Category Archives: Weeds

Plants (weeds)

A-Rated, Weeds

Hygrophila polysperma (Roxb.) T. Anderson

April 10, 2019 Raj Randhawa

California Pest Rating Profile for

Hygrophila polysperma (Roxb.) T. Anderson: Indian swampweed
Lamiales- Acanthaceae
Pest Rating: A | Proposed Seed Rating: P

DOWNLOAD PEST RATING profile

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.

Pest Rating: A | Proposed Seed Rating: P

Updated on 7/12/2019 by ls

C-Rated, Weeds

Field Bindweed | Convolvulus arvensis L.

November 29, 2018 Javaid Iqbal

California Pest Rating for

Convolvulus arvensis L.: Field bindweed

Family: Convolvulaceae

Pest Rating: C | Proposed Seed Rating: R

PEST RATING PROFILE

Initiating Event:

Convolvulus arvensis is currently C-rated. A pest rating proposal is required to support an official pest rating based on current information.

History & Status:

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.

Consequences of Introduction:

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.

Economic Impact: Convolvulus arvensis grows rapidly and competes with native vegetation and agricultural crops. Yield reductions of 20-80% have been reported in annual crops, including cereals and grain legumes (Phillips and Timmons, 1954; Black et al., 1994). Convolvulus arvensis can impede harvesting of annual crops because the crop becomes entangled with the twining stems of this plant. The heavy infested foliage contains alkaloids that can cause intestinal problems in horses (Todd et al., 1995). 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, 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.

Consequences of Introduction to California for Convolvulus arvensis (Field bindweed): High (15)

–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.

Final Score:

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

Uncertainty:

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.

Conclusion and Rating Justification:

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.

References:

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

Todd, F. G., Stermitz, F. R., Schultheis, P., Knight, A. P., and Traub-Dargatz, J. L. 1995. Tropane alkaloids and toxicity of Convolvulus arvensis. Phytochemistry 39:301-303.

USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). Accessed September 19, 2018.
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

Responsible Party:

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.

*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: R

Posted by ls

D-Rated, Weeds

American Eelgrass | Vallisneria americana Michx.

November 2, 2018 Raj Randhawa

California Pest Rating for

Vallisneria americana Michx.: American eelgrass

Hydrocheritales: Hydrocharitaceae

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

PEST RATING PROFILE

Initiating Event:

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)

History & Status:

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.

Consequences of Introduction:

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.

Consequences of Introduction to California for Vallisneria americana (American eelgrass) 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: 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.

–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 (7)

Uncertainty:

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.

Conclusion and Rating Justification:

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.

References:

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/

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;

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: D | Proposed Seed Rating: N/A

Posted by ls

A-Rated, Ratings, Weeds

desert knapweed: Volutaria tubuliflora

September 25, 2018 Dean Kelch 2 Comments

California Pest Rating for

Desert knapweed: Volutaria tubuliflora (Murb.) Sennen

Family: Asteraceae

Pest Rating: A | Seed Rating: R

PEST RATING PROFILE

Initiating Event:

This plant has been rated as “Q” on the CDFA Plant Pest Rating list for 2 years.

History & Status:

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).

Consequences of Introduction:

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

Risk is High (3), as the plant is naturalized 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.

Consequences of Introduction to California for Desert knapweed: High (14)

Add up the total score and include it here.

–Low = 5-8 points

–Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: 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.

Final Score:

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

Uncertainty:

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.

Conclusion and Rating Justification:

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.

References:

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

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: A | Proposed Seed Rating: R

Posted by ls

B-Rated, Weeds

Wall Fumitory | Fumaria muralis

April 27, 2018 Raj Randhawa

California Pest Rating Profile for

Fumaria muralis Sand W.D. J. Koch | Wall Fumitory

Ranunculales: Papaveraceae

Pest Rating: C | Seed Rating: Not Rated

Initiating Event:

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.

History & Status:

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.

Consequences of Introduction to California for Fumaria muralis (wall fumitory) Medium (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: 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.

–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:

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

Conclusion and Rating Justification:

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.

References:

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

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.

Updated on 7/11/2019 by ls

A-Rated, Weeds

European Mistletoe | Viscum album L

April 12, 2018 Rachel Avila

Figure 1:
Viscum album (2001 CDFA)

California Pest Rating for

Viscum album L: European mistletoe

Santalales: Viscaceae

Pest Rating: A | Proposed Seed Rating: R

PEST RATING PROFILE

Initiating Event:

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

History & Status:

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:
Phoradendron serotinum ©2011 Jorg & Mimi Fleige

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.

Consequences of Introduction:

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.

Consequences of Introduction to California for European mistletoe:

Total score: 11

Low = 5-8 points

Medium = 9-12 points

High = 13-15 points

-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.

Final Score:

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

Uncertainty:

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.

Conclusion and Rating Justification:

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.

References

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:

https://calphotos.berkeley.edu/cgi/img_query?enlarge=0175+3301+2364+0094

Author:

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

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: A | Proposed Seed Rating: R

Posted by ls

D-Rated, Weeds

Pickerelweed | Pontederia cordata L

April 9, 2018 Karen Olmstead

Robert H. Mohlenbrock
USDA, NRCS 1995
Northeast Wetland Flora
@ USDA NRCS PLANTS

California Pest Rating for

Pickerelweed (Pontederia cordata L)

Family: Pontederiaceae

Pest Rating: D | Proposed Seed Rating: None

PEST RATING PROFILE

Initiating Event:

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).

History & Status:

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.

Consequences of Introduction

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.

Consequences of Introduction to California for P. cordata: Medium (9)

Add up the total score and include it here.

–Low = 5-8 points

–Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: Pontederia cordata is has only been detected sporadically in California. It receives a Not established (0) 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.

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (9)

Uncertainty:

The plant has been a popular aquatic landscaping plant for decades, but has not established itself as a pest. Uncertainty is Low.

Conclusion and Rating Justification:

Based on the score listed above the pest is low risk for further invasions of California. At this point a D rating is justifed.

References:

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.

Author:

Karen Olmstead, Environmental Scientist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6879; plant.health@cdfa.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: D | Proposed Seed Rating: None

Posted by ls

Weeds

Slender Russian Thistle | Salsola collina

February 20, 2018 Raj Randhawa

California Pest Rating for

Slender Russian Thistle plant — Click on image for photo citation.

Slender Russian Thistle | Salsola collina Pallas

Caryophyllales: Chenopodiaceae

Pest Rating: A | Proposed Seed Rating: P

PEST RATING PROFILE

Initiating Event:

Salsola collina Pallas is a listed as a noxious weed in California . It is regarded as an invasive weed in Colorado. It has widespread distribution in many U.S. states and Canada. This plant has been introduced in lower 48 states and is considered a major noxious weed in North America. It has not been reported growing in natural environment of California. Currently, it has been rated as “A”. A pest risk proposal is required to evaluate this rating.

History & Status:

Background: Salsola collina is an erect annual forb in the goosefoot family. It is a round, bushy, much branched plant growing 1-3.5 feet high. The branches are slender and soft when young and woody when mature. The leaves are alternate. Flowers are small, green white or pink in color. It produces about 30 seeds per seed head (Swearingen & Bargeron, 2016).

Salsola collina was reported for the first time in North America from Minnesota by J.W. Moore in 1938. Later it was discovered in Colorado, Iowa and Missouri. Reports of S. collina for Arizona and New York are based on specimen cited by S. Rilke in 1999. Its actual distribution seems to be underestimated because of its confusion with deviant forms of S. tragus. (Flora of North America).

Slender Russian thistle typically grows in sandy soils on dry plains, in cultivated fields, roadsides, waste places, grain growing areas and disturbed plant communities. It prefers light to medium soils but can also grow in vary alkaline and saline soils. The only limitation is that it cannot grow in shade (USDA Forest Services, 2006).

Worldwide Distribution: Salsola collina is native to eastern Europe and Asia. It is considered as a Eurasian import and has become a dominant tumble weed in North America. This species is reported to be widespread in Midwestern states of United States and Canada. It is currently present in Colorado, Iowa, Illinoise, Kansas, Kentucky, Massachusetts, Minnesota, Missouri, Montana, North Dakota, Nebraska, Oklahoma, South Dakota, Utah, West Virginia and Wyoming. In Canada, it is distributed in the province of Alberta, Manitoba, Ontario and Saskatchewan (Kartesz, 1994). This species is considered invasive in Colorado and a quarantine weed in California.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: Salsola collina is not listed as a harmful organism in any other country. However, other Salsola species like S. tragus have been reported as harmful organism in Brazil (PCIT-PExD).

California Distribution: Salsola Collina has not been found growing in the natural environment in California

California Interceptions: Salsola collina has been intercepted 83 times from January 1990 through October 2017 by CDFA. These interceptions were mostly through various border stations inspections of vehicles entering the state (PHPPS- PDR Database)

The risk Salsola Collina (Slender Russian thistle) would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Salsola collina has the ability to grow in dry plains areas of California’s central valley extending from Shasta County in north to Imperial County in the south. (CA Plains Database, 2017).The ability of this plant to grow on roadsides, grain growing areas and naturally disturbed areas make it vulnerable to grow in these areas in California. It receives a 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) Known Pest Host Range: Salsola collina does not need one particular host but grow wherever ecological conditions are favorable. This species can grow on plains, semi natural and naturally disturbed areas, abandoned and cultivated fields and waste places in California. It cannot grow in shade and in areas with heavy soil types. It 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: Salsola collina reproduces by seeds. It produces 30 seeds per seed head. This plant flowers from July to September and the seeds ripen from September to October. Seeds remain viable for less than a year. Seeds dispersal can happen when plants are mowed after seeds set occurs. Tillage can favor germination of seeds. Roads and highway may allow windblown plants to disperse to long distance, spreading seeds to a wider area. 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: Salsola collina can reduce yield and quality of various agricultural crops. It can depletes soil moisture, interfere with tillage operations. Large windblown plants can reduce highway safety by obstructing views along right of ways. (USDA- Forest Services, 2006). It receives a Medium (2) in this category

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

Economic Impact: A, 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: 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: Salsola Collina is likely to threaten native plant ecosystems. It has the ability to deplete soil moisture. Windblown plants can accumulate along trees and fence lines and can possibly cause serious fire hazards in dry plains of California. Salsola collina is not likely to impact threatened and endangered species, however it can impact the quality of cultivated plants and is a roadside nuisance. It receives a High (3) in this category

Environmental Impact: A, 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: 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 Salsola collina (slender russian thistle) 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: Salsola Collina has not been found occurring in natural environment of California and receives a Not established (0) 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.

Final Score:

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

Uncertainty:

Salsola Collina is a noxious and quarentine weed in California and CDFA has been successfully intercepting this species at the state borders. Another similar species, Salsola tragus is a common species in California. Because S. collina resembles S. tragus, there may be a possibility that this species is present in southern California where large infestations of S. tragus occur (Cal –IPC, 2017)

Conclusion and Rating Justification:

Salsola Collina has not been found in the natural environment of California. If this species were to introduce accidently, it can cause significance economic and environmental impacts to agricultural and natural resources of California. Therefore, an “A” rating is justified.

References:

California Invasive Species Council, 2017. Plant assessment form. Salsola tragus. http://www.cal-ipc.org/plants/paf/salsola-tragus-plant-assessment-form/

California Plains Database, 2017. CA home town locator. Local information, resources and data https://california.hometownlocator.com/features/physical,class,plain.cfm

Flora of North America. Volume 4, page 399,400,402 http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200006908

Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR. http://explorer.natureserve.org/servlet/NatureServe?searchName=Salsola%20collina

Pest and Damage Record Database, Plant Health and Pest Prevention Services, California Department of Food and Agriculture. Accessed 11/17/2017 http://phpps.cdfa.ca.gov/user/frmLogon2.asp

Swearingen, J., C. Bargeron. 2016. Invasive Plant Atlas of the United States. University of Georgia Center for Invasive Species and Ecosystem Health https://www.invasiveplantatlas.org/subject.html?sub=6354

Phytosanitary Certificate Issuance & Tracking System (PCIT), Phytosanitary Export Database (PExD), USDA, APHIS. Accessed 11/17/2017 https://pcit.aphis.usda.gov/PExD/faces/ReportFormat.jsp

Author:

Raj Randhawa, 1220 ‘N’ Street, Room 221, Sacramento CA 95814, (916)403-6617, raj.randhawa@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: A | Proposed Seed Rating: P

Posted by ls

Weeds

Mexican Pokeweed | Phytolacca heterotepala

February 20, 2018 Raj Randhawa

California Pest Rating for

PhytolaccaHeterotepala plant — Photo by: Robert Sikora

Mexican pokeweed | Phytolacca heterotepala H. Walter

Caryophyllales: Phytolaccaceae

Pest Rating: A | Proposed Seed Rating: R

PEST RATING PROFILE

Initiating Event:

Phytolacca heterotepala has been present as a weed in the San Francisco Bay Area since the 1950s. It was recently found for the first time growing in a pasture in San Luis Obispo County (PDR 400P06359971, 400P06359972; Cal Flora 2018) and confirmed as a new county record. Phytolacca heterotepala is currently Q-rated. A permanent pest rating proposal is required to support an official pest rating.

History and Status:

Background: Phytolacca heterotepala was first documented from California in 1915 from a nursery in San Francisco [A. Eastwood s.n. CAS] (Howell 1960). Naturalized populations were documented starting in 1955 for San Francisco County [L. Jones s.n., CAS-BOT-BC434466], in 1959 for Santa Barbara County [E. Blakley 2942, CAS-BOT-BC434440], in 1960 for Santa Clara County [J. H. Thomas 8763 1960, DS577499], in 1974 for Marin County [P. Ellman s.n., CAS652035], and in 2003 for Alameda County [S. Pugh s.n., JEPS103234] (Howell 1960, Munz and Keck 1968, CAS Botany Collection Database 2018, CCH 2018). Except for some San Francisco collections, most of these comprise waits in disturbed areas or gardens.The populations from Santa Clara and Santa Barbara counties are presumed extirpated.

Plants can reach 2.5 m (Jepson eFlora 2018, Nienaber and Thieret 2004). Sepals are greenish, oblong and unequal; the largest sepal is twice as wide as the smallest. The stamens are in two whorls. It has been documented in California establishing from cultivation and in disturbed areas at an elevation up to 100 meters. Flowering starts in summer and continues into the winter months (Jepson Flora).

Phytolacca heterotepala may be mistaken for the more common and widespread Phytolacca americana L, which is introduced in California and native to the eastern United States. Phytolacca heterotepala is similar morphologically to and sometimes treated as a synonym of Phytolacca icosandra L. (red inkplant, tropical pokeweed), which is native to Arizona, Mexico, and northern South America and introduced in California (San Diego County) (CCH 2018, Davis 1985, Rzedowski and Calderón de Rzedowski 2000, Steinmann 1997, Xu et al. 2017). We follow treatments of the genus for California (Howell 1960, Jepson eFlora 2018), North America (Nienaber and Thieret 2004), and phylogenetically (Ali et al. 2015).

Synonyms: Not known.

Worldwide Distribution: Phytolacca heterotepala is native to Mexico and northern South America. In addition to its introduction and establishment in California, this taxon is documented as a newly established (Ortiz 1987) and invasive species in two areas of Portugal (Domingues de Almeida and Freitas 2006, Invasive plants in Portugal, 2016).

Official Control: Phytolacca heterotepala has not been reported as a harmful plant in other states and nations (USDA APHIS PCIT).

California Distribution: Phytolacca heterotepala has been present as a weed in the San Francisco Bay Area since the 1950s, and recently has been found in San Luis Obispo County (Jepson eFlora 2018, CalFlora 2018).

California Interceptions: Phytolacca heterotepala has been intercepted twice by CDFA in 2017 through general surveys in San Luis Obispo County (PDR 400P06359971, 400P06359972; CalFlora po67404).

The risk Phytolacca heterotepala (Mexican pokeweed) would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Phytolacca heterotepala has the ability to grow in disturbed areas of California and persist from cultivation. Since its presence has been observed in north coast and central coast areas, it may be able to spread to south coast areas of California. It is unknown if it may spread to inland areas of the state It 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: Phytolacca heterotepala does not need one particular host but grow wherever ecological conditions are favorable. It 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: Phytolacca produces multiseeded fleshy berries that are eaten and dispersed by birds. It can reproduce vegetatively from root sprouts. It has not spread widely despite being present in CA for more than 100 years.. 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: All parts of Phytolacca spp. (pokeweed, pokesalad) are potentially toxic to mammals (Roberge et al. 1986, FDA Poisonous Plant Database 2008. If this species spreads in California, hand pulling and foliar applications could increase production costs. Manual removal is not recommended without appropriate personal protection, and once established, eradication can be difficult. Although PAPs provide plant defence and resistance to infection by viruses and some fungus, Phytolacca is a host of pokeweed crinkle virus (, that can infect sugar beets, chard, spinach, and cucumber (Lackey 1965). However, it currently, has only been detected in urban waste areas. It has not spread to agricultural areas despite its long presence along the central coast of CA. It receives a Medium (2) in this category

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

Economic Impact: E, 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: Pokeweed crinkle virus can infect native California species (e.g., Adenostoma, Eriogonum), and may affect rare and endangered taxa (Lackey 1965). Phytolacca heterotepala occurs in disturbed areasand may outcompete other weeds.. 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 Phytolacca heterotepala (Mexican pokeweed): Medium (10)

Add up the total score and include it here.

-Low = 5–8 points

-Medium = 9–12 points

-High = 13–15 points

6) Post Entry Distribution and Survey Information: Phytolacca heterotepala is naturalized in the San Francisco Bay Area (Alameda, Marin, San Francisco counties) and recently documented in San Luis Obispo County. Two historic naturalized populations (Santa Clara and Santa Barbara counties) are presumed extirpated. 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.

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (9)

Uncertainty:

Phytolacca heterotepala has been present as a weed in the San Francisco Bay Area since the 1950s. The recent interceptions in San Luis Obispo County indicate that it may be spreading. No recent surveys have been performed for this taxon in California, so it may be possible that Phytolacca heterotepala occurs elsewhere in the state. Lacking studies, there is uncertainty regarding impacts to California’s agricultural and natural resources.

If plants suspected to be Phytolacca heterotepala are found in your area, please submit samples to the nearest Agricultural Commissioner office or to Botany California Department of Food and Agriculture, Plant Pest Diagnostic Center t Botany Lab for determination and vouchering as specimens in the plant herbarium.

Conclusion and Rating Justification:

Although Phytolacca heterotepala has been present as a weed in the San Francisco Bay Area since at least 1950s, it has recently spread to San Luis Obispo County. There is potential to spread into additional, suitable habitats but these areas are disturbed and weedy in nature. Therefore, an “A” rating is justified.

References:

Ali, M. A., J. Lee, S.-Y. Kim, S.-H. Park, and F. M. Al-Hemaid. 2015. Molecular phylogenetic analyses of internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA indicate monophyly of the genus Phytolacca L. (Phytolaccaceae). Bangladesh Journal of Plant Taxonomy 22(1):1-8.

The Calflora Database [A Non-Profit Organization]. 2018. Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals, including the Consortium of California Herbaria [web application] Accessed January 24, 2018. http://www.calflora.org/cgi-bin/noccdetail.cgi?seq_num=po67404

California Academy of Sciences [CAS]. 2010–2018. Institute for Biodiversity Science and Sustainability, Department of Botany, California Academy of Sciences [CAS]. CAS Botany Collection Database. Accessed January 24, 2018. http://researcharchive.calacademy.org/research/botany/coll_db/index.asp

Consortium of California Herbaria [CCH]. 2018. Data provided by the participants of the Consortium of California Herbaria [CCH]. Regents of the University of California 2018. Accessed January 24, 2018. http://ucjeps.berkeley.edu/consortium/

Davis, J. I. 1985. Introgression in Central American Phytolacca (Phytolaccaceae). American Journal of Botany 72(12):1944-1953.

Domingues de Almeida, J. D., and H. Freitas. 2006. Exotic naturalized flora of continental Portugal-A reassessment. Botanica complutensis 30:117-130.

FDA Poisonous Plant Database. 2008 (data updated May 2008). Accessed January 24, 2018 https://www.accessdata.fda.gov/scripts/Plantox/

Howell, J. T. 1960. A Mexican pokeberry in San Francisco, California. Leafl. W. Bot. 9: 81–83.

iNaturalist. 2018. Accessed January 24, 2018. http://www.inaturalist.org

Invasive plants in Portugal, 2016. Phytolacca Americana- Factsheet http://invasoras.pt/en/gallery/phytolacca-americana-en/

Irvin, J. D., and F. M. Uckun. 1992. Pokeweed antiviral protein: ribosome inactivation and therapeutic applications. Pharmacology & therapeutics 55(3):279-302.

Jepson eFlora. Accessed January 24, 2018 http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=38167

Lackey, C. F. 1965. Pokeweed crinkle leaf, caused by a virus transmitted by dodder from desert shrubs in Southern California. Plant Disease Reporter 49(12):1002-1005.

Munz, P. A., and D. D. Keck. 1968. A California flora and supplement. University of California Press, Berkeley, CA.

Nienaber, M.A., and J. Thieret. 2004. Phytolaccaceae. Pp. ##–## in Flora North America Editorial Committee (eds.) Flora of North America North of Mexico, Vol. 4: Magnoliophyta: Caryophyllidae, Part 1. Oxford University Press, New York, NY. Accessed January 24, 2018. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242415004

Ortiz, S. 1987. Phytolacca heterotepala H. Walter en Portugal. Anales del Jardín Botánico de Madrid 44(2):555.

Phytosanitary Certificate Issuance & Tracking System (PCIT), Phytosanitary Export Database (PExD), USDA, APHIS. Accessed January 23, 2018. https://pcit.aphis.usda.gov/PExD/faces/PExDReport.jsp

Roberge, R., E. Brader, M. L. Martin, D. Jehle, T. Evans, F. Harchelroad, G. Magreni, G. Gesualdi, C. Belardi, and M. Sayre. 1986. The root of evil—pokeweed intoxication. Annals of emergency medicine 15(4):470-473.

Rzedowski, J., and G. Calderón de Rzedowski. 2000. Notas sobre el género Phytolacca (Phytolaccaceae) en México. Acta Botanica Mexicana 53:49-66.

Steinmann, V. W. 1997. Phytolacca icosandra L.(Phytolaccaceae): new to the continental United States. Madroño 44(1):108-109.

Xu, S. Z., Z. Y. Li, and X. H. Jin. 2017. DNA barcoding of invasive plants in China: A resource for identifying invasive plants. Molecular Ecology Resources doi.org/10.1111/1755-0998.12715.

Author:

Raj Randhawa, 1220 ‘N’ Street, Room 221, Sacramento CA 95814, (916)403-6617, raj.randhawa@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;

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

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Pest Rating: A | Proposed Seed Rating: R

Posted by ls

Weeds

False Pickerel Weed | Monochoria vaginalis (Burm.f.) C. Presl ex Kunth

January 31, 2018 Kyle Beucke 11 Comments

California Pest Rating for

False Pickerel Weed | Monochoria vaginalis (Burm. f.) C. Presl ex Kunth

Commelinales: Pontederiaceae

Pest Rating: A | Proposed Seed Rating: R

PEST RATING PROFILE

Initiating Event:

Monochoria vaginalis, a Federal Noxious Weed, is currently Q-rated. Seeds of this species were recently found in rice from California. A permanent pest rating proposal is required to support an official pest rating.

History & Status:

Background: Monochoria vaginalis is a shiny, green aquatic herb that grows to 20 inches tall. Leaf shape varies; sessile leaves are narrow and lanceolate in shape and measure up to 5 cm in length, whereas petiolate leaves are heart-shaped and measure up to 8 cm in length and 5 cm in width (Flora of North America). The flowers are light blue and often open under water (Eckert et al., 2012). The seeds are approximately 1 mm in length and are oblong with longitudinal ribs (Scher et al., 2015). They germinate discontinuously, which makes this plant difficult to control (CABI, 2018). Monochoria vaginalis is found in rice fields, stagnant/slow areas of rivers, ponds, and other wet habitats at low elevations (Guofang and Horn, 2000; Smith, 1979). In constantly flooded conditions, it grows as a perennial (Strand, 2013). Even as an annual, however, it appears that it may require continuously flooded conditions that last long enough to allow germination, development, and fruiting to take place (Kunii and Okibe, 1999). Monochoria vaginalis is reported to be a serious weed in rice fields in Asia (Barrett and Seaman; 1980; CABI, 2018). It is currently a common weed at the Rice Experiment Station at Biggs, California (Al-Khatib et al., 2017). Weeds at this station were reported to severely impact rice yield, but the amount of yield reduction attributable to M. vaginalis is not known (Fischer, 2014). Monochoria vaginalis is used as a vegetable and medicine in Asia (CABI, 2018; Guofang and Horn, 2000).

Worldwide Distribution: Monochoria vaginalis is native to Asia and western Australia. It has been reported to occur in Australia, Bhutan, China, Cambodia, India, Indonesia, Japan, Korea, Laos, Malaysia, Myanmar, Nepal, Pakistan, Philippines, Russia, Sri Lanka, Thailand, and Vietnam. It has also been reported from Fiji, Central America, South America, Mexico, and the United States (California and Hawaii). The records from the United States and some of the other localities (including Fiji) represent introductions (Aston; CABI, 2018; Gonzalez et al., 1977; Guofang and Horn, 2000; Horn and McClintock, 2012; Oppenheimer, 2011; Pacific Island Ecosystems at Risk, 2008; Smith, 1979).

Monochoria vaginalis has been reported to occur in “natural ponds” in India, at stream edges and in swamps and mud-pools in Australia, and in shallow, ephemeral (dry for half of the year) ponds in Cambodia (Aston; Maxwell, 2009; Meena and Rout, 2016). Thus, this plant may pose a threat to vernal pools in California.

Official Control: Monochoria vaginalis (along with M. hastata) is listed as a Federal Noxious Weed and the genus Monochoria is listed as a regulated plant pest by the United States. Monochoria vaginalis is also regulated by the following states: Alabama (Class A noxious weed), California (Q-rated quarantine plant), Florida (Class 1 prohibited aquatic plant), Massachusetts (prohibited plant), North Carolina (Class A noxious weed), Oregon (quarantine plant), South Carolina (invasive aquatic plant), and Vermont (Class A noxious weed) (United States Department of Agriculture). It is also on the South African list of prohibited alien plants (Invasive Species South Africa, 2016).

California Distribution: There are 11 collections of M. vaginalis from the Biggs area in Butte County (from 1954 to 1991), mostly from the vicinity of the rice experiment station, (Consortium of California Herbaria). As of 1980, it was apparently restricted to the Biggs area and was one of the most abundant weeds in the rice fields there (Barrett and Seaman, 1980). There is one collection from Tehama County (Consortium of California Herbaria), a disjunct of 55 miles. The apparently slow spread of this weed in California may be related to seed dispersal in this species occurring after the pre-harvest drainage of rice fields (Strand, 2013).

California Interceptions: Monochoria vaginalis has not been intercepted in California.

The risk Monochoria vaginalis would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Monochoria vaginalis appears to tolerate a wide range of climates, based on the range of localities it has become established in (including Butte County, California). It appears likely that it could become established in many areas in California, but limited to areas where there is sufficient water. Therefore, Monochoria vaginalis 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) 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.

– 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: Monochoria vaginalis can reproduce via seeds as well as through rhizomes. This weed can produce an average of 29,700 seeds per plant (Kunii and Okibe, 1999). Therefore, it 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: Monochoria vaginalis is reported to cause significant yield losses in rice (CABI, 2018). If it spread into a larger portion of California, it could impact rice cultivation, including lowering yield and increasing production costs. As a Federal Noxious Weed, the presence of M. vaginalis could lead to the loss of markets and change normal cultural practices in rice cultivation. In addition, as an aquatic weed, M. vaginalis could interfere with the supply of water for agricultural purposes. It receives a High (3) in this category.

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

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

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

Economic Impact Score: High (3)

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

– Medium (2) causes 2 of these impacts.

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

5) Environmental Impact: Monochoria vaginalis has been reported to occur in a variety of habitats in Asia, including streams, swamps, and ponds/pools, including ephemeral ponds in Cambodia that are dry for half of the year. Therefore, this plant may be capable of invading these habitats in California. Vernal pools are a particularly threatened habitat in California; it is estimated that only 3–10% of these pools remain on the Pacific Coast (Gerhardt and Collinge, 2003). If M. vaginalis invades vernal pools, riparian areas, or other similar habitats in California, it could compete with native plants, threatening both them as well as wildlife dependent on the native plants. Rare plants that could be threatened include Boggs Lake hedge hyssop (Gratiola heterosepala H. Mason & Bacigal.), delta tule pea (Lathyrus jepsonii E. Green var. jepsonii), prickly spiralgrass (Tuctoria mucronata (Crampton) Reeder), and false venus’ looking glass (Legenere limosa (E. Greene) McVaugh) (Calflora). In addition, if M. vaginalis became a more widespread pest in rice fields, it could trigger additional treatment programs. Therefore, it receives a High (3) in this category.

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

Environmental Impact: A, B, C, D

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

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

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

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

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

Score the pest for Environmental Impact. Score:

Environmental Impact Score: High (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 Monochoria vaginalis: High (14)**

Add up the total score and include it here.

–Low = 5–8 points

–Medium = 9–12 points

-High = 13–15 points

6) Post Entry Distribution and Survey Information: Based on the available specimen records, within California, Monochoria vaginalis is presumed to be established only in Butte County. 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.

Final Score:

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

Uncertainty:

Monochoria vaginalis has been established in Butte County, California since the 1950s. There is one occurrence documented in Tehama County. It is not known to have spread significantly within or from this area. This could be an indication that this weed has limited invasive potential in California. In addition, although it is reportedly a common weed in rice in the vicinity of Biggs, California, little information is available on any impact that can be directly attributed to M. vaginalis there. Fuller and Barbe (1983) suggest that this weed is not able to become a significant problem in California rice because of the density of the rice plants in commercial operations in this state. Therefore, this weed may not have the potential to develop into a serious weed of rice in California.

If plants suspected to be Monochoria vaginalis are found in your area, please bring samples to the nearest Agricultural Commissioner office [https://www.cdfa.ca.gov/exec/county/countymap/] to be submitted to the Botany Lab for determination and voucher specimens in the herbarium of the California Department of Food and Agriculture (CDA).

Conclusion and Rating Justification:

Monochoria vaginalis is a Federal Noxious Weed that could potentially become a more widespread pest of rice in California, and it could also invade ecosystems including vernal pools and riparian areas. It is apparently restricted in distribution in California at the present time. For these reasons, an “A” weed rating and “P” seed rating is justified.

References:

Al Khatib, K., Godar, A.S., Lee, M., Ceseski, A., McCauley, K.E., Stogsdill, J.R., Brim-DeForest, W., Linquist, B.A., Espino, L., and R.G. Mutters. 2017. Weed control in CA rice: Evaluation of new weed control tools. Rice Field Day. Wednesday, August 30, 2017. California Cooperative Rice Research Foundation, Inc., University of California, and United States Department of Agriculture.

Aston, H.I. Flora of Australia Online. Monochoria vaginalis. Accessed January 10, 2018. http://www.anbg.gov.au/abrs/online-resources/flora/stddisplay.xsql?pnid=57579

Barrett, S.C.H. and D.E. Seaman. 1980. The weed flora of Californian rice fields. Aquatic Botany. 9: 351–376.

CABI. 2018. Invasive Species Compendium. Wallingford, UK: CAB International. Accessed January 10, 2018. www.cabi.org/isc

Calflora. Accessed January 30, 2018. http://www.calflora.org

Consortium of California Herbaria. Accessed January 10, 2018 http://ucjeps.berkeley.edu/consortium/

Eckert, J., Williams, J., Lundberg, J., and A. Fischer. 2012. Traits for field identification of Monochoria vaginalis and species of Heteranthera at different growth stages. Accessed January 25, 2018. http://wric.ucdavis.edu/events/archived_events/poster_Ducksalad_2012.pdf

Fischer, A. 2014. 2014 Annual Report (January 1, 2014 – December 31, 2014). Weed control in rice. California Rice Research Board. Accessed January 30, 2018 http://www.carrb.com/14rpt/2014%20Fischer%20RP1.pdf

Flora of North America. Accessed January 25, 2018. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200027397/

Fuller, T.C. and G.D. Barbe. 1981. Taxonomy and ecology of some rice weeds of California. pp. 60–65 in: Proceedings of the Ninth Asian-Pacific Weed Science Society Conference. National Science and Technology Authority and Philippine Tobacco Research and Training Center.

Gonzalez, J., Garcia, E., and M. Perdomo. 1977. Important rice weeds in Latin America.

Guofang, W. and C.N. Horn. 2000. Pontederiaceae. Flora of China. 24: 40–42.

Horn, C.C. and E. McClintock. 2012. Monochoria vaginalis, in Jepson Flora Project (eds.). Jepson eFlora. Accessed January 10, 2018. http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=33961

Invasive Species South Africa. 2016. Notice 4: List of prohibited alien species in terms of section 67(1). Government Gazette. 40166: 80–87.

Kunii, H. and K. Okibe. 1999. Comparative ecology of Monochoria korsakowii and M. vaginalis. Hydrobiologia. 415: 29–33.

Maxwell, J.F. 2009. Vegetation and vascular flora of the Mekong River, Kratie and Steung Treng Provinces, Cambodia. Maejo International Journal of Science and Technology. 3(1): 143–211.

Meena, T. and J. Rout. 2016. Macrophytes and their ecosystem services from natural ponds in Cachar district, Assam, India. Indian Journal of Traditional Knowledge. 15(4): 553–560.

Oppenheimer, H. 2011. New Hawaiian plant records for 2009. Bishop Museum Occasional Papers. 110: 5–10.

Oraze, M.J., Grigarick, A.A., Lynch, J.H., and K.A. Smith. 1988. Spider fauna of flooded rice fields in northern California. Journal of Arachnology. 16: 331–337.

Pacific Island Ecosystems at Risk. 2016. Monochoria vaginalis. Accessed January 10, 2018. http://www.hear.org/pier/species/monochoria_vaginalis.htm

Scher, J. L., Walters, D.S., 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. Accessed January 25, 2018. http://idtools.org/id/fnw

Smith, A.C. 1979. Flora Vitiensis Nova. A New Flora of Fiji (Spermatophytes Only). Volume 1. Pacific Tropical Botanical Garden, Lawai, Kauai, Hawaii. 494 pp.

Strand, L. 2013. Integrated Pest Management for Rice – Third Edition. UCANR Publications. 98 pp.

United States Department of Agriculture. Natural Resources Conservation Service. Plants Database. Accessed January 10, 2018. https://plants.usda.gov

University of Guam and the Secretariat of the Pacific Community. 2014. https://www.doi.gov/sites/doi.gov/files/uploads/pac_regional_biosecurity_plan_for_micronesia_and_hawaii_volume_ii.pdf

Author:

Kyle Beucke, 1220 N Street, Room 221, Sacramento, CA, 95814, 916-403-6741, 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: A | Proposed Seed Rating: R

Posted by ls

Weeds

Tree of Heaven | Ailanthus altissima (Miller)

January 17, 2018 Kyle Beucke

California Pest Rating for

Tree of Heaven | Ailanthus altissima (Miller)

Family: Simaroubaceae

Pest Rating: C | Proposed Seed Rating: R

PEST RATING PROFILE

Initiating Event:

This plant has been included on the CDFA noxious weed list.

History & Status:

Background: Tree of heaven is a (mostly) dioecious, medium-sized tree that grows to approximately 30 meters high. The long (>50 cm), pinnately compound leaves contain 13-25 lanceolate leaflets measuring 8-13 centimeters each. Fruits are produced in large clusters and are winged, facilitating dispersal via wind. The tree can root sprout vigorously, especially when damaged, forming thickets of 100s of stems covering over 0.4 hectares. Tree of heaven was planted extensively in the early days of California and many of these plants have persisted as clonal clumps or thickets.

Worldwide Distribution: Tree of heaven is native to China and has been introduced to many temperate localities throughout the world, including the United States.

Official Control: This tree is listed as a noxious weed by at least five states (California, Connecticut, Massachusetts, New Hampshire, Oregon, and Vermont).

California Distribution: Tree of heaven is widespread in California; it has been reported in 39 counties (Alameda, Amador, Butte, Calaveras, Contra Costa, El Dorado, Fresno, Humboldt, Inyo, Los Angeles, Kern, Marin, Mariposa, Mendocino, Monterey, Napa, Nevada, Orange, Placer, Riverside, Sacramento, San Bernardino, San Diego, San Francisco, San Joaquin, San Luis Obispo, San Mateo, Santa Clara, Santa Cruz, Siskiyou, Solano, Sonoma, Stanislaus, Sutter, Trinity, Tuolomne, Tulare, Ventura, and Yolo).

California Interceptions: Tree of heaven is submitted to the CDFA Botany Lab about once a year for identification.

The risk tree of heaven would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: It is apparent that tree of heaven can tolerate the conditions found throughout much of the state of California, because it is already present over much of the state. 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: Tree of heaven 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: Tree of heaven can reproduce via seed as well as clonally. Seeds are produced in great number (up to one million seeds/tree/year) and can be dispersed via wind. However, it only rarely reproduces by seed in California and then only along riparian corridors. Most populations or clusters of trees are persisting from horticulture. Due to its ability to root sprout, tree of heaven can be very long-lived and hard to eradicate. Therefore, 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: Tree of heaven can cause damage to structures, etc. in urban areas. The leaves are apparently somewhat irritating to skin. However, there does not appear to be any data quantifying economic damage resulting from this species. Therefore, it receives a Low (1) in this category.

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

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

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: Although it is often associated with disturbed or urban areas, tree of heaven appears to be able to compete successfully with native plants. Disturbed and riparian habitats appear to be especially threatened. Impacts in California are unknown, but this tree is common in riparian areas and may be displacing native plants. Characteristics of tree of heaven that could allow it to displace native flora include clonal reproduction and allelopathic chemicals found in its tissues, which have been shown to inhibit germination and growth of other plants. Tree of heaven is considered an invasive wildland pest plant by the California Invasive Plant Council. Therefore, it receives a High (3) in this category.

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

Environmental Impact: A, 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: 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 tree of heaven: Medium (12).

Low = 5-8 points

Medium = 9-12 points

High = 13-15 points

6) Post Entry Distribution and Survey Information: Tree of heaven is already present over much of California. Therefore, it receives a High (-3) 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.

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (9)

Uncertainty:

Although tree of heaven has been present in the United States for a long time, it appears to still be spreading in the western part of the country, including California. The full impact of this species, especially in riparian areas, may be yet to be seen. However, unlike in eastern North America, there is little indication that tree of heaven commonly established via seed in California.

Conclusion and Rating Justification:

Tree of heaven may be a serious threat where it has been planted in the past, especially in riparian areas. However, it is already widely distributed across the state. A “C” rating is justified.

References:

Calflora http://www.calflora.org

California Invasive Plant Council. http://cal-ipc.org

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

Encyclaweedia. https://www.cdfa.ca.gov

Jepson eFlora. http://ucjeps.berkeley.edu/eflora

Kowarik, I. and I. Säumel. 2007. Biological flora of Central Europe: Ailanthus altissima (Mill.) Swingle. Perspectives in Plant Ecology. 8: 207-237.

Lawrence, J.G. 1991. The ecological impact of allelopathy in Ailanthus altissima (Simaroubaceae). American Journal of Botany. 78(7): 948-958.

Oregon Department of Agriculture, Noxious Weed Control Program http://www.oregon.gov/oda/shared/Documents/Publications/Weeds/TreeOfHeavenProfile.pdf

United States Department of Agriculture, Plants database. https://plants.usda.gov

United States Forest Service, Fire Effects Information System. https://www.feis-crs.org/feis/

Author:

Kyle Beucke, 1220 N Street, Room 221, Sacramento, CA, 95814, 916-403-6741, 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: R

Posted by ls

Weeds

Giant Ragweed | Ambrosia trifida L.

January 10, 2018 Kyle Beucke

California Pest Rating for

Giant Ragweed | Ambrosia trifida L.

Family: Asteraceae

Pest Rating: B

PEST RATING PROFILE

Initiating Event:

This plant has been included on the CDFA noxious weed list.

History & Status:

Background: Giant ragweed is a large (to 2 meters tall), annual herb. The stems have black, longitudinal lines and are covered with hairs. Leaves are palmately 3- to 5-lobed and are sparsely covered with tiny, stiff hairs. Fruits (“burrs”) are 6-12 mm long and are tapered and blunt on one end and widened with 5-8 teeth on the other end. Giant ragweed grows best in disturbed areas with moist, fertile soil, and it is an important weed. Ragweed pollen is a major cause of allergies, and the pollen of this species is a known allergen.

Worldwide Distribution: Native to eastern North America. Giant ragweed has been introduced to, and is now established in western North America and much of Asia and Europe.

Official Control: Giant ragweed is listed as a noxious weed in at least three states (California, Delaware, and Illinois).

California Distribution: Giant ragweed has been reported in 10 California counties (Contra Costa, Glenn, Orange, Los Angeles, Madera, Monterey, San Diego, San Joaquin, San Luis Obispo, and Siskiyou). Most of these records are from residential gardens. According to one source, it is not naturalized in California, but occurs as a waif and/or garden escape.

California Interceptions: Recent collections from 2011 through 2014 originated from gardens or as seed contaminants intercepted at the CA border. It is commonly intercepted in feed seed shipments entering the state.

The risk giant ragweed would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Giant ragweed thrives in temperate climates, and it is already present in ten counties in California. Therefore, it receives a High (3) 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: Giant ragweed does not require any one host, but grows wherever ecological conditions are favorable. It receives a High (3) 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: Most seeds of giant ragweed fall near the parent plant and they are apparently not eaten in large number by wildlife. However the seeds float and are apparently able to be transported readily via water. Therefore, it receives a Medium (2) 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: Giant ragweed is an important weed in crop systems, especially corn and soybean. Infestations could lead to a loss of markets. Giant ragweed has already developed resistance to herbicides, so it could increase production costs. Therefore, it receives a High (3) in this category.

Economic Impact: A, B, C

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

Economic impact Score: 3

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

-Medium (2) causes 2 of these impacts.

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

5) Environmental Impact: Giant ragweed is able to out-compete other plants in open areas, including crop systems as well as grasslands. It has been scored as a plant with a high risk of invasiveness by the California Invasive Plant Council. Giant ragweed is often controlled with herbicides, and it has developed resistance to certain pesticides. It could trigger new treatment programs. Therefore, it receives a High (3) in this category.

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: High (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 giant ragweed: High (14)

-Low = 5-8 points

-Medium = 9-12 points

-High = 13-15 points

6) Post Entry Distribution and Survey Information: Giant ragweed has been reported in ten California counties, but it seems likely that its distribution within the state could expand further. Therefore, it receives a Medium (-2) 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.

Final Score:

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

Uncertainty:

As stated before, giant ragweed has been present in California for at least 80 years. Many of the available records are from residential gardens. It has not, so far, been shown to be a serious problem either agriculturally or environmentally in this state; nevertheless, there is a chance that if it made its way to a new, favorable locality in the state it could behave differently.

Conclusion and Rating Justification:

Based on the potential economic and environmental impact of this weed, and the fact that it is commonly found on feed mill seed entering the state (and is likely to have further opportunities for establishment without regulation), a “B” rating is justified.

References:

Bassett, I.J. and C.W. Crompton. 1982. The biology of Canadian weeds. 55. Ambrosia trifida L. Canadian Journal of Plant Science. 62: 1003-1010.

Bullock, J.M., Chapman, D., Schafer, S., Roy, D., Girardello, M., Haynes, T., Beal, S., Wheeler, B., Dickie, I., Phang, Z., Tinch, R., Čivić, K., Delbaere, B., Jones-Walters, L., Hilbert, A., Schrauwen, A., Prank, M., Sofiev, M., Niemelä, S., Räisänen, P., Lees, B., Skinner, M., Finch, S., and C. Brough. 2010. Assessing and controlling the spread and the effects of common ragweed in Europe. Contractor: Natural Environment Research Council, UK. 456 pp.

California Invasive Plant Council. http://cal-ipc.org

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

Encycloweedia. https://www.cdfa.ca.gov/plant/IPC/encycloweedia/encycloweedia_hp.html

Goplen, J.J., Sheaffer, C.C., Becker, R.L., Coulter, J.A., Breitenbach, F.R., Behnken, L.M., Johnson, G.A., and J.L. Gunsolus. 2016. Giant ragweed (Ambrosia trifida) seed production and retention in soybean and field margins. Weed Technology. 30: 246-253.

Megyeri, K. 2011. The impact of Ambrosia trifida (giant ragweed) on native prairie species in an early prairie restoration project. Thesis. University of New Orleans. Accessed from: http://scholarworks.uno.edu/cgi/viewcontent.cgi?article=1001&context=honors_theses

Webster, T.M., Loux, M.M., Regnier, E.E., and S.K. Harrison. 1994. Giant ragweed (Ambrosia trifida) canopy architecture and interference studies in soybean (Glycine max). Weed Technology. 8: 559-564

Author:

Kyle Beucke, 1220 N Street, Room 221, Sacramento, CA, 95814, 916-403-6741, 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:

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Comment Format:

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

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Pest Rating: B

Posted by ls

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