Category Archives: Weeds

Plants (weeds)

Weeds

Jointvetch | Aeschynomene spp.

California Pest Rating for
Jointvetch | Aeschynomene spp.
Rosidae; Fabales; Fabaceae
Pest Rating: A  |  Proposed Seed Rating: P
PEST RATING PROFILE
Initiating Event:

A. rudis has been rated as “A” on the CDFA Plant Pest Rating List after being detected in a rice field in California.

History & Status:

Jointvetches are tropical emergent aquatic or terrestrial perennial, to 2 m tall that bear typical pea type flowers and jointed legume seed pods. There are about 150 species of jointvetch in subtropical and tropical areas of the world. No species are native to the Western United States, but one species (A. rudis) has been introduced. Plants are typically annual in California. Infestations were restricted to rice fields in Colusa County, California. Heavy infestations can reduce rice harvest yields, and seed is difficult to remove from rice grains during the milling process. Rough jointvetch (A. rudis) has often been misidentified as Indian jointvetch (A. indica) or northern jointvetch (A. virginica) in the Southeastern U.S. All are weeds of rice. The most common detection of these plants is as seed contaminants, but seeds are difficult to diagnose to the species level. Only a few species of jointvetch are likely to find a pathway to establishment in California (e.g., A. rudis and A. indica). Nevertheless, as these species are important rice field and wetland invaders, and species are hard to distinguish via seed, the genus is treated as a whole for purposes of risk assessment.

Official Control: May be eradicated from its one known site in California.

California Distribution:  In California, this plant is known only from a rice field in Colusa County.

California Interceptions: It has been sent to the CDFA Diagnostics Laboratory for identification and has been detected in imported seed samples.

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 plants appeared in California and could, presumably, spread to similar habitats elsewhere in the state.

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

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

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

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

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

Risk is Medium (2). The plant produces via numerous seeds that seem to be able to spread as a contaminant in rice seed, as well as by other means such as water and water birds.

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 could lower crop yield in rice, could lower crop value, trigger more treatments, and, as it can form dense stands in wet soil or shallow water, interfere with water delivery.

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 can disrupt wetlands. As such it could suppress native species, including rare wetland species, such as California hibiscus (Hibiscus lasiocarpus var. occidentalis) and California red-legged frog (Rana draytonii). The plant is toxic to mammals. Its presence triggers more treatments to control this weed.

Consequences of Introduction to California for Jointvetches:

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

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

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

-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:

Although zigzag jointvetch was successfully eradicated in California, the behavior of zigzag jointvetch (Aeschynomene rudis) and Indian jointvetch (Aeschynomene indica) in other areas of the world demonstrates the genus’ weedy potential in California.

Conclusion and Rating Justification:

The genus contains bad weeds of wetlands and rice fields. An A rated is justified for the genus, as the potential harm is great from introduction of any of the weedy species.

References:

Carulli, J. P. 1988. Aeschynomene rudis Benth. (Fabaceae) in the United States. Bartonia 54:18-20.


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.

Hrusa, F., B. Ertter, A. Sanders, G. Leppig, and E. Dean. 2002. Catalog of non-native vascular plants occurring spontaneously in California beyond those addressed in The Jepson Manual. Part I. Madroño 49: 61-98.

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

Egyptian Broomrape | Orobanche aegyptiaca Pers.

California Pest Rating for
Egyptian broomrape | Orobanche aegyptiaca Pers.
Lamiales: Orobanchaceae
Pest Rating: A  |  Proposed Seed Rating: P
PEST RATING PROFILE
Initiating Event:

Egyptian broomrape was found for the first time in North America in Solano County, California in July, 2014.

History & Status:

Egyptian broomrapes are annual plants that grow from seed and require a host to survive. They are a parasitic plants that grow on the roots of Broad-leaf hosts and obtain all of their nutrients and water from these plants. As such, they can seriously reduce the yield of infected crops. Seeds germinate in response to chemicals released by host plant roots. The broomrape seedling root then attaches itself to the host plant root and remains underground until flowering. The plant has no chlorophyll and no photosynthetic leaves. Flowering stems emerge about 6 weeks after germination, then flower and begin to set seed within 2–3 weeks. Seed capsules dry and shatter in summer. One plant can produce over 100,000 seeds per year and seeds may lay dormant in the soil for more many years. Broomrape seed can be spread by footwear, livestock, machinery, vehicles, flooding, as well as by contaminated fodder, seed and soil. Egyptian broomrape is a relative of branched broomrape and belongs to a species group that is among the world’s worst crop weeds. Most authorities treat Orobanche ramosa and Orobanche aegyptiaca as distinct species, and in most keys there is a clear differentiation between them on the basis of corolla length and hairiness of anthers; in practice many specimens fall on the borderline and are difficult to place with certainty. Some authorities segregate this species group of Orobanche as the genus Phelipanche, in which case the species in question is known as Phelipanche aegyptiaca Pomel. Nevertheless, as a broad approach to Orobanche is followed in the Jepson Manual and will be followed in Flora North America, the species will be recognized as Orobanche aegyptiaca here. In the wild in Europe, Egyptian broomrape attacks annual composites (members of the aster family, Asteraceae), although it occasionally attacks members of the legume family (Fabaceae) and other broad-leaved plants. Egyptian broomrape attacks a broad array of field crops and some ornamentals. Tomato, potato, tobacco, eggplant, peppers, peas, carrot, celery, mustard, spinach, and chrysanthemum are among the susceptible plants. In areas such as southern Russia melons are also potential hosts. Established broomrape infestations can reduce crop yields by up to 70%, threaten export markets, and they are extremely difficult to eradicate.

Official Control:

Egyptian broomrape has been a “Q” listed noxious weed in California since it was recently found. Although the species has not yet been given a permanent official pest designation in the United States, it is included as a federal listed noxious weed under the genus Orobanche (all species that are not native or already widespread).

California Distribution: One site in Solano County.

California Interceptions: Egyptian broomrape has been detected only in eastern Solano County, California.

United States: The finding of Egyptian broomrape in California is the first detection for North America.  

International: Egyptian broomrape is native to the Middle East and is also found as a crop weed in Eastern Europe, at least 3 countries in Africa and in the warmer parts of Asia. Before this detection in California, its only Western Hemisphere report was in Cuba.

This risk Egyptian broomrape would pose to California is evaluated below.

Consequences of Introduction: 

1)  Climate/Host Interaction: The plant has attacked crops in many countries in the Eastern Hemisphere. It is more adapted to warmer climates than its close relative branched broomrape. This makes it well adapted to the regions of California where most row crops are grown. Therefore, Egyptian broomrape scores as High (3) in this category.

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

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

2)  Host Range: Risk is High (3) as Egyptian broomrape is documented to attack at least 23 crops grown in California. Important crops it is known to attack include tomato, olive, melons, cucumbers, eggplants, and carrot. Therefore, Egyptian broomrape scores as High (3) in this category.

Evaluate the host range of the pest. Score:

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

3)  Pest Dispersal Potential: Egyptian broomrape produces numerous seeds that seem to last for years and be able to spread via equipment and on animals (including humans). The seed bank is highly persistent. Egyptian broomrape receives a High (3) in this category.

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

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

4)  Economic Impact: Egyptian broomrape can lower crop productivity in susceptible row crops by up to 70%. This can make profitable crops unprofitable, affect land value, and result in quarantine. Furthermore, the weed may also be present on broadleaf weeds in fields when non-host crops are grown, affecting marketability of additional crops due to potential seed contamination. Egyptian broomrape receives a High (3) in this category.

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

A. The pest could lower crop yield.
B. The pest could lower crop value (includes increasing crop production costs).
C. The pest could trigger the loss of markets (includes quarantines).
D. The pest could negatively change normal cultural practices.
E. The pest can vector, or is vectored, by another pestiferous organism.
F. The organism is injurious or poisonous to agriculturally important animals.
G. The organism can interfere with the delivery or supply of water for agricultural uses.

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

5)  Environmental Impact: Egyptian broomrape is likely to trigger new treatments by land managers. The plant has not yet spread to the wild in California. However, certain native plants such as our annual composites (Asteraceae) and legumes such as clovers (Trifolium) are likely susceptible to attack from Egyptian broomrape. These include such rare or endangered species such as Contra Costa goldfields (Lasthenia conjugens), Suisun aster (Symphyotrichum lentum), Delta tule pea (Lathyrus jepsonii jepsonii), and showy Indian clover (T. amoenum).   Egyptian broomrape receives a High (3) in this category.

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

A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes
B.  The pest could directly affect threatened or endangered species
C.  The pest could impact threatened or endangered species by disrupting critical habitats
D.  The pest could trigger additional official or private treatment programs
E.  Significantly impacting cultural practices, home/urban gardening or ornamental plantings.

Score the pest for Environmental Impact. 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 Branched broomrape: High (15)

Add up the total score and include it here.

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

6)  Post Entry Distribution and Survey Information: Egyptian broomrape  has been found in 1 county in California, and may be eradicable. It receives a Low (-1) in this category.

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

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

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: High (14)

Uncertainty:

The experience in the Middle East shows the potential of this species to disrupt crop systems. Its potential effects on the environment are more speculative and necessarily more uncertain.

Conclusion and Rating Justification:

Egyptian broomrape is a bad agricultural weed because of its ability to reduce yields, produce large numbers of long-lived seeds, and its ease of spread. Therefore, its advent into California can be viewed as a significant event in North American agriculture. It should be included in regulations such as the California Code of Regulations Section 4500 list of noxious weeds as it is already included on the USDA noxious weed list.

References:

Blanco G. & M. Cueto. 2011. Orobanche in Claves de la Flora Vascular de Andalucía Oriental. G. Blanca, B. Cabezudo, M. Cueto, C. Morales Torres & C. Salazar, eds.  Servicio de Publicaciones de las Universidades de Almería, Granada, Jaén y Málaga. Universidad de Granada. Granada, Spain.

CABI. Invasive Species Compendium:  Orobanche aegyptiaca. Accessed online 7/21/2014: http://www.cabi.org/isc/datasheet/37742

Carlón, L. G. Gómez Casares, M. Laínz, G. Moreno Moral, Ó. Sánchez Pedraja, & G. M. Schneeweiss. Annotated Checklist of Host Plants of Orobanchaceae: Accessed 7/10/2014: http://www.farmalierganes.com/Flora/Angiospermae/Orobanchaceae/Host_Orobanchaceae_Checklist.htm#L_Host

Chater, A. O. & D. A. Webb. 1971. Orobanche in Flora Europaea Vol. 3: Diapensiaceae to Myoporaceae. T. G. Tutin, V. H. Heywood, N. A. Burges, D. H. Valentine, S. M. Walters, & D. A. Webb, eds. Cambridge University Press. United Kingdom.

Grupo Botánico Cantábrica. Index of Orobancheaceae: Phelipanche aegyptiaca.  Accessed online 7/16/2014: http://www.farmalierganes.com/flora/angiospermae/orobanchaceae/phelipanche/Phelipanche_aegyptiaca/Phelipanche_aegyptiaca.htm

Kasasian, L. 1971. Orobanche spp. PANS Pest articles and News Summaries 17: 1.

USDA Plants Database, Orobanche ramosa. Accessed 7/16/2014: http://plants.usda.gov/core/profile?symbol=orra

Jacobsohn, R., A. Greenberger, J. Katan, M. Levi & H. Alon. 1980. Control of Egyptian Broomrape (Orobanche aegyptiaca) and Other Weeds by Means of Solar Heating of the Soil by Polyethylene Mulching. Weed Science 28: 312–316
.

http://www.infonet-biovision.org/default/ct/705/pests

Eizenberg, H., T. Lande, G. Achdari, A. Roichman & J. Hershenhorn. Effect of Egyptian Broomrape (Orobanche aegyptiaca) Seed-burial depth on parasitism dynamics and chemical control in tomato. 2007. Weed Science 55: 152–156
.

Sedigheh S, R. Aptin, & Y. A. Zoheir. 2009. Application soil solarization on the control of Egyptian broomrape in greenhouse. International Journal of Natural and Engineering Sciences 3: 59-64.

Ghannam, I., R. Barakat, & M. Al-Masri. 2007. Biological control of Egyptian broomrape (Orobanche aegyptiaca) using Fusarium spp. Phytopathologia Mediterranea [Online], 46.2: 177-184.

Web. 24 Oct. 2012
6. http://www.flowersinisrael.com/Orobancheaegyptiaca_page.htm

Eizenberg, H, Y. Goldwasser, S. Golan, D. Plakhine, & J. Hershenhorn. 2004. Egyptian broomrape (Orobanche aegyptiaca) Control in tomato with sulfonylurea herbicides—greenhouse studies. Weed Technology 18: 490–496.

Eizenberg, H., D. Plakhine, J. Hershenhorn, Y. Kleifeld, and B. Rubin. Resistance to broomrape (Orobanche spp.) in sunflower (Helianthus annuus L.) Is Temperature Dependent. Journal of Experimental Botany 54: 1305-311.

Hamamouch, N. 2004. Engineering resistance to Orobanche aegyptiaca: evidence of sarcotoxin IA as an anti-parasite protein and macromolecule movement from host to parasite. Diss. Virginia Polytechnic Institute and State University.

Joel, D. M., J. Hershenhorn, H. Eizenberg, R. Aly, G. Ejeta, P. J. Rich, J. K. Ransom, J. Sauerborn, & D. Rubiales. 2007. Biology and management of weedy root parasites. Horticultural Reviews 33: 267-350.

Fernandez-Aparicio, M. Sillero, J. C. Rubiales, D. 2009. Resistance to broomrape species (Orobanche spp.) in common vetch (Vicia sativa L.). Crop Protection 28: 7-12.

Doronina, A. Y. Orobanche aegyptiaca. Interactive agricultural Ecological Atlas of Russia and Neighboring Countries. Accessed July, 2014. http://www.agroatlas.ru/en/content/weeds/Orobanche_aegyptiaca/

Hershenhorn J,, H. Eizenberg, E. Dor, Y. Kapulnik, & Y. Goldwasser. 2009. Phelipanche aegyptiaca management in tomato. Weed Research 49:34–37.

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

Goatsrue (Galega officinalis)

California Pest Rating for
Goatsrue (Galega officinalis)
Pest Rating: A  |  Seed Rating: P
PEST RATING PROFILE
Initiating Event:

There is a recent detection of goatsrue found growing in Eastern Mendocino County. This is the first detection of this species occurring spontaneously in California.

History & Status:

Background: Goatsrue is a deep-rooted perennial, sprouting each spring from a crown and taproot reaching 2 to 6 feet tall by late summer. Plants may have up to 20 hollow stems. The first seedling leaves are large, oval and dark green. The mature leaves are alternate, odd-pinnate with six to ten pairs of leaflets. The white and bluish to purplish pea-like blossoms are borne in terminal or axially racemes. A single plant may produce upwards of 15,000 pods. Goatsrue seeds drop on the ground when mature and may be spread by water, equipment, or animals. Goatsrue seeds typically remain dormant until scarified and may remain viable for ten or more years.
Goatsrue is a USDA federally listed noxious weed. A member of the legume family, goatsrue was introduced into Utah in 1891 as a potential forage crop. Goatsrue now occupies in excess of 60 square miles in Cache, County, Utah. Within this area, goatsrue infests cropland, fence lines, pastures, roadsides, waterways, and wet, marshy areas. The plant’s stems and leaves contain a poisonous alkaloid, galegin, which renders the plant unpalatable to livestock, and toxic in large quantities. It is particularly lethal to sheep.
Goatsrue is controlled by herbicides such as 2,4-D plus Dicamba or glyphosate, although the crowns of treated plants may remain viable up to seven years unless retreated or removed. New herbicide chemistry may improve success rates. Tillage in row crops can suppress regrowth and break up the seed production cycle. Utah weed control personnel indicate that goats rue control is very difficult, requiring significant amounts of time and labor. Their experience reinforces the concept that early detection and rapid control is the most effective means of preventing large-scale establishment.

Official Control: Goatsrue is listed as a noxious weed in Alabama, Florida, Massachusetts, Minnesota,Nevada, North Carolina, Oregon, Pennsylvania, South Carolina, Vermont, and Washington.

Worldwide Distribution: Goatsrue is native to the Middle East; it viewed as naturalized throughout most of Europe, western Asia, and western Pakistan.

U.S. Distribution: In the U.S. goatsrue is found in 12 states, including CA, OR, WA, UT, & CO. The largest infestations occur in Cache County, Utah, where it was first introduced to the U.S. Populations in states other than CA and UT may be historic.
California Distribution: Currently, Goatsrue is known from Cow Mountain in Eastern Mendocino and Western Lake Counties.

The risk goatsrue 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. Goatsrue would be expected to colonize riparian areas, pond margins, wetlands, roadside ditches, irrigation canal banks, and moist forest edges.

2)  Pest Host Range: Score: 3

Evaluate the host range of the pest:

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

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

3)  Pest Dispersal Potential: Score: 3

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 vehicles. It also has ben detected as a seed contaminant in commercial seed lots.

4)  Economic Impact: Score: 3

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 high (3) as goatsrue lowers range value and productivity and requires expensive treatments to control. As goatsrue is a federal noxious weed, there is a chance that goatsrue would trigger limitation of interstate shipment of hay or other crops from where it occurs.

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: 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) in California, as goatsrue is an aggressive invader of marginal 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 white sedge, Thomkin’s sedge, Delta eryngo, Bogg’s Lake hedge hyssop, western lily, Gambell’s watercress, and Calistoga popcornflower. 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 Goatsrue:
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 distribution in California: High (14).

6)  Post Entry Distribution and Survey Information: Goatsrue has been found in in 1 locality in California; This may have spread from seed spread via a vehicle and/or 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 (13)

Uncertainty:

This plant has just entered California, but it is spreading quickly via riparian corridors. It is not known how far its spread will extend, but the uncertainty is low that it will be invasive. Riparian habitat represents a small percentage of habitat in California, but it is widespread throughout the state and is disproportionally important due to its high water availability and high woody plant cover.

Conclusion and Rating Justification:

Conclusions of the harm(s) associated with this pest to California using all of the evidence presented above: Proposed Rating: based on the score listed above the pest is a high risk. This justifies an “A” rating. As the plant is limited to one small areas, as far as is known, prompt and effective action would have a significant effect on the future impacts of this species.

Literature

Evans, J. O. & M. L. Ashcroft 1982. Goatsrue. Utah Agr. Exp. Stat. Res. Report.

Barrett, R. 2013. Oregon Department of Agriculture Plant Pest Risk Assessment for Goatsrue, Galega officinalis. Accessed 6/12/2015: http://www.oregon.gov/ODA/shared/Documents/Publications/Weeds/PlantPestRiskAssessmentGoatsrue2013.pdf

Oldham, M, C. V. Ransom, M. H. Ralphs, and D. R. Gardner. 2011.
Galegine Content in Goatsrue (Galega officinalis) Varies by Plant Part and Phenological Growth Stage. Weed Science 59: 349-352.

USDA Plants, Galega officinalis. Acessed 6/12/2015:
http://plants.usda.gov/core/profile?symbol=GAOF

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

Tree Spurge | Euphorbia dendroides

California Pest Rating for
Tree Spurge  |  Euphorbia dendroides
Pest Rating: B  |  Proposed Seed Rating: R
PEST RATING PROFILE
 Initiating Event:

Collection in Santa Barbara County.

History & Status:

Background: Tree spurge is a small shrub (to 2 meters) native the Mediterranean Region. It is a semi-succulent plant with ascending candelabra-like branches and elliptical leaves without a petiole about 17 mm long. The flowers (cyathia) are borne in spring. The floral bracts are bright greenish yellow. Like all true spurges, the branches and leaves exude an irritating white latex when damaged. Although it most likely arrived in CA as a garden plant, it is no longer available in the trade (except rarely as seed). Its distribution is limited by cold, as it is intolerant of frost.

Worldwide Distribution: California Distribution: Tree spurge is currently restricted to Southern Santa Barbara County, Ventura County, and the foothill region between Altadena and Pasadena in Los Angeles County.

United States: There are no naturalized populations of tree spurge outside of CA in the United States.

International: Tree spurge  is native to the Mediteranean Region where it is found in Southern Europe and Northern Africa. It is naturalized in southwestern Australia.

This risk tree spurge will pose to California is evaluated below.

Consequences of Introduction:  3

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 high (3), as the plant is naturalized in more than 8 localities throughout CA.

2)  Pest Host Range:  3

Evaluate the host range of the pest:

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

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). The plant reproduces via rather large seeds that are thrown some distance from the mother plant. Nevertheless, its ability to disperse seems limited, as populations do not spread rapidly.

 4)  Economic Impact:  1

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 low (1) as tree spurge will be restricted to forest edges, coastal scrub, and arroyos.

5) Environmental Impact:  3

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). In California, tree spurge has disrupted natural sagebrush scrub communities, has triggered additional treatment programs to control it, and crowds out native species that coexist with or foster rare species.

Consequences of Introduction to California for tree spurge:

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

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

Total points based on above criteria: 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: -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: 10

Uncertainty:

There is no uncertainty as to whether this plant can establish in CA.

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. Given its ability to spread much more widely and ongoing control efforts, a B rating would be justifed.

References:

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

Consortium of California Herbaria (ucjeps.berkeley.edu/consortium/). 2014.

Global Compendium of Weeds: http://www.hear.org/gcw/species/euphorbia_dendroides/

Jepson Flora Project (eds.) 2013. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on Mar 28 2014

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

Echium plantagineum L.: Paterson’s curse

California Pest Rating for
Echium plantagineum L.:  Paterson’s curse
Lamiales: Boraginaceae
Pest Rating: A  |  Proposed Seed Rating: P

 

PEST RATING PROFILE
Initiating Event:

This plant has been detected spreading in Sonoma County, California.

History & Status:

Paterson’s curse is a softly hairy, winter annual that produces a branched inflorescence of the “fiddleneck” type. The showy, bell-shaped flowers are usually purple but also blue or pink with 2 of the 4 stamens emerging from the corolla tube. Each flower produces 4 small nutlets. Paterson’s curse is an attractive plant and has been included in “wildflower” mixes on occasion. In Australia it has served as a rangeland plant in dry areas, but its use for livestock is risky (see below). Because of its toxicity to livestock, Paterson’s curse has been listed as a noxious weed by the state of Oregon.

Official Control: Paterson’s curse has never been seen as a potential problem in California, as it has not been detected as spreading from introduction sites until now. It has never been subject to official control.

California Distribution:  Paterson’s curse is reported from San Diego, Marin (historic) and Sonoma Counties

California Interceptions: Vouchered specimens are known from San Diego and Marin Counties.

United States: Paterson’s curse is known also from a limited area of Oregon

International: Paterson’s curse is native to the western Mediterranean. It is reported as naturalized and a serious environmental and rangeland weed in Australia, Eastern Europe, the Near East, and Southern South America. It is occasional in New Zealand.

The risk Paterson’s curse would pose to California is evaluated below.

Consequences of Introduction: 

1)  Climate/Host Interaction: The plant has adapted to a wide area in its native range and is highly invasive in areas of Australia ecologically similar to California. Therefore Paterson’s curse receives a High (3) in this category.

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

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

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

Evaluate the host range of the pest. Score:

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

3)  Pest Dispersal Potential: Paterson’s curse produces via numerous seeds and spreads rather slowly. The seed bank is moderately persistent. Once established, Paterson’s curse is hard to eradicate. Paterson’s curse 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: Young growth is readily eaten and provides considerable sustenance to stock, whilst older growth is rough and hairy and generally avoided by stock. The hairiness can cause slavering, dermatitis, inflammation and itching to animals and man. Paterson’s curse contains toxins that cause cumulative chronic liver damage and animal mortality, especially if substantial amounts of herbage are eaten over prolonged periods. Horses are the most susceptible of common livestock. Paterson’s curse is considered the primary cause of pyrrolizidine alkaloid poisoning in horses in Australia and toxicity in cattle in Brazil. Paterson’s curse is also the major cause of sheep deaths from primary pyrrolizidine alkaloid poisoning in New South Wales. Paterson’s curse replaces superior range species and can significantly reduce row crop production under certain regimes (e.g., no till cultivation). Paterson’s curse receives a High (3) in this category.

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

A.  The pest could lower crop yield.
B.  The pest could lower crop value (includes increasing crop production costs).
C.  The pest could trigger the loss of markets (includes quarantines).
D.  The pest could negatively change normal cultural practices.
E.  The pest can vector, or is vectored, by another pestiferous organism.
F.  The organism is injurious or poisonous to agriculturally important animals.
G.  The organism can interfere with the delivery or supply of water for agricultural uses.

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

5)  Environmental Impact: Paterson’s curse is likely to trigger new chemical treatments by ranchers and land managers. The plant can dominate grasslands and roadsides, excluding native plants and lowering biodiversity. Rare taxa that might be affected include grassland species such as showy Indian clover (Trifolium amoenum) and CA filaree (California macrophylla), vernal pool species such as Burke’s goldfields (Lasthenia burkei) and CA tiger salamander (Ambystoma californiense), and grazers such as tule elk (Cervus canadensis nannodes). The plant can disrupt natural communities. Paterson’s curse 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 Paterson’s curse: High (14)

Add up the total score and include it here.

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

6)  Post Entry Distribution and Survey Information: Paterson’s curse has been found in in 2-3 counties in California, but may still 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: High (13)

Uncertainty:

Paterson’s curse has been in California a long time, but has not spread widely. Its behavior in Australia and the site in Sonoma suggest that it is just beginning its spread here in California.

Conclusion and Rating Justification:

A very bad weed. Deserves an A rating as known populations are limited. Chances of state eradication are high.

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/).

Culvenor C. C. J., M. V. Jago, J. E. Peterson, L. W. Smith, A. L. Payne, D. G. Campbell, J. A. Edgar & J. L. Frahn. 1984. Toxicity of Echium plantagineum (Paterson’s Curse). 1. Marginal toxic effects in Merino wethers from long-term feeding. Australian Journal of Agricultural Research, 35: 293-304.

Culvenor C. C. J, 1956. The alkaloids of Echium plantagineum L. I. Echiumine and Echimidine. Australian Journal of Chemistry 9: 512-520.

Dellow J.J., & J. T. Seaman. 1985. Distribution of Echium plantagineum L. and its association with pyrrolizidine alkaloid poisoning in horses in New South Wales. Plant Protection Quarterly 1: 79-83.

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

Invasive Species Compendium. Echium plantagineum. Accessed 2/10/2015: http://www.cabi.org/isc/datasheet/20400

Kozuharov, S. . 1972. Echium in Flora Europaea Vol. 3: Diapensiaceae to Myoporaceae. T. G. Tutin, V. H. Heywood, N. A. Burges, D. H. Valentine, S. M. Walters & D. A. Webb, eds. Cambridge University Press. United Kingdom.

Seaman JT, 1987. Pyrrolizidine alkaloid poisoning of sheep in New South Wales. Australian Veterinary Journal, 64: 164-167.

Schild A. L., A. C. Motta, C. F. Riet Correa, F. C. Karam & F. B. Grecco. 2004. Photosensitization in cattle in Southern Brazil. In: Acamovic T, Stewart CS, Pennycott TW, eds. Poisonous Plants and Related Toxins. Wallingford, UK: CABI Publishing: 62-166.

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

Chrysanthemoides monilifera: Bitou bush

California Pest Rating for
Chrysanthemoides monilifera: Bitou bush
Asterales: Asteraceae
Pest Rating: A  |  Proposed Seed Rating: R
PEST RATING PROFILE
Initiating Event:

This plant has been recently discovered spreading from a single population in Orange County.

History & Status:

Background:  Bitou bush is a small shrub (to 2 meters) native the Cape Region of South Africa. It is a semi-succulent plant with ascending candelabra-like branches and elliptical leaves without a petiole about 80 mm long. The flowers heads are borne in summer through fall. The ray flowers and disk flowers are bright yellow. Although it most likely arrived in CA as a garden plant, it is no longer available in the trade (except rarely as seed). Its distribution is limited by cold, as it is intolerant of frost.

Official Control: Bitou bush has not been subject to official control.

California Distribution:  Known from 3 historic populations in Orange and San Diego Counties. These most likely are or were persisting from cultivation.

California Interceptions:  None.

United States:  Bitou bush has been reported from California only.

International:  Bitou bush is native to South Africa. It is reported as naturalized and as an environmental weed in Australia and New Zealand where millions of dollars have been spent on control efforts.

This risk Bitou bush would pose to California is evaluated below.

Consequences of Introduction:

1)  Climate/Host Interaction: The plant has had at least 3 introductions in CA. One of these populations is beginning to spread. It is very invasive in eastern Australia in areas with a similar climate to parts of California. Therefore Bitou bush receives a High (3) in this category.

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

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

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

Evaluate the host range of the pest. Score:

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

3)  Pest Dispersal Potential:  Bitou bush produces via numerous achenes (“seeds”) that are enclosed in a fleshy fruit dispersed by birds. Bird dispersal is an efficient means of plants establishing new populations. The seed bank is moderately persistent. Known populations have not spread until recently. Bitou bush 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:  Bitou bush does not persist well in grazed areas due to browsing and trampling. Bitou bush 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:  Chrysanthemoides monilifera out competes native vegetation in coastal environments in Australia and New Zealand, and invasion can lead to a decline in both floral and faunal diversity, changing ecosystem composition. It changes ecosystem processes by altering nutrient cycling, particularly nitrogen cycling, at the expense of native species and creating heavy shade in normally high light areas. It is considered a “weed of national significance” in Australia and has replaced entire stands of native species. This species is tolerant of saline conditions near coastal areas. In addition, it can create a favorable environment for other invasive weeds. Rare taxa that might be affected include strand species such as Laguna Beach dudleya (Dudleya stolonifera) and sagebrush scrub species such as California gnatcatcher (Polioptila californica). Because it forms dense patches, it could interfere with recreation along the coast and invade expensive coastal properties requiring control. Bitou bush 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 Bitou bush: Medium (12)

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:  Bitou bush is very local 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:

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

Uncertainty:

As Bitou bush has invaded Australia and is beginning to spread in CA, uncertainty is low.

Conclusion and Rating Justification:

A potentially bad weed in CA.  Bitou bush merits an “A” rating to prevent its further spread in California. It has a low risk as a potential seed contaminant, so it should be restricted in seed for planting.

References:

Adamson, R. S. & T. M. Salter 1950. Flora of the Cape Peninsula. Juta & Co. Cape Town.

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.

Bond, P. & P. Goldblatt 1984. Plants of the Cape Flora: A descriptive catalogue. National Botanic Gardens of South Africa, Kirstenbosch.

Consortium of California Herbaria accessed 1/21/2015: ucjeps.berkeley.edu/consortium/

Coutts-Smith, A. J., & P. O. Downey. 2006. Impact of weeds on threatened biodiversity in NSW. CRC for Australian Weed Management, Adelaide, Australia.

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

Grice, A. C., S. Campbell, R. Breaden, F. Bebawi, & W. Vogler. 2008. Habitat management guide-Rangelands: Ecological principles for the strategic management of weeds in rangeland habitats. CRC for Australian Weed Management, Adelaide, Australia.

Lindsay, E. A., & K. French. 2005. Litterfall and nitrogen cycling following invasion by Chrysanthemoides monilifera ssp. rotundata in coastal Australia. Journal of Applied Ecology 42: 556-566.

USDA Weed Risk Assessment of Chrysanthmoides monilifera accessed 1/21/2015: http://www.aphis.usda.gov/plant_health/plant_pest_info/weeds/downloads/wra/Chrysanthemoides_monilifera_WRA.pdf

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

Bermuda grass (Cynodon dactylon)

California Pest Rating
Bermuda grass (Cynodon dactylon)
Pest Rating: D  |  Proposed Seed Rating: None
PEST RATING PROFILE
Initiating Event:

A new find of this plant submitted to the Plant Laboratory for identification.

History & Status:

Background:  Bermuda grass is a long-lived, warm season turf grass. It is a densely spreading perennial, with deeply penetrating roots and low stems to 25 cm tall. It was introduced from Africa in 1751 and is widely spread throughout the southwest and southern United States. It is found in most areas of California at elevations below 3,000 feet and is common in gardens, landscapes, turf areas, orchards, roadsides, vineyards, and industrial areas. Bermuda grass is listed as a noxious weed in Arkansas and Utah. It previously was listed as a “C” rated weed in California, but it was removed from the list, as it is listed as an official crop in state seed regulation.

California Distribution:  Bermuda grass has been collected in most counties in California except for the exteme NE part of the state (Modoc County). Many of these collections represent plants persistng from horticulture, but many are naturalized as well.

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

United States:  Because Bermuda grass has a long history of use in North America as a turf or range grass, it occurs in all but the most northern states and in all but the coldest regions of states where it occurs.

International:  Bermuda grass is native to Africa, India, and western Asia. It is introduced in North and South America and in Australia, as well as to other areas with warm temperate climates.

The risk Bermuda grass would pose to California is evaluated below.

Consequences of Introduction:

1)  Climate/Host Interaction:  Risk is High (3), as the Bermuda grass is naturalized throughout Southwestern North America and is 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:  Bermuda grass seeds are light, and dispersed primarily by wind and water. Seeds eaten by animals are widely dispersed. Motor vehicles also disperse Bermuda grass seed. The plant spreads quickly via long rhizomes and stolons and can regenerate from small pieces. Therefore, Bermuda grass 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:  Bermuda grass has been used widely as a turf grass and for forage in warm environments. Bermuda grass seed is produced by many seed companies and newer sterile cultivars are sold in flats; this is a positive economic value. When Bermuda grass invades areas, it can compete with or exclude other valuable species. Bermuda grass 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:  In the southwestern United States, Bermuda grass occurs in riparian areas and in grasslands adjacent to streams and marshes. It is a frequently encountered understory grass in mesquite woodlands in the desert. On Santa Rosa Island, Bermuda grass is a common understory plant in riparian woodland dominated by willows and cottonwoods. In the Sacramento River valley, Bermuda grass occurs on gravel bars where the willow canopy is not too dense. As it is a common garden weed, especially in vegetable gardens, Bermuda grass causes problems for home gardeners at the same time it is useful as a warm season turf for lawns. Therefore, Bermuda grass 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 Bermuda grass: High (13)

Add up the total score and include it here.

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

6)  Post Entry Distribution and Survey Information:  Bermuda grass is widespread in CA. It receives a High (-3) in this category.

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

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

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 has been known in SW North America for over 200 years and spreading populations are common. Therefore, there is low uncertainty.

Conclusion and Rating Justification:

Proposed Rating: The pest has invaded much of California. Further spread within these areas is possible. As bermuda grass is an official crop in California, a rating of “D” 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: Accessed 2/9/2015: http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=2570

Carey, Jennifer H. 1995. Cynodon dactylon in Fire Effects Information System,
U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, accessed 1/29/2015:  http://www.feis-crs.org/beta/

Clark, R. A., W. L. Halvorson, A. A. Sawdo, & K. C. Danielsen. 1990. Plant communities of Santa Rosa Island, Channel Islands National Park. Tech. Rep. No. 42. University of California, Davis, Institute of Ecology, Cooperative National Park Resources Studies Unit. Davis, CA.

Conard, S. G., R. L. MacDonald, & R. F. Holland. 1980. Riparian vegetation and flora of the Sacramento Valley. In: A. Sands ed. Riparian forests in California: Their ecology and conservation. University of California, Division of Agricultural Sciences: 47-55.

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

Cudney, D. W., C. L. Elmore, & C. E. Bell. Cynodon dactylon in UC IM Online accessed 1/29/2015: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7453.html

Stubbendieck, J., S. L. Hatch, & K. J. Hirsch. 1986. North American range plants. 3rd ed. University of Nebraska Press. Lincoln, NE.

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

Buffel grass (Pennisetum ciliare)

California  Pest Rating
Buffel grass (Pennisetum ciliare)
Pest Rating:  D  |  Proposed Seed Rating:  None
PEST RATING PROFILE
Initiating Event:

A new find of this plant submitted to the Plant Laboratory for identification.

History & Status:

Background:  Buffelgrass is a long-lived perennial bunchgrass. It is a densely tufted perennial, with deeply penetrating roots and erect stems to 60 cm tall. It was introduced into North America as livestock foage in arid areas. Its weedy qualities suit it for desert range conditions. It is listed as a noxious weed in Arizona.

California Distribution: Buffelgrass has been collected in Imperial, Orange, Riverside and San Bernadino Counties.

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

United States:  Buffelgrass was introduced into Texas and Arizona in the 1930s and 1940s to stabilize overgrazed rangelands and provide livestock forage. Buffelgrass also established in Arizona from seed dispersed from Sonora, Mexico where over 1,000,000 acres of native desert and thornscrub vegetation was converted to buffelgrass pasture. Buffelgrass also was introduced into Hawaii.

International:  Buffelgrass is native to Africa, India, and western Asia. It is introduced in North and South America and in Australia.

The risk Buffelgrass would pose to California is evaluated below.

Consequence of Introduction:

1)  Climate/Host Interaction:  Risk is High (3), as buffelgrass is naturalized in the desert throughout Southwestern North America and is 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:  Buffelgrass seeds are light, umbrella-like, and dispersed primarily by wind and water. Barbed bristles on buffelgrass fruits allow for long-distance dispersal in animal skin and fur.  Motor vehicles also disperse buffelgrass seed.  Buffelgrass can begin producing seeds at 3 months from germination and continue seed production for more than 10 years. Therefore, buffelgrass 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:  Buffelgrass has been used as forage in arid environments, and this is a positive economic value. But when buffelgrass invades new habitats, there is often a loss of soil fertility, an increase in soil erosion that increases surface water runoff, and this results in degraded water quality. Buffelgrass 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:  In Hawaii, buffelgrass invades and dominates a variety of vegetation types. In natural areas, it tends to form dense swards that exclude native vegetation, decreasing biodiversity and altering successional processes. In upland arid regions, buffelgrass can transform native desert shrub and thornscrub into grasslands. For instance, in Arizona buffelgrass excludes native shrubs such as creosote (Larrea tridentata), saltbush (Atriplex spp.), and bursage (Ambrosia spp.) and their associated native grasses and forbs. In Hawaii, buffelgrass displaces native pili grass (Heteropogon contortus) communities and discourages the succession of native woody species. In lowland riparian areas, buffelgrass can replace native riparian vegetation along riverbanks. In the arid areas of Queensland, Australia, buffelgrass outcompetes and displaces native grasses and riparian vegetation. By dominating riparian areas and their moist refuges within arid regions, buffelgrass threatens keystone habitats that are vital to the survival of many plant and animal species. Buffelgrass could negatively affect sensitive desert riparian species such as the federally endangered Southwestern Willow flycatcher (Empidonax traillii extimus). Therefore, buffelgrass 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 buffelgrass: High (13)

Add up the total score and include it here.

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

6)  Post Entry Distribution and Survey Information:  Buffelgrass is regional in CA. 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:  Medium (11)

Uncertainty:

This plant has been known in SW North America for over 80 years and spreading colonies have been detected. So, there is low uncertainty.

Conclusion and Rating Justification:

Proposed Rating: based on the score listed above, the pest is medium risk for further invasions of California. This plant shows invasive qualities; in California it is already known from 5 counties. Nevertheless, as buffelgrass is an official crop in California, a “D” rating 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

Collinette, S. 1999. Wildflowers of Saudi Arabia. National Commission for Wildlife Conservation, Kingdom of Saudi Arabia. Riyadh.

Consortium of California Herbaria:  cjeps.berkeley.edu/consortium/
Daehler, C.C. & D.A. Carino. 1998. Recent replacement of native pili grass (Heteropogon contortus) by invasive African grasses in the Hawaiian Islands. Pacific Science 53: 220-227.

Hauser, A. S. 2008. Pennisetum ciliare. In: Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. Accessed 1/25/2015:
http://www.fs.fed.us/database/feis/plants/graminoid/pencil/all.html

Tu, M. Pennisetum ciliare in Bugwood Wiki accessed 1/27/2015: http://wiki.bugwood.org/Pennisetum_ciliare

Ward, J. P.; S. E. Smith, & M. P. McClaran. 2006. Water requirements for emergence of buffelgrass (Pennisetum ciliare). Weed Science. 54: 720-725.

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