Pacific Island Ecosystems at Risk (PIER)


Aeschynomene americana


RISK ASSESSMENT RESULTS: High risk, score: 12


Australian/New Zealand Weed Risk Assessment adapted for Hawai‘i.

Research directed by C. Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service

Information on Risk Assessments
Original risk assessment

Aeschynomene americana (American joint vetch, shyleaf))

Answer

1.01

Is the species highly domesticated?

y=-3, n=0

n

1.02

Has the species become naturalized where grown?

y=-1, n=-1

y

1.03

Does the species have weedy races?

y=-1, n=-1

n

2.01

Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical”

See Append 2

2

2.02

Quality of climate match data (0-low; 1-intermediate; 2-high) see appendix 2

2

2.03

Broad climate suitability (environmental versatility)

y=1, n=0

n

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

y

2.05

Does the species have a history of repeated introductions outside its natural range? y=-2

?=-1, n=0

y

3.01

Naturalized beyond native range y = 1*multiplier (see Append 2), n= question 2.05

y

3.02

Garden/amenity/disturbance weed y = 1*multiplier (see Append 2)

n=0

n

3.03

Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2)

n=0

y

3.04

Environmental weed y = 2*multiplier (see Append 2)

n=0

n

3.05

Congeneric weed y = 1*multiplier (see Append 2)

n=0

y

4.01

Produces spines, thorns or burrs

y=1, n=0

n

4.02

Allelopathic

y=1, n=0

n

4.03

Parasitic

y=1, n=0

n

4.04

Unpalatable to grazing animals

y=1, n=-1

n

4.05

Toxic to animals

y=1, n=0

n

4.06

Host for recognized pests and pathogens

y=1, n=0

n

4.07

Causes allergies or is otherwise toxic to humans

y=1, n=0

n

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

4.09

Is a shade tolerant plant at some stage of its life cycle

y=1, n=0

n

4.1

Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island)

y=1, n=0

y

4.11

Climbing or smothering growth habit

y=1, n=0

n

4.12

Forms dense thickets

y=1, n=0

n

5.01

Aquatic

y=5, n=0

n

5.02

Grass

y=1, n=0

n

5.03

Nitrogen fixing woody plant

y=1, n=0

y

5.04

Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers)

y=1, n=0

n

6.01

Evidence of substantial reproductive failure in native habitat

y=1, n=0

n

6.02

Produces viable seed.

y=1, n=-1

y

6.03

Hybridizes naturally

y=1, n=-1

6.04

Self-compatible or apomictic

y=1, n=-1

y

6.05

Requires specialist pollinators

y=-1, n=0

n

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

n

6.07

Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1

See left

1

7.01

Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas)

y=1, n=-1

n

7.02

Propagules dispersed intentionally by people

y=1, n=-1

y

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

7.04

Propagules adapted to wind dispersal

y=1, n=-1

n

7.05

Propagules water dispersed

y=1, n=-1

n

7.06

Propagules bird dispersed

y=1, n=-1

n

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

y

7.08

Propagules survive passage through the gut

y=1, n=-1

y

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

n

8.02

Evidence that a persistent propagule bank is formed (>1 yr)

y=1, n=-1

y

8.03

Well controlled by herbicides

y=-1, n=1

8.04

Tolerates, or benefits from, mutilation, cultivation, or fire

y=1, n=-1

y

8.05

Effective natural enemies present locally (e.g. introduced biocontrol agents)

y=-1, n=1

Total score:

12

Supporting data:

Source

Notes

1.01

No evidence

1.02

(1)A. americana is a common weed in India and Puerto Rico. (2)Naturalized in Sri Lanka - a common weed in rice fields.

(1)Holm et al.1997. An electronic atlas of weeds and invasive species. CD ROM database Version 1. (2)Amaratunga, K.L.D. 1977. A provisional list of weeds found in arable soilsin Sri Lanka with special reference to the three noteworthy new weed records. Ceylon journal of science. 12(2): 185

1.03

No evidence

2.01

Native to Central America and tropical South America, extending as far south as Argentina and north to Florida, United States, and the West Indies.

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm

2.02

2.03

(1)Altitude range: Sea level to 1 000 m in Jamaica. (2)But restricted to wet habitats

(1)http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm (2)http://edis.ifas.ufl.edu/DS126

2.04

Native to Central America and tropical South America, extending as far south as Argentina and north to Florida, United States, and the West Indies.

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm

2.05

Introduced to African countries like Zimbabwe, Nigeria, , Zambia and in Asia to India, Indonesia and Sri Lanka.

http://www.ildis.org/LegumeWeb/6.00/taxa/1187.shtml

3.01

(1)A. americana is a common weed in India and Puerto Rico. (2) Naturalized along waterways in Florida

(1)Holm et al.1997. An electronic atlas of weeds and invasive species. CD ROM database Version 1. (2) Craig, R. M. 1978. Native vegetation along constructed channels in peninsular Florida. Proceedings of the Florida State Horticultural Society 91: 85-88

3.02

No evidence

3.03

(1) 'Forage aeschynomene might become a weed problem in rice if plants are past the seedling stage when flood water is applied and could cause weed problems in soybeans; but, in most situations, cultural and chemical control practices should provide adequate control.' (2)Naturalized in Sri Lanka - a common weed in rice fields

(1)THRO-A-M {a}; WIER-A-T; BARKER-F-G. 1990. WEED POTENTIAL OF THE FORAGE LEGUME AESCHYNOMEN AESCHYNOMENE-AMERICANA IN RICE ORYZA-SATIVA AND SOYBEANS GLYCINE-MAX. Weed-Technology.; 4 (2): 284-290.. (2)Amaratunga, K.L.D. 1977. A provisional list of weeds found in arable soilsin Sri Lanka with special reference to the three noteworthy new weed records. Ceylon journal of science. 12(2): 185

3.04

No evidence

3.05

Aeschynomene is a principal weed in Brazil and A. sensitiva is a common weed in Puerto Rico

Holm et al.1997. An electronic atlas of weeds and invasive species. CD ROM database Version 1.

4.01

No evidence

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm

4.02

No evidence

4.03

No evidence

4.04

'American joint vetch withstands heavy grazing well; under these conditions it branches readily close to the ground and develops a low, dense, leafy canopy.' … 'Cattle readily graze A. americana… .'

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm

4.05

Toxicity none recorded.

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm

4.06

The only disease noted to date has been powdery mildew on ungrazed seed crops.

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm

4.07

No evidence

4.08

[possibly if it is allowed to dry out; normally it would be grazed before this happens] Response to fire: Fire during the growing season is unlikely and a fire during the late dry season is most likely to increase the germination of the hard seed, at the same time reducing competition for the establishing seedlings.

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm

4.09

Shade experiments indicated a min. of 45% incident light was required for good A. americana establishment. Allowing light to penetrate through the grass canopy to emerging legume seedlings was important and resulted in better legume stands and higher pasture quality.

Kalmbacher, R. S.; Martin, F. G. 1983 . Light penetrating a Bahiagrass canopy and its influence on establishing jointvetch. Agronomy Journal,.75: 465-468

4.1

(1)Soil requirements: Quite widely adapted, but particularly suited to wet, low-lying, sandy soils and to similarly located solodics of coastal lowland country. (2)tolerated solodic soil and a black cracking clay

(1)http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm (2)Ross, B. J.; Cameron, A. G. 1991. Pasture legume evaluation on seasonally flooded soils in the Northern Territory. Tropical Grasslands .25: 32-36.

4.11

Not a climber

http://www.ildis.org/LegumeWeb/6.00/taxa/1187.shtml

4.12

No evidence

5.01

5.02

5.03

An erect-ascending, annual or short-lived perennial, shrub-like legume, 1 to 2 m tall. It is estimated in Florida that the equivalent of 112 kg./ ha N are added each year to the pasture system by American joint vetch

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm

5.04

6.01

Joint vetch seeds heavily when erect making seed easy to harvest, but also seeds well under grazing so that cattle soon spread joint vetch through all their paddocks.

http://www.dpi.qld.gov.au/pastures/4398.html

6.02

Germinates in the first spring storms and grows through summer.

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm

6.03

No information

6.04

(1)Breeding system: Uncertain, but believed to be essentially cleistogamic, pollination taking place before the flowers open. (2) 'Aeschynomene americana L., a self-pollinating annual legume, occurs throughout the Caribbean region..'

(1)http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm (2)THRO-A-M. 1988. COLLECTION AND CHARACTERIZATION OF GERMPLASM RESOURCES OF THE FORAGE LEGUME AESCHYNOMENE-AMERICANA IN LOUISIANA USA. Tropical-Grasslands. 22 (4): 150-159.

6.05

Self pollinating.

6.06

stands must regenerate from seed

Chaparro, C.J.; Sollenberger, L.E.; Linda, S.B.1991. Grazing management effects on aeschynomene seed production.

Crop science 31: 197-201

6.07

(1)An erect-ascending, annual or short-lived perennial, shrub-like legume, 1 to 2 m tall. (2)Aeschynomene americana, or common aeschynomene, is a true annual that flowers and produces seed in the early fall. Plants usually die after seed has matured.

(1)http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm (2)http://edis.ifas.ufl.edu/BODY_AA189

7.01

Probably not - propagules do not have any means of attachment.

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm

7.02

forage crop

7.03

Probably not - 'Seeds about 4 mm long and gray-green to dark and light brown.' (but may be harvested with hay and dispersed in that manner)

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm

7.04

7.05

7.06

7.07

Seed is widely distributed by cattle, both on their coats and in dung.

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm

7.08

Seed is widely distributed by cattle, both on their coats and in dung.

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm

8.01

Seeds about 4 mm long and gray-green to dark and light brown.

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000001.htm

8.02

hard-seeded legume

8.03

tolerated 2,4-DB amine (as Butyrac or Butoxone) and 2,4-D amine (as Weedar 64) each at 0.5 lb a.i./acre and Basagran [bentazone] 0.75 lb a.i.

Walker, R. H.; Wyatt, D. R.; Abney, P. B. 1988. Game-food crops show tolerance to postemergence-applied herbicides. Highlights of Agricultural Research, Alabama Agricultural Experiment Station, Vol.35, No.1, p.13 .

8.04

Graze the plants back to about 8 to 14 inches and move to the next pasture. Maintaining a 14 inch stubble will allow for maximum regrowth and good seed production.

http://edis.ifas.ufl.edu/BODY_AA189

8.05

Don’t know


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This page updated 23 February 2005