 4 cm and commonly branch during the second year of growth. These culms are hollow, with walls 2 to 7 mm thick and divided by partitions at the nodes. The nodes vary in length from 12 to 30 cm. The leaves are conspicuously two-ranked, 5 to 8 cm broad at the base and tapering to a fine point. The bases of the leaves are cordate and more or less hairy-tufted, persisting long after the blades have fallen. There can be variability in leaf and cane dimensions within a stand, possibly in response to water availability. Arundo donax was widely planted in the 19th century in CA for its bamboo-like stems. It’s planting was actively promoted in the 1950s by the USDA for use in erosion control along stream banks.

Arundo donax has been nominated as one of the top 100 Worst Invaders of the World by the Invasive Species Specialist Group of the World Conservation Union (http://www.issg.org). It was first introduced to the United States by Spanish colonists in the 1700’s and introduced again to California in the early 1800’s for erosion control in drainage canals. It is now a major invasive threat to riparian areas in California, as well as other southwestern states and it is listed as one of the twenty most invasive weeds in California and as a noxious weed in Texas.

Large infestations of Arundo donax are difficult to eradicate given that all

rhizomes must be removed or killed to prevent re-sprouting. This can cost from $7000-$25000 per acre, depending on difficulty of access. Typically a combination of mechanical removal and application of a systemic herbicide (e.g., glyphosate) provide the best control. Care must be taken to ensure that removed plant material does not sprout. Research on the biological control of Arundo donax in the United States has led to the recent release of a wasp, Tetramesa romana Walker (Hymenoptera: Eurytomidae), but its effects on population levels of Arundo donax are currently unknown .

 Worldwide Distribution: Arundo donax is native to many tropical to warm temperate regions from northern Africa and the Middle East eastwards through eastern and southeastern Asia (CABI, 2011a). It has been introduced into similar climates around the world in southern Europe, Central America, South America, and the Caribbean. It is invasive in southern Africa, the western United States, southern Europe, and the Azores (Weber, 2003).

California Distribution: Arundo donax is found along waterways throughout much of CA as far north as southern Humboldt County. It is missing from Northeastern CA, the high mountains, and it is rare in the desert region (Consortium of California Herbaria).

California Interceptions: Arundo donax is occasionbally sold in nurseries in CA and has been detected during nursery surveys.

This risk Arundo donax would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: The risk of Arundo donax is High (3) as illustrated by the broad distribution of the pest in California and its spread over the last 100 years.

-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) Host range.  Arundo donax does not require any one host, but grows wherever ecological conditions are favorable. It receives a High (3) in this category.

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

Evaluate the host range of the pest:

-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: Arundo donax is a plant that spreads via water flow and human dispersal from rhizomes or stem fragments. It does not reproduce from seed in North America. The Risk is Medium (2).

Evaluate the dispersal potential of the pest:

-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: Risk is Medium (2) as Arundo donax only occasionally invades agricultural land. It can lower yields in some ranching systems, where Arundo donax blocks access to water. Although Arundo donax was once recommended for stream bank stabilization, its shallow roots mean that bank undercutting is frequent in Arundo donax infestations. Bridge and levee damage or failure have been partially ascribed to dense Arundo donax stands, due to flow conveyance loss.

Evaluate the economic impact of the pest to California using these criteria: Economic Impact: B, G 

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

Economic Impact Score: 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.

5) Environmental Impact: Risk is High (3) in California, as Arundo donax is an ecological transformer, it excludes native riparian species, leads to unshaded streams detrimental to migratory fish stocks, increases fire frequency, and degrades endangered species habitat (e.g., willow fly catcher).

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

Environmental Impact Score: A, C, D

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: 3

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

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

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

Consequences of Introduction to California for Arundo donaxRating (Score) High (13)

Low = 5-8 points

Medium = 9-12 points

High = 13-15 points

6) Post Entry Distribution and Survey Information: Arundo donax is widespread in CA. It receives a High (-3) in this category.

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.

-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.

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (10)

Uncertainty:

As this plant is well established as an invasive species in CA, there is little uncertainty associated with this assessement.

Conclusion and Rating Justification:

Based on the score listed above the pest is a high risk. This would justify an “A” rating if the species were not widely established in California. As the plant is found in over 50% of California counties, the pest would best be assigned a “B” or “C” rating. Many millions of dollars have been spent (by the state and other entities) to control Arundo donax in California. Many millions more will be spent in the near future. A “B” rating recognizes the large range of Arundo donax in California, but acknowledges the value of excluding it from new areas and preventing reinfestation of eradicated infestations.


References:      

Bell, G. P. 1997. Ecology and management of Arundo donax, and approaches to riparian habitat restoration in Southern California. In Plant Invasion: Studies from North America and Europe. J.H. Brock, M. Wade, P. Pysek and D. Green, eds. Leiden, the Netherlands: Backhuys, pp. 104-114.

Boose, A.B. and J.S. Holt. 1999. Environmental effects on asexual reproduction in Arundo donax. Weed Research 39:117-127.

Consortium of California Herbaria. Accessed 6/12/2014: ucjeps.berkeley.edu/consortium/

Goolsby, J. A., D. Spencer, and L. Whitehand. 2009. Pre-release assessment of impact on Arundo donax by the candidate biological control agents Tetramesa romana (Hymenoptera: Eurytomidae) and Rhizaspidiotus donacis (Hemiptera: Diaspididae) under quarantine conditions. Southwestern Entomologist 34:359-376.

Newhouser, M., C. Cornwall and R. Dale. 1999. Arundo: A Landowner Handbook. Accessed 6/12/2014: http://teamarundo.org/education/landowner_handbook.pdf

Perdue, R.E. 1958. Arundo donax: source of musical reeds and industrial cellulose. Economic Botany 12:368-404.

Racelis, A.E., Goolsby, J., Moran, P.J. 2009. Seasonality and movement of adventive populations of the arundo wasp (Hymenoptera: Eurytomidae), a biological control agent of giant reed in the Lower Rio Grande Basin in south Texas. Southwestern Entomologist. 34(4):347-357.

USDA Arundo donax. Accessed 6/12/2014: http://plants.usda.gov/core/profile?symbol=ardo4

Weber, E. 2003. Invasive Plant Species of the World: A Reference Guide to Environmental Weeds. CABI Publishing, U.K. 4. Dudley, T., Department of Integrative Biology, University of California, Berkeley, USA and IUCN/SSC Invasive Species Specialist Group (ISSG). 2006. Arundo donax. Accessed 6/12/2014: http://www.issg.org/database/species/ecology.asp?si=112&fr=1&sts=sss&lang=EN

Wijte, A.H. B. M., T. Mizutani, E.R. Motamed, M.L. Merryfield, D.E. Miller and D.E. Alexander. 2005. Temperature and endogenous factors cause seasonal patterns in rooting by stem fragments of the invasive giant reed, Arundo donax (Poaceae). Int. J. Plant Sci. 166(3):507-517.


Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6650;

dean.kelch[@]cdfa.ca.gov


Comment Period: 11/6/17 – 12/21/17 (CLOSED)


Pest Rating: B  | Proposed Seed Rating: R


Posted by dk

Balloon Plant | Asclepias physocarpa

California  Pest Rating
Balloon Plant | Asclepias physocarpa
Family:  Apocynaceae
Pest Rating: C | Proposed Seed Rating: None

 


PEST RATING PROFILE
Initiating Event:

Asclepias physocarpa is currently Q-rated and was recently intercepted at the Benton Border Station (PDR BE0P06666758). A pest rating proposal is required to support an official pest rating.

History & Status:

Background: Asclepias physocarpa, commonly called balloon plant, is native to southeast Africa. It is an upright, shrubby perennial that typically grows 4-6′ tall and has lanceolate green leaves. This milkweed family member is perhaps best noted for its soft, spherical (balloon-like), lime-green seed pods, which are 5-7.5 cm long and covered with soft spines 7-10 mm long7. Pods change in color to tan before splitting open in the fall to release large numbers of small, black seeds, which measure approximately 4.5 mm long by 2 mm wide and are topped with a tuft of silky-white hairs approximately 3 cm long. These seeds are wind-dispersed1, 3.

Asclepias physocarpa is a food plant for the larvae of the monarch butterflies (Danaus spp.). The caterpillars are immune to the poisonous alkaloids in Asclepias physocarpa and have developed the ability to store them and pass them on to the pupa and adult butterfly, that are then unpalatable and/or poisonous to predators5.

Asclepias physocarpa is sometimes placed in the segregate genus Gomphocarpus, but recent evidence support retaining it in the large genus Asclepias (milkweeds) 2.

 Worldwide Distribution: Asclepias physocarpa is native to South Africa, Swaziland, and Mozambique. It was introduced to various Mediterranean countries, China, India, Mexico, Central America, tropical South America, and Western Australia1.

Official Control: Asclepias physocarpa is not considered to be a noxious weed by any state government authorities6. However, it is listed as an invasive weed in Hawaii, French Polynesia, the Canary Islands, New Caledonia, China, Australia, Cuba, Jamaica, India, and Italy1.

California Interceptions: One recent interception record (PDR BE0P06666758) was reported in the Pest and Damage Record Database by CDFA4. A few voucher specimens have been collected from gardens and in disturbed areas near new developments in southern CA.

The risk Asclepias physocarpa (Balloon Plant) would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Asclepias physocarpa can grow in waste places, disturbed sites, and roadsides. It may able to establish in a larger but limited part of California. Therefore, it receivesMedium (2) in this category.

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

– 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: Asclepias physocarpa does not require any one host, but grows wherever ecological conditions are favorable. It receives a High (3) in this category.

Evaluate the host range of the pest.

– 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: Asclepias physocarpa spreads by seeds and each seed has a tuft of silky hairs that facilitates dispersal by wind and water. They may also be dispersed as a contaminant of crops, fodder, soil, or in mud attached to animals or machinery1. Each plant produces several hundred seeds per year. It receives a Medium (2) in this category.

Evaluate the host range of the pest.

– 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: Asclepias physocarpa has been cultivated in California for decades, but apparently has rarely escaped gardens. It exudes a milky white latex that is poisonous to livestock and humans, so an infestation could reduce the productivity of pastures1. It receives a High (3) in this category.

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

Economic Impact:  D, F

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.

5) Environmental Impact: Asclepias physocarpa has so far not invaded wildland in California. It could be expected to invade flood plains or other disturbed areas. In wet, tropical areas, such as Hawaii, it can form dense thickets in pastures. It is unlikely to do this in the drier climate of California. As a garden weed, it could trigger additional private treatment programs. It receives a Medium (2) in this category.

Environmental Impact: D

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 Asclepias physocarpa (Balloon Plant): Medium (12)  

-Low = 5-8 points

Medium = 9-12 points

High = 13-15 points

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

6) Post Entry Distribution and Survey Information: No official records indicating this species is established in the environment of California have been found, so it receives a Not Established (0) in this category.

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:

-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: 

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (12)

Uncertainty:

This plant is not known to be established in California. No official survey has been conducted to confirm its presence. However, it has been growing in the environment of California as a common garden plant and has never been noticed as invasive weed.

Conclusion and Rating Justification:

Conclusions of the harm associated with this pest to California using all of the evidence presented above: Proposed Rating: Based on the score listed above, Asclepias physocarpa is medium risk. However, its low frequency in California after years of cultivation suggest that it will not become invasive, so a “C” rating is justified.


References:

Crop protection Compendium (Cabi). Accessed August 24, 2017: http://www.cabi.org/isc/datasheet/114618

Fishbein M., Chuba D., Ellison C., Mason-Gamer R. J., Lynch S. P. 2011. Phylogenetic relationships of Asclepias (Apocynaceae) inferred from non-coding chloroplast DNA sequences. Systematic Botany 36: 1008–1023. Missouri Botanical Garden online. Accessed August 24, 2017:  http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=e373

Pest and Damage Record Database, California Department of Food and Agriculture, Plant Health and Pest Prevention Services. Accessed   August 24, 2017: http://phpps.cdfa.ca.gov/user/frmLogon2.asp

South Africa National Biodiversity Institute, Plantzafrica, online. Accessed August 24, 2017: http://pza.sanbi.org/gomphocarpus-physocarpus

USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). Accessed August 24, 2017.
https://pcit.aphis.usda.gov/pcit/

Weeds of Australia, Biosecurity Queensland, online. Accessed August 24, 2017.       https://keyserver.lucidcentral.org/weeds/data/media/Html/gomphocarpus_physocarpus.htm


Responsible Party:

Javaid Iqbal, California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6695; plant.health[@]cdfa.ca.gov.


Comment Period:* CLOSED

11/3/17 – 12/18/17


*NOTE:

You must be registered and logged in to post a comment.  If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.

 


Photo of Ballon plant (Asclepias physocarpa), photographed in Tonga. Photo By: Tauʻolunga, via Wikimedia Commons

Pest Rating: C | Proposed Seed Rating: None


Posted by ls

Alligatorweed | Alternanthera philoxeroides

California Pest Rating for
Alligatorweed | Alternanthera philoxeroides
Family:  Amaranthaceae
Pest Rating: A | Proposed Seed Rating: R

 


PEST RATING PROFILE
Initiating Event:

There was a recent find of alligatorweed in Solano County; this is the first detection in northern California in many years.

History & Status:

Background: Alligatorweed is a perennial herb with horizontal to ascending stems to 1 m long, rooting at the nodes. The flowers are small and borne in small heads with white floral bracts. Like many aquatic emergent, it has distinctive submerged and emersed forms. The submerged form has hollow, floating, emergent and submerged stems. Terrestrial plants have solid stems. Typically, plants grow rooted in soil in shallow water and form dense, interwoven floating mats that extend over the surface of deeper water. Mats can become quite dense and nearly impenetrable. The floating mats can break away and follow currents to colonize new sites. Mats disrupt the natural ecology of a site by reducing light penetration and crowding out native species. Serious infestations can create anoxic, disease-promoting, and mosquito-breeding conditions.

Worldwide Distribution: This weed is found in wet, disturbed areas. It is also a weed of rice and sugar cane fields in tropical and subtropical regions. Native to southern Asia, alligatorweed is now found in tropical and subtropical regions around the world. It is considered an invasive species in Australia, China, New Zealand, and Thailand. Alligatorweed has been introduced throughout the southeastern United States from Virginia to Texas.

Official Control: Alligatorweed has had a CDFA rating of A as a pest in California for decades. The population in Los Angeles County has been managed intermittently over the years by the county, but it still persists.  It has official status as a weed in Alabama, Arizona, Arkansas, California, Florida, South Carolina, and Texas.

California Distribution:  Alligatorweed occurs in several southern California counties. It also has been detected in Contra Costa and Kings Counties, where it is eradicated. There was a recent find of 2 colonies in southern Solano County.

California Interceptions: Alligatorweed has been sent to CDFA by land managers.

The risk Alternanthera philoxeroides (alligatorweed) poses to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Risk is Medium (2), as the plant occurs in wetlands such as the Delta and creeks and rivers, as well as irrigation canals and watering ponds. These habitats are limited but widely distributed in California.

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

– 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: Most plants do not require any one host, but grow wherever ecological conditions are favorable. It receives a High (3) in this category.

Evaluate the host range of the pest.

– 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: Risk is Medium (2). Alligatorweed can spread rapidly via water movement and on boats and equipment as stem fragments. It is also grown as an aquarium plant and occasionally discarded into waterways. Seeds evidently are not produced in the United States.

Evaluate the natural and artificial dispersal potential of the pest.

– 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: Risk is High (3), as the plant can lower crop yields in rice fields, trigger state or international quarantines, and force changes in cultural practices by blocking canals. It has spread widely in the southeast, and has proven difficult to eradicate both there and in California. Its mats can improve habitat for mosquito larvae, leading to larger mosquito populations.

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

Economic Impact: A, C, D, E, G

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

Economic Impact Score: 3

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

– Medium (2) causes 2 of these impacts.

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

5) Environmental Impact: Risk is High (3) as alligatorweed could further invade the water systems of California, disrupt natural wetland communities and potentially lower biodiversity by invading wetlands. The dense growth impedes water movement, blocks the growth of native plants, and reduces available habitat for water birds and fish. Its invasion in the Delta and its tributaries could degrade habitat of rare species such as Mason’s lilaeopsis (Lilaeopsis masonii), Sacramento River Chinook salmon (Oncorhynchus tshawytscha),  and Giant garter snake (Thamnophis gigas).  Its presence would trigger additional control measures.

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

Environmental Impact: A, C, D

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: 3

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

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

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

Consequences of Introduction to California for Alternanthera philoxeroides (alligatorweed) : High (13)

-Low = 5-8 points

-Medium = 9-12 points

High = 13-15 points

6) Post Entry Distribution and Survey Information: Alligatorweed currently is known from 3-4 populations in northern and southern California. It receives a Medium (-2) in this category.

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: -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:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (11)

Uncertainty:

Uncertainty is low, as alligatorweed has established in wetlands in California and other states. There is some uncertainty as to the actual distribution of this plant in California, as, like some other aquatic weeds, it is likely to be overlooked.

Conclusion and Rating Justification:

Conclusions of the harm(s) associated with this pest to California using all of the evidence presented above:

Proposed Rating: Despite its limited ability to disperse between watersheds, this is a potentially significant weed in California of both natural wetlands and irrigation canals. Because of its potential economic impacts, it deserves an A rating, as it has proven tenacious and is actively spreading.

References:

Baldwin, B. G., D. H. Goldman, D. J. Keil, R. Patterson, T. J. Rosatti, and D. H. Wilken, editors. 2012. The Jepson manual: vascular plants of California, second edition. University of California Press, Berkeley.

Consortium of California Herbaria. Accessed 10/3/2017:  ucjeps.berkeley.edu/consortium/

Florida Dept of Agriculture Weed of the Month: Alternanthera sessilis. Accessed 10/3/2017: http://www.freshfromflorida.com/Divisions-Offices/Plant-Industry/Plant-Industry-Publications/Weed-of-the-Month/April-2011-Alternanthera-Sessilis

Invasive Plant Atlas of the Mid-South. alligatorweed. Accessed 10/3/2017:    https://www.gri.msstate.edu/ipams/species.php?CName=Alligatorweed


Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6650. plant.health[@]cdfa.ca.gov.


Comment Period: CLOSED

10/17/17 – 12/1/17*


*NOTE:

You must be registered and logged in to post a comment.  If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.


Pest Rating: A | Proposed Seed Rating: R


Posted by ls

Laportea canadensis


Canadian wood-nettle (Laportea canadensis), photographed at Brooklyn Botanic Garden (New York) in September
Canadian wood-nettle (Laportea canadensis), photographed at Brooklyn Botanic Garden (New York) in September. Photo By: Raffi Kojian (http://Gardenology.org) [CC BY-SA 3.0], via Wikimedia Commons
California Pest Rating for
Laportea canadensis)
Pest Rating: D | Proposed Seed Rating: N/A

 


PEST RATING PROFILE
Initiating Event:

This plant has been rated as “Q” by the CDFA Botany Lab in response to a border detection.

History & Status:

Wood nettle is a common perennial herb native to eastern North America, where it is found growing in moist to wet soil in the understory of Eastern Deciduous Forests. It has a strong family resemblance to the common nettle (Urtica dioica), but unlike most other members of the nettle family, it has alternate leaves. These leaves are broadly heart-shaped with a toothed margin. The plant is sparsely covered by stinging hairs. The effect of touching it is similar to touching common nettles, but not as severe. Native Americans used wood nettle to treat incontinence and tuberculosis, to counteract poison, as a love medicine, and to facilitate childbirth.

Official Control: There is no known official control at this time.

California Distribution:  None.

California Interceptions:  A new interception was made in Yolo County on 6/14/2017 (PDR NE0P06655513).

Consequences of Introduction: 

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

Risk is Low (1), as the preferred habitat of wood nettle (moist, dense, deciduous forest) does not occur 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: Evaluate the host range of the pest.  Risk is High (3) as weeds do not require any one host, but grow wherever ecological conditions are favorable. 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: Evaluate the natural and artificial dispersal potential of the pest. Risk is Medium (2). The plant produces numerous seeds that are apparently able to spread via water distribution. Patches may be the result of root sprouting. 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: Evaluate the likely economic impacts of the pest to California using the criteria below.

Economic Impact: 

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: Risk is Low (1). No economic impact, even where it is common in Eastern North America.

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

Environmental Impact:

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:  Low (1).  The plant is well integrated into its native landscape, and is not known to be weedy. It is unlikely to be adapted to any part of California.

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 wood nettle:

Add up the total score and include it here. (8)

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. (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: (8)

Uncertainty:

Wood nettle is poorly adapted to California and it is not known to be weedy elsewhere; there is low uncertainty.

Conclusion and Rating Justification:

An Eastern woodland native. A D rating is recommended.

References:

Consortium of California Herbaria (ucjeps.berkeley.edu/consortium/).

‪ Flora of North America Editorial Committee, eds.  1993+.  Flora of North America North of Mexico.  16+ vols.  New York and Oxford.

Moerman, Daniel E. 1986. Medicinal plants of native America. Museum of Anthropology, University of Michigan, Ann Arbor.


Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6650; plant.health[@]cdfa.ca.gov


Comment Period: CLOSED

45-day comment period: 7/18/17 – 9/1/17


NOTE:

You must be registered and logged in to post a comment.  If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.


Pest Rating: D | Proposed Seed Rating: N/A


Posted by ls

Branched Broomrape | Orobanche ramosa

Branched broomrape | Orobanche ramosa (Photo by CDFA)California Pest Rating
Orobanche ramosa L., branched broomrape
Lamiales; Orobanchaceae
Pest Rating: A |  Seed Rating: P 

 


PEST RATING PROFILE
Initiating Event:

This plant has been rated as “A” on the CDFA Plant Pest Rating list for some years.

History & Status:

Branched broomrapes are annual plants that grow from seed and require a plant host to survive. It is a parasitic plant that grows on the roots of Broad-leaf hosts and obtains all of its nutrients and water from these plants. Seeds germinate in response to chemicals released by host plant roots. The broomrape seedling root then attaches itself to the host plant root and remains underground until flowering. The plant has no chlorophyll and no noticeable leaves. Flowering stems emerge from the ground about 6 weeks after germination; flowering and seed set occur within 2–3 weeks. Seed capsules dry and shatter in summer. One plant can produce over 100,000 seeds and seeds may lay dormant in the soil for more than 40 years. Broomrape seed can be spread by livestock, machinery, vehicles, flooding, and contaminated fodder, seed and soil. Branched broomrape is among the world’s worst crop weeds and poses a serious threat to the vegetable industry in California. It has been reported to attack 25 different crops including lettuce, tobacco, and tomatoes. Once established, branched broomrape can reduce crop yields by up to 70% and it is extremely difficult to eradicate. For this reason, it is often regulated and trading partners that import fresh host material may limit or exclude trade in these commodities.

Official Control: Branched broomrape has been an “A” listed noxious weed in California for many years. There was a state control and eradication program in California for branched broomrape that lasted over 20 years; it was discontinued in the late 1970s. It is also a federally listed noxious weed and is listed as noxious in Alabama, Arizona, Florida, Massachusetts, Minnesota, North Carolina, Oregon, South Carolina, Texas, and Vermont.

California DistributionBranched broomrape was known from about a dozen infestations of agricultural fields in Central and Southern California. Most of these sites have been developed over the years and therefore the plant is likely eradicated at these sites (there have been no detections in over 30 years). A known extant infestation is in northern San Benito County; this population reappeared after more than 30 years, when the field was planted to tomatoes.  A second occurrence was found in 2014 in San Joaquin County, in an area near known infestations from the 1970s.

California Interceptions: Vouchered specimens are known from Sacramento, Alameda, San Benito, San Joaquin, Santa Clara, and Ventura Counties.

United States: Branched broomrape has been found in California, Illinois, Kentucky, North Carolina, New Jersey, and Texas.

International: Branched broomrape is native to the Mediterranean. It is reported as naturalized and as an environmental and agricultural weed in Europe and western Asia. It has also been detected in Australia where they are transitioning from attempted eradication efforts to ongoing management.

This risk Branched broomrape would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: The plant has attacked crops in many countries spanning many climates. It is highly variable and this variation seems to be tied to differential ecological preferences. Therefore, It scores as High (3) in this category.

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.

2) Host Range: Risk is High (3) as branched broomrape attacks 25 crop species and probably has the potential to attack many native species as well.

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.

3) Pest Dispersal Potential: Branched broomrape produces numerous seeds are documented to last for decades and are able to spread via equipment and on animals (including humans). The seed bank is highly persistent. Branched broomrape receives a High (3) in this category.

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.

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

Economic Impact: A, B, C, D

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

Economic Impact Score: Branched broomrape receives a High (3) in this category.  Branched broomrape can lower crop productivity in susceptible row crops by up to 70%. This can affect land value and result in quarantine.  

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

Environmental Impact: A, B, D

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.

Environmental Impact Score: Branched broomrape receives a High (3) in this category. Branched broomrape is likely to trigger new treatments by land managers. The plant has not yet spread to the wild in California. However, certain native plants such as clovers (Trifolium) are likely susceptible to branched broomrape. These include such rare or endangered species as showy Indian clover (T. amoenum), Buck’s clover (T. buckwestiorum), and Monterey clover (Trifolium trichocalyx).   

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 Branched broomrape: High (15)

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: Branched broomrape has been recently found in three counties in California, but may be eradicated. It receives a Medium (-2) in this category.

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.

-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:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: High (13)

Uncertainty:

The experience in the mid 20th century of California and in Australia show the potential of this species to disrupt crop systems. Its effects on the environment are more speculative and necessarily more uncertain.

Conclusion and Rating Justification:

A terrible agricultural weed because of its ability to produce large numbers of long-lived seeds and its ease of spread. It deserves an A rating as it is likely to have a high impact if it spreads again in California. Development has removed most known sites, but it is otherwise difficult to treat.

References:

Baldwin, B. G., D. H. Goldman, D. J. Keil, R. Patterson, T. J. Rosatti, and D. H. Wilken, editors. 2012. The Jepson manual: vascular plants of California, second edition. University of California Press, Berkeley.

Consortium of California Herbaria: ucjeps.berkeley.edu/consortium/

Cooke, D. 2002. Control of branched broomrape; a literature review. Animal and Plant Control Commission of South Australia.

Flora of North America Editorial Committee, eds. 1993+.  Flora of North America North of Mexico.  16+ vols.  New York and Oxford.

NSW Department of Primary Industries. Weed alert; branched broomrape: http://www.dpi.nsw.gov.au/agriculture/pests-weeds/weeds/profiles/broomrapes

USDA Plants Database, Orobanche ramosa: http://plants.usda.gov/core/profile?symbol=orra


Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6650; plant.health[@]cdfa.ca.gov


Comment Period: CLOSED

45-day comment period: 7/18/17 – 9/1/17


NOTE:

You must be registered and logged in to post a comment.  If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.


Pest Rating: A |  Proposed Seed Rating: P



Posted by ls

Myrtle Spurge | Euphorbia myrsinites


California Plant Pest Rating for
Myrtle Spurge (Euphorbia myrsinites)
Pest Rating: A  |  Proposed Seed Rating: R

 


PEST RATING PROFILE
Initiating Event:

Collection in Lassen County by county staff and submission to the CDFA Botany Lab.

History & Status:

Background: Myrtle spurge is a deciduous, perennial herb (to 10 cm tall by 40 cm wide) native to southeastern Europe through Asia Minor. It is a semi-succulent plant with prostrate branches and awl-shaped, blue leaves without a petiole approximately 2 cm long. The flowers (cyathia) are borne in spring. The floral bracts are bright greenish yellow. Like all true spurges, the branches and leaves exude an irritating white latex when damaged. It arrived in CA as a garden plant, and it can be found at nurseries in the north and at higher elevations. It’s is extremely cold hardy, but evidently doesn’t thrive in areas with severe summer drought.

California Distribution: Myrtle spurge is currently restricted in California. There are 2 small populations, persisting but not spreading, known along the coast in Alameda and Ventura Counties. It was once collected in Kern County. A small population in Quincy, Plumas County has evidently been eradicated. The recent find, in Lassen County, is reportedly spreading from nearby cultivation. A similar case exists east of Macarthur, Shasta County.

United States: Myrtle spurge is highly invasive in Utah and other western, interior states including Wyoming, Colorado, Eastern Oregon, Washington and New Mexico. It has also been collected as waif in a few eastern states such as Wisconsin and Virginia.

International: Myrtle spurge is native to southeastern Europe through Asia Minor.

Regulation: Myrtle spurge is listed as a noxious weed in Colorado, Oregon, Washington and Utah.

This risk Myrtle spurge will 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. Risk is Medium (2), as the plant could naturalize throughout higher elevation mountains and in the “sagebrush” area of northeastern California.

– 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) Pest Host Range:  Risk is High (3) as weeds do not require any one host, but grow wherever ecological conditions are favorable.

Evaluate the host range of the pest: 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:  Risk is Medium (2). The plant reproduces via numerous, rather large seeds that are thrown some distance from the mother plant. Nevertheless, its ability to disperse seems limited, as populations do not spread rapidly. It is unlikely to be found in commercial crop seed.

Evaluate the dispersal potential of the pest:

-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: Risk is High (3) as Myrtle spurge, where established, lowers the rangeland productivity, is unpalatable to livestock, and, where common, will necessitate herbicide treatments for control. As it is a noxious weed in several western states, infested commodities could be excluded from those states that list it as noxious.

Evaluate the economic impact of the pest to California using these criteria:

Economic Impact: A, C, D

A. The pest could lower crop yield

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

C. The pest could trigger the loss of markets (includes quarantines by other states or countries)

D. The pest could negatively change normal production cultural practices

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:  Risk is High (3). In California, Myrtle spurge could disrupt natural bunchgrass and sagebrush scrub communities. Once established, it would trigger additional treatment programs to control it, as in Utah. It would crowd out native species that coexist with or foster rare species.

Evaluate the environmental impact of the pest on California using the following criteria:

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

Environmental Impact: B, C, D

A. The pest could directly affect threatened or endangered species

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

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

D. Significantly impacting cultural practices, home/urban gardening, or ornamental plantings.

Environmental Impact Score: 3

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

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

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

Consequences of Introduction to California for Myrtle spurge:

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

Low = 5-8 points

Medium = 9-12 points

High = 13-15 points

Total points based on above criteria: High (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: 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: 13

Uncertainty:

Because there is ample evidence of its invasiveness in Utah, Oregon and Colorado, there is little uncertainty that this plant can establish and become invasive in similar climatic areas of California.

Conclusion and Rating Justification:

Conclusions of the harm(s) associated with this pest to California using all of the evidence presented above: Proposed Rating: Based on the score listed above the pest is a High risk. It has the ability to spread more widely in California. Its current limited distribution in California makes the feasibility of eradication high. An A rating is justifed.

References:

Baldwin, B. G., D. H. Goldman, D. J. Keil, R. Patterson, T. J. Rosatti, and D. H. Wilken, editors. 2012. The Jepson manual: vascular plants of California, second edition. University of California Press, Berkeley.

Consortium of California Herbaria (cjeps.berkeley.edu/consortium/). 2014.

Global Compendium of Weeds: http://www.hear.org/gcw/species/euphorbia_myrsinites/

Jepson Flora Project (eds.) 2013. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on Mar 28 2014

Washington State Weed Control Board; Myrtle Spurge. Accessed 6/18/2017: http://www.nwcb.wa.gov/weeds/myrtle-spurge


Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6650; plant.health[@]cdfa.ca.gov


Comment Period: CLOSED

45-day comment period:  7/17/17 – 8/31/17


NOTE:

You must be registered and logged in to post a comment.  If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.


Pest Rating: A  |  Proposed Seed Rating: R


Posted by ls

Sahara Mustard | Brassica tournefortii

California Pest Rating for
Brassica tournefortii Gouan. | Sahara mustard
Pest Rating: C | Proposed Seed Rating: R

 


PEST RATING PROFILE
Initiating Event:

This plant has been rated as “Q” by CDFA botany staff.

History & Status:

The genus Brassica comprises about 40 species and many agricultural cultivars such as cabbage, mustard, bok choi, brussel sprouts, canola, broccoli, turnip, etc. Sahara mustard, as the name implies, is a species adapted to dry, sandy soils.

Sahara mustard forms a basal rosette like most mustards from which grows a highly branched inflorescence with hundreds of typical mustard 4-parted yellow flowers. The basal leaves generally have more than a dozen pairs of lobes or leaflets; this is more than is typical for most other Brassica spp. As the plant fruits, it dies. The dense tangle of stems and fruits breaks off at ground level and tumbles over the ground in windy situations, releasing seeds as it moves through the landscape. The seeds sometimes occur as a contaminant in agricultural seed lots and they are easily distinguishable from other mustard seeds.

Official Control: Some land managers control this plant, but where it is adapted it is generally too common to control it well.

California Distribution:  Sahara mustard is known from at least 15 counties in California; most are in the southern California. It is very common in warm desert regions.

California Interceptions: Sahara mustard was first collected in California in the 1920s from the Coachilla Valley. From that region, it has spread widely to surrounding areas.

United States: Sahara mustard is known from California, Texas, New Mexico, Arizona, and Nevada in the United States.

International:  Sahara mustard occurs in all of North Africa from Morocco through Egypt, in southern Europe, and through Western Asia. It is an introduced weed in Australia.

Consequences of Introduction: 

1) Climate/Host Interaction:  Risk is Mediium (2), as the plant is naturalized on roadsides in the desert and then moves into open desert from these areas. More recent finds in coastal California indicates that it may invade southern coastal areas as well.

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:  Risk is High (3) as weeds do not require any one host, but grow wherever ecological conditions are favorable.

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:  Risk is Medium (2). The plant produces a large number of seeds that spread along roads. It then spreads into the desert interior via the “tumbleweed” inflorescences. It is especially good at exploiting sandy soils.

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: The presence of this plant in the Anza Borrego desert impacts the spring wildflower tourist industry, as the plant outcompetes native wildflowers that form the basis of an important tourist industry. If it infests row crops or irrigated areas, it lowers crop value or crop yield.

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

Economic Impact: A, B, C, F

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: Risk is High (3) as the plant is able to dominate desert areas that are home to sensitive species such as desert tortoise, blunt-nosed leopard lizard, and many rare native plants.

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

Environmental Impact:  A, C, D

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.

Environmental Impact Score: 3

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

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

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

Consequences of Introduction to California for Sahara mustard: 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: Sahara mustard has been found in many counties in California, most commonly in the south. It has spread widely during the last 20 years in California. It receives a High (-3) in this category.

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.

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:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (10)

Uncertainty:

Given that populations of Sahara mustard have exploded in the last 20 years, uncertainty is low. It only remains to be seen how well it can invade the Mediterranean coastal and central regions of California. The likelihood is that it has fully invaded the areas where it is best adapted and newer incursions will occur, but that they will prove to be limited.

Conclusion and Rating Justification:

Although Sahara mustard may be somewhat limited in its spread by its environmental preferences, it has shown itself quite invasive where it is adapted. Because it is so widespread, especially in the desert areas, it should be given a C rating.

References:

Baldwin, B. G., D. H. Goldman, D. J. Keil, R. Patterson, T. J. Rosatti, & D. H. Wilken, editors. 2012. The Jepson manual: vascular plants of California, second edition. University of California Press, Berkeley.

Berry, K. H., T. A. Gowan, D.M. Miller & M. L. Brooks. 2014. Models of Invasion and Establishment for African Mustard (Brassica tournefortii). Invasive Plant Science and Management 7: 599-616.

Bhagirath S. Chauhan, Gurjeet Gill, and Christopher Preston (2006) African mustard (Brassica tournefortii ) germination in southern Australia. Weed Science: September 2006, Vol. 54, No. 5, pp. 891-897.

Cal_IPC website. Sahara mustard (Brassica tournefortii) research. Accessed 12/17/2015: http://www.cal-ipc.org/ip/research/saharan/index.php

Consortium of California Herbaria: ucjeps.berkeley.edu/consortium/

Malusa, J., B. Halvorson, and D. Angell. 2003. Distribution of the exotic mustard Brassica tournefortii in the Mohawk Dunes and Mountains, Arizona. Desert Plants 19:31–36.

Sanders, A., & R. Minnich. 2000. Brassica tournefortii. in Bossard, C. C., J. M. Randall, and M. M. Hochovsky. Invasive Plants of California’s Wildlands. University of California Press, Berkeley, CA.


Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6650; plant.health[@]cdfa.ca.gov


Comment Period: CLOSED

45-day comment period: July 14, 2017 – August 28, 2017


NOTE:

You must be registered and logged in to post a comment.  If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.


Pest Rating: C | Proposed Seed Rating: R


Posted by ls 

English Ivy, Irish Ivy & Algerian Ivy | Hedera spp.

California Pest Rating for
English Ivy, Irish Ivy & Algerian Ivy  |  Hedera spp.
Pest Rating: None |  Proposed Seed Rating: None

 


PEST RATING PROFILE
Initiating Event:

This plant is subject to a petition to the Secretary to list English ivy (Hedera helix) as a noxious weed.

History & Status:

True ivies (Hedera spp.) are vining, evergreen plants with dark, glossy, (generally) lobed leaves. When they reach something to climb on, they grow upwards using innumerable adventitious roots that sprout from the stems. After growing upward into sun, the plant changes it growth form, producing unlobed leaves and rigid stems that project from the framework. These fertile stems produce many small green flowers in compound umbels. The fruits are black berries (yellow in H. helix subsp. poetarum) that are generally dispersed by birds, sometimes to a great distance from the mother plant. Although a single ivy plant can carpet a ~0.1 hectare area or take over a tree, it is the bird-dispersed seed that account for most of the continuous spread of the plants.

The various species of ivy are difficult to distinguish and they sometimes hybridize. Even in their home range, widespread cultivation of non-native species or cultivars make identification difficult. The most common species in cultivation on the West Coast are English ivy (H. helix), Irish ivy (H. hibernica) and Algerian ivy (H. algeriensis, synonym H. canariensis). They can be distinguished by the types of hairs on the underside of the leaves, as well as by their chromosome number. Nevertheless, because of confusion between the species, all three will be treated together.

Ivies are popular ground covers in gardens, where they can dominate large areas with a weed resistant mat. Many cultivars have been developed over the years and some gardeners form collections of the various forms. As pot plants, they are often trained over frameworks into topiaries.

Worldwide Distribution: Ivies are widespread throughout Eurasia, northern Africa and the Canary Islands (Hedera algeriana). As adventives, ivies are widespread in forested temperate and warm temperate areas of the world. In the United States, ivies have been found as introductions in all western, all eastern and all southern states.

Official Control: Ivies are listed as official weeds in Oregon and Washington. In California, some State Parks and other land management agencies have instituted ivy control in lands under their jurisdiction.

California Distribution:  Aside from frequent usage in gardens, ivies are adventive in much of the state in the understory of forests. Ivies are only lacking in the hotter, drier areas.

California Interceptions:  Ivies have been collected over 350 times in California, although many of these collections represent plants persisting from cultivation.

The risk ivies 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.

Risk is High (3) as the plant is naturalized in many localities in CA. It prefers the north where there are extensive forests and higher rainfall, but ivies have proved themselves capable of spreading under favorable conditions (e.g., along rivers and creeks) in many areas of California. In Washington, Irish ivy is more invasive than English ivy and much more invasive than Algerian ivy. However, this relationship may differ in other parts of the West Coast. English ivy may be more invasive 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: Evaluate the host range of the pest.

Risk is High (3) as weeds do not require any one host, but grow wherever ecological conditions are favorable.

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: Evaluate the natural and artificial dispersal potential of the pest.

Risk is Medium (2). The plants produce large vines that can dominate significant areas. Mature plants can form thousands of bird-dispersed seeds per year.

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: Evaluate the likely economic impacts of the pest to California using the criteria below.

Risk is Medium (2) as the plants can lower timber crop value by interfering with tree seedling establishment, damage adult trees by overgrowing them and poison livestock if grazed extensively.

Economic Impact Score: 2

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.

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

Risk is High (3) as the plant can dominate forest understories and forest margins, excluding native plants and lowering biodiversity, and can exclude cultural plants from a landscape. They can also affect threatened or endangered species by overgrowing their food plants, e.g., covering rocky slopes supporting the host plant of the San Bruno elfin butterfly (Callophrys mossii bayensis).

Environmental Impact. Score: 3

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.

– 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 true ivies:

Add up the total score and include it here. High (13)

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. (-3)

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: (10)

Uncertainty:

The dry climate has limited ivies’ spread in CA. However, they are still spreading in shady forest and riparian habitats, as they are in OR & WA.

Conclusion and Rating Justification:

These are very bad forest weeds. The magnitude of their planted and escaped populations preclude regional control and ensure their continued widespread distribution. Currently, classifying true ivies as noxious weeds would not significantly impact its current or future distribution, as they would continue to spread despite regulation. Many birds feed on ivy berries and can travel long distances from existing residential and naturalized sources.

Similar invasive and widespread plants have been given a C rating. Only a small number of noxious weeds are C rated weeds; However, the California Food and Agriculture Code section 5004 states that “In determining whether or not a species shall be designated a noxious weed for the purposes of protecting silviculture or important native plant species, the director shall not make that designation if the designation will be detrimental to agriculture.” As ivies are largely weeds of forest areas and are mainstays of the nursery agricultural sector, they would fall under this stricture.

Classifying Hedera spp. as noxious weeds would harm agriculture by preventing the sale of popular nursery plants. At this point in their invasion curve, newly planted ivies represent a very small contribution to the existing populations. Any regulation of this plant would have little or no consequence in limiting its invasiveness or reducing the costs of ivy management. Therefore, given the economic and horticultural importance, no rating is recommended for English ivy, Irish ivy and Algerian ivy at this time.

References:

Ackerfield J. & J. Wen. 2002. A morpholometric analysis of Hedera L. and its taxonomic implications. Adansonia 24:197–212.

Aizpuru I., C. Aseguinolaza, P. M. Uribe-Echebarría, P. Urrutia, e I. Zorrakín. 2003. Claves ilustradas de la flora del País Vasco y Territorios Limítrofes. Eusko Jaurlarizaren. Vitoria-Gasteiz, Spain.

Baldwin, B. G., D. H. Goldman, D. J. Keil, R. Patterson, T. J. Rosatti, and D. H. Wilken, editors. 2012. The Jepson Manual: Vascular Plants of California, second edition. University of California Press, Berkeley, CA.xw

Bramwell, D & Z. Bramwell. 1994. Flores Silvestres de las Islas Canarias. Editorial Rueda. Madrid, Spain.

Consortium of California Herbaria (ucjeps.berkeley.edu/consortium/).

King County: English Ivy, Hedera helix. Accessed 2/15/2017. http://www.kingcounty.gov/services/environment/animals-and-plants/noxious-weeds/weed-identification/english-ivy.aspx

Midori M. C., S. H. Reichard, & C. W. Hamilton. 2006. Prevalence of different horticultural taxa of ivy (Hedera spp., Araliaceae) in invading populations. Biol. Invasions 8:149-157.

USDA Plants; Hedera helix. Accessed 2/15/2017:  https://plants.usda.gov/core/profile?symbol=HEHE

Vargas P., H. A. McAllister, C. Morton, S. L. Jury & M. J. Wilkinson. 1999.  Polyploid speciation in Hedera (Araliaceae): phylogenetic and biogeographic insights based on chromosome counts and ITS sequences. Plant Systematics and Evolution 219:165–179.

Webb, D. A. 1968. Hedera in Flora Europaea Vol. 2: Rosaceae to Umbelliferae. T. G. Tutin, V. H. Heywood, N. A. Burges, D. H. Valentine, S. M. Walters, & D. A. Webb, eds. Cambridge University Press. United Kingdom.

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6650; plant.health[@]cdfa.ca.gov


Comment Period: CLOSED

45-day comment period: Feb 22, 2017 – April 8, 2017


Pest Rating: None |  Proposed Seed Rating: None


Posted by ls

False Yellowhead | Dittrichia viscosa (L.) Greuter

California Pest Rating for
False Yellowhead | Dittrichia viscosa (L.) Greuter
Asteridae: Asteraceae
Pest Rating: A  |   Proposed Seed Rating: P

 


PEST RATING PROFILE
Initiating Event:

False yellowhead (Dittrichia viscosa) has been rated as “Q” on the CDFA Plant Pest Rating since 2014. This plant is on the “Alert list” for Environmental weeds in Australia. Recent reports of its presence in Solano County has prompted issuance of a permanent rating.

History & Status:

False yellowhead (Dittrichia viscosa) is an erect, perennial, soft-wooded shrub, 1–1.5 m tall and 1 m wide. Its leaves are greyish-green, partially clasping and elliptical. The yellow flowers are daisy-like and 10–20 mm across, with radiating petal-like flowers. The flowers are surrounded by narrow, triangular, sticky bracts. The seeds are approximately 2 mm long, with about 15–25 bristles at the base (Ratcliffe, 1976). The roots can be quite substantial, even in small plants. The young stems and leaves are covered with glandular hairs which exude a sticky foul-smelling oil. The oil can cause allergic reactions. It is native to Northern Africa, the Middle East, India, and southern Europe (Brullo & de Marco, 2000), but it  has expanded its range in response to human disturbance and proved tolerant of harsh water and mineral stress (Wacquant, 1990; Thompson, 2005; Murciego et al. 2007). False yellowhead inhabits disturbed places, roadsides, pastures, fields, riparian woodlands, levees, washes, and margins of tidal marshes. (Blanco 2011; Wacquant, 1990).  False yellowhead was first found in California in 2014 (Consortium of California Herbaria). False yellowhead’s ecology seems to be similar to its close relative stinkwort (D. graveolens), a serious weed in California (Ditomaso & Brownsey, 2013; Wacquant, 1990).

Official Control: False yellowhead has not been listed as a harmful organism (Phytosanitary export database- USDA Phytosanitary Certificate issuance and Tracking system (PExD). The Solano County Agricultural Commissioner’s staff has been controlling and monitoring this plant since it was first found.

California Distribution:  Known only from Solano County in California (Consortium of California Herbaria).

California Interceptions: It has been found growing along McGary Road in Solano County, as reported multiple times by the county agricultural commissioner’s office. (Pest and Damage Report Database). It has not yet been intercepted at CA borders.

United States: False yellowhead was collected in three states in the eastern U.S. (USDA Plants), but it is unlikely that it persisted beyond the late1800s. (FNA, 1993+).

International: False yellowhead is common throughout the Mediterranean. Its native range includes the coasts of southern Europe (including France, Spain, Greece, Italy, Bulgaria and Turkey), the Middle East (Israel, Jordan and Syria), as well as northern Africa (Algeria, Egypt and Libya) (Ratcliffe, 1976; Brullo & de Marco, 2000). It is spreading rapidly in Southeastern and Southwestern Australia (Baldwin et al., 2012).

The risk False yellowhead would pose to California is evaluated below:

Consequences of Introduction: 

1) Climate/Host Interaction: False yellowhead is a ruderal plant species adapted to areas disturbed and altered by human activity (Wacquant, 1990). The typical habitats of viscosa include arroyos, abandoned agricultural fields, roadsides, trails, and disturbed urban sites (Ratcliffe, 1976). It occurs on various soil types and is tolerant of high mineral soils (Wacquant, 1990). Although it is drought tolerant, it prefers the margins of wetlands (Warlop et al., 2010). Once established after disturbance, it can spread to less disturbed situations (Wurcquart, 1990). Therefore, false yellowhead receives a High (3) in this category.

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) Host Range: Risk is High (3) as weeds do not require any one host, but grow wherever ecological conditions are favorable.

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: False yellowhead spreads via seed. Seed dispersal is aided by an arrangement of bristles at the end of the seed (pappus) that catches the wind. (Australian Weed Management Guide). It produces prolific seed that secretes a sticky exudate causing seed to cling to clothing, animal fur and machinery. The seed bank of its close relative Stinkwort is moderately persistent (Cal-IPC). False yellowhead receives a High (3) 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: False yellowhead can lower range productivity. It is unpalatable to livestock (Philbey and Morton, 2000). Furthermore, because of the barbs on the pappus of the seeds, it leads to enteritis and other gastrointestinal disease in livestock. As they are similar to those of Stinkwort, false yellow head is likely to have similar impacts on livestock. It is thought that false yellowhead would have similar impacts on grazing animals. Thirty years after introduction to South Australia, false yellowhead is a bad weeds of roadsides. Some people are allergic and develop severe dermatitis after contacting false yellowhead plants (Máñez et al., 1999; Hernández et al., 2001). It is also allelopathic to other plants and suppresses seed germination (Omezzine et al., 2011).  False yellowhead receives a Medium (2) in this category.

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

Economic Impact: D, F

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.

5) Environmental Impact: False yellowhead is likely to trigger new chemical treatments by ranchers and land managers. The plant can dominate roadsides, disturbed grassland, and wetland margins, excluding native plants and lowering biodiversity (Australia Weed Management Guide). Rare taxa that might be affected in CA include grassland species such as showy Indian clover (Trifolium amoenum) and CA filaree (California macrophylla), and vernal pool species such as Burke’s goldfields (Lasthenia burkei) and CA tiger salamander (Ambystoma californiense). The plant can disrupt natural communities and exclude cultural plants from a landscape. False yellowhead receives a High (3) in this category.

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

Environmental Impact:  A, C, D

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

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

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

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

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

Score the pest for Environmental Impact:

Environmental Impact Score: 3

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

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

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

Consequences of Introduction to California for False yellowhead: High (14)

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: False yellowhead has been found in one county in California. It receives a Low (-1) in this category.

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: -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:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: High (13)

Uncertainty:

Uncertainty is low, as the plant has spread widely in the Mediterranean and South Australia. It also shows signs of fast establishment in its one known occurrence in California.

Conclusion and Rating Justification:

An A rating is recommended, as the plant is invasive, but not yet widespread. There is still the chance to eradicate this plant from North America.

References:

Australian Weed Management Guide. False yellowhead. Accessed 10/11/2016:

https://www.environment.gov.au/biodiversity/invasive/weeds/publications/guidelines/alert/pubs/d-viscosa.pdf

Baldwin, B. G., D. H. Goldman, D. J. Keil, R. Patterson, T. J. Rosatti, and D. H. Wilken, editors. 2012. The Jepson manual: vascular plants of California, second edition. University of California Press, Berkeley.

Blanco G. 2011. Dittrichia in Claves de la Flora Vascular de Andalucía Oriental. G. Blanca, B. Cabezudo, M. Cueto, C. Morales Torres & C. Salazar, eds.  Servicio de Publicaciones de las Universidades de Almería, Granada, Jaén y Málaga. Universidad de Granada. Granada, Spain.

Brullo, S & de Marco, G. 2000. Taxonomical revision of the genus Dittrichia (Asteraceae), Portugaliae Acta Biol. 19: 341–354.

Consortium of California Herbaria. Accessed 10/11/2016: ucjeps.berkeley.edu/consortium/

Flora of North America Editorial Committee, eds (FNA).  1993+.  Flora of North America North of Mexico.  16+ vols.  New York and Oxford.

Hernández, V., R. M. del Carmen, S. Máñez, J. M. Prieto, R. M. Giner, & J. L. Ríos. 2001. A mechanistic approach to the in vivo anti-inflammatory activity of sesquiterpenoid compounds isolated from Inula viscosa. Planta Medica 67: 726-731.Máñez, S., M. C. Recio, I. Gil, C. Gómez, R. M. Giner, P. G. Waterman & J. L. Ríos 1999. A glycosyl analogue of diacylglycerol and other antiinflammatory constituents from Inula viscosa. Journal of Natural Products 62: 601-604.

Murciego, A. M., A. G. Sánchez, M. A. R. González, E. P. Gil, C. T. Gordillo, J. C. Fernández & T. B. Triguero 2007. Antimony distribution and mobility in topsoils and plants (Cytisus striatus, Cistus ladanifer and Dittrichia viscosa) from polluted Sb-mining areas in Extremadura (Spain). Environmental Pollution 145: 15-21.

Omezzine, F., A. Rinez, A. Ladhari, M. Farooq & R. Haouala. 2011. Allelopathic potential of Inula viscosa against crops and weeds. International Journal of Agriculture and Biology 13: 841-849.

Parolin P, M Ion Scotta, & C Bresch. 2014. Biología de Dittrichia viscosa, una planta ruderal del Mediterráneo. Phyton (Buenos Aires) vol.83.

Philbey A. & A.G. Morton 2000. Pyrogranulomatous enteritis in sheep due to penetrating seed head of Dittrichia graveolens. Australian Veterinary Journal 78: 858-860

Pest and Damage Record Database, Plant Health and Pest Prevention Services, CA Department of Food and Agriculture. Assessed Date: 10/18/2016

Phytosanitary Export Database- USDA Phytosanitary Certificate issuance and Tracking system (PExD), Date Assessed: 10/18/2016. https://pcit.aphis.usda.gov/PExD/faces/PExDReport.jsp

Ratcliffe, D. 1976. Dittrichia in Flora Europaea Vol. 4: Plantaginaceae to Compositae. T. G. Tutin, V. H. Heywood, N. A. Burges, D. H. Valentine, S. M. Walters, & D. A. Webb, eds. Cambridge University Press. United Kingdom.

Sinden J., R. Jones, S. Hester, D. Odom, C. Kalisch & R. James (2004). The economic impact of weeds in Australia. Report to the CRC for Australian Weed Management. Pp. 1-65.

Thompson, J. D. 2005. Plant Evolution in the Mediterranean. Oxford University Press, Oxford.

USDA Plants; Dittrichia viscosa. Accessed 10/11/2016: http://plants.usda.gov/core/profile?symbol=DIVI6

Wacquant, J. P. 1990. Biogeographical and physiological aspects of the invasion by Dittrichia (ex-Inula) viscosa W. Greuter, a ruderal species in the Mediterranean Basin. Pp. 353-364 in Biological Invasions in Europe and the Mediterranean Basin. F. di Castri, A.J. Hansen, and M. Debussche, eds. Springer Netherlands, Dordrecht.


Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6650; plant.health[@]cdfa.ca.gov


Comment Period: CLOSED

45-day comment period: Dec 1, 2016 – Jan 15, 2017


Pest Rating: A  |   Proposed Seed Rating: P


Posted by ls