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Prickly Acacia | Vachellia Nilotica

California Pest Rating  for

Vachellia nilotica

Click on image for photo citation
Vachellia nilotica:  Prickly acacia
Solanales: Febaceae (Caesalpinioideae)
Pest Rating: A | Proposed Seed Rating: P
PEST RATING PROFILE
Initiating Event:

Vachellia (Acacia) nilotica is a federal noxious weed and is one of the 20 worst weeds in Australia because of its invasiveness, potential to spread, economic and environmental impacts. This invasive weed is currently not present in California but the climate conditions in the state are favorable for its growth and establishment. There is currently no pest rating designated for V. nilotica. A pest rating proposal is needed to assign a permanent rating.

History & Status:

Background: Vachellia nilotica (L.) P.J.H. Hurter & Mabb. is a medium sized tree that can reach a height of 10 m. The crown is flat or round and branches can droop downward. Young branches are smooth and grey to brown in color. Leaves are twice compound. The flowers are yellow, borne in small heads 1 cm in diameter and appear from September to January depending upon the rainy season. Pods are flat, straight or slightly curved, are fleshy when young with reddish hairs and are deeply constricted between each seed; they do not split but break open. This species occurs in wooded grassland and scrub escarpment, low lying forests, in deep soil and along rivers (South Africa National Biodiversity Institute, 2005).

Vachellia nilotica was introduced in Australia as a source of gum arabic and was cultivated as a fodder and shade plant for livestock in semi-arid pastures. It is also grown as garden ornamental in drier inland areas in Australia (Environmental Weeds of Australia, 2016).

Vachellia nilotica prefers semi-arid, warmer temperate, and sub-tropical regions but is also found in tropical environments and will grow near water sources in arid areas. It is most commonly found growing in grasslands, pastures and open woodlands. Within these plant communities it inhabits floodplains, open plains, gullies, areas near waterways (i.e. creeks and streams) and areas near other water sources (i.e. dams and bores). It also grows on recently cleared land, near stockyards and farm buildings, and along roadsides. (Environmental Weeds of Australia, 2016).

Worldwide Distribution: Vachellia nilotica is native to the arid and semi-arid regions of Africa and western Asia, the Indian sub-continent (i.e., India, Pakistan, and Myanmar) and the Arabian peninsula (i.e., Oman and Yamen). It has been introduced in China, Australia, the Caribbean, Indian Ocean islands, Mauritius, the United States, Central America, South America and the Galápagos Islands. It has naturalized in several countries where it has been introduced as a medicinal, forage and fuelwood plant (GRIN Database).

In the United States, it has been introduced in Arizona, California and Florida, Puerto Rico and Virgin Islands in the past. (Scher et.al, 2015).It has been introduced in China, Australia (in Northern Territory and Queensland where it is considered to be a pest plant of national importance), the Caribbean, Indian Ocean islands, Mauritius, the United States, Central America, South America and the Galápagos Islands. It has naturalized in several countries where it has been introduced as a medicinal, forage and fuelwood plant. It has been introduced in China, Australia (in Northern Territory and Queensland where it is considered to be a pest plant of national importance), the Caribbean, Indian Ocean islands, Mauritius, the United States, Central America, South America and the Galápagos Islands. It has naturalized in several countries where it has been introduced as a medicinal, forage and fuelwood plant.

 Official Control: Vachellia nilotica is a federal noxious weed (Federal Noxious Weed Regulations, 2010) and is listed as a harmful organism in French Polynesia, Honduras and New Zealand (PCIT-PExD).

California Distribution: Vachellia nilotica is not found growing in the natural environment in California.

California Interceptions:  Vachellia nilotica has never been intercepted by CDFA through any detection activities (border stations, high risk pest exclusion, detection surveys etc.).

The risk Vachellia nilotica (prickly acacia) would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Vachellia nilotica has the ability to grow in warm deserts, the south coast area of California is a possible habitat as these areas provide warmer and near tropical environments for its growth. However, the risk of invasion is high in near tropical areas where there are both good water supply to promote high seed production and presence of livestock to disperse seeds. It receives a Medium (2) 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) Known Pest Host Range: Weeds do not need one host but grow wherever ecological conditions are favorable. Vachellia nilotica receives a High (3) in this category.

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: Vachellia nilotica reproduces mainly by seed. It flowers in 3-4 years in ideal conditions. Mature tree can produce 200-3000 pods, each pod carrying 8-16 seeds. Seed production is higher during wet years where trees are close to water channels (Carter, 1998). Seeds are dispersed by large herbivores like cattle and sheep. Transportation of livestock that have ingested seeds can lead to dispersal over long distance. Seeds can also spread by water, particularly during floods after heavy rains and by mud adhering to legs of animals or vehicles. Strong winds can also carry seeds pods over short distances (Environmental Weeds of Australia, 2016). Vachellia nilotica 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: The spread of Vachellia nilotica trees can reduce the amount of available pasture for livestock. Dense thickets of V. nilotica trees can restrict access, impede the movement of vehicles and livestock, and may even reduce land values. Irrigation systems can become more expensive to operate because the tree can use some of the water (CABI 2017). Being a federal noxious weed and if it were to establish in California, it could impact international trade. (USDA APHIS Weed Risk Assessment). It receives a (High) in this category.

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

Economic Impact: A, C, 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:  Vachellia nilotica can outcompete pasture grasses for water in open forest and woodlands, and grasslands. Such losses of groundcover can facilitate water and wind erosion and leads to soil degradation. Serious invasion by this species can heavily disrupt natural communities. Approximately seven million hectares of the Mitchell grass plains in northern Australia have been infested by V. nilotica. Establishment of this species can cause a significant change in vegetation structure and can threaten the integrity and biodiversity of grassland communities. Changes in vegetation can pose a threat to survival of endangered species in these areas (Environmental Weeds of Australia, 2016). It receives a High (3) in this category.

Environmental Impact: A, B, C

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

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

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

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

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

Score the pest for Environmental Impact. Score:

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

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

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

Consequences of Introduction to California for Vachellia nilotica (prickly acacia): 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: Vachellia nilotica has never been found in the environment 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: High (13).

Uncertainty:

Vachellia nilotica is a listed as a federal noxious weed that may be introduced to California for cultivation as a fodder and shade plant for livestock in pasture areas and also as garden ornamentals in the inland areas. Because this species is economically useful, introduction can be possible through international transport by passengers. There are nine species in the Vachellia nilotica species complex; this can make it difficult to identify. Early detection surveys can confirm the presence of Vachellia nilotica. Since it has not established in California, its ability to invade the warm, dry areas of California is unknown.

Conclusion and Rating Justification:

Vachellia nilotica has not been found in the natural environment of California. If this species were to be cultivated deliberately or if introduced accidently, it could cause significant economic and environmental impacts. Therefore, as it is not yet established in California and invasion is possible, an “A” rating is justified.

References:

CABI, 2017. Acacia nilotica. In: Invasive Species Compendium. Wallingford, UK: CAB International. Accessed 10/11/2017

http://www.cabi.org/isc/datasheet/2342

CARTER, J. O. 1998. 7.2 Acacia nilotica: A tree legume out of control. Pp. 338–351 in H. M. Shelton and R. C. Gutteridge (eds.), Forage tree legumes in tropical agriculture. Tropical Grassland Society of Australia, St. Lucia, Queensland. Accessed 10/12/2017

https://www.cabdirect.org/cabdirect/abstract/19940601700

Environmental Weeds of Australia for Biosecurity Queensland 2016. Vachellia nilotica

Accessed 10/12/2017.

https://keyserver.lucidcentral.org/weeds/data/media/Html/vachellia_nilotica.pdf

Germplasm Resources Information Network (GRIN) Database 2015. Vachellia Nilotica (L.) P.J.H. Hurter & Mabb. Accesses 10/11/2017

https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?465206

Phytosanitary Certificate Issuance & Tracking System (PCIT), Phytosanitary Export Database (PExD), USDA, APHIS. Accessed 10/10/2017

https://pcit.aphis.usda.gov/PExD/faces/ReportFormat.jsp

South African National Biosecurity Institute 2005. Biodiversity of Life. Vachellia nilotica subsp. Kraussiana. Accessed 10/10/2017

http://pza.sanbi.org/vachellia-nilotica-subsp-kraussiana

Scher, J. L., D. S. Walters, and A.J. Redford. 2015. Federal noxious weed disseminules of the U.S., Edition 2.2. California Department of Food and Agriculture, and USDA APHIS Identification Technology Program. Fort Collins, CO. [10/11/2017]

http://idtools.org/id/fnw/factsheet.php?name=14575

Update of Federal Noxious Weed Regulations 2010. A Rule by USDA Animal and Plant Health Inspection Services.

https://www.federalregister.gov/documents/2010/11/10/2010-28346/update-of-noxious-weed-regulations

Weed Risk Assessment for Acacia Nilotica (L.) Willd. Ex Delile. Version 6, June 2, 2009. USDA Animal and Plant Health Inspection Services. National Weed Program Risk Assessment.

https://www.aphis.usda.gov/plant_health/plant_pest_info/weeds/downloads/wra/AniloticaWRA.pdf

Author:

Raj Randhawa, 1220 ‘N’ Street, Room 221, Sacramento CA 95814, (916) 654-0317, plant.health[@]cdfa.ca.gov

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.

*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;

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

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

Pest Rating: A | Proposed Seed Rating: P

Posted by ls

Weeds

Jewels of Opar/Fameflower | Talinum Paniculatum

pink flower in green leaves
Jewels of Opar/Talinum paniculatum | Photo by Ronggy
California Pest Rating for
Jewels of opar / Fameflower | Talinum paniculatum
 Family:  Portulacaceae
Pest Rating: C | Proposed Seed Rating: None
PEST RATING PROFILE
Initiating Event:

Jewels of opar was intercepted for the first time at the Needles border station in July 2017 (PRD NE0P06655879); this plant has not yet been rated. A pest rating proposal is required to determine a permanent rating for this pest.

History & Status:

Background:  Talinum paniculatum (jewels of opar or fameflower) is a fleshy, shrubby, erect, glabrous, herbaceous plant from the purslane family (Portulacaceae) that grows up to 120 centimeters tall. Jewels of opar is probably the most widespread species of the genus, as it is frequently encountered as a weed. The small, delicate, pink flowers in cloudlike panicles contrast attractively with the golden yellow, round seed capsules and are produced almost year-round. The leaves are glossy and bright green; they are sometime used as a vegetable1.

Worldwide Distribution: Jewels of opar is native to tropical America, but is now a pantropical weed. It occurs as an adventive scattered throughout tropical Africa, and is locally cultivated in Ghana and Nigeria4. Jewels of opar is also reported from Mexico, the West Indies, Central America, South America, and the southern United States. It was introduced to central Argentina, central Africa, and southern Asia2.

United States:  Jewels of opar is known from Arizona, New Mexico, Texas, Louisiana, Kentucky, North Carolina, South Carolina, Georgia, and Florida2. It is generally thought to be native to the southwest and adventive eastward, where it is often weedy1, 3.

map for Jewels of opar

California Distribution: Jewels of opar has not yet been detected in California, although it known to occur as greenhouse weed4.

Official Control: Jewels of opar is not considered to be a noxious weed by any State government authorities5.

California Interceptions: Jewels of opar was recently intercepted at the Needles border station in July 2017 in a shipment from Texas (PRD NE0P06655879)4.

The risk Talinum paniculatum (Jewels of opar) would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Jewels of oparis adapted to central and southern America and it would presumably thrive in similar climates. It may be able to establish in limited part of California but it does not seem to tolerate the summer drought found in most of CA. It receives a Low (1) 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: Jewels of opardoes 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: Jewels of opar reproduces by seed and stem cutting. The seeds are small (1 mm long), have a lenticular to comma-shape, and are produced in large numbers. There are about 5000 seeds per gram3. These seeds could be dispersed short distances by foraging animals, human activity, or by wind. They may be dispersed longer distances by vehicles and in contaminated agricultural produce. It receives a Medium (2) 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: Jewels of oparis considered to be a pantropical weed, but its invasiveness is not addressed in literature. It occurs in cultivated land, roadsides, and in forest edges. It rarely, if ever grows in dense stands, but can seed around grasslands in moist hot summer areas. It can be nuisance weed in greenhouses. It receives a Low (1) in this category.

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

Economic Impact:  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 1

– 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: Jewels of oparhas not yet naturalized in California, although it is common in heated greenhouses, especially those devoted to cacti & succulents. It 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 Talinum paniculatum (Jewels of opar): Low (8)

–Low = 5-8 points

–Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: Jewels of oparhas never been documented as naturalized 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: Low (8)

Uncertainty:

Jewels of opar has never been documented as naturalized in California but it was recently intercepted at the CDFA Needles Inspection Station. The environment of California is not new for this weed. It has been in greenhouses in CA for years and has not escaped; therefore, the uncertainty about this species is low.

Conclusion and Rating Justification:

Nevertheless, it can be nuisance weed in greenhouses and should be include in nursery cleanliness standards. 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 low risk weed. A “C” rating is recommended.

References:
  1. Encyclopedia of living forms. LLife, Online. Accessed August 7, 2017. http://www.llifle.com/Encyclopedia/SUCCULENTS/Family/Portulacaceae/32895/Talinum_paniculatum
  2. Flora of North America,     Accessed August 7, 2017.    http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200007021
  3. Philippine Medicinal Plants.    Accessed August 7, 2017. http://www.stuartxchange.org/Talinum.html
  4. Plantnet online.  Accessed August 7, 2017. http://uses.plantnet-project.org/en/Talinum_paniculatum_(PROTA)
  5. Pest and Damage Record Database, California Department of Food and Agriculture, Plant Health and Pest Prevention Services. Accessed August 7, 2017.  http://phpps.cdfa.ca.gov/user/frmLogon2.asp
  6. USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). Accessed August 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:

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.

*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: C | Proposed Seed Rating: None

Posted by ls

Weeds

Turkey Berry | Solanum torvum

TURKEY BERRY
California Pest Rating for
Turkey Berry |  Solanum torvum
Solanales: Solanaceae
Pest Rating: C |  Proposed Seed Rating: N/A
PEST RATING PROFILE
Initiating Event:

Solanum torvum was recently intercepted by Los Angeles County Agricultural commissioner’s office at Long beach on 7/20/2017. Molecular analysis has confirmed the identification of this species on 8/11/2017. This invasive weed has been given a temporary Q rating. A pest rating is required to assign a permanent rating for this species.

History & Status:

Background: Solanum torvum is an evergreen, multi-branched shrub or small tree that grows to 16 feet high. Leaves bear star shaped (stellate) hairs and scattered, flattened, broad-based, straight to slightly hooked prickles. Fruits are globose to ovoid, about half an inch wide and borne in erect clusters. Each fruit contains about 200 seeds (FDACS). The root system includes a deep and strong woody taproot with numerous woody laterals. Solanum torvum grows in a wide range of habitats throughout the tropics and the subtropics. It grows best in warm, moist, fertile conditions but once established it can withstand drought by shedding its leaves (CABI 2016). It is cultivated for its edible fruits that are eaten when immature (Langland and Burks, 1998)

Solanum torvum invades human disturbed open sites and is a major weed in pastures, roadsides, wastelands and plantations. It prefers moist, fertile soil but can also tolerate draught. It can form dense thickets in disturbed areas such as vacant lots, brushy pastures, recently abandoned farms, landslides and river banks; it is considered a weed in Florida, Hawaii, Papua New Guinea, French Polynesia and Tonga (Wagner et-al. 1999)

Worldwide Distribution:  Solanum torvum is native to the Antilles (Wagner et al. 1999). Langeland and Burks (1998) report that S. torvum is native from Mexico to Peru and Venezuela, and in the West Indies and Bermuda where it occurs in wet thickets, dry brushy plains, woodland clearings, and rocky hillsides. It is cultivated throughout the world for its edible fruits (Wagner et al. 1999) and has become a pantropical weed. S. torvum is reported as a weed in Florida, Hawaii, Australia, French Polynesia, Tonga, Samoa, Papua New Guinea, and elsewhere (PIER 2003, PLANTS 2003).

Official Control: Solanum torvum is reported as a harmful weed in China, Fiji, French Polynesia, Israel, Republic of Korea and Peru (PCIT-PExD). In the U.S., it is a federal noxious weed. This species has been listed as a noxious weed in Alabama, Florida, Hawaii, Minnesota, North Carolina, Vermont, Massachusetts, South Carolina, Oregon and California (USDA- NRCS)

California Distribution:  Solanum torvum has not been found growing in the natural environment of California.

California Interceptions:  Solanum torvum was intercepted seven times between January 1, 1990 and August 22, 2017 by CDFA’s high risk inspections, dog teams, and project survey for weeds.  Most of the interceptions have been in shipments from Florida.

The risk Solanum torvum (turkey berry) would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Solanum torvum has established as a weed in the tropics of Florida and Hawaii. Since this species predominantly dominates human disturbed open sites and is rarely found on naturally disturbed sites (Nature Serve Explorer 2017), it has a limited potential of becoming established in sub-tropical areas in southern California and the central coast. Solanum torvum 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) Known Pest Host Range:  Solanum torvum does not require one particular host, but grows wherever ecological conditions are favorable. Even though it can grow and establish in disturbed and open areas, it might grow poorly in the lower humidity environment of California. This species cannot survive under closed forest canopy areas (PIER (Pacific Islands Ecosystems at Risk). It receives a Low (1) in this category.

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: Solanum torvum reproduces solely by seeds. Seedlings establish their roots quickly and become woody. Pollination is by insects. The seeds are spread by fruit eating birds and bats as well as by construction machinery and contaminated soil (CABI: Datasheet: Solanum torvum). This species was initially introduced to many areas through cultivation of its edible fruit. Unless introduced to California through cultivation, it is not likely to spread and get established. It 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: Solanum torvum is an invasive weed of pastures, roadsides and open native vegetation. It is also found in cassava and other perennial crops not exposed to cultivation (CABI) and can potentially reduce yield of these crops. None of these crops are grown in California. If this species were to establish in CA, use of various control methods could increase crop production costs. torvum is potentially poisonous to animals and possibly carcinogenic to humans. (Cuda and Parker et. al 2002). S. torvum is resistant to Meloidogyne spp and is used as a rootstock for grafting tomatoes in susceptible areas. Its resistance to Pseudomonas solanacearum and phomopsis fruit rot has also been reported (CABI). It receives a Medium (2) in this category.

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

Economic Impact: B, 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: Establishment of Solanum torvum can impact native biodiversity in the wet tropics due to its ability to form large, impenetrable thickets that can displace native species and alter vegetation structure in formerly open areas. However, it is also possible that its impact will not increase in future. (Nature Serve 2017). It receives a Medium (2) in this category.

Environmental Impact: A

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

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

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

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

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

Score the pest for Environmental Impact Score: 2

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

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

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

Consequences of Introduction to California for Solanum torvum (turkey berry): Low (8)

Add up the total score and include it here.

–Low = 5-8 points

–Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: Solanum torvum has never been found in the environment 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: Low (8)

Uncertainty:

Solanum torvum is a federal noxious weed that may be introduced to California, as it is cultivated in certain parts of the world for its edible fruit. If introduced either through cultivation or by artificial means, it is less likely to spread to open, disturbed and abandoned farm land, pastures and riverbanks because of limited availability of water in California. Presence of similar Solanum species can complicate identification; however, early detection surveys in California can confirm the presence and possibly eradication this species if it were found in a small area. Wet tropical weeds can become nursery or row crop weeds in CA, but this is not common.

Conclusion and Rating Justification:

Solanum torvum (turkey berry) has never been found in the environment of California; it is less likely to have a significant economic and environmental impact if it were to enter the state. Nevertheless, it could be invasive in limited, irrigated areas & it is a federal noxious weed. Therefore a “C” rating is justified.

References:

Solanum Torvum – UF/IFAS Center for Aquatic and Invasive species, Florida Department of Agriculture and Natural Resources (FDACS)

http://www.freshfromflorida.com/Divisions-Offices/Plant-Industry/Bureaus-and-Services/Bureau-of-Entomology-Nematology-Plant-Pathology/Botany/Noxious-Weeds/Solanum-torvum-turkeyberry

Center for Agriculture and Biosciences International (CABI) Datasheet: Solanum Torvum (turkey berry).

http://www.cabi.org/isc/datasheet/50559

Cuda, J.P., Parker, P.E. and Coon, B.R. et al. 2002. Evaluation of exotic Solanum spp. (Solanales: Solanaceae) in Florida as host plants for the leaf beetles Leptinotarsa defecta & L. Texan (Coleoptera: Chrysomelidae). Florida Entomologist. 85(4): 599-610.

Langeland, K.A. and K.C. Burks. 1998. Identification and Biology of Non-Native Plants in Florida’s Natural Areas. University Press of Florida, Gainesville, FL. Nature Serve Explorer 2017. Solanum torvum

http://explorer.natureserve.org/servlet/NatureServe?searchName=Solanum+torvum

PIER (Pacific Islands Ecosystems at Risk). 2002. Invasive Plant Species: Solanum torvum. Available: http://www.hear.org/pier

PLANTS (National Plants Database). 2003. Online database. United States Department of Agriculture (USDA), Natural Resources Conservation Services (NRCS), National Plant Data Center, Baton Rouge, LA. Available: https://plants.usda.gov/core/profile?symbol=SOTO4

Pest and Damage Report Database, Plant Health And Pest Prevention Services, California Department of Food and Agriculture.

http://phpps.cdfa.ca.gov/index.asp

Starr, Forest, Starr Kim and Lloyd Loope, April 2013, United States Geological Survey—Biological Resources Division, Haleaka Field Station, Maui, Hawaii

Swarbrick, John T. 1997. Weeds of the Pacific Islands. Technical paper no. 209. South Pacific Commission, Noumea, New Caledonia.

USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) –Phytosanitary Export Database (PExD). Harmful organism by country and commodity report- Solanum torvum. https://pcit.aphis.usda.gov/PExD/faces/PExDReport.jsp

Wagner, Warren L. /Herbst, Derral R. /Sohmer, S. H. 1999. Manual of the flowering plants of Hawaii. Revised edition. Bernice P. Bishop Museum special publication. University of Hawai‘i Press/Bishop Museum Press, Honolulu.

Author:

Raj Randhawa, California Department of Food and Agriculture

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0317; plant.health[@]cdfa.ca.gov.

*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.

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

Posted by ls

Weeds

Giant Reed | Arundo donax

Giant Reed
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 donax:  Rating (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

Pest Rating: B  | Proposed Seed Rating: R

Posted by dk

Weeds

Balloon Plant | Asclepias physocarpa

Ballon Plant
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 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: 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

*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

A-Rated, Weeds

Alligatorweed | Alternanthera philoxeroides

California Pest Rating for
white flower with green leaves
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.

*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

Weeds

Smallflower Hawksbeard | Crepis pulchra

California Pest Rating for
Crepis pulchra: Smallflower hawksbeard
Family:  Asteraceae 
Pest Rating: C | Proposed Seed Rating: R
PEST RATING PROFILE
Initiating Event:

Crepis pulchra had no previous pest rating; it has been reported in Napa, Solano and Contra Costa counties. A pest rating proposal is required to determine a permanent rating for this pest.

History & Status:

Background: Crepis pulchra is a flowering plant in the daisy family with the common name smallflower hawksbeard. Crepis pulchra is widespread in Europe, Central Asia and parts of Africa. It has become naturalized in the parts of United States and Canada1. It is annual herb up to 40 inches tall with erect, glandular stem. One plant can produce up to 40 flower heads and each flower can produce 30 yellow ray florets. The leaves are alternate, toothed and the basal leaves are pinnately lobed. Flowering occurs from April to August. It can grow up to 3000 m elevation in dry open habitats, rolling grasslands, pastures, abandoned fields, waste areas, railroads and roadsides1.

Worldwide Distribution: Crepis pulchra is widespread across much of Europe, Morocco, Algeria, western and central Asia. It has been  reported in Ontario Canada  and TX, OK, MO, AR, LA, MS, AL, FL, GA, SC, NC,VA, DE, WV, OH, IL, KY, TN & OR in the United States3,1.

Official Control: Crepis pulchra is not declared or considered noxious by any state government authorities7.

California Distribution:  Crepis pulchra currently is known in limited areas of Solano, Napa & Contra Costa counties2.

California Interceptions: There were 8 vouchers submitted from Solano, Napa & Contra Costa counties between 1999 and 20112.

The risk Crepis pulchra (Smallflower hawksbeard) would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: The plant has adapted to a wide area in the eastern states and Oregon. California has similar ecologically conditions as its native range, so it may be established on a larger but limited part of California. Therefore Crepis pulchra 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: 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: Crepis pulchra reproduces only by seed; each plant can produce 40 seeded fruits5. These fruits are dispersed short distances by foraging animals, human activity or by wind. They may be dispersed longer distances by vehicles, on larger animals and in contaminated agricultural produce. It receives a Medium (2) 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: Crepis pulchra is a weed in some agricultural situations and it may reduce crop yield where it establishes. It receives a Low (1) in this category.

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

Economic Impact: A

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: 1

– 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: Crepis pulchra has not yet spread widely in California. If it does spread, it might trigger new chemical treatments by ranchers and land managers. It receives a Medium (2) in this category.

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

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 Crepis pulchra (Smallflower hawksbeard): Medium (10)

–Low = 5-8 points

–Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: Crepis pulchra has been reported in Napa, Solano & Contra Costa counties and seems likely to be restricted to this area at this time. 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: Medium (9)

Uncertainty:  

Crepis pulchra has been present in California about 30 year ago and it is localized in a limited area. Due to its relatively noninvasive nature, there are limited chances that it will spread widely in 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 medium risk. A “C” rating is recommended, because of lake of evidence of its invasiveness.

References:
  1. Flora of North America online.  Accessed March 9, 2017 http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242416376
  2. Jepson Herbarium. Online UC Berkeley.  Accessed March 9, 2017  http://ucjeps.berkeley.edu/cgi-bin/get_consort.pl?taxon_name=Crepis%20pulchra
  3. Plant profiles  USDA    Accessed March 9, 2017 https://plants.usda.gov/core/profile?symbol=CRPU3
  4. 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
  5. Wildflower of the southeastern US.   Accessed March 9, 2017  http://2bnthewild.com/plants/H270.htm
  6. S. National Plant Germplasm System Accessed March 9, 2017 https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?id=310895
  7. USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). Accessed January 03, 2017 https://pcit.aphis.usda.gov/pcit/
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.

*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.]

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Pest Rating: C | Proposed Seed Rating: R

Posted by ls

Weeds

Jeweled distaff thistle | Carthamus oxyacantha

2 Comments

Jewel distaff thistle (photo by Steve Hurst, hosted by the USDA-NRCS PLANTS Database)
Jewel distaff thistle (photo by Steve Hurst, hosted by the USDA-NRCS PLANTS Database)

California Pest Rating for
Jeweled distaff thistle | Carthamus oxyacantha
Family:  Asteraceae
Pest Rating: B | Proposed Seed Rating: P
PEST RATING PROFILE
 Initiating Event:

Jeweled distaff thistle was reported in California in the late 1970’s and had no previous pest rating. A pest rating proposal is required to determine a permanent rating for this pest.

History & Status:

Background: Jeweled distaff thistle is a spiny-leaved annual weed that can grow up to 1.5 m tall. Like other spiny plants in the genus Carthamus, this species is not eaten by livestock, enabling it to spread on grazing lands2. The yellow flowers are born in flower heads approximately two to three cm in diameter and the leaves are covered with spines. It is a wild safflower relative found in arid and semi-arid environments in central and southern Asia5. It was collected in 1978 in Monterey County, California. It is considered by the United States Department of Food and Agriculture to be a noxious weed subject to eradication if found. Jeweled distaff thistle is a pernicious weed of agricultural lands especially, it reduces the yield of cereal crops. Jeweled distaff thistle most closely resembles cultivated safflower; it has smaller heads and much spinier leaves1.

Worldwide Distribution: Jeweled distaff thistle is reported from Afghanistan, India, Iran, Iraq, Saudi Arabia, Syria, Kyrgyzstan, Uzbekistan, Pakistan, Azerbaijan, Armenia, Tajikistan and Turkmenistan4.

California Distribution:  It was reported only in Monterey County, where it may be eradicated.

Official Control: Jeweled distaff thistle is listed as a harmful organism in

Colombia, Honduras and Mexico6. It is listed by U.S. Federal government as Noxious weed in Florida, Minnesota South Carolina, Massachusetts and Class

“A” Noxious weed for Alabama, North Carolina and Vermont7.

California Interceptions: Historically, only two vouchers were submitted in 1978 from Monterey County3.

The risk Carthamus oxyacantha (Jeweled distaff thistle) would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Jeweled distaff thistle is adapted to central and southern Asia and similar climates. It may able to establish in a larger but limited part of California like Carthamus tinctorius. 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: Jeweled distaff thistle 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: Jeweled distaff thistle reproduces only by seed; each plant can produce up to 36 flower head that produces 15 to 20 single-seeded fruits5. These flower heads are dispersed short distances by foraging animals, human activity or by wind. They may be dispersed longer distances by vehicles, on larger animals and in contaminated agricultural produce. It receives a Medium (2) 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: Jeweled distaff thistle could invade crops, especially summer season crops in California. It could decrease crop yield and can lower the crop value, as it has been reported in its native range. Where adapted it displaces both native plants and other plants; this could negatively change normal cultural practices. It had spiny-tipped leaves with phyllaries heads which could injured the agriculturally important animals.  It receives a High (3) in this category.

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

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: Jeweled distaff thistle has not yet spread widely in California. If it does spread, it might trigger new chemical treatments by ranchers and land managers. It receives a Medium (2) in this category.

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

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 Carthamus oxyacantha (Jeweled distaff thistle): Medium (12)

–Low = 5-8 points

–Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: Jeweled distaff thistle has been reported only in Monterey County and seems likely eradicated in this area. 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 (11)

 Uncertainty:

Jeweled distaff thistle has been known in California for decades, although it has not yet spread widely, there is nothing to stop it spreading in the appropriate habitats. There is some uncertainty as to how well it can spread in California if it escapes.

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 medium risk weed with a distribution in Monterey County. A “B” rating is recommended, as the plant is invasive and is a federal noxious weed.

References:
  1. Flora of North America  online   Accessed April 26, 2017. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200023631
  2. Federal Noxious Weed Dissminules of U.S. Accessed May 9, 2017.    http://keys.lucidcentral.org/keys/FNW/FNW%20seeds/html/fact%20sheets/Carthamus%20oxyacantha.htm
  3. 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. Accessed May 9, 2017.
    http://ucjeps.berkeley.edu/cgi-bin/get_consort.pl?taxon_name=Carthamus+oxyacantha&county=06053
  4. US National Plant Germplasm system. Accessed May 9, 2017. https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?9239
  5. Sullaiman Mohammed, Mohammad A Fredan 2015, American Journal of Environmental Sciences. Accessed May 9, 2017.
    http://thescipub.com/PDF/ajessp.2015.125.132.pdf
  6. USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). Accessed May 9, 2017
    https://pcit.aphis.usda.gov/pcit/
  7. USDA  Natural Resouces Conservation Services online. Accessed May 9, 2017
    https://plants.usda.gov/core/profile?symbol=CAOX6
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.

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: B | Proposed Seed Rating: P

Posted by ls

Weeds

Laportea canadensis

Canadian wood-nettle and photographed at Brooklyn Botanic Garden 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

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

Weeds

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 Distribution:  Branched 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

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

Weeds

Myrtle Spurge | Euphorbia myrsinites

Flower in California
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

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

Weeds

Sahara Mustard | Brassica tournefortii

1 Comment
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

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