Plants (weeds)
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Posted by ka
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Posted by ka
Robert Price, CDFA Primary State Botanist. 3294 Meadowview Road, Sacramento, CA 95832
plant.health[@]cdfa.ca.gov.
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Posted by ka
Karen Olmstead, Environmental Scientist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6879; plant.health[@]cdfa.ca.gov
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
Updated on 7/12/2019 by ls
Karen Olmstead, Environmental Scientist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6879; plant.health[@]cdfa.ca.gov
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
Updated by ls
Raj Randhawa, 1220 ‘N’ Street, Room 221, Sacramento CA 95814, (916) 654-0317, plant.health[@]cdfa.ca.gov.
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.
Updated on 7/12/2019 by ls
Convolvulus arvensis is currently C-rated. A pest rating proposal is required to support an official pest rating based on current information.
Background: Convolvulus arvensis is a deep-rooted perennial herb with prostrate stems. The leaves are hairless and obovate with a notched base, and they reach up to 7.5 cm long and 3 cm wide. The flowers are trumpet shaped, white to pink in color, and 2.5 cm to 3.8 cm inches wide. Reports indicate that seeds of this species can persist in soil for up to 60 years and the roots are reported to grow up to 30 feet deep (Appleby, 1999). It is a highly invasive garden and agricultural weed that difficult to eradicate. It is also found in other habitats, including wooded areas.
Worldwide Distribution: Convolvulus arvensis is native to Eurasia and has been introduced widely to temperate and tropical regions throughout the world. It may be found between 60°N and 45°S latitude (Discover Life, 2016).
Official Control: Convolvulus arvensis is listed as a harmful organism in Australia, Ecuador, Honduras, Nauru, Nicaragua, and Taiwan. It is listed as a noxious weed in Alaska, Arizona, Arkansas, Hawaii, Idaho, Iowa, Kansas, Michigan, Minnesota, Missouri, Montana, North Dakota, South Dakota, Texas, Utah, Wisconsin, Wyoming, California, Colorado, New Mexico, and Oregon.
California Distribution: Convolvulus arvensis was first reported in California in 1850 in San Diego (CalFlora 2018, CCH 2018). It has since spread, and it is documented from all counties in California except Del Norte.
California Interceptions: Convolvulus arvensis has been intercepted 123 times from 2003 through September 2018 by CDFA. These interceptions were mostly through seed certification program and general botany surveys (PHPPS- PDR Database).
The risk Convolvulus arvensis (field bindweed) would pose to California is evaluated below.
1) Climate/Host Interaction: Convolvulus arvensis has become widely established throughout California, so it has demonstrated that the climates and habitats found in the state are conducive to its establishment. This plant can grow in nurseries, crops, vineyards, and range land. Therefore, it receives a High (3) 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: Convolvulus arvensis 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: Convolvulus arvensis spreads by seed and sprouted rhizomes and roots. Each plant produces up to 500 seeds that can be viable in the soil for up to 20 or more years. These seeds can be dispersed by birds, water, and contaminated farm vehicles. The most common dispersal method of this weed is the use of contaminated seed stocks in Commerce. It receives a High (3) in this category
Evaluate the natural and artificial dispersal potential of the pest.
– Low (1) does not have high reproductive or dispersal potential.
– Medium (2) has either high reproductive or dispersal potential.
– High (3) has both high reproduction and dispersal potential.
Evaluate the economic impact of the pest to California using the criteria below.
Economic Impact: A, B, C, 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: Convolvulus arvensis can compete with native vegetation for nutrients, moisture, space, and light, which could decrease the biodiversity of infested areas in California. Infestations of this plant could trigger additional private treatment programs in infested areas. It receives a High (3) in this category.
Evaluate the environmental impact of the pest on California using the criteria below.
Environmental Impact: A, 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.
–Low = 5-8 points
-Medium = 9-12 points
-High = 13-15 points
6) Post Entry Distribution and Survey Information: Convolvulus arvensis is fully established and widespread 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.
The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (12)
Convolvulus arvensis has been in California for over 120 years and it has become established in every county except Del Norte, although in limited areas. Therefore, it is little uncertainty associated with this assessment.
Based on the score listed above, Convulvulus arvensis is medium risk. It will continue to spread, but it is already widespread through the state. Because it is so widespread in California, a “C” rating is recommended.
Appleby, A. 1999. Field bindweed (Convolvulus arvensis). Accessed September 19, 2018.
http://www.css.orst.edu/newsnotes/9903/weed.html#Field Bindweed
CABI Crop Protection Compendium online data sheet. Convolvulus arvensis (bindweed). CABI Publishing 2011. Accessed September 18, 2018
https://www.cabi.org/isc/datasheet/15101
CalFlora: Information on California plants for education, research and conservation. Accessed September 18, 2018.
http://www.calflora.org/
Consortium of California Herbaria [CCH], 2018. Data provided by the participants of the Consortium of California Herbaria. Regents of the University of California. Accessed September 2018. http://ucjeps.berkeley.edu/consortium/.
Phillips, W. and Timmons, F. 1954. Bindweed – how to control it. Bulletin 366, Fort Hays Branch, Kansas Agricultural Experimental Station, Manhattan, Kansas, USA.
Pest and Damage Record Database, California Department of Food and Agriculture, Plant Health and Pest Prevention Services. Accessed September 18, 2018. http://phpps.cdfa.ca.gov/user/frmLogon2.asp
University of California Agriculture and Natural Resources. Accessed September 18, 2018.
http://ipm.ucanr.edu/PMG/PESTNOTES/pn7462.html
USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). Accessed September 19, 2018.
https://pcit.aphis.usda.gov/pcit/
Javaid Iqbal; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6695
Dean Kelch, Primary State Botanist, California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6650; plant.health[@]cdfa.ca.gov.
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Posted by ls
Vallisneria americana was observed growing in water district pond in Shasta county in 2007. Vallisneria species have been intercepted by county and at CDFA border stations in 2011, 2016 and 2018. This species is introduced to California. It has been given a temporary rating of Q by CDFA. A pest rating proposal is required to assign a permanent rating.
Synonyms: Vallisneria neotropicalis (ITIS Database)
Background: Vallisneria americana is a submersed perennial plant that is common in both still and fast flowing waters. It is a popular aquarium plant. It needs 5 cm thick of rich soil, full light and water temperature of 18-20 degrees Celsius for cultivation (Lady Bird Johnson Wildflower Center 2016).
Vallisneria americana grows from underground runners, and forms tall underwater meadows. Its leaves are approximately one-inch wide and several feet long and arise in clusters from the roots. The leaves have rounded tips and raised veins. The upper leaf parts often float on the water surface. This species produces separate male and female flowers. Female flowers are more conspicuous. Mature flowers detach and float on the surface of water. The fruit is a banana-like capsule and contains tiny seeds (University of Florida, 2018).
The native range of Vallisneria americana incudes Asia, Australia, North America, Central America, and South America. It prefers slow moving water and is mainly found in lakes, ponds and streams at least 10 feet deep. Fishes and invertebrates use this species as a refuge. This plant also grows in brackish water and in rivers with various salinity levels (Brand, 2015).
Worldwide Distribution: Vallisneria americana is widely distributed in eastern North America and is present in Canada, Cuba, Dominican Republic, Guatemala, Haiti, Honduras, Jamaica, Mexico and the United States. (IUCN Red List of Threatened Species).
In the Unites States, Vallisneria americana is present in the eastern states and specimens have been collected from Connecticut, Florida, Illinois, Louisiana, Minnesota, North Carolina, Ohio, Vermont, Virginia and Wisconsin (Wunderlin et-al., 2018) and spreading towards the west coast, being reported in Washington, Arizona, New Mexico, Texas, Nebraska (Lady Bird Johnson Wildflower Center 2016).
Official Control: Vallisneria americana has been reported as a harmful organism in Indonesia and Timor-Leste and is under official control (USDA- APHIS- PCIT).
California Distribution: Vallisneria americana has been observed occurring naturally in Shasta county and a voucher specimen has been confirmed by the CDFA Plant Pest Diagnostics Center (Consortium of California Herbaria, 2018).
California Interceptions: Vallisneria species have been intercepted few times by CDFA, through border station inspections and through weed and vertebrate surveys (Pest and Damage Report Database, 2018).
The risk Vallisneria americana (American eelgrass) would pose to California is evaluated below.
1) Climate/Host Interaction: Vallisneria americana grows in lakes and slow-moving rivers, primarily in neutral to basic waters (IUCN). It grows from stoloniferous clumps submerged under water. In shallow waters, its leaves can float the on surface of the water. It can grow well in wetland gardens and habitats. It is likely to grow in lakes, ponds, reservoirs and rivers in California. (Lady Bird Johnson Wildflower Center 2016) 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: Vallisneria americana do not require one host but can occur wherever environmental conditions are favorable for its growth and establishment. It receives a Medium (2) 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: Vallisneria americana reproduces through seeds in its natural habitat, but flowering is rare and most reproduction is through vegetative spread via runners in aquariums. These runners root and form a new plant. It is likely to disperse through water and humans. As it is dioecious with male and female flowers on different plants, it is unlikely to produce seed in an introduced population. Therefore, only vegetative reproduction is likely. It receives Low (-1) 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: Vallisneria americana is good source of turtles and other aquatic wild life. It is also good for wetland gardens and habitats. This species is most likely to be introduced through aquarium plants that are discarded. If established, Vallisneria americana could impede water flow in irrigation canals and storage ponds. It could affect drainage of water bodies and can impact their agricultural and recreational use (CABI 2018). Once this species is well established, it can be difficult to remove. Vallisneria americana can serve as a nursery for fishery species. It can also stabilize shorelines and improve water quality by filtering. It receives a Low (1) in this category.
Evaluate the economic impact of the pest to California using the criteria below.
Economic Impact: 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: 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: Vallisneria americana is an important food to canvasback ducks. Its dense underwater structures provide a great habitat for fish and invertebrates (New England Wild Flower Society 2011-2018). Vallisneria americana provides both food and refuge for many aquatic species. Like Vallisneria spiralis, this species may form dense beds resulting in displacement of native aquatic plants (MAF Biosecurity New Zealand 2010). Because Vallisneria americana is a common species of submerged aquatic vegetation in low salinity estuarine areas, it seems likely to become established in wetlands in California (Rozas and Minello, 2006). 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.
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.
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: Vallisneria americana has been found growing in a settling pond in northern California but has not fully established in the state and 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.
The final score is the consequences of introduction score minus the post entry distribution and survey information score: Low (7)
Vallisneria americana has been observed growing in a man-made pond in a very limited area of California. Suitable aquatic habitats exist for this species in parts of CA. However, despite the widespread use of this species as an aquarium plant for over a century and its ability to spread vegetatively in open waters, it has not yet established in California.
Vallisneria americana has been only observed in California in 2007 and has not caused any significant impacts to state agriculture and the natural environment. Though it is popular in the aquarium trade, it is not established in CA except for a small area in Shasta county despite its widespread distribution in North America and elsewhere. Therefore, a “D” rating is justified.
Brand, R. 2015. Jungle Val – How to Grow and Take Care for Jungle Vallisneria. Aquarium Tidings. Your source for aquarium information since 2010. Retreived 7/17/2018. https://aquariumtidings.com/jungle-val-vallisneria/
CABI. 2018. Invasive species compendium. Vallisneria spiralis (eel weed). Retrieved 7/23/2018. https://www.cabi.org/isc/datasheet/56573
CDFA Pest and Damage Report Database. 2018. Vallisneria americana. Plant Health and Pest Prevention Services. CA Department of Food and Agriculture. Retrieved 07/18/2018. http://phpps.cdfa.ca.gov/user/frmLogon2.asp
Center for Aquatic and Invasive Plants. 2018. University of Florida. Institute of Food and Agricultural Sciences. Retrieved 7/18/2018. http://plants.ifas.ufl.edu/plant-directory/vallisneria-americana/
Consortium of California Herbaria. 2018. Data provided by the participants of the CCH. University of California. Retrieved 7/23/2018. http://ucjeps.berkeley.edu/cgi-bin/get_consort.pl
Integrated Taxonomic Information System (ITIS) on-line database. ITIS Report. Vallisneria americana Michx. Taxonomic Serial No. 38591. Retrieved 07/23/2018. http://www.itis.gov/citation.html
IUCN. 2016. The IUCN Red List of Threatened Species. Version 2016-1. Retrieved 7/28/2018. www.iucnredlist.org.
Lady Bird Johnson Wildflower Center. 2016. Inspiring the conservation of native plants. Vallisneria americana Michx. University of Texas, Austin. Retrieved 7/18/2018. https://www.wildflower.org/plants/result.php?id_plant=VAAM3
MAF Biosecurity New Zealand. 2010. Eelgrass: Vallisneria spiralis. Eelgrass: Vallisneria spiralis. Retrieved 7/24/2018. http://www.biosecurity.govt.nz/pests/vallisneria-spiralis
New England Wild Flower Society, 2011-2018. Vallisneria americana Michx. 180 Hemenway Road, Framingham, MA 01701. Retrieved 7/24/2018. https://gobotany.newenglandwild.org/species/vallisneria/americana/
Rozas, L. P. and Minello, T.J. 2006. Nekton use of Vallisneria americana Michx. (wild celery) beds and adjacent habitats in coastal Louisiana. Estuaries and Coasts 29:297-310. Retrieved 07/23/2018. http://www.galvestonlab.sefsc.noaa.gov/research/fishery_ecology/recentresearch/wildcelery/index.html
USDA Natural Resources Conservation Service. 2018. PLANTS Profile. Vallisneria americana Michx. USDA NRCS National Plant Data Team. Retrieved 7/24/2018. https://plants.usda.gov/core/profile?symbol=VAAM3
USDA Phytosanitary Certificate Issuance & Tracking System (PCIT), Phytosanitary Export Database (PExD). Harmful organism report: Vallisneria americana. Accessed 07/17/2018. https://pcit.aphis.usda.gov/PExD/faces/ReportFormat.jsp
Wunderlin, R. P., Hansen, B.F., Franck, A. R., and Essig, F.B., 2018. Atlas of Florida Plants [S. M. Landry and K. N. Campbell, USF Water Institute.] Institute for Systematic Botany, University of South Florida, Tampa. Retrieved 07/24/2018. http://florida.plantatlas.usf.edu/
Raj Randhawa, 1220 ‘N’ Street, Room 221, Sacramento CA 95814, (916) 654-0317, plant.health@cdfa.ca.gov.
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.
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.
♦ 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;
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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.
Posted by ls
This plant has been rated as “Q” on the CDFA Plant Pest Rating list for 2 years.
The genus Volutaria comprises plants in the thistle tribe (Cardueae) of the daisy family (Asteracaeae). Many of the 17 species in this genus were originally described in the genus Centaurea, the genus that includes star-thistles, knapweeds, and bachelor’s buttons; the two genera are closely related. Volutaria differs from Centaurea in lacking a terminal spine shield on the tips of the inflorescence bracts and in having flowers subtended by scales rather than bristles. Desert knapweed is a pink-flowered (sometimes white-flowered in Southeastern Morocco), annual or short-lived perennial species. It was collected from a naturalized population near Anza Borrego in San Diego County, California. At this spot, it was tentatively identified as Canary Island knapweed (Volutaria canariensis), a closely related species endemic to the Canary Islands. Desert knapweed seems to be spreading steadily in the Anza Borrego Area. Another species, Volutaria muricata, was introduced to limited localities in three counties in Southern California along the coast. We have no current information on its range and persistence. However, several species within the Centaurea group are known noxious weeds in California, including purple starthistle (Centaurea calcitrapa), diffuse knapweed (Centaurea diffusa), Iberian starthistle (Centaurea iberica), spotted knapweed (Centaurea stoebe), Malta starthistle (Centaurea melitensis), meadow knapweed (Centaurea jacea s.l.), yellow starthistle (Centaurea solstitialis), and squarrose knapweed (Centaurea squarrosa).
Desert knapweed has the largest native range of any species of Volutaria. It is widespread across northern Africa, as well as in other areas of the Region, where it inhabits drier localities and desert transition zones. Its expansion into some of these areas may be recent. It prefers nitrogen enriched soils and therefore has proven to spread rapidly along roadsides, as well as in dry farming areas and irrigated fields.
The San Diego County Agricultural Commissioner’s office initiated control measures against this plant. They are part of a coordinated effort to eradicate this plant from North America by County, State, and city staff, as well as by the non-profit organization CalIPC and private volunteers.
Worldwide Distribution: Desert knapweed occurs throughout North Africa from Morocco to Egypt, in southern Europe (Spain, Sicily, and Turkey), the Canary Islands, and in Arabia. There is a recent report of it being detected in Chile. In North America the only known populations of Desert knapweed are in southern California.
Official Control: Desert knapweed is currently listed on the California noxious weed list (under the name Volutaria canariensis; Canary Island knapweed). Desert knapweed has been recently (8/2018) as a Category A noxious weed in the state of Nevada.
California Interceptions: Desert knapweed was found after it had established along a road in the Anza Borrego Desert in 2009 (San Diego County). A new detection of a small colony along Newport Bay in Orange County was reported in 2015 and the Chula Vista plants in 2016 (San Diego County).
1) Climate/Host Interaction: Evaluate if the pest would have suitable hosts and climate to establish in California.
Risk is High (3), as the plant is naturalized on roadsides in the desert, where it is spreading rapidly. Two more recent finds in Orange and San Diego counties indicate that it may invade southern coastal areas in California as well.
Score: 3
-Low (1) Not likely to establish in California; or likely to establish in very limited areas.
-Medium (2) may be able to establish in a larger but limited part of California.
-High (3) likely to establish a widespread distribution in California.
2) Known Pest Host Range: Evaluate the host range of the pest.
Risk is high (3) as weeds do not require any one host, but grow wherever ecological conditions are favorable.
Score: 3
-Low (1) has a very limited host range.
-Medium (2) has a moderate host range.
-High (3) has a wide host range.
3) Pest Dispersal Potential: Evaluate the natural and artificial dispersal potential of the pest.
Risk is Medium (2). The plant produces a moderate number of seeds that spread along roads, although large plants may produce thousands of seeds. Its appearance via some unknown pathway in such a remote area attests to its ability to spread under the right circumstances. During the 5 years that it has been detected, it has slowly increased its range in the Anza Borrego Desert. It was in Newport Bay since at least 1987, where it is currently known from seven spots. The seed lasts at least 3 years in the seed bank.
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 Score: Evaluate the economic impact of the pest to California using the criteria below.
The presence of this plant in the Anza Borrego desert may in the future impact the spring wildflower tourist industry if the plant behaves like another noxious desert weed, Sahara mustard (Brassica tournefortii). If it infests row crops or irrigated areas, it could lower crop value or crop yield.
Score: 3 (A, B, C)
A. The pest could lower crop yield.
B. The pest could lower crop value (includes increasing crop production costs).
C. The pest could trigger the loss of markets (includes quarantines).
D. The pest could negatively change normal cultural practices.
E. The pest can vector, or is vectored, by another pestiferous organism.
F. The organism is injurious or poisonous to agriculturally important animals.
G. The organism can interfere with the delivery or supply of water for agricultural uses.
-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 Score: Evaluate the environmental impact of the pest on California using the criteria below.
Risk is high (3) as the plant might be able to dominate desert and dry coastal areas that are home to sensitive species such as desert tortoise, blunt-nosed leopard lizard, and many rare native plants.
Score: 3 (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.
Score the pest for Environmental Impact. Score: 3
Low (1) causes none of the above to occur.
Medium (2) causes one of the above to occur.
High (3) causes two or more of the above to occur.
Add up the total score and include it here.
–Low = 5-8 points
–Medium = 9-12 points
–High = 13-15 points
6) Post Entry Distribution and Survey Information: Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included.
Desert knapweed has been found in three counties in California. Its range at this time is limited. It receives a Low (-1) in this category.
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: High (13)
Given that the weed history of Desert knapweed is just being deciphered, it is difficult to assess potential risk. Nevertheless, given its rapid spread in Anza Borrego it seems likely to be a major invasive. Given its long distance dispersal, its noxious relatives, and the effects of other introduced annuals such as Sahara mustard on desert ecosystems, it seems best to attempt eradication of the currently small populations.
Although Desert knapweed may be limited in its spread by its environmental tolerance, it may nevertheless become a severe pest within the desert and along the southern California coast in disturbed areas. This is based on its ecology in the Old World. As the species currently is highly restricted in its range in North America and eradication may be possible, we recommend that Desert knapweed be rated as A.
Calleja, J. A., Garcia-Jacas, N., Roquet, C., & Susanna de la Serna, A. 2016. Beyond the Rand Flora pattern: Phylogeny and biogeographical history of Volutaria (Compositae). Taxon 65: 315-332.
Consortium of California Herbaria. Accessed 1/31/2017: http://ucjeps.berkeley.edu/consortium/
Devesa, J. A. & Martinez, J. L. 2014. Volutaria Cass. In Devesa, J.A., Quintanar, A. & Garcia, M. A. (eds.). Flora iberica XVI: 272-278. Real Jardín Botánico, CSIC, Madrid.
Teillier, S., Macaya, J., Sisanna, A. & Calleja, J. A. 2014. Volutaria tubuliflora (Murb.) Sennen (Asteraceae), nueva especie alóctona asilvestrada para Chile. Gayana Bot. 71: 276-279.
Wagenitz, G. 1991. Volutaria canariensis Wagenitz, Candollea 46: 408.
Volutaria, a new invasive knapweed. Accessed 1/28/2017:
http://tchester.org/bd/species/asteraceae/volutaria_canariensis.html
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.
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Posted by ls
Fumaria muralis has been observed growing naturally in Santa Clara county in February 2018 by Italian botanist Valerio Lazzeri. This species is thought to be new to California. CDFA has not intercepted this species via any regulatory means to date and no rating has been assigned to this species. A pest rating proposal is required to assign a permanent rating.
Background:
Fumaria muralis is a sprawling annual herb that is delicate, hairless, branched and dull green in color. Its stems are weak, angular and are 10-50cm long. The leaves are finely divided down to midrib, lance to pear shaped, and form a rosette on young plants. Flowers are small, tubular and narrow with a red to pink to purple coloring and darker tips (Global Net Academy, 2018). Fumaria muralis can be distinguished from other related species by its larger flowers that have pink petals with a dirty red color at the tips. Flowering time is from June to December. It has less than 15 flowers per flowerhead and the fruit stems are erect (International Environmental Weed Foundation, 2005).
Fumaria muralis is native to Europe and north Africa (Western Australia Herbarium, 2017). It occurs commonly in crops, pastures, roadsides, home gardens and waste places (Tamar Natural Resource Management, 2015). Any soil disturbance can cause mass emergence of seedlings. Naturalized populations are found in agricultural fields but it has also been found on pond margins, in coastal dunes, on rough grounds and in dumps (Groom, 2013)
Fumaria muralis can germinate throughout the year but the main flush occurs from April to October. It grows actively from May to November. It can be difficult to control due to a persistent soil seed bank. Herbicide treatment may or may not be effective because various fumaria species can be resistant to herbicides (Western Australia Herbarium, 2017).
Worldwide Distribution:
Fumaria muralis is native in Europe and North Africa. It is widely naturalized outside its native range. Naturized populations occur in southern Australia (Western Australia Herbarium, 2017), Tasmania (Global Net Academy, 2018), and Canada (Brouillet et al. 2010)
Official Control:
Fumaria muralis has been reported as a harmful organism in Brazil and is under official control (USDA- APHIS- PCIT).
California Distribution: Fumaria muralis has been recently (February 2018) observed occurring naturally in Santa Clara county and a voucher specimen has been confirmed by a botanist in Italy, Valerio Lazzeri.
California Interceptions: Fumaria muralis has not been intercepted by CDFA through any regulatory pathways.
The risk Fumaria muralis (wall fumitory) would pose to California is evaluated below.
Consequences of Introduction:
1) Climate/Host Interaction: Fumaria muralis grows in plant hardiness zone of 5 -9 in Europe. It prefers heavy soils and high April rainfall (Murrumbidgee Catchment Management Authority, 2008). Fumaria muralis is growing naturally in limited areas of California, near habitats like creek, trails and parks. It is also likely to grow in pastures, roadsides, home gardens and waste lands. 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: Fumaria muralis do not require one host but can occur where environmental conditions are favorable for its growth and establishment. 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: Fumaria reproduces seeds can remain viable in in the ground for up to 20 years. Seeds can germinate throughout the year and the plant can grow actively for half the year. Dispersal is through contaminated seed, soil movement and water runoff. Long and short range dispersal can also be aided by human and ant activity. It receives a High (3) in this category
Evaluate the natural and artificial dispersal potential of the pest.
– Low (1) does not have high reproductive or dispersal potential.
– Medium (2) has either high reproductive or dispersal potential.
– High (3) has both high reproduction and dispersal potential.
4) Economic Impact: Fumaria muralis may compete strongly with crops, particularly cereals, vegetable and legume crops. The impacts of Fumaria sp. depends on the affected crop, time of emergence and density of infestation (Norton 2003). Fumaria species can reduce wheat yields by up to 40% and canola yields by up to 36% (Best management practices for dryland cropping systems, 2008). If this species were to establish in California, cultural practices such as cultivation, crop rotation, grazing, burning crop residues, use of competitive crops and seed cleaning would likely to be modified to reduce its growth and establishment. It receives a High (3) in this category.
Evaluate the economic impact of the pest to California using the criteria below: A, B, D
A. The pest could lower crop yield.
B. The pest could lower crop value (includes increasing crop production costs).
C. The pest could trigger the loss of markets (includes quarantines).
D. The pest could negatively change normal cultural practices.
E. The pest can vector, or is vectored, by another pestiferous organism.
F. The organism is injurious or poisonous to agriculturally important animals.
G. The organism can interfere with the delivery or supply of water for agricultural uses.
Economic Impact Score: 3
– Low (1) causes 0 or 1 of these impacts.
– Medium (2) causes 2 of these impacts.
– High (3) causes 3 or more of these impacts.
5) Environmental Impact: Fumaria muralis is not likely to lower biodiversity and change ecosystems. Fumaria spps. can be weeds of gardens, roadsides and disturbed areas and are not likely to affect endangered and threatened species in California. Because it is a likely garden weed, it could impact home and urban gardening. It receives a Medium (2) in this category.
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.
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: Fumaria muralis has been found occurring naturally in limited part of California but has not established fully in the state and 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.
The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (12)
Fumaria muralis has been observed growing naturally but in very limited areas. Since it is like other weedy Fumaria spps, it could be more widespread than currently reported. Further sampling and examining other Fumaria specimens may reduce uncertainty regarding current distribution of this species
Fumaria muralis has been verified in California in 2018, but it has not caused any significant economic and environment impacts to the State’s agriculture and urban environment yet. However, recent credible reports indicate that is more widespread than recognized and occupies areas where other fumitory species might be expected. According to reports from Europe, it acts as other weedy species of Fumaria, so it would likely have no more impact than they do; therefore, its impacts would be modest. A “C” rating is justified.
Brouillet et al. 2010+. Fumaria muralis Sonder ex W.D.J. Koch in VASCAN, the Database of Vascular Plants of Canada. Accessed 03/05/2018: https://www.gbif.org/species/100018818
http://data.canadensys.net/vascan/taxon/29050
Cal Flora 2018. Information on wild California plants for conservation, education and appreciation. Fumaria muralis. Accessed 03/01/2018: https://www.calflora.org/entry/observ.html#srch=t&obs=parsons&cols=b
GlobalNet Academy 2018. Training and Consultancy Organization. Australia. Accessed 03/01/2018: https://www.globalnetacademy.edu.au/what-weed-is-that-fumaria/
Groom, Q. 2013. Manual of the Alien plants of Belgium. Accessed 03/16/2018: http://alienplantsbelgium.be/content/fumaria-muralis
International Environmental Weed Foundation (IEWF) 2005. Common Invasive plants in Australia. Fumaria muralis. Accessed 03/06/2018: http://www.iewf.org/weedid/Fumaria_muralis.htm
Murrumbidgee Catchment Management Authority, 2008. Best management practices for dryland cropping systems Fumaria species. New South Wales Government. Department of Primary Industries. Accessed 03/05/2018: http://archive.lls.nsw.gov.au/__data/assets/pdf_file/0007/495349/archive-fumitory.pdf
Phytosanitary Certificate Issuance & Tracking System (PCIT), Phytosanitary Export Database (PExD), USDA, APHIS. Accessed 03/01/2018: https://pcit.aphis.usda.gov/PExD/faces/ReportFormat.jsp
Tamar Natural Resource Management 2015. Tamar Valley Weed Strategy- Fumitory. Tasmania, Australia. Accessed 03/06/2018: http://www.weeds.asn.au/tasmanian-weeds/view-by-common-name/fumitory/
Western Australia Herbarium 2017. Flora base-The Western Australia Flora 2017. Accessed 03/01/2018: https://florabase.dpaw.wa.gov.au/browse/profile/2971
Raj Randhawa, 1220 ‘N’ Street, Room 221, Sacramento CA 95814, (916) 654-0317, plant.health[@]cdfa.ca.gov
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.
Updated on 7/11/2019 by ls
This plant has been rated as “B” on the CDFA Plant Pest Rating list for some years.
Background: European mistletoe (Viscum album) is a hemiparasite of broad-leaved trees and shrubs that can be found on its hosts stems. It depends on the host for water, mineral nutrients, and some carbohydrates. Depending on the health of the host plant and severity of infestation it weakens its host, leaving it susceptible to damage from insects, increasing host mortality rates. European mistletoe is spread by seed dispersal from birds eating its berries and expelling the viscin covered seeds.
Found natively in Eurasia and North Africa this plant was introduced to California in the early 1900s by noted plant breeder Luther Burbank at his experimental farm outside Sebastopol, where it still occurs.
European mistletoe (Fig. 1) is sometimes confused with the native California mistletoe (Phoradendron serotinum) (Fig. 2) that is common in the area where European mistletoe is adventive. Differences in leaf form are the easiest way to distinguish them; European mistletoe has narrow propeller-shaped leaves, while California mistletoe has widely ovate leaves. European mistletoe has dichotomously branched stems that diverge at >40%, while California mistletoe has branches that generally diverge at <45%. European mistletoe has only a few fruits per cluster (generally <5), while California mistletoe has many fruits per cluster (generally >5).
Figure 2:Worldwide Distribution: European mistletoe has a native range from North Africa to southern England, southern Scandinavia, and western Russia. It can infect numerous species of broad-leaved trees and conifers in temperate to tropical regions.
Official Control: Viscum album is a prohibited plant in New Zealand.
California Distribution: European mistletoe was introduced to the Sebastopol area of Sonoma County as an ornamental from Eurasia around 1900, but it was not until 1966 that the taxon was recorded as present in California (Howell 1966). Surveys performed in 1971 covered 16 square miles in Sebastopol and Graton, and found 310 infected trees in 21 species (Scharpf and McCartney 1975). Surveys performed in 1984 covered 63 square miles in Sebastopol, Graton, Forestville, Santa Rosa, and Cotati, and found 554 infected trees in 22 species (Hawksworth and Scharpf 1986). Surveys performed in 1984 covered 71 square miles across Occidental, Forestville, Fulton, Santa Rosa, and Cotati, and found 664 infected trees in 23 species (Hawksworth et al 1991). Current specimen records show that it is present in Sebastopol and Santa Rosa. There is one recorded occurrence in Sacramento, but this record is most likely spurious.
California Interceptions: None
The risk European mistletoe would pose to California is evaluated below.
1) Climate/Host Interaction: California has a climate suitable to European The area it has established in is surrounded by scattered oaks and conifers forests. while it has yet to be recorded expanding to these trees, there is potential as it has established itself on oaks and conifers forests in its native range. Therefore, it scores as Medium (2) in this category.
-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 Medium (2) as European mistletoe can infect numerous species of broad-leaved trees and conifers in temperate to tropical regions, which are found throughout California. In California, it has been detected on native bigleaf maple (Acer macrophyllum), red alder (Alnus rubra) California buckeye (Aesculus californica), Fremont Cottonwood (Populus fremontii), and Pacific willow (Salix lasiandra). It has also been found on introduced species of birch (Betula), persimmon (Diospyros spp.), locust (Robinia spp.), hickory (Carya spp.), ash (Fraxinus spp.), hawthorn (Crataegus spp.) apple (Malus spp.), plum (Prunus spp.), pyracantha (Pyracantha spp.), mountain-ash (Sorbus spp.), Maple (Acer spp.), elm (Ulmus spp.), and poplar (Populus spp.) Therefore, it scores as Medium (2) in this category.
-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: Viscum album is spread primarily by birds, which eat and carry the fruit to other trees. Since introduction to Sonoma County, spread has increased from point of origin to more than 71 square miles at last survey in 1991. The current distribution and pattern of infestation is not known. Therefore, it scores as Low (1) in this category.
-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: Within its native range European mistletoe infects apple and other commercial fruit trees; however, it’s damage is limited as these hosts are pruned regularly, preventing further damage and slowing its spread. Therefore, it scores as High (3) in this category.
A, B, C, D
A. The pest could lower crop
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
E. The pest can vector, or is vectored, by another pestiferous
F. The organism is injurious or poisonous to agriculturally important
G. The organism can interfere with the delivery or supply of water for agricultural uses.
-Low (1) causes 0 or 1 of these impacts.
-Medium (2) causes 2 of these impacts.
-High (3) causes 3 or more of these impacts.
5) Environmental Impact: European mistletoe has potential to find hosts in a variety of California trees and shrubs. Many of these hosts are found within riparian corridors, such as willows, and impacts to this environment could affect multiple special status species that depend on a riparian habitat. In Sonoma County riparian trees provide nesting habitat for a variety of birds, including Swanson hawk, and roots provide shelter for California freshwater shrimp. European mistletoe also impacts urban street trees and fruit orchards in Europe, leading to increased pruning to prevent damage to the trees. Therefore, it scores High (3) in this category.
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
C. The pest could impact threatened or endangered species by disrupting critical habitats.
D. The pest could trigger additional official or private treatment
E. The pest significantly impacts cultural practices, home/urban gardening or ornamental plantings.
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.
Total score: 11
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. -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: Sebastopol area of Sonoma County.
-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: 10
Medium. This plant has had the opportunity to spread further in California, but it has not succeeded so far. This plant has hosts and dispersal techniques that are adaptable to California, but it has a history in the state with little impacts. It is known from younger street trees less than 15 years in place, so the reasons for its restriction are not known; it is possible that it is still in its lag phase and may increase its rate of spread once it becomes more prevalent.
European mistletoe currently is known from only Sonoma County in CA; it has the potential to move beyond its established area in California. As the current list of infected hosts shows, it could use riparian corridors to move throughout the state. If this plant does spread it might have significant impacts to native trees and commercial orchards. Despite its current slow rate of spread, an A rating is justified.
Calflora: Information on California plants for education, research and conservation. Berkeley, California: The Calflora Database: http://www.calflora.org/ (Accessed: March 20, 2018).
California Department of Food and Agriculture, Encycloweedia: Data Sheets: https://www.cdfa.ca.gov/plant/IPC/encycloweedia/weedinfo/viscum.htm (Accessed: March 20, 2018).
Consortium of California Herbaria: ucjeps.berkeley.edu/consortium/ (Accessed: March 20, 2018).
Hawksworth, F.G., Scharpf, R.F., & Marosy, M. 1991. European mistletoe continues to spread in Sonoma County. California Agriculture. 45: 39-40.
Howell, J. T. 1966. Viscum album in California. Leaflets of Western Botany 10(13):244.
Scharpf, R., and F. Hawksworth. 1976. Luther Burbank introduced European mistletoe into California. Plant Disease Reporter 60(9):740-742.
Photo Sources:
Viscum album: ©2001 CDFA Used with Permission. Retrieved April 6, 2018 at
Phoradendron serotinum: ©2011 Jorg & Mimi Fleige, Creative Commons Attribution-NonCommercial 3.0. Retrieved April 6, 2018, at https://calphotos.berkeley.edu/cgi/img_query?enlarge=0000+0000+0211+1177
Rachel Avila, Environmental Scientist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6813; plant.health[@]cdfa.ca.gov
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.
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.
♦ 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;
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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.
Posted by ls
Pontederia cordata currently does not have a rating. It has recently been recommended by Project Plant Right and by the California Invasive Plant Council as a viable alternative for water hyacinth (Eichhornia crassipes) in water gardens. Reports that P. cordata may be spreading spontaneously in California have prompted this review (Kelch & Murdock, 2012).
Background: Pontederia cordata is a perennial, herbaceous, emergent aquatic plant native to the eastern United States. It has light green stems and leaves, and showy blue-violet flower spikes. The plant can reach four feet tall with the spike growing to six inches in length. Pontederia cordata typically grows in shallow water (not more than three feet deep), and inhabits marshes, bogs, and the margins of lakes and streams.
Worldwide Distribution: Pontederia cordata is native to Canada, Central America, Brazil, the West Indies and Argentina (Horn, 2002). It is naturalized in parts of Australia, Europe, and Africa. It is considered invasive in Kenya (BioNET-EAFRINET, 2011) and South Africa (Invasive Species South Africa, 2018). Pontederia cordata is native to the eastern United States. The native distribution of P. cordata is from Nova Scotia to Minnesota, south to Florida and Texas (NRCS, 2002).
Official Control: Pontederia cordata is officially a controlled weed in South Africa.
California Distribution: Pontederia cordata is not currently established in California. There have been occasional finds, but limited in scope. Currently these are interpreted as waifs.
California Interceptions: Pontederia cordata has collected a total of nine specimens in California. The Consortium of California Herbaria has records in Alameda, San Joaquin, Monterey, and Riverside counties.
The risk P. cordata would pose to California is evaluated below.
1) Climate / Host Interaction: Pontederia cordata prefers fresh, non-turbid water (Lougheed et al, 2001) which limits the areas of establishment. Risk is Medium (2), as cordata may be able to establish in fresh water areas, an uncommon habitat in much of California.
Evaluate if the pest would have suitable hosts and climate to establish in California. Score:
– Low (1) Not likely to establish in California; or likely to establish in very limited areas.
– Medium (2) may be able to establish in a larger but limited part of California.
– High (3) likely to establish a widespread distribution in California.
2) Host Range: Risk is High (3) as weeds do not require any one host, but grow wherever ecological conditions are favorable.
Evaluate the host range of the pest. Score:
– Low (1) has a very limited host range.
– Medium (2) has a moderate host range.
– High (3) has a wide host range.
3) Pest Dispersal Potential: Capers et al, 2009 reviewed the functional dispersal traits of aquatic plants and ranked cordata as a “Poorly dispersing species”. While this plant has the capability of reproducing sexually in its native range, it appears to be limited in other areas, including California, to vegetative reproduction by rhizome. Therefore, P. cordata receives a Low (1) 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: Pontederia cordata can form patches which, if such patches developed in canals, could potentially interfere with water flow (Cichra, 2001). Pontederia cordata receives a Low (1) in this category.
Evaluate the economic impact of the pest to California using the criteria below.
Economic Impact: 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: 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: The vegetation and seeds are edible to wildlife (NRCS, 2002) and the plant is a good filtration plant for nitrates (Song et al, 2014). However, if cordata were to form large patches it could potentially interfere with water flow and trigger treatment programs. Therefore, P. cordata 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.
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.
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: Pontederia cordata is has only been detected sporadically in California. 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.
The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (9)
The plant has been a popular aquatic landscaping plant for decades, but has not established itself as a pest. Uncertainty is Low.
Based on the score listed above the pest is low risk for further invasions of California. At this point a D rating is justifed.
BioNET-EAFRINET. 2011. “Keys and Fact Sheets: Pontederia cordata (Pickerel Weed). https://keys.lucidcentral.org/keys/v3/eafrinet/weeds/key/weeds/Media/Html/Pontederia_cordata_(Pickerel_Weed).htm Accessed: February 28, 2017
CalFlora: http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=9390 Accessed: February 28, 2017
Capers, R.S., Selsky, R. & Bugbee, G.J. 2009. “The relative importance of local conditions and regional processes in structuring aquatic plant communities”. Freshwater Biology. doi:10.1111/j.1365-2427.2009.02328.x
Cichra, C. 2001. “Physical and vegetative characteristics of floating islands”. J. Aquat. Plant Manage. 39:107-111. July 2001.
Consortium of California Herbaria: http://ucjeps.berkeley.edu/ Accessed: March 1, 2017
Horn, C.N. 2002. Pontederiaceae. In: Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 20+ vols. New York and Oxford. Vol. 26, pp. 45-46.
Invasive Species South Africa. 2018. Plants Search: Pickerel weed (Pontederia cordata). http://www.invasives.org.za/legislation/item/311-pickerel-weed-pontederia-cordata Accessed February 28, 2018
Kelch, D.G., Murdock, A., 2012. Flora of the Carquinez Strait Region, Contra Costa and Solano Counties, California. Madroño 59:47–108.
Long, R.W. & Lakela, O. 1976. A Flora of Tropical Florida: A Manual of the Seed Plants and Ferns of Southern Peninsular Florida, second edition. Banyon Books, Miami, Florida.
Lougheed, V.L., Crosbie, B. & Chow-Fraser, P. 2001. “Primary determinants of macrophyte community structure in 62 marshes across the Great Lakes basin: latitude, land use, and water quality effects”. Can. J. Fish. Aquat. Sci. 58:1603-1612.
Natural Resources Conservation Service. 2002. “Plant Fact Sheet: Pickerelweed (Pontederia cordata L.). United States Department of Agriculture https://plants.usda.gov/factsheet/pdf/fs_poco14.pdf Accessed February 28, 2018
Song, B., Mallin, M.A., Long, A., & McIver, M.R. 2014. “Factors controlling microbial Nitrogen removal efficacy in constructed stormwater wetlands”. Water Resources Research Institute of the University of North Carolina. WRRI Project No. 11-06-W
June 2014.
Karen Olmstead, Environmental Scientist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6879; plant.health@cdfa.gov
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
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