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Weeds

Parthenium hysterophorus L. | Santa Maria feverfew

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2100033-Parthenium-hysterophorusL_CharlesTBryson-USDA-AgResearchService-Bugwood.org
California Pest Rating for
Family: Asteraceae
Parthenium hysterophorus L. – Santa Maria feverfew
Pest Rating: A |  Seed Rating: P
PEST RATING PROFILE
Initiating Event:

This plant has been rated as “Q” on the CDFA Plant Pest Rating List after a find in a greenhouse growing in coir from Sri Lanka. There have been two detections of this plant in Orange County in 2016.

Synonym:

Parthenium lobatum Buckley

History & Status:

Santa Maria feverfew is an aggressive, annual, herbaceous weed of highly negative economic importance. This erect, ephemeral herb is known for its vigorous growth and high fecundity, especially in warmer climates. It is native to the southern United States, Mexico, Central and South America; however the native range north of Mexico is not clear. Santa Maria feverfew is a prolific weed belonging to the daisy family (Asteraceae), producing thousands of small flower heads each yielding several single-seeded fruits on reaching maturity. Within the past century it has found its way to Africa, Australia, Asia and many Pacific Islands. It has now become one of the world’s seven most serious weeds in warm climates. It is found on abandoned lands, residential areas, railway tracks, road right-of-ways, drainage and irrigation canals, lawn edges, and other disturbed areas. It has wide adaptability, drought tolerance, high seed production ability and a long-lived soil seed bank. This weed invades established gardens, plantations and vegetable crops. Due to its high fecundity, a single plant can produce 10,000 to 15,000 viable seeds in one year and the fruits can disperse and germinate to cover large areas.

Official Control: Santa Maria feverfew is recognized as invasive weed in certain countries of Asia, Africa and Oceania. In 2014, it was added to the California list of noxious weeds (CCR Section 4500).

Much research has been carried out in South Asia on the control of this plant, including biological control. It has not yet established in California and no work has been done here.

California Distribution: One population was found on the U.C. Campus in Riverside in 1981. This population is evidently gone (Andrew Sanders, pers. comm.). Populations of Santa Maria feverfew have been found growing in two areas of California recently in Orange County (in 2016) and it has not yet naturalized in California.

California Interceptions:  Santa Maria feverfew has not been intercepted at California borders.

United States Distribution: Santa Maria feverfew has a native range in in the subtropical regions of North and South America and has been found in many Eastern states. It is now well established in the Southern United States

International Range: Santa Maria feverfew is native to Mexico, Central and South America. It is distributed in parts of Asia, Africa, North America, the Caribbean, Europe and Oceania.

This risk Santa Maria feverfew would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Santa Maria feverfew is a weed of semi-arid subtropical, tropical and warmer temperate regions. It is often found in riparian zones. It is able to invade natural ecosystems and has the ability to cause habitat changes in native grasslands and open woodlands. The climate in inland regions of California is more continental with some semi-arid areas. The Central Valley has hotter summers with a mediterranean style climate. This weed is likely to establish in small areas of California. Score: 2

Evaluate if the pest would have suitable hosts and climate to establish in California.  Score: 2

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

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

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

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

Evaluate the host range of the pest.

Low (1) has a very limited host range.

Medium (2) has a moderate host range.

High (3) has a wide host range.

3) Pest Dispersal Potential: Risk is High (3). The plant produces via numerous seeds that are able to spread rather quickly. Santa Maria feverfew can be dispersed through water, farm machinery, industrial machinery, feral animals, humans, vehicles, stock fodder, and movement of stock, grain and seed (PAG 2000). It can also be spread by wind due to its small and light seed size (Navie et al., 1996; Taye, 2002). Score: 3

Evaluate the natural and artificial dispersal potential of the pest. Score: 3

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

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

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

4) Economic Impact: Risk is high (3) as the plant can lower range productivity and land value. Santa Maria feverfew has been known to impact pastoral regions and can replace forage plants. This weed is considered to be a cause of allergic respiratory problems, contact dermatitis, and mutagenicity in human and livestock. Crop production is drastically reduced in infested fields owing to its ability to suppress growth of other plants (allelopathy). Santa Maria feverfew can also impact crop production indirectly by serving as an alternate hosts for other plant pests and disease causing organisms. It is estimated that in heavily infested crops, the cultivation costs may be doubled because the prepared ground must be re-worked to eliminate the emergent parthenium weed seedlings (Chippendale and Penetta). Score: 3

Evaluate the likely economic impacts of the pest to California using the criteria below. Score: 3

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

Score the pest for Environmental Impact:

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

Medium (2) causes 2 of these impacts.

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

5) Environmental Impact: Risk is high (3) as the plant can disrupt natural communities and cultural plants in a landscape. It can cause prolonged toxic effects on the soil environment. The invasive ability and its allelopathy have given Santa Maria feverfew the ability to disrupt ecosystems by replacing dominant flora and suppressing natural vegetation, thereby becoming a threat to biodiversity. Sparse vegetation is seen in infested areas. Santa Maria feverfew has an adverse effect on native plants. It has been reported to cause irreversible habitat change in native Australian grasslands, open woodlands, river banks and flood plains. Santa Maria feverfew rapidly invade new surroundings and often replaces indigenous species. Score: 3

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

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

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

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

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

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

   Score the pest for Environmental Impact:

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 Santa Maria feverfew:

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

Low = 5-8 points

Medium = 9-12 points

High = 13-15 points

6) Post Entry Distribution and Survey Information: Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included. Score: -1

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

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

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

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

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information. Final score: 13

Uncertainty:

The extent of suitable habitat in CA is not clear, but this plant has shown itself to be capable of wide invasion where warmth and some summer water are available.

Conclusion and Rating Justification:

A very bad weed. Despite its limited adaptability to California, it deserves an A rating, as it is so harmful and as it has invaded similar habitats in Australia.

References:

Adkins, S.W. and S.C. Navie. 2006. Parthenium weed: a potential major weed for agro-ecosystems in Pakistan. Pak. J. Weed Sci. Res. 12: 19-36.

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

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

Lakshmi C. & C. R. Srinivas. 2007. Parthenium: A wide angle view. Indian J. Dermatol Venereol Leprol. 73:296–306.

Patel, S. 2011. Harmful and beneficial aspects of Parthenium hysterophorus: an update. 3 Biotech. 1: 1–9.

National Plant Germplasm System: GRIN database: USDA APHIS

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

Weeds of the United States and Canada: Southern Weed Science Society (USDA Natural Resource Conservation) http://plants.usda.gov/core/profile?symbol=PAHY

Invasive Species Compendium: Parthenium hysterophorus http://www.cabi.org/isc/datasheet/45573

PAG, 2000. Parthenium weed. Parthenium Action Group Information Document. CSIRO, Australia.

http://www.chris.tag.csiro.au/parthenium/information.html.

Navie SC, McFadyen RE, Panetta FD, Adkins SW, 1996. The biology of Australian weeds. 27. Parthenium hysterophorus L. Plant Protection Quarterly, 11(2):76-88; 4 pp. of ref.

Taye T, 2002. Investigation of pathogens for biological control of parthenium (Parthenium hysterophorus L) in Ethiopia. PhD Thesis. Humboldt University of Berlin, Germany.

Chippendale JF, Panetta FD, 1994. The cost of parthenium weed to the Queensland cattle industry. Plant Protection Quarterly, 9(2):73-76; 14 ref.

Distribution of Santa Maria feverfew in 1994 (Adkins and Navie, 2006)
Distribution of Santa Maria feverfew in 1994 (Adkins and Navie, 2006)
Responsible Party:

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

Pest Rating: A |  Proposed Seed Rating: P

Posted by ls 

Weeds

Giant Knotweeds | Fallopia japonica, F. sachalinensis, & F. X bohemica

California Pest Rating for
Giant knotweeds |  Fallopia japonica, F. sachalinensis, & F. X bohemica
Pest Rating: A |  Proposed Seed Rating: R
PEST RATING PROFILE
Initiating Event:

Japanese and giant knotweeds have been listed as A rated plants by CDFA for  many years. Bohemian knotweed has a Q rating.

History & Status:

Background: The giant knotweeds comprise 2 species and their hybrid: Japanese knotweed (F. japonica), giant knotweed (F. sachalinensis), and Bohemian knotweed (F. X bohemica).  They are large bamboo-like herbs to over 4 m tall under ideal conditions. They spread via underground rhizomes and can form extensive patches that exclude other vegetation. Where well adapted, they can spread via seed as well.  They produce copious biomass in areas with a year-long supply of soil moisture, and often overtop surrounding vegetation. This changes the shade profile, competitive environment, and hydrology of the community. Older stands are quite dense and can impede water flow along streams. Originally imported as an ornamental screen or hedge plant, giant knotweeds are native to Asia. In North America, this plant is not held in check by natural enemies and is capable of thriving and spreading in a wide range of conditions, especially riverbanks, roadsides and other moist, disturbed areas.

Giant knotweed is the biggest of the three species, sometimes exceeding 16 feet in height. The stems are smooth, hollow and light green, resembling the canes of bamboo, and sparingly branched. The leaves are 6 to 16″ long, with a deeply heart-shaped base and a blunt leaf tip. Diagnostic hairs on the leaf underside are long, thin and wavy. Giant knotweed has been declared noxious in California, Oregon, and Washington. Japanese knotweed is smaller (to 8’) and has hairless leaves. It has has been declared noxious in Alabama, California, Oregon, Vermont, and Washington. Bohemian knotweed is intermediate between the parents. Despite its hybrid origin, Bohemian knotweed produces fertile seed that can spread the plant. As it has often been misidentified, the range of Bohemian knotweed is likely larger than is recognized currently.

Official Control: Several counties in California have controlled giant knotweeds where they are found.

Worldwide Distribution: Giant knotweeds are native to Japan and Eastern Asia. They  heave been widely planted and escaped in all but the driest regions of North America.

California Distribution: Giant knotweeds are known from detected populations scattered throughout the state. Most of these represent planted plants that have spread vegetatively. Giant knotweeds can spread best, both vegetatively and by seed, in Northwestern California, especially Humboldt and Siskiyou Counties.

This risk giant knotweeds pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Evaluate if the pest would have suitable hosts and climate to establish in California. Score: 2

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

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

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

Risk is Medium (2) as illustrated by the moist habitat of the plant in states where it occurs. Giant knotweeds are expected to colonize riparian areas, pond margins, wetlands, roadside ditches, irrigation canal banks, and moist forest edges. They will also spread in neglected gardens and urban waste areas.

2) Known Pest Host Range: Evaluate the host range of the pest. Score: 3

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

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

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

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

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

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

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

Risk is High (3) as the plant spreads via water flow, human dispersal, and by seed in favorable regions.

4) Economic Impact: Evaluate the likely economic impacts of the pest to California using the criteria below. Score: 2

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

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

– Medium (2) causes 2 of these impacts.

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

Risk is Medium (2) as the plants regrow very rapidly and often invade fallow fields and meadows. Pulling or digging out the weed has some effect if repeated regularly. All waste plant material must be burnt, as Japanese knotweed can survive composting. Burning the plant in situ is ineffective. Sheep, goats, cattle and horses will graze the young shoots.

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

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

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

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

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

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

Score the pest for Environmental Impact. Score: 3

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

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

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

Risk is High (3) as the plant can dominate wetland habitats that are particularly important for native species, including sensitive species. In addition, the plant changes the profile and disrupts natural communities. It often triggers treatment programs. It is highly invasive in urban areas and in ornamental plantings.

Consequences of Introduction to California for giant knotweeds:

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

–Low = 5-8 points

–Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included. (-1)

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

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

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

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

Final Score:

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

Uncertainty:

Giant and Japanese knotweeds are invasive in favorable habitats in CA. Bohemian knotweed can be expected to act like its parents. Therefore, uncertainty is low.

Conclusion and Rating Justification:

Bad weeds of horticultural areas, waste areas, and marginal wetlands. They deserve an A rating. The chance of eradication is moderate to high.

Literature:

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

Beerling, D. J., J. P. Bailey, and A. P. Conolly. 1994. Fallopia japonica (Houtt.) Ronse Decraene. J. Ecol. 82: 959-979.

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

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

Stone, Katharine R. 2010. Polygonum sachalinense, P. cuspidatum, P. × bohemicum. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer): http://www.fs.fed.us/database/feis/

Zika, P. F. and A. L. Jacobson. 2003. An overlooked hybrid Japanese knotweed (Polygonum cuspidatum × sachalinense; Polygonaceae) in North America. Rhodora 105: 143-152.

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.

Pest Rating: A |  Proposed Seed Rating: R

Posted by ls

Weeds

Parrotfeather Myriophyllum aquaticum (Vell.) Verdc.

California Pest Rating
Parrotfeather Myriophyllum aquaticum (Vell.) Verdc.
Saxifragales; Haloragaceae
Pest Rating: C |  Proposed Seed Rating: R
PEST RATING PROFILE
Initiating Event:

This plant was given a Q rating by the CDFA botany lab in 2015.

History & Status:                                  

Parrotfeather is originally from South America and has been introduced into several continents because of its popularity as a pond plant. Parrotfeather has established in bodies of water in California where it forms very dense mats of vegetation.

Parrotfeather is a perennial rooted aquatic plant that has both submersed and emergent forms. Branched stems grow up to 2 m long and 5 mm in diameter. Emersed branch networks form a horizontal pattern with extensive lateral branching followed by vertical growth. Emergent leaves are arranged in whorls of 3 to 6 leaves around the stem. The leaves themselves are divided, giving them a feathery appearance. Tiny, white flowers are produced on short stalks at the base of emergent leaves. In North America only female plants are known. Adventitious roots emerge from the stem nodes allowing the plants to grow vegetatively. The plants die back to rhizomes during the winter.

Official Control: Parrotfeather is listed as a noxious weed in Alabama, Connecticut, Maine, Massachusetts, Vermont, and Washington

Worldwide Distribution: Parrotfeather is native to South America. It has been introduced to Southeast Asia, Australia, New Zealand, South Africa, Japan and North America.

United States Distribution: Parrotfeather has been introduced to all states except the Interior West and the Central Northern States.

California Distribution:  Parrotfeather occurs in at least 27 California counties distributed throughout the state. As aquatic plants are under-collected and many water column weeds are superficially similar, it is likely more widely distributed than these collections indicate.

California Interceptions. Sent to CDFA by land managers.

Consequences of Introduction: 

1) Climate/Host Interaction: Evaluate if the pest would have suitable hosts and climate to establish in California. Score: 3

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

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

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

Risk is High (3). Although open water habitat is sparse in CA, Parrotfeather has been able to spread to at least half the counties in the state. It has shown the ability to spread wherever appropriate habitat is available. Parrotfeather grows in slow-moving freshwater lakes, ponds, streams, and ditches; it responds well to high nutrient environments, where it grows in shallow water and on wet soil along shorelines; it is tolerant of moderate water fluctuations. It prefers freshwater but tolerates some salinity, so it could colonize wide areas in the CA Delta Region. Parrotfeather grows best in shallow water environments in which light reaches the bottom, but it can occur as a floating plant in the deeper waters of lakes. Parrot feather appears to prefer warmer, milder climates but is not seriously affected by frost. Once established, Parrotfeather persists despite variations in the environment.

2) Known Pest Host Range: Evaluate the host range of the pest. Score: 3

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

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

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

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

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

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

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

Risk is High (3). Only female plants have been detected in North America, but like other water column plants, Parrotfeather grows and spreads extensively via vegetative means. Any small fragment can grow into a new colony if it reaches the appropriate shallow water habitat. As this plant is a popular pond plant, accidental and purposeful dissemination by hobbyists is a major pathway of spread.

4) Economic Impact: Evaluate the likely economic impacts of the pest to California using the criteria below. Score: 3

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

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

– Medium (2) causes 2 of these impacts.

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

Risk is High (3) as the dense growth can lead to flooding problems, impede irrigation, and obstruct recreational activities including boating, fishing, and swimming. It is a known weed of rice paddies, reducing yields. Parrotfeather has also been shown to provide excellent habitat for mosquito larvae; mosquitoes spread West Nile and zika viruses.

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

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

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

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

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

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

Score the pest for Environmental Impact. Score: 3

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

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

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

Risk is high (3) as Parrotfeather has escaped cultivation and has spread into water bodies through intentional plantings and growth of plant fragments. The brittle nature of stems results in many fragments; these root easily in moist soils to establish new colonies. Plant fragments with their robust leaves and stems, and thick waxy cuticle, can survive periods out of water. Fragments can spread by currents, water fowl, and by boats. Parrot feather is present year round and may provide cover but has very little food value for wildlife. Its dense growth leads to competition with native vegetation and could impact sensitive species such as Bogg’s Lake hedge hyssop (Gratiola heterosepala), Lobb’s buttercup (Ranunculus lobbii), and Gambell’s watercress (Rorippa gambelii).

Consequences of Introduction to California for Uruguayan water primrose:

Add up the total score and include it here. (15)

Low = 5-8 points

Medium = 9-12 points

High = 13-15 points

6) Post Entry Distribution and Survey Information: Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included. Score: -3

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

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

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

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

Final Score:

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

Uncertainty:

There is low uncertainty, as the plant has established in California and other states.

Conclusion and Rating Justification:

A widespread and potentially significant weed in CA of both natural wetlands and irrigation canals. Nevertheless, its wide distribution in CA and its availability in the aquarium and pond plant trade render it unlikely that regulation of its sale would be effective. It deserves a C rating, as it has spread widely through California. Eradication is impossible at this point in time.

References:

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

Bossard, C.C., J.M. Randall, M.C. Hoshovsky, M.C. 2000. Invasive plants of California’s wildlands. University of California Press, Berkeley, California.

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

Chambers, P.A., J.W. Barko, C.S. Smith. 1993. Evaluation of invasions and declines of submersed aquatic macrophytes. Journal of Aquatic Plant Management 31: 218-220.

USDA, NRCS. 2015. The PLANTS Database (http://plants.usda.gov, 18 December 2015). National Plant Data Team, Greensboro, NC 27401-4901 USA.

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.

Pest Rating: C |  Proposed Seed Rating: R

Posted by ls

Weeds

Bearded Creeper | Crupina vulgaris Pers. ex. Cass.

common-crupina_1459126-UtahStateUniv-bugwood-WEB
California Pest Rating for
Bearded creeper | Crupina vulgaris Pers. ex. Cass.
Asteridae: Asteraceae
Pest Rating: A | Proposed Seed Rating: P

 

PEST RATING PROFILE
Initiating Event:

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

History & Status:

Bearded creeper is a winter annual, with erect, openly branched flowering stems to 60 cm tall at maturity. Most germination occurs after the first significant rains of fall/early winter, but germination can continue throughout the rainy season. Fall germinating plants exist as basal rosettes until flowering stems bolt in spring. Rosette leaves wither as flowering commences in late spring/early summer. Bearded creeper is adapted to many environmental conditions, is highly competitive for water and nutrients, and often produces solid stands. This adaptation to various conditions may be because it has been introduced from several locations in southern Europe. Although not an aggressive species in its native habitats, its adaptation to rough grazing lands of the Mediterranean region renders it invasive in natural grasslands of western North America. Here it contributes to degradation of native plant communities, lower forage production and increased risk of soil erosion.

Official Control: As Bearded creeper has been an “A” listed noxious weed for years, most or all of the few historic localities have been treated and eradicated.

California Distribution:  Modoc Plateau, North Coast Ranges (Sonoma Co.); to 250 m (850 ft).

California Interceptions: Vouchered specimens are known from Modoc and Sonoma Counties.

United States: Bearded creeper is known also from Idaho, Oregon, and Washington.

International: Bearded creeper is native to Europe. It is reported as naturalized and as an environmental weed in Canada.

This risk Bearded creeper would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: The plant has adapted to a wide range of habitats in its native range and is demonstrated to have had multiple introductions into Western North America. Therefore bearded creeper 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) 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: Bearded creeper produces via numerous seeds that seem to be able to spread rather slowly. The seed bank is moderately persistent. Once established, bearded creeper can persist and has proven difficult to eradicate. Bearded creeper 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: Bearded creeper can lower range productivity, land value, and can trigger state quarantines. Bearded creeper receives a High (3) in this category.

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

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

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

– Medium (2) causes 2 of these impacts.

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

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

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

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

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

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

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

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

Score the pest for Environmental Impact. Score:

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

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

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

Consequences of Introduction to California for Bearded creeper: 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: Bearded creeper has been found in in 2 counties in California. It receives a Low (-1) in this category.

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

–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:

Limited dispersability and fast treatment response has restricted bearded creeper’s spread so far in CA. However, it has shown great ability to spread if neglected, as in OR & ID.

Conclusion and Rating Justification:

A very bad weed. Deserves an A rating as all known populations have been treated. Chances of state eradication are high with sustained efforts.

References:

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

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

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

Garnatje, T., R. Vilatersana, C. T. Roché, N. Garcia-Jacas, A. Susanna & D. C. Thill. 2002. Multiple introductions from the Iberian peninsula are responsible for invasion of Crupina vulgaris in western North America. New Phytologist 154: 419-28.

Invasive Species Compendium; Crupina vulgaris: http://www.cabi.org/isc/datasheet/13697

Thill, D.C., C.T. Roche and D.L. Zamora. 1999. Common crupina. Pp. 189-201. In, Biology and Management of Noxious Rangeland Weeds. Eds. R.L. Sheley and J.K. Petroff, Oregon State Univ. Press, Corvallis.

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.

Comment Period:

The 45-day comment period opened on July 8, 2016 and closes on Aug 22, 2016.

Comment Format:

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

Example Comment: 

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

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♦  Comments may not be posted if they:

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

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

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

Pest Rating: A | Proposed Seed rating: P

Posted by ls

Weeds

Dagger-flower | Mantisalca salmantica (L.) Briq. & Cavill.

California Pest Rating for
Dagger-flower | Mantisalca salmantica (L.) Briq. & Cavill.
Synonym: Centaurea salmantica L.
Asterales: Asteraceae
Pest Rating: A |  Proposed Seed Rating: P
PEST RATING PROFILE
Initiating Event:

This plant has been rated as “Q” by CDFA since it was detected in a dried plant arrangement in 2015.

History & Status:

Dagger-flower is a perennial or biennial knapweed native to the Mediterranean Region including Israel, Morocco, and Mallorca. It has spread to Switzerland, Britain, Germany, and southern Scandinavia as a result of anthropogenic disturbance. It occupies disturbed areas, roadsides and rocky areas.

It is occasionally found as a grain or bird seed casual introduction. It is adventive on several continents, although it has not yet become a significant weed of agriculture except in Europe adjacent to its original range.

Official Control: None.

California Distribution:  A single collection from Healdsburg (Sonoma County) is known from 1896. Evidently it did not persist.

California Interceptions: It was submitted to the CDFA botany laboratory in a dried plant arrangements (PDRs #19TP06465296, 130P06398197, 490P06380234, & 500P06138704).

United States: In addition to California, Dagger-flower has been collected once or twice in Arizona as a waif.

International: Dagger-flower is native to the Mediterranean. It is reported as naturalized and as an environmental weed in South Africa. It is also sparingly introduced into Australia and Asia.

This risk Dagger-flower would pose to California is evaluated below.

Consequences of Introduction: 

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

Risk is High (3), as the plant is native to an area with a very similar climate. It is very widespread in this area and has spread north in response to human disturbance.

2) Known Pest Host Range: Evaluate the host range of the pest. Score: 3

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

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

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

3) Pest Dispersal Potential: Evaluate the natural and artificial dispersal potential of the pest. Score: 2

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

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

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

Risk is Medium (2). The plant produces via numerous seeds that seem to be able to spread rather slowly. The seed bank is moderately persistent.

4) Economic Impact: Evaluate the likely economic impacts of the pest to California using the criteria below. Score: 2

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

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

– Medium (2) causes 2 of these impacts.

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

Risk is Medium (2) as the plant could lower range productivity, invade row crops, and could negatively change normal cultural practices.

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

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

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

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

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

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

Score the pest for Environmental Impact. Score: 3

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

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

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

Risk is high (3) as the plant could dominate roadsides and invade rangelands as happened with the closely related yellow star-thistle, excluding native plants and lowering biodiversity. If it were to spread in CA, the plant could disrupt natural communities and exclude cultural plants from a landscape.

Consequences of Introduction to California for Dagger-flower:

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

–Low = 5-8 points

–Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included. Score: -0. Detected once in CA but disappeared.

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

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

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

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

Final Score

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

Uncertainty:

High. This plant has had the opportunity to invade North America, but it has not succeeded so far. However, the behavior of some of its close relatives, as well as its ability to spread following human disturbance point to a high chance of spread once the species established in CA. Despite 2 known historic detections in the SW U.S., this has not happened.

Conclusion and Rating Justification:

A potentially bad weed. Deserves an A rating as several of its relatives are weeds in California and it comes from a very similar climate. As it is not yet established in California, a conservative approach to exclusion is justified.

References:

Alanen, A., T. Bongard, E. Einarsson, H. Hansen, L. Hedlund, K.Jansson, M. Josefsson, M. Philipp, O. T. Sandlund, A. E. Svart, H. E. Svart, & I. Weidema. 2004. Introduced Species in the Nordic Countries (Denmark) under Nordic Council of Ministers (NMR), subgroup Natur-og Friluftslivsgruppen.

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

Bromilow, C. 1995. Problem Plants of South Africa. Briza Publications, Arcardia, South Africa.

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

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

Hanf, M. 1983. The Arable Weeds of Europe, with their seedlings and seeds. BASF Aktiengesellschaft, D-6700 Ludwigshafen. Germany.

Holm, L. G., Pancho, J. V., Herberger, J. P. and Plucknett, D. L. 1979. A Geographical Atlas of World Weeds. John Wiley and Sons New York, USA.

Susana, A., N. Garcia-Jacas, O. Hidalgo, R. Vilatersana, & T. Garnatje. 2006. The Cardueae (Compositae) Revisited: Insights from ITS, trnL-trnF, & matK Nuclear and Chloropolast DNA Analysis. Annals of the Missouri Botanic Garden. 93: 150-171.

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.

Pest Rating: A |  Proposed Seed Rating: P

Posted by ls 

Weeds

Jointed Bulrush | Schoenoplectus articulatus (L.) Palla

California Pest Rating for
Jointed bulrush  |  Schoenoplectus articulatus (L.) Palla
Family: Cyperaceae
Synonym: Scirpus articulatus L.
Pest Rating: D |  Proposed Seed Rating: N/A
PEST RATING PROFILE
 Initiating Event:

This plant recently has been detected in dried flower arrangements coming from India to California.

History & Status:

Jointed bulrush is an annual or perennial grass-like plant that has the ability to grow in both flooded and moist, upland conditions; this makes it a widespread wetland plant throughout the paleotropics. It has also been noted as a weed in rice. Seedling emergence can occur in both saturated and aerobic-moist soil, demonstrating that this plant does not require a saturated soil and that it can emerge from a moist soil. Jointed bulrush is not yet known from California, but it is considered a weed of rice in India where it is native. It can be distinguished from California native species of Schoenoplectus by the spikelets being clustered near the base of the stem, rather than near the apex.

Official Control: None in California. It is used as an element in dried plant arrangments from India and Southeast Asia.

California Distribution:  Jointed bulrush does not occur in California at this time.

California Interceptions: One detection (PDR #19TP06465285) attached to a shipment of a dried plant arrangement from India that came through Virginia.

The threat that Jointed bulrush would pose to California is evaluated below.

Consequences of Introduction: 

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

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

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

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

Risk is low (1), as the plant occurs in tropical wetlands only. Our rice fields are in colder areas and the subtropical area of California has little of the potential habitat.

2) Known Pest Host Range: Evaluate the host range of the pest. Score: 3

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

– Medium (2) has a moderate host range.

– High (3) has a wide host range.

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

3) Pest Dispersal Potential: Evaluate the natural and artificial dispersal potential of the pest. Score: 2

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

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

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

Risk is Medium (2). The plant produces via numerous seeds and spreads in water. This might limit the speed of its spread. It could also be spread via the pathway of untreated fruiting stems being included in dried floral arrangements. Effective treatment of such plant material before entry into the U.S. would prevent any such accidental introduction.

4) Economic Impact: Evaluate the likely economic impacts of the pest to California using the criteria below. Score: 2

A. The pest could lower crop yield.

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

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

D. The pest could negatively change normal cultural practices.

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

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

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

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

– Medium (2) causes 2 of these impacts.

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

Risk is Medium (2) as the plant can lower crop yields and force changes in cultural practices where it is established.

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

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

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

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

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

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

Score the pest for Environmental Impact. Score: 2

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

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

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

Risk is Medium (2) as, once established, it could conceivably invade the water systems of southern California and disrupt natural wetland communities.

Consequences of Introduction to California for Jointed bulrush:

Add up the total score and include it here. (10)

–Low = 5-8 points

–Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included. Score: -0. Not yet established in CA.

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

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

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

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

Final Score

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

Uncertainty:

Uncertainty is relatively high. Jointed bulrush is not naturalized in California yet, It’s current weediness seems restricted to rice fields in tropical areas. Nevertheless, other wetland weeds have surprised us by invading areas colder than their native range. Any detection of Jointed bulrush in the ambient environment in CA should prompt a reevaluation of its potential risk.

Conclusion and Rating Justification:

A potential weed in wet areas of the tropics, this plant is unlikely to establish in CA. This plant deserves a D rating as it is unlikely to be invasive in CA, although it is a rice field weed in its native range of India. Due to the paucity of references to its weediness, Jointed bulrush does not seem to be as destructive as some other rice field weeds.

References:

Baskin, C. C. & J. M. Baskin. 2001. Chapter 11: Plants with Specialized life-cycles or habitats in Seeds: Ecology, Biogeography, and Evolution of Dormancy and Germination. Academic Press (Elsevier). San Diego, California.

Bopal, B. 1991. Ecology and management of aquatic vegetation in the Indian subcontinent. Kluwer International Press. Dordrecht, Netherlands.

Moody, K. 1989. Weeds Reported in Rice in South and Southeast Asia. International Rice Research Institute. Manila, Philippines.

Shanker, C. 2013. Flora from Cuttack for ID. Efloraofindia Internet site accessed on 5/15/2016:

https://groups.google.com/forum/?hl=en-GB#!topic/indiantreepix/UQk-KIWRfEo

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.

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

Posted by ls

Weeds

Salsola tragus L.: Russian-thistle

California Pest Rating for
Salsola tragus L.: Russian-thistle
Caryophyllidae; Chenopodiaceae
Pest Rating: C  |  Proposed Seed Pest Rating: R
PEST RATING PROFILE
Initiating Event:

This plant has been rated as “C” on the CDFA Plant Pest Rating list and was recently assigned a Q rating by the botany lab.

History & Status:

Russian-thistle is a densely-branched, sub-shrubby annual, to about 1 m tall, with inconspicuous flowers and 5-winged fruits. Fruiting plants die and detach from their roots, forming a “tumbleweed” that tumbles over the ground, dispersing the single-seeded fruits far and wide. Russian-thistle is part of the confusing taxonomic complex that is native to the Old World and Australasia. In the current Jepson Manual, a narrow species interpretation is accepted and our plants are recognized as Salsola tragus. Russian-thistle can act as an alternate host for the virus that causes curly-top in sugarbeets, tomatoes, and melons. Russian-thistle favors disturbed sites, silty dry sites, and saline desert areas; It was introduced into the United States in South Dakota in 1874 as a contaminant of flax seed.

Official Control:  Russian-thistle has been a “C” listed noxious weed by California.

California Distribution:  Russian-thistle is known from all areas of California except for the North Coast and adjacent mountains.

California Interceptions: Fruits of Russian-thistle are detected commonly in vehicles entering California.

United States: Russian-thistle has been found in all states except Alaska and Florida.

International: Russian-thistle is native to arid, disturbed, and saline areas of Eurasia.

This risk Russian-thistle poses to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: The plant is particularly adapted to hot interior zones but is widespread in many coastal areas as well. Its widespread distribution demonstrates its ability to occupy California. Therefore, Russian-thistle 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) 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: Russian-thistle produces via numerous seeds that seem to be able to spread via the tumbleweed habit. Russian-thistle 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: Russian-thistle invades cropland, as well as rangeland. It can also serve as a host for curly-top virus. In some instances, detached plants have impeded traffic traversing arid areas. Russian-thistle receives a High (3) in this category.

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

A.  The pest could lower crop yield

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

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

D.  The pest could negatively change normal production 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: Russian-thistle is likely to trigger new chemical treatments by ranchers and land managers. The plant can dominate subsaline areas or desert washes, excluding native plants and lowering biodiversity. Endangered taxa that might be affected include those that use arid areas such as the brittlescale (Atriplex depressa) and alkali mariposa-lily (Calochortus striatus). It might also reduce habitat value for endangered animals such as the giant kangaroo rat (Dipodomys ingens) by displacing food plants. The effect on local invertebrates is unknown, but the invertebrate fauna associated with Russian-thistle are unlikely to be as diverse as those that associate with native plants that are displaced by Russian-thistle. The plant can disrupt natural communities. Russian-thistle receives a High (3) in this category.

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

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

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

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

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

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

Score the pest for Environmental Impact.

–Low (1) causes none of the above to occur
–Medium (2) causes one of the above to occur
–High (3) causes two or more of the above to occur

Consequences of Introduction to California for Russian-thistle: High (15)

Add up the total score and include it here.

–Low = 5-8 points
–Medium = 9-12 points
–High = 13-15 points

6) Post Entry Distribution and Survey Information: Russian-thistle has been found in in all but 3 counties 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:

There is little uncertainty, as this is an invasive agricultural and environmental weed in California.

Conclusion and Rating Justification:

A terrible weed because of its ability to grow in arid poorly vegetated regions. Because it has spread throughout most or nearly all of its potential range, it merits a C rating.

References:

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

CDFA Encycloweedia; Salsola tragus. Accessed 5/25/2015: http://www.cdfa.ca.gov/plant/ipc/encycloweedia/weedinfo/salsola.htm

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

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

Longland, W. S. 1995. Desert rodents in disturbed shrub communities and their effects on plant recruitment. General Technical Report Intermountain Research Station, USDA Forest Service No. INT-GTR-315: 209-215.

U.S.D.A. Plants database. Salsola tragus. Accessed 5/24/2015:  http://plants.usda.gov/core/profile?symbol=SATR12

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.

Pest Rating: C | Proposed Seed Pest Rating: R

Posted by ls

Weeds

Common reed (Phragmites australis)

Aside
California Pest Rating for
 Common reed (Phragmites australis):
 Phragmites australis cf. subsp. altissimus (non-native)
Pest Rating: C |  Proposed Seed Rating: R
— and —
Phragmites australis subsp. americanus (native)
Pest Rating: D |  Proposed Seed Rating: None
PEST RATING PROFILE
Initiating Event:

Phragmites australis has been given a Q rating by the CDFA botany laboratory.

History & Status:

Background: Common reed is a tall, erect, perennial wetland grass, 1 to 3 meters high. It spreads via rhizomes and seeds. Local spread of Common reed is predominantly through vegetative growth and regeneration, while establishment of new populations occurs through dispersal of seeds, rhizomes, and sod fragments. Common reed is one of the most widely distributed flowering plants. It occurs on every continent except Antarctica and is cosmopolitan in temperate zones. Common reed is widely distributed in North America; it occurs in all U.S. states except Alaska. Common reed is native to Puerto Rico and occurs as a nonnative in Hawaii. That said, populations in different continental areas vary in their morphology, haplotypes, genetics, and ecology. These different forms have been given sub-specific status in some cases. Research has shown that an adventive form (tentatively identified as Phragmites australis subsp. altissimus), probably introduced from the Western Europe in the late 19th century, had colonized wide areas in North America and had largely displaced native ecotypes in the northeastern U.S. by 1940. This form is considerably more invasive than native ecotypes and displays much higher productivity and ability to invade a variety of wet habitats.

Large infestations of Common reed are difficult to eradicate given that all rhizomes must be removed or killed to prevent re-sprouting. In addition care must be taken to ensure that only the invasive, non-native subspecies is removed. Typically a combination of mechanical removal and application of a systemic herbicide (e.g., glyphosate) provide the best control.

Common reed is listed as a noxious weed in Alabama, Connecticut, Massachusetts, South Carolina, Vermont, and Washington. Much of the weed management budget in Nebraska is spent on controlling the non-native ecotype of common reed.

 Worldwide Distribution: Common reed is native to many warm temperate and tropical regions from throughout the world. The non-native subspecies seems to have been introduced from western Europe.

California Distribution: Common reed is found along waterways throughout much of CA. It is rarely collected in the Central Valley of California, but it is extremely common in the Delta Region.

California Interceptions: Common reed is occasionally sold in nurseries in CA. Plumes of unknown sub-specific identity are also used in dried plant arrangements imported from Asia and other areas.

This risk Common reed would pose to California is evaluated below.

Consequences of Introduction: 

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

– Low (1) not likely to establish in California; or likely to establish in very limited areas
-Medium (2) may be able to establish in a larger but limited part of California
-High (3) likely to establish a widespread distribution in California

Risk is Medium (2) as illustrated by the broad distribution of the invasive form in other states. It is limited by its preference for wetlands and ditches.

2) Pest Host Range:

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

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

3) Pest Dispersal Potential:

Evaluate the dispersal potential of the pest:

-Low (1) does not have high reproductive or dispersal potential
-Medium (2) has either high reproductive or dispersal potential
–High (3) has both high reproduction and dispersal potential

Risk is High (3) as the plant spreads via water flow and human dispersal from rhizomes or stem fragments. It expands it range via seed dispersal or rhizome fragments.

4) Economic Impact:

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

A.  The pest could lower crop yield

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

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

D.  The pest could negatively change normal production cultural practices

-Low (1) causes 0 or 1 of these impacts
–Medium (2) causes 2 of these impacts
-High (3) causes 3 or more of these impacts

Risk is Medium (2) as Common reed can invade agricultural land, especially along irrigation canals and in rice paddies. Non-native common reed is much more likely to colonize small water features and channels than native ecotypes. It also forms larger, denser colonies than the native subspecies. In these situations it can block or slow irrigation water and cause water loss via evapotranspiration. It can lower yields in some ranching systems, where Common reed may block livestock access to water.

5) Environmental Impact: 

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

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

Score the pest for Environmental Impact:

-Low (1) causes none of the above to occur
-Medium (2) causes one of the above to occur
–High (3) causes two or more of the above to occur

Risk is High (3) as non-native common reed can be  an ecological transformer; it can exclude native riparian species, and dry out or cover small open water sources. Native ecotypes can be dominant in large wetland situations, but non-native ecotypes are much more likely to invade and cause impacts in smaller, isolated water sources. This may have a significant impact on wildlife in arid California, where access to small or isolated water sources plays an important part in population success of some species.

Consequences of Introduction to California for Common reed: 

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

-Low = 5-8 points
-Medium = 9-12 points
-High = 13-15 points

Total points based on above criteria, which does not take into account the pathogen’s already wide distribution in California: High (13).

6) Post Entry Distribution and Survey Information:  Common reed is widespread in CA. It receives a Low (-1) in this category.

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

–Not established (0) Pest never detected in California, or known only from incursions.
–Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).
–Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.
-High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

 Final Score:

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

Uncertainty:

Unfortunately, there is almost no discrimination between native and non-native ecotypes of common reed in California in past literature and on specimen labels. Recent genetic work has indicated that much of the common reed in California, especiually in the Delta region, is the non-native ecotype.

Conclusion and Rating Justification:

Proposed Rating: based on the score listed above the pest is a moderate risk species. This would justify an “A” rating if the species is not widely established in CA already.

As the non-native ecotype’s current range in California is widespread, a “C” rating is recommended for the non-native subspecies and a “D” rating is recommended for the much less invasive native subspecies.

References:   

Amsberry, L., M. A. Baker, P. J. Ewanchuk, & M. D. Bertness. 2000. Clonal integration and the expansion of Phragmites australis. Ecological Applications. 10: 1110-1118.

Plut, K., J. Paul, C. Ciotir, M. Major & J. R. Freeland. 2011. Origin of non-native Phragmites australis in North America, a common wetland invader. Fundam. Appl. Limnol. 179: 121–129.

Invasive Plants. Common reed. Accessed 8/20/2015:

http://www.invasiveplants.net/phragmites/phrag/morph.htm

Papchenkov V.G. 2008. About distribution of Phragmites altissimus (Benth.) Nabille (Poaceae). Russian J. of Biological Invasions 1: 202-205.

Randolph M. Chambers R. M., L. A. Meyerson, & K. Saltonstall. 1999. Expansion of Phragmites australis into tidal wetlands of North America.  Aquatic Botany 64: 261–273.

Saltonstall, K. 2002. Cryptic invasion by a non-native genotype of the common reed, Phragmites australis, into North America. Proc Natl Acad Sci USA 99: 2445–2449.

Saltonstall, K.,& J. Stevenson. 2007. The effects of nutrients on seedling growth of native and introduced Phragmites australis. Aquatic Botany. 86: 331-336.

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.

Phragmites australis cf. subsp. altissimus (non-native)
Pest Rating: C |  Proposed Seed Rating: R
Phragmites australis subsp. americanus (native)
Pest Rating: D |  Proposed Seed Rating:  None

Posted by ls

Weeds

Phyllanthus urinaria L.; Chamberbitter

California Pest Rating
Phyllanthus urinaria L.; Chamberbitter
Euphorbiaceae; Malpighiales
Pest Rating: C | Proposed Seed Rating: R
PEST RATING PROFILE
Initiating Event:

The species was given a temporary Q rating in 2014.

History & Status:

Chamberbitter is an herbaceous, annual herb that can grow 20-70 cm in height. The leaves are elliptic and borne distichously along the stem. They are superficially similar to those of sensitive plant (Mimosa pudica), but in fact sensitive plant has compound leaves with elliptic leaflets. The small flowers are sessile under the leaf axils and quickly give rise to six-lobed, pumpkin-shaped fruits that dehisce explosively releasing 6 seeds. Chamberbitter seems not to be native to the United States, but it is a widely distributed tropical weed. It is weedy species nurseries, gardens and lawns in tropical areas. It is a pest of rice in Southeast Asia.

Official Control: Chamberbitter has been a “Q” listed weed in California since late 2014.

California Distribution:  Chamberbitter currently is not known from California.

California Interceptions: Chamberbitter has been detected in nursery stock entering California from Florida.

United States:  Chamberbitter is widespread in the Southern United States. It is listed as a noxious weed in Alabama.

International: Chamberbitter is reported as naturalized and as an environmental and agricultural weed in much of the tropics.

The risk Chamberbitter would pose to California is evaluated below.

 Consequences of Introduction: 

1) Climate/Host Interaction: It is an invasive species of disturbed areas, nurseries, lawns and wet fields in the tropics and subtropics. Although it may spread in agricultural situations with adequate water, chamberbitter is unlikely to be suited to escape widely in the environment, except in warmer areas that have abundant water in the late spring and summer. This might apply in nurseries in Southern California, as well as in some rice fields. It scores as 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) 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: Chamberbitter is a prolific seed producer that disperses its seeds via explosive fruits. The seeds can remain dormant for an extended period of time. They germinate during the wet, warm conditions and the seedlings mature quickly (within 2 weeks in some cases). Seed requires light to germinate. A germination rate of up to 80% was observed at temperatures of 25–35°C, but germination was poor at 20°C or 40°C. Germination of seed is also poor under moisture stress conditions. Chamberbitter 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: Chamberbitter is a weed in some agricultural situations. Its worst effects are as a lawn weed that is difficult to eradicate. Chamberbitter receives a Low (1) in this category.

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

A.  The pest could lower crop yield

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

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

D.  The pest could negatively change normal production 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: The plant has not yet spread in California. If it does spread, Chamberbitter might trigger new treatments by nursery and turf farm managers. Chamberbitter receives a Low (1) in this category.

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

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

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

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

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

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

Score the pest for Environmental Impact.

–Low (1) causes none of the above to occur
-Medium (2) causes one of the above to occur
-High (3) causes two or more of the above to occur

Consequences of Introduction to California for Chamberbitter: 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: Chamberbitter has not been found established in California. Its range at this time is limited. It receives a (0) in this category.

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

–Not established (0) Pest never detected in California, or known only from incursions.
–Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).
–Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.
–High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score:

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

Uncertainty:

This plant is not widely adapted to the dry environments of California. Nevertheless, locally in warmer areas with irrigation, it could invade and prove troublesome. It is an especially invasive pests of nurseries and well watered lawns.

Conclusion and Rating Justification:

Chamberbitter is a potential weed of nurseries, turf farms and watered gardens in southern California. It may invade irrigated crops such as rice and cotton in warm areas as well, although this is less likely given the management regime in CA rice fields. Because of its real but restricted potential to invade California, chamberbitter deserves for a C pest rating.

References:

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

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

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

Weaver, R. 2010. Phyllanthus urinaria L., the chamber bitter or gripe weed. Accessed 5/23/2015: http://www.freshfromflorida.com/Divisions-Offices/Plant-Industry/Plant-Industry-Publications/Weed-of-the-Month/August-2010-Phyllanthus-Urinaria-L.-The-Chamber-Bitter-Or-Gripe-Weed

USDA Plant Profile: Phyllanthus urinaria. Accessed May 16, 2015:

http://plants.usda.gov/core/profile?symbol=PHUR

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.

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

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Pest Rating: C | Proposed Seed Rating: R

Posted by ls

Weeds

Yellow Floating-heart | Nymphoides peltata (Gmel.) Kuntze

California Pest Rating for
Yellow Floating-heart Nymphoides peltata (Gmel.) Kuntze
Pest Rating: A  |  Proposed Seed Rating: R
PEST RATING PROFILE
Initiating Event:

There is a recent detection of Yellow Floating-heart found growing in Los Angeles County. This is the third detection of this species occurring spontaneaously in California and the only recent one.

History & Status:

Background: Yellow Floating-heart is an aquatic plant of the family Menyanthaceae native to Eurasia. It has cordate floating leaves that support a lax inflorescence of yellow flowers with fringed petal margins. The fruit is a capsule bearing many flattened seeds with stiff marginal hairs. It has adventitious roots along an underwater stem. Like many aquatic plants, Yellow Floating-heart can reproduce vegetatively and spread over large areas of water. Because it has floating leaves it can photosynthesize rapidly and outcompete many other aquatic plants. Yellow Floating-heart  aggressively colonizes in lakes, riparian zones, water courses, and other wetlands.

Little information is available on the control of Yellow floating-heart. Based on the plant’s characteristics, mechanical and hand removal would likely be effective. It is not known whether biological or chemical controls are effective on Yellow Floating-heart. New Zealand information suggests that hand clearing is possible with small infestations and herbicides need to be used for larger infestations.

Worldwide Distribution: Yellow floating-heart is native to Eurasia and it is naturalized in New Zealand, Great Britain, North America, and Australia. In the U.S. it has been found in 25 states, including CA, TX, WA, & AZ.

California Distribution: Yellow Floating-heart has been found in very limited areas of El Dorado, Del Norte, Monterey, and Los Angeles Counties.

California Interceptions: Yellow Floating-heart is occasionbally sold in nurseries in CA as a pond plant and this is the most likely pathway for introduction into the environment.

This risk Yellow Floating-heart would pose to California is evaluated below:

Consequences of Introduction:

1) Climate/Host Interaction: Evaluate if the pest would have suitable hosts and climate to establish in California.  Score: 2

-Low (1) not likely to establish in California; or likely to establish in very limited areas
-Medium (2) may be able to establish in a larger but limited part of California
-High (3) likely to establish a widespread distribution in California

Risk is Medium (2) as illustrated by the localized range of the plant in states where it occurs. Yellow Floating-heart would be expected to colonize riparian areas, ponds, wetlands, roadside ditches, irrigation canals, and shallow lake margins.

2) Pest Host Range: Evaluate the host range of the pest: 3

– Low (1) has a very limited host range
– Medium (2) has a moderate host range
– High (3) has a wide host range

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

3) Pest Dispersal Potential:  2. Evaluate the dispersal potential of the pest:

-Low (1) does not have high reproductive or dispersal potential
–Medium (2) has either high reproductive or dispersal potential
-High (3) has both high reproduction and dispersal potential

Risk is Medium (2) as the plant spreads via water flow and escape from yard water features. Once established it can spread quickly.

4) Economic Impact:  2. Evaluate the economic impact of the pest to California using these criteria:

A.  The pest could lower crop yield

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

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

D.  The pest could negatively change normal production cultural practices

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

–Medium (2) causes 2 of these impacts

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

Risk is Medium (2) as Yellow Floating-heart lowers can impede water flow in irrigation canals, as well as interfere with navigation.

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

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

Score the pest for Environmental Impact: 3

-Low (1) causes none of the above to occur
-Medium (2) causes one of the above to occur
–High (3) causes two or more of the above to occur

Risk is High (3) in California, as Yellow Floating-heart is an aggressive invader of wetlands. As such, it displaces native plant species in these important habitats. Species outcompeted and excluded potentially include such state and federal endangered plants as, Bogg’s Lake hedge hyssop and Gambell’s watercress. Potential effects on endangered wildlife include breeding habitat modification, and food disruption (either directly from food plant exclusion, or indirectly via insect prey reduction). Potentially affected species include the Point Arena mountain beaver, red-legged frog, yellow-legged frog, and California tiger salamander.

Consequences of Introduction to California for Nymphoides peltata 

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

-Low = 5-8 points
-Medium = 9-12 points
-High = 13-15 points

Total points based on above criteria, which does not take into account the pest’s distribution in California: Medium (12).

6) Post Entry Distribution and Survey Information: Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included. Score: -1

-Not established (0) Pest never detected in California, or known only from incursions.
–Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).
-Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.
-High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score:

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

Uncertainty:

This plant entered California long ago, but this is the first find in over a decade. It is not known how far its spread will extend. Shallow water habitat represents a small percentage of habitat in California, but it is widespread throughout the state and is disproportionally important due to its water availability and importance for agriculture and wildlife. Given the limited distribution of this plant, it may be possible to eradicate it at this time. Although it has not yet spread widely, there is nothing to stop it spreading in the appropriate habitats.

Conclusion and Rating Justification:

Conclusions of the harm(s) associated with this pest to California using all of the evidence presented above: Proposed Rating: Based on the score listed above the pest is a Medium risk. As the plant is limited to small areas at this time, prompt and effective action would have a signifiant effect on the future impacts of this species. Therefore, a rating of “A”is proposed.

Literature:

USDA Plants. Accessed 10/15/15: https://plants.usda.gov/core/profile?symbol=NYPE

Washington State Weed website. Accessed 10/15/15: Dept of Ecology; State of WA. Non-native Invasive Freshwater Plants:Yellow Floating Heart (Nymphoides peltata). http://www.ecy.wa.gov/programs/wq/plants/weeds/floatingheart.html

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.

Pest Rating: A  |  Proposed Seed Rating: R

Posted by ls 

Weeds

Ludwigia decurrens (winged water-primrose)

11 Comments
California Pest Rating for
Ludwigia decurrens (winged water-primrose)
Myrtales; Onagraceae
Pest Rating:  A  |  Seed Rating:  P
PEST RATING PROFILE
Initiating Event:

This plant was been detected in California in 2011.

History & Status:

Winged water-primrose is an invasive weed that was identified in Butte County rice fields in 2011. Most infestations are along borders of fields and canals; however, this weed can thrive in the flooded environment within rice fields. Winged water-primrose can disperse through seeds and plant fragments floating in the irrigation water and tillage and harvest equipment.

Official Control: Butte County has been carrying out control in partnership with rice growers.

California Distribution:  Winged water-primrose occurs in several rice fields in Butte County, California. It has persisted in low number despite several years of attempted eradication.

California Interceptions: Winged water-primrose was found in a rice field inspection.

Other range: It is native to the southeastern U.S. and has been introduced into Japan where it is an invasive weed of rice.

Consequences of Introduction: 

1) Climate/Host Interaction: Evaluate if the pest would have suitable hosts and climate to establish in California. Score: 2

– Low (1) Not likely to establish in California; or likely to establish in very limited areas.
– Medium (2) may be able to establish in a larger but limited part of California.
– High (3) likely to establish a widespread distribution in California.

Risk is Medium (2), as the plant could occur in wetlands such as the Delta as well as in rice fields.

2) Known Pest Host Range: Evaluate the host range of the pest. Score: 3

– Low (1) has a very limited host range.
– Medium (2) has a moderate host range.
– High (3) has a wide host range.

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

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

– Low (1) does not have high reproductive or dispersal potential.
– Medium (2) has either high reproductive or dispersal potential.
– High (3) has both high reproduction and dispersal potential.

Risk is High (3). The plant produces via numerous seeds and can spread rapidly in water, in poorly-cleaned seed, and on farming equipment. It is likely to have been introduced into California from a seed lot.

4) Economic Impact: Evaluate the likely economic impacts of the pest to California using the criteria below. Score: 3

A.  The pest could lower crop yield.

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

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

D.  The pest could negatively change normal cultural practices.

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

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

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

– Low (1) causes 0 or 1 of these impacts.
– Medium (2) causes 2 of these impacts.
– High (3) causes 3 or more of these impacts.

Risk is High (3) as the plant can lower crop yields, trigger quarantines, and force changes in cultural practices.

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

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

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

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

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

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

Score the pest for Environmental Impact. Score: 3

– Low (1) causes none of the above to occur.
– Medium (2) causes one of the above to occur.
– High (3) causes two or more of the above to occur.

Risk is High (3) as the plant could invade the water systems of California, disrupt natural wetland communities and potentially lower biodiversity by invading wetlands.

Consequences of Introduction to California for Winged water-primrose:

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

–Low = 5-8 points
–Medium = 9-12 points
–High = 13-15 points

6) Post Entry Distribution and Survey Information: Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included. Score: Low (-1)

–Not established (0) Pest never detected in California, or known only from incursions.
–Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).
–Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.
–High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score:

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

Uncertainty:

It is a weed of rice in other localities and seems similar in biology to its relatives that are also weeds of rice in California. So, the uncertainty is low.

Conclusion and Rating Justification:

A potentially significant weed in CA of both natural wetlands and rice fields. Deserves an A rating as it’s so invasive in Japan and other rice growing regions.

References:

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

Chandrasena, J. P. N. R. 1988. Ludwigia decurrens Walt. – A new rice field weed in Sri Lanka. Journal of National Scientific Council, Sri Lanka 16: 97-103.

UC Rice Blog: Behavior of Winged Primrose Willow and Herbicide Options for Control. http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=7778

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.

Pest Rating:  A  |  Proposed Seed Rating:  P

Posted by ls

Weeds

Cheatgrass | Bromus tectorum

California Pest Rating for
Cheatgrass  Bromus tectorum
Pest Rating: C  |  Proposed Seed Rating: None
PEST RATING PROFILE
Initiating Event:

This plant is implicated in changing fire regimes in western states.

History & Status:

Cheatgrass is an annual grass. It is a tufted annual; although not large, it can colonize preferred habtat in large numbers, especially after disturbance.  The spikelets consist of several florest that are pendent at maturity. Cheatgrass can be grazed early in the year, but as it matures the spikey awns render it less suitable for this purpose. As such it is inferior to  perennial grasses in regards to livestock production. A survey of 11 western states in 1964 showed that cheatgrass was present on at least 60 million acres. Its range is larger now.

California Distribution: Cheatgrass  has been collected in all counties of California exept the driest deserts in the southeast of the state.

California Interceptions: Several vouchers have been submitted to CDFA for identification.

United States: Cheatgrass was introduced to North America independently several times via ship ballast, contaminated crop seed, and packing material. Cheatgrass now occurs throughout most of the United States, Canada, Greenland, and northern Mexico.

International:  Cheatgrass  is native to northern Africa, Europe, and western Asia. It is introduced in North and South America, Australia, New Zealand, Japan, and Iceland.

This risk Cheatgrass  would pose to California is evaluated below.

Consequences of Introduction:

1) Risk is high (3), as Cheatgrass is naturalized in the drier regions throughout western North America and is still spreading.

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: Cheatgrass seeds are light and produced prolifically. The awns on Cheatgrass fruits allow for long-distance dispersal in animal skin and fur. Motor vehicles also disperse Cheatgrass fruits. Cheatgrass can begin producing seeds at 3 weeks from germination or, given available water and nutrients, can bloom later in the season with many more flowers. It can germinate in the fall or winter depending on the year and the climate. Therefore, Cheatgrass 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: Cheatgrass has been used as forage in arid environments in the Intermontane West, and this is a positive economic value. It is less nutritious than the perennial bunchgrasses that it often replaced. When Cheatgrass invades new habitats, there is often an increase in fire that removes perennials, including grasses and sagebrush steppe shrubs from the area. Livestock browse shrubs as a source of protein in the late season. As shrubs are eliminated by fire, fall and winter digestible protein sources are lost. Cheatgrass is also a row crop weed, although this is less of an issue than its effects on rangeland.

Cheatgrass receives a High (3) in this category.

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

The pest could lower crop yield.

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

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

C.  The pest could negatively change normal cultural practices.

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

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

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

– Low (1) causes none of the above to occur.
– Medium (2) causes 2 of these impacts.
– High (3) causes 3 or more of these impacts.

5)  Environmental Impact: Cheatgrass invades and dominates a variety of vegetation types, especially sagebrush steppe. In natural areas, it tends to form dense swards that exclude native vegetation and increase the ability of fire to spread. In some arid regions, Cheatgrass can transform native sagebrush scrub into non-native grasslands. This, in turn, decreases the native biodiversity and removes habitat for wildlife including birds such as the species of concern Greater Sage Grouse (Centrocercus urophasianus) and its distinct population segment, the Bi-state Sage Grouse, as well as other sagebrush steppe endemics. Therefore, Cheatgrass receives a High (3) in this category.

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

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

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

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

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

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

Score the pest for Environmental Impact. Score:

– Low (1) causes none of the above to occur.
– Medium (2) causes one of the above to occur.
– High (3) causes two or more of the above to occur.

Consequences of Introduction to California for Cheatgrass: High (15)

Add up the total score and include it here.

–Low = 5-8 points
-Medium = 9-12 points
–High = 13-15 points

6) Post Entry Distribution and Survey Information: Cheatgrass is regionally common in CA. It receives a High (-3) in this category.

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

–Not established (0) Pest never detected in California, or known only from incursions.
–Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).
–Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.
-High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score:

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

Uncertainty:

This plant has been known in SW North America for over 100 years and it has proved highly invasive. So, there is low uncertainty.

Conclusion and Rating Justification:

Proposed Rating: based on the score listed above, cheatgrass is still spreading but has occupied the majority of its potential habitat in California. This plant has been invasive; in California it is already known from most counties. Because this plant is so widespread, a rating of C is justified.

References:

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

CalFlora: http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=12041

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

Pellant, M. 1996. Cheatgrass: the Invader That Won the West. Bureau of Land Management, Boise Idaho.

U.S. Forest Service. Cheatgrass. Accessed 8/20/2015:

http://www.fs.fed.us/database/feis/plants/graminoid/brotec/all.html

Young, J. A.  & C. D. Clements. 2007. Cheatgrass and Grazing Rangelands. Rangelands, 29:15-20.

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.

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: C  |  Proposed Seed Rating: None

Posted by ls