Category Archives: Weeds

Plants (weeds)

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.

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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

Weeds

Spanish Mercury | Mercurialis ambigua

California Pest Rating for
Spanish Mercury  |  Mercurialis ambigua
Pest Rating: B  |  Proposed Seed Rating: R
PEST RATING PROFILE
Initiating Event:

This plant has been rated as “B” on the CDFA Plant Pest Rating list for 3 years

History & Status:

Spanish mercury is a modest annual herb with alternate, oval leaves. It has tiny flowers in short spikes in the axils of the leaves. In Flora Europaea Spanish mercury is included as a variant of dog mercury (Mercurialis annua), a European weed that has been found in the San Francisco Bay Area. In most Spanish floras the taxa are treated as distinct. Spanish mercury differs from dog mercury in its wider leaves, shorter flower spikes and in its polyploidy (multiple chromosome sets). It has been demonstrated that these hexaploid plants arose between a tetraploid M. annua (dog mercury) and a diploid M. huetii.  In addition to these differences, Spanish mercury may differ from dog mercury in its weedy behavior. In its natural habitat in Spain it occurs in open areas protected from the hottest sun with common weeds such as bristly oxtongue (Helminthostachys echioides), shining geranium (Geranium lucidum), purple false-brome (Brachypodium distachyon), ripgut brome (Bromus diandrus), hairy cress (Cardamine hirsuta), common chickweed (Stellaria media), sow-thistle (Sonchus oleraceus), mouse-ear chickweed (Cerastium glomeratum), bur-chervil (Anthriscus caucalis), common pimpernel (Anagallis arvensis), red brome (Bromus madritensis), and plumeless thistle, (Carduus tenuiflorus). Spanish mercury has shown itself to be very invasive in nursery situations. It has also been found in mulch adjacent to public buildings and on the edge of a vineyard.

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

California Distribution:  Because of the taxonomic confusion with dog mercury, Spanish mercury was not recognized in California until the 2000s. Nevertheless, its incursion seems to be rather recent, as older vouchered specimens are dog mercury. It is, so far, always limited in distribution. It has been found in Alameda, Contra Costa, Napa, Monterey, and Yolo Counties.

California Interceptions:  Spanish mercury has never been found coming into California.

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 naturalized in mulched landscapes, around nurseries and in vineyards. Once its population builds up it can be expected in areas occupied by the widespread weed associates mentioned above.

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 numerous seeds that seem to be able to spread rather well via pathways that have to do with landscaping and nursery operations.

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). Based on the mercuries being known crop weeds on several continents, the plant is likely to interfere with crop production and can lower crop value. It shows an incipient ability to be a nuisance weed in gardens, especially in open garden beds.

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 open, disturbed areas, excluding other plants and lowering biodiversity and can exclude cultural plants from a landscape.

Consequences of Introduction to California for Spanish mercury:

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. (-2)

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

–Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).
–Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.
–High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score:

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

Uncertainty:

Annual mercuries are widespread as agricultural weeds throughout the world. Which of these is dog mercury versus Spanish mercury is unknown. Nevertheless, it seems to be actively spreading in Central California. The eventual effects are in the future and must be projected with significant uncertainty. The seeds of Spanish mercury are quite similar to those of dog mercury and identification of seed contaminants must reflect this uncertainty.

Conclusion and Rating Justification:

A potentially bad weed of horticultural areas, vineyards, and possibly open, grassy habitats. Deserves a B rating as it is present in > 5 cos.

References:

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

‪Fernández, I. F. 2001. Claves de Flora Iberica: Plantas Vasculares de la Península Ibérica e Islas Baleares, Volume 1. CSIS Press. Madrid.

Flora of Sierra de La Parra (Badajoz). Accessed 11/15/2015:

http://sierradelaparrabadajoz.blogspot.com

López G.B., M. C. Romero, B. Cabezudo, C. M. Torres, & C. Salazar. 2011.

Claves de la Flora Vascular de Andalucía Oriental. Universidad Almería.

Obbard, D. J., Harris, S. A., Richard J. A. Buggs, & Pannell, J. R. 2006. Hybridization, Polyploidy, and the Evolution of Sexual Systems in Mercurialis (Euphorbiaceae). Evolution 60: 1801–1815.

Thomas, R. G. 1958. Sexuality in Diploid and Hexaploid Races of Mercurialis annua L. Annals of Botany, N.S. 22: 55-72.

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: B  |  Proposed Seed Rating: R

Posted by ls

Weeds

Froelichia gracilis (Hook.) Moq.; Slender snakecotton

California Pest Rating for
Froelichia gracilis (Hook.) Moq.; Slender snakecotton
Amaranthaceae: Caryophyllales
Pest Rating: D  |  Proposed Seed Rating: None
PEST RATING PROFILE
Initiating Event:

The species was given a temporary Q rating in 2014.

History & Status:

Slender snakecotton is an herbaceous, short-lived perennial (often an annual in weedy situations) that can grow 20-70 cm in length. The plant branches from the base, creeping along the ground and then becoming erect. The whole plant is covered in white, silky hairs. The leaves occur mostly on the lowers parts of stems and are narrowly lanceolate, narrower than in closely related taxa. The largest leaves measure 8 cm (3 in.) long and 1 cm wide. The apetalous flowers of Froelichia gracilis are arranged in a 3-rowed spiral on 1-3 cm long spikes and appear in summer to early fall. The seeds of this plant are small, measuring 1.2-1.4 mm. Although widely distributed and native to the southern United States, slender snakecotton seems not to be native to California. It is a weedy species of roadsides, railroads, farms and pastures, riverbanks, vacant lots, overgrazed rangelands, and sandy soils. It tolerates cold winters, but can also occur in moist subtropical areas.

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

California Distribution:  Slender snakecotton is known from 3 interceptions in California (two from Los Angeles and one from Shasta County).

California Interceptions: Vouchered specimens are known from Los Angeles and Shasta Counties.

United States:  Slender snakecotton is widespread in the Southern United States. It is generally viewed as adventive in the northern and northeastern U.S. It is listed as a noxious weed in Connecticut.

International: Slender snakecotton is reported as naturalized and as an environmental and agricultural weed in Queensland, Australia.

The risk Slender snakecotton would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: It is an invasive species of roadsides, railroads, farms, riverbanks, vacant lots, overgrazed rangelands, and sandy areas. It is been detected in 2 counties with radically different climates, but has not spread widely. Although it may spread in agricultural situations with adequate water, its rarity in the state, despite being native to nearby states, indicates that it is unlikely to spread quickly. Therefore. It scores as Low (1) in this category.

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

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

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

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

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

Evaluate the host range of the pest. Score:

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

-Medium (2) has a moderate host range.

–High (3) has a wide host range.

3) Pest Dispersal Potential: Slender snakecotton produces numerous seeds that can spreads via agricultural activity. Slender snakecotton 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: Slender snakecotton is a weed in some agricultural situations. There is little report of significant effects however. Slender snakecotton 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).

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.

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 widely in California. If it does spread, Slender snakecotton might trigger new treatments by land managers. As it invades open areas, it may outcompete native plants that also colonize open, sandy soils. Slender snakecotton 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. The pest could significantly impact 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 Slender snakecotton: Low (8)

Add up the total score and include it here.

-Low = 5-8 points

-Medium = 9-12 points

-High = 13-15 points

6)  Post Entry Distribution and Survey Information: Slender
snakecotton has been found in in 2 counties in California. Its range at this time is limited. It receives a Medium (-2) in this category.

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

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

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

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

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

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Low (6)

Uncertainty:

The rarity of this plant in California despite being first detected in Los Angeles in 1955 and its widespread range in the rest of North America render it unlikely that this plant will invade many new areas and increase its density and acreage.

Conclusion and Rating Justification:

Slender snakecotton deserves an D rating at this time, because of its limited range in California, despite being native to nearby states.

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/

Csurhes S.  & Y. Zhou . 2008. Weed Risk Assessment of Cotton-tails, Froelichia floridana and F. gracilis. Biosecurity Queensland Department of Primary Industries and Fisheries, Brisbane, Australia.

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

Reed, C. F. 1962. New records for Froelichia in eastern United States. Castanea 27: 59-61.

USDA Plant Profile: Froelichia gracilis. Accessed May 16, 2015:

http://plants.usda.gov/core/profile?symbol=FRGR3

Washington State Weed Control Board: Slender snakecotton. Accessed September 16, 2014:

http://www.nwcb.wa.gov/detail.asp?weed=12

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: None

Posted by ls

Weeds

Enchylaena tomentosa R. Br.; Ruby saltbush

California Pest Rating for
Enchylaena tomentosa R. Br.; Ruby saltbush
Chenopodiaceae: Caryophyllales
Pest Rating: A  |  Proposed Seed Rating: R
PEST RATING PROFILE
Initiating Event:

The species was detected in San Diego County in 2014 and given a “Q” rating.

History & Status:

Ruby saltbush is an open, straggling shrub native to Australia that can grow up to 2 m tall and wide, but is usually much shorter. Grazing and low nutrient soils in full sun limit the height of the plant, but it is quite capable of clambering over adjacent vegetation. Leaf color in California specimens is dark blue-green. The leaves are succulent, 1-2 cm long, cylindrical, and may be hairy or smooth. Stems are distinctively marked with parallel lines. The flowers are small, occurring in the leaf axils. The sepals become fleshy and red when the fruit ripens, simulating a juicy berry.

Official Control: Ruby saltbush has not been subjected to official control.

California Distribution:  Ruby saltbush is known from a single infestation in Central San Diego County, California. The plants grow along a sloping road bank and an adjacent arroyo surrounded by residential development. As other vegetation along the road bank may be horticultural in origin, it seems likely that the plant was planted intentionally as a novel, low maintenance landscape shrub. The oldest known specimen in California was collected in 2014.

California Interceptions: Vouchered specimens are known from San Diego County, although they have not yet been accessioned.

United States:  Ruby saltbush is known only from California in the United States.

International: Ruby saltbush is native to Australia, where it is widely distributed in arid and semiarid areas in various shrubby or grassland plant communities. It is especially common in slightly saline soils. It is reported as naturalized in New Caledonia.

The risk Ruby saltbush would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: The plant occurs in grassland and coastal scrub. It is spreading in ruderal areas near the coast. It is tolerant of slightly saline soils. Therefore, its adaptation to coastal habitats in southern California is likely high. 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: Ruby saltbush produces numerous red, fleshy fruits that are typical of bird-dispersed woody plants. Hundreds to the low 1000s of fruits are produced by a mature shrub. Ruby saltbush 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: It has not yet had an impact on agricultural lands and future possible impacts are unknown. Ruby saltbush is browsed by livestock under adverse conditions, but its range value is not high. It 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).

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: Ruby saltbush is overgrowing adjacent vegetation such as jojoba and prickly pear cactus; it is dense and its sprawling stems can smother other plants. In adjacent areas it is growing as scattered plants that may be suppressing other coastal scrub species through competition. Rare taxa that might be affected include strand species such as creeping lotus (Acmispon prostratus) and coastal scrub species such as California gnatcatcher (Polioptila californica). Because it forms dense patches, Ruby saltbush could interfere with recreation along the coast. Ruby saltbush 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 could significantly impact 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 Ruby saltbush: Medium (11)

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: Ruby saltbush has been found in in 1 locality in California; This may have spread from cultivation. It receives a Low (-1) in this category.

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

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

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

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

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

Final Score:

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

Uncertainty:

This plant is showing the ability to spread in disturbed areas near the coast. Its future potential impact on agriculture, if allowed to spread, is unknown.

Conclusion and Rating Justification:

This plant is just beginning its spread in California. It shows tendencies of invasiveness and it is strictly limited in distribution now. The probability of eradication is high. It should be given a rating of “A” to encourage attention to this plant.

References:

Calflora; Enchylaena tomentosa. Accessed 2/22/2015:                            http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=13047

Florabase; Enchylaena tomentosa. Accessed 2/22/2015: http://florabase.dpaw.wa.gov.au/browse/profile/2511

USDA Plants Database, Enchylaena tomentosa. Accessed 2/22/2015: http://plants.usda.gov/core/profile?symbol=ento3

Western Australia Department of Agriculture; ruby salt bush. Accessed 2/22/2015: https://www.agric.wa.gov.au/ruby-saltbush

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

Medicago scutellata (L.) Wilson; Snail Medic

California Pest Rating for
Medicago scutellata (L.) Wilson; Snail Medic
Fabales: Fabaceae
Pest Rating: D  |  Proposed Seed Rating: N/A
PEST RATING PROFILE
Initiating Event:

This plant has been rated as “Q” by the CDFA Botany Laboratory.

History & Status:

Snail Medic is an annual herb with trifoliate leaves and comparatively large (6-7 mm) fruits that spiral (hence the common name), but lack prickles. The leaves are softly hairy and inconspicuously glandular. Flowers are borne on stems shorter than the petioles in groups of 2-3. In California, it appears in disturbed areas.

Official Control:  None.

California Distribution:  Snail Medic is known from Butte, Santa Clara, Monterey, and San Luis Obispo Counties.

California Interceptions: Vouchered specimens are known from Butte, Santa Clara, Monterey, and San Luis Obispo Counties.

United States: Snail Medic has only been found in North America in Delaware outside of California.

International: Snail Medic is native to Europe.

This risk Snail Medic would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: The plant has adapted to disturbed areas. It was first collected in 1924. Despite this early detection and its adaptation to ruderal habitats, it has not yet spread widely. It receives a Low (1) in this category.

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

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

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

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

2) 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: Snail Medic produces via numerous seeds that seem to be able to spread via gravity, and wildlife. Snail Medic 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: Snail Medic may invade croplands as a weed in certain areas. Snail Medic 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).

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:  Snail Medic is not likely to trigger new chemical treatments by ranchers and land managers, as it is much less invasive than its congener bur-clover (Medicago polymorpha). The plant is never dominant in CA. The plant is unlikely to disrupt natural communities. Snail Medic 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. The pest significantly impact 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 Snail Medic: Low (8)

Add up the total score and include it here.

–Low = 5-8 points

-Medium = 9-12 points

-High = 13-15 points

6) Post Entry Distribution and Survey Information: Snail Medic has been found in in 3 counties in California, but seems to be eradicated. 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: Low (7)

Uncertainty:

Snail Medic has been in California a long time, but has spread very modestly. Although some weeds do take decades to show their true potential in an invaded area, it is not terribly likely to be true for snail medic. Therefore, uncertainty is medium to low.

Conclusion and Rating Justification:

Not a bad weed in CA and unlikely to become one. It may have a use as a small forage plant. A D rating is proposed.

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.

Florabase; Snail Medic:  http://florabase.dpaw.wa.gov.au/browse/profile/2450

USDA Plants Database. Medicago scutellata. Accessed 6/12/2015:

http://plants.usda.gov/core/profile?symbol=MESC6

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

European Frogbit | Hydrocharis morsus-ranae L.

California Pest Rating for
European Frogbit | Hydrocharis morsus-ranae L.
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.

History & Status:

European frogbit is an annual herbaceous aquatic plant native to Europe. European frog-bit is generally free-floating but in situations where the vegetation is dense enough, the leaves may become emergent. It has been found in the Great Lakes Basin since the 1930s, but is now spreading into inland streams and lakes within the larger area surrounding the Great Lakes. It is considered invasive as it can displace native flora, possibly resulting in habitat impacts on native fauna by reducing oxygen content of bodies of water. European frogbit populations increase in size rapidly by vegetative reproduction and forms dense mats. These mats can infest irrigation canals.  There are no effective controls for this species at this time. European frogbit was planted in ponds in Ottawa in 1932. It apparently escaped from these ponds; by 1939 it was found in the Rideau Canal and by 1967 it had spread into Lake Ontario, Lake Erie, and several localities in New York.

Official Control: None in California.

California Distribution:  European frogbit does not occur in California at this time.

California Interceptions: None.

This threat European frogbit 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 the plant could occur in wetlands such as the Delta.

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 overwintering turions, as well as spreading rapidly in water via vegetative growth.

4  Economic Impact: Evaluate the likely economic impacts of the pest to California using the criteria below. Score: 1

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 low (1) as the plant can impede irrigation.

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.  Significantly impacting 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 lake communities and potentially lower biodiversity by covering lake surfaces.  

Consequences of Introduction to California for European frogbit:

Add up the total score and include it here. (12)

—Low = 5-8 points

—Medium = 9-12 points

—High = 13-15 points

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

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

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

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

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

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

Uncertainty:

It’s not here yet, but it is invasive in the Great Lakes Region.

Conclusion and Rating Justification:

A potentially weedy plant, especially in mountain lakes and cooler freshwater basins. Deserves an A rating, as it’s so invasive in other states.

References:

Catling P.M., Dore W.G., 1982, Status and identification of Hydrocharis morsus-ranae  and Limnobium spongia  (Hydrocharitaceae ) in northeastern North America, Rhodora 84(840): 523-545.

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

Global Invasive Species database: http://www.issg.org/database/species/ecology.asp?si=862

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

Limnobium laevigatum | South American spongeplant

California Pest Rating for
Limnobium laevigatum  |  South American spongeplant
Pest Rating: A  |  Proposed Seed Rating: P
PEST RATING PROFILE
Initiating Event:

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

History & Status:

South American spongeplant is a perennial herbaceous aquatic plant native to South America. South American spongeplant is generally free-floating but in situations where the vegetation is dense enough, the leaves may become emergent. It has been found on the San Joaquin River and in the Sacramento-San Joaquin Delta. Spongeplant can form thick mats across the water causing problems for boats, fish, and water infrastructure. It can spread rapidly through quick seed production and vegetative growth. The small, floating seeds easily disperse once produced. It is invasive as it can displace native flora, possibly resulting in habitat impacts on native fauna by reducing oxygen content of bodies of water. Spongeplant populations increase in size rapidly by vegetative reproduction and form dense mats. These mats can infest irrigation canals.

Official Control: An extensive control project has been carried out by the state of California.

California Distribution: South American spongeplant has been found in Alameda, Fresno, Riverside, Shasta, Fresno, Mariposa, and Humboldt Counties. It has been eradicated from some of these counties, but persists in the Delta.

California Interceptions:  Specimens have been sent to CDFA for confirmation.

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 can occur in many wetlands such as the Delta.

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, as well as spreading rapidly in water via vegetative growth. Large rafts of plants can be redistributed by wind to new areas. South American spongeplant is occasionally available in the aquarium trade and such plants could form the nexus for new infestations if discarded or dispersed into wetlands.

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 impede irrigation, boating, fishing, and swimming. It ruins views of water; and effects tourism, threatens water supplies (blocks canals, pumps, dams), and increases flooding.

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.  Significantly impacting 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 further water systems of California, disrupt natural lake communities and potentially lower biodiversity by covering lake surfaces.  It can block birds’ access to water and suffocate fish and other animals by sealing water surface from air. Dying plants steal oxygen in water.

 Consequences of Introduction to California for South American spongeplant: 

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: -2

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

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

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

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

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

Uncertainty:

Known invasive in California. Minimal uncertainty.

Conclusion and Rating Justification:

A potentially terrible weed in California. Deserves an A rating as it has invaded certain areas and undoubtedly has the ability to spread much more. Because of this potential future harm, an A rating is justified.

References:

Akers, P. 2010. South American spongeplant. PDF download 3/12/2015:

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CEsQFjAD&url=http%3A%2F%2Fwww.cdfa.ca.gov%2Fphpps%2Fipc%2Fhydrilla%2Fsos%2Fsos_info%2Fsos_info.ppt&ei=ivc1U-rHAumIyAHNn4G4CA&usg=AFQjCNGI_x3yja7B_I7Hx6p8yzEwHC2l4A&sig2=iq4wwbbd_V_WhCQMTkf_8g&bvm=bv.63808443,d.aWc&cad=rja

CalIPC website. Limnobium laevigatum. Accessed 3/12/2015:

http://www.cal-ipc.org/ip/management/plant_profiles/Limnobium_laevigatum.php

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

Global Invasive Species database. Accessed 3/12/2015: http://www.issg.org/database/species/ecology.asp?si=862

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

Flowering-rush | Butomus umbellatus

California Pest Rating for
Flowering-rush | Butomus umbellatus
Pest Rating: B  |  Proposed Seed Rating: R
PEST RATING PROFILE
Initiating Event:

This plant was recently added to the Washington and Oregon noxious weed lists and it seems to be spreading.

History & Status:

Flowering rush is a perennial aquatic plant in the monotypic family, Butomaceae. First detected in North America in the 19th century along the St. Laurence River, it has spread into the Great Lake Region and begun to spread across the Northern United States and Southern Canada. Its habitat is lake shorelines and slow moving waters to a depth of around 2 meters. It is especially well adapted to the fluctuating water levels found in reservoirs, a habitat to which few other plants are adapted, but that has increased under anthropogenic conditions. Where it occurs, flowering rush densities can vary from scattered clumps to populations exceeding 50% cover. It has been documented in Idaho and Montana, but populations in Western North American are still limited. There are no infestations identified in California. The plant is spread via horticulture and water and it still is occasionally available from nurseries that sell pond plants.

California Distribution:  Flowering rush has not yet been detected in California.

California Interceptions: None.

United States Distribution: Flowering rush is distributed across the northern tier of states, including Washington.

World Distribution: This weed is native to Eurasia

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 montane lakes, as well as irrigation canals and watering ponds in northern CA and at higher elevations.

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 can spread in water and on boats and equipment via seeds and rhizomes. It is also grown as a pond plant.

4)  Economic Impact: Evaluate the likely economic impacts of the pest to California using the criteria below. Score: 1

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 Low (1) as the plant can impede water flows in unlined canals.

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.  Significantly impacting 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 the plant could invade the water systems of California, disrupt natural wetland communities and potentially lower biodiversity by invading wetlands. This dense growth impedes water movement, blocks the growth of native plants, and reduces available habitat for water birds and native fish.

Consequences of Introduction to California for Water-primrose:

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

Final Score:

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

Uncertainty:

Medium. The plant has established in other states, but the extent of its adaptability to California unknown.

Conclusion and Rating Justification:

A potentially troublesome weed of wetlands, especially in northern and montane regions of California.  Deserves a B rating as it has proven weedy elsewhere, but its eventual spread in California may be limited as current infestations are in climates with cold winters.

References:

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

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

Hroudová Z., A. Krahulková, P. Zákravsky, & V. Jarolimová. 1996. The Biology of Butomus umbellatus in shallow waters with fluctuating water level. Hydrobiologia 340: 1-3.

Invasive Plants of Wisconsin: Butomus umbellatus, flowering-rush, www.uwgb.edu/biodiversity/ herbarium/invasive_species/butumb01.htm

Kings County, WA Noxious Weeds. Butomus umbellatus. Accessed 3/12/2015: http://www.kingcounty.gov/environment/animalsAndPlants/noxious-weeds/weed-identification/flowering-rush.aspx

Miller, G. 2011. Oregon Risk Assessment of Butomus umbellatus. Accessed 3/12/2015: http://www.oregon.gov/ODA/shared/Documents/Publications/Weeds/PlantPestRiskAssessmentFloweringRush2013.pdf

Lavoie C., Jean M., Delisle F., Letourneau G. 2003. Exotic plant species of the St. Lawrence River wetlands: a spatial and historical analysis. Journal of Biogeography 30: 537-549

Wisconsin Department of Natural Resources – Invasive Plant Species – Flowering Rush (Butomus umbellatus). Accessed 3/12/2015: dnr.wi.gov/invasives/fact/rush_flowering.htm

USDA Plants. Butomus umbellatus. Accessed 3/12/2015: http://plants.usda.gov/java/profile?symbol=BUUM

Rice P., Dupuis V. 2008 Flowering rush: An invasive aquatic macrophyte infesting the headwaters of the Columbia River system. Northern Interior Columbia Basin Invasive Aquatic Plant Summit. 10/21/2008

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: B  |  Proposed Seed Rating: R

Posted by ls