Pacific Island Ecosystems at Risk (PIER)


Citrus arantifolia


RISK ASSESSMENT RESULTS: Low risk, score: 2 (low risk based on second screen)


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

Citrus aurantifolia (Christm. & Panzer) Swingle;Citrus aurantiifolia, lime, Mexican lime, Key lime

Answer

1.01

Is the species highly domesticated?

y=-3, n=0

y

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

n

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

4.01

Produces spines, thorns or burrs

y=1, n=0

y

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

y

4.05

Toxic to animals

y=1, n=0

n

4.06

Host for recognized pests and pathogens

y=1, n=0

y

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

n

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

n

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

y

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

6.07

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

See left

3

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

y

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

n

7.08

Propagules survive passage through the gut

y=1, n=-1

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

n

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

y

Total score:

2

Supporting data:

Notes

Source

1.01

"Key lime has been under cultivation or semicultivation for thousands of years. Improved horticultural varieties, which have bigger, generally seedless fruits and thornless plants, now dominate the local and international fruit markets. The unimproved type is still managed commercially and is the basis for a juice and lime oil industry (Morton 1987)."

http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf

1.02

(1)"Key lime is the name used most often to refer to a primitive race of Citrus aurantiifolia cultivated and naturalized in the West Indies." (2)Widely distributed in secondary forests (savoka) and natural forests in western warm regions.

(1)http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf (2)http//members.lycos.co.uk/WoodyPlantEcology/docs/mad-inv.rtf

1.03

no evidence of being weedy

2.01

Origin and geographic distribution Lime is believed to have originated in northern India and adjoining parts of Burma, or in northern Malesia. Amazingly there are no records of wild lime in Thailand. The lime is now cultivated throughout the tropics and in warm subtropical areas.

Ravie Sethpakdee, 2003. Citrus aurantifolia (Christm. & Panzer) Swingle. [Internet] Record number 1490 from TEXTFILE On-line. Verheij, E.W.M. and Coronel, R.E. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Monday, 17 May 2004.

2.02

2.03

(1)The lime is at home in the lowland tropics, although it grows up to 1000 m altitude or more. The tree is sensitive to cold but is quite drought-resistant. (2)It thrives in the lowland tropics, although it can be found up to 1000 m in elevation or more. High incidence of bacterial canker is a limiting factor in the wet tropics, but under dry conditions irrigation is necessary

(1)Ravie Sethpakdee, 2003. Citrus aurantifolia (Christm. & Panzer) Swingle. [Internet] Record number 1490 from TEXTFILE On-line. Verheij, E.W.M. and Coronel, R.E. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Monday, 17 May 2004. (2)http://ecocrop.fao.org/

2.04

Origin and geographic distribution Lime is believed to have originated in northern India and adjoining parts of Burma, or in northern Malesia. Amazingly there are no records of wild lime in Thailand. The lime is now cultivated throughout the tropics and in warm subtropical areas.

Ravie Sethpakdee, 2003. Citrus aurantifolia (Christm. & Panzer) Swingle. [Internet] Record number 1490 from TEXTFILE On-line. Verheij, E.W.M. and Coronel, R.E. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Monday, 17 May 2004.

2.05

"Key lime is believed to be native of eastern Malaysia. It was introduced to the Asian mainland early in historical times and carried by Arab traders to the Middle East and eventually came to Europe during the Crusades (Burkill 1997). The species was introduced to the West Indies by Columbus during his second voyage (Ehler 2002). Key lime has been planted throughout the tropics and has naturalized in at least Puerto Rico, the Virgin Islands (Little and Wadsworth 1964), and the Florida Keys (Nelson 1996)."

http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf

3.01

(1)"Key lime is the name used most often to refer to a primitive race of Citrus aurantiifolia cultivated and naturalized in the West Indies." (2)Widely distributed in secondary forests (savoka) and natural forests in western warm regions.

(1)http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf (2)http//members.lycos.co.uk/WoodyPlantEcology/docs/mad-inv.rtf

3.02

no evidence

3.03

no evidence

3.04

no evidence

3.05

Citrus reticulata var. unshu on the list of SC Noxious Pests Legislation. "The Commission hereby delegates to the Director the authority to determine and implement appropriate measures to eradicate, control, or slow the spread of those plant pests designated in paragraph 2 below."; "The State Crop Pest Commission is designating certain organisms as plant pests, that is, organisms that directly or indirectly may injure or cause disease or damage in plants (or their products) and which may be a serious agricultural threat to the State. " [the satsuma orange appears to be listed not because it is naturalized but because it cannot be imported from Japan due to quarantine pests - see http://www.epa.gov/fedrgstr/EPA-IMPACT/2001/April/Day-18/i9628.htm]

http://drpsp.clemson.edu/dpi/npp.htm

4.01

"twigs armed with short stiff sharp spines. "

4.02

no evidence

4.03

no evidence

4.04

"Cattle grazing encourages it somewhat by eliminating some of the competition without damaging it."

http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf

4.05

no evidence

4.06

AB: "Host range: Affects Rutaceous plants, primarily Citrus spp., Fortunella spp., and Poncirus spp., world-wide. Quarantined pathogen in many countries. Economically important hosts are cultivated orange, grapefruit, lime, lemon, pomelo and citrus rootstock."

Brunings, A. M. Gabriel, D. W. (2003) Xanthomonas citri [Xanthomonas axonopodis pv. citri]: breaking the surface. Molecular Plant Pathology, 2003, Vol. 4, No. 3, pp. 141-157, many ref.

4.07

"The oil of the fruit peel was observed to be photosensitising. Oils from different kinds of lime varied in their activity (Sams 1941). The furanocoumarins of the species are given by Pathak et al. (1962); C. acida yields 5-methoxypsoralen. The role of photoallergy versus phototoxicity requires clarification." (2) "Essential oils of Key lime and some other citrus fruits cause phytophotodermatosis in sensitive individuals (Bruneton 1999)." [limited sensitized individuals]

(1) http://bodd.cf.ac.uk/index.html
(2) http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf

4.08

"Key lime is an evergreen, spiny shrub or small tree to 6 m in height."

http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf

4.09

(1)"Key lime is intolerant of shade and will not survive long under a closed forest canopy." (2)High light requirements

(1)http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf (2)http://plantsdatabase.com/go/49906

4.1

(1)"Limes can grow on poor soils and tolerate heavier soils than oranges" (2)Optimal soil texture- Rich, Acceptable soil pH- Neutral (3)Soil tolerance: heavy, medium, light

Ravie Sethpakdee, 2003. Citrus aurantifolia (Christm. & Panzer) Swingle. [Internet] Record number 1490 from TEXTFILE On-line. Verheij, E.W.M. and Coronel, R.E. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Monday, 17 May 2004. (2)http://www.crescentbloom.com/Plants/Specimen/CI/Citrus%20aurantiifolia.htm (3)http://ecocrop.fao.org/

4.11

"Key lime is an evergreen, spiny shrub or small tree to 6 m in height."

http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf

4.12

no evidence

5.01

"Naturally reproduced trees may be seen on roadsides, fencerows, abandoned farms, secondary forests, and coastal hammocks."

http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf

5.02

shrub to small tree; Rutaceae

5.03

shrub to small tree; Rutaceae

5.04

shrub to small tree

6.01

"Naturally reproduced trees may be seen on roadsides, fencerows, abandoned farms, secondary forests, and coastal hammocks."

http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf

6.02

"In South-East Asia air layering is the normal method, elsewhere the trees are raised from seed."

Ravie Sethpakdee, 2003. Citrus aurantifolia (Christm. & Panzer) Swingle. [Internet] Record number 1490 from TEXTFILE On-line. Verheij, E.W.M. and Coronel, R.E. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Monday, 17 May 2004.

6.03

Limes hybridize freely with other Citrus species, and many hybrids are known, e.g. Lemonimes ( lime x lemon), Limequats (lime x kumquat).

Ravie Sethpakdee, 2003. Citrus aurantifolia (Christm. & Panzer) Swingle. [Internet] Record number 1490 from TEXTFILE On-line. Verheij, E.W.M. and Coronel, R.E. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Monday, 17 May 2004.

6.04

(1)"Self-pollination occurs, but self-incompatibility limits fruit set." (2)Most cultivars are self-fruitful through self-pollination

(1)Ravie Sethpakdee, 2003. Citrus aurantifolia (Christm. & Panzer) Swingle. [Internet] Record number 1490 from TEXTFILE On-line. Verheij, E.W.M. and Coronel, R.E. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Monday, 17 May 2004. (2)http://www.uga.edu/fruit/citrus.htm

6.05

"Copious secretion of nectar by a floral disk attracts insects, especially honey bees, which pollinate the flowers."

Ravie Sethpakdee, 2003. Citrus aurantifolia (Christm. & Panzer) Swingle. [Internet] Record number 1490 from TEXTFILE On-line. Verheij, E.W.M. and Coronel, R.E. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Monday, 17 May 2004.

6.06

"Root suckers and suckers on older branches, characterized by stout sharp spines, are common." [could find no mention of natural spread by root suckers - only suckers attached to the base of the main plant]

Ravie Sethpakdee, 2003. Citrus aurantifolia (Christm. & Panzer) Swingle. [Internet] Record number 1490 from TEXTFILE On-line. Verheij, E.W.M. and Coronel, R.E. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Monday, 17 May 2004.

6.07

"Seedlings begin to fruit in 3 to 6 years (Morton 1987).."

http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf

7.01

Fruit a globose to ovoid berry, 3—6 cm in diameter, sometimes with apical papillae, greenish-yellow; peel very thin, very densely glandular; segments with yellow-green pulp-vesicles, very acid, juicy and fragrant. Seeds small, plump, ovoid, pale, smooth with white embryos (polyembryonic). [unlikely, juicy fruit with relatively large seeds]

Ravie Sethpakdee, 2003. Citrus aurantifolia (Christm. & Panzer) Swingle. [Internet] Record number 1490 from TEXTFILE On-line. Verheij, E.W.M. and Coronel, R.E. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Monday, 17 May 2004.

7.02

"Key lime is believed to be native of eastern Malaysia. It was introduced to the Asian mainland early in historical times and carried by Arab traders to the Middle East and eventually came to Europe during the Crusades (Burkill 1997). The species was introduced to the West Indies by Columbus during his second voyage (Ehler 2002). Key lime has been planted throughout the tropics and has naturalized in at least Puerto Rico, the Virgin Islands (Little and Wadsworth 1964), and the Florida Keys (Nelson 1996)."

http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf

7.03

humans consume fruit and discard seeds

7.04

Fruits in one collection in Puerto Rico ranged from 3.0 to 4.5 cm in diameter and weighed from 19 to 51 g. Air-dried seeds separated from them averaged 0.0702 + 0.0037 g/seed or 14,000 seeds/kg. [unlikely, large fruit]

http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf

7.05

no evidence

7.06

(1) "In the West Indies, the seeds are mainly dispersed by gravity and humans. There are undoubtedly animal vectors in the original native habitat." [juicy fruit, animal dispersal syndrome but no evidence of bird dispersal - fruit is green, human altered through cultivation]
(2) "Common fruits eaten include citrus, mango, Northern Bloomwood, and Apple Box." [unspecified citrus fruit used by fruit eating bat]

(1) http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf

(2) http://animaldiversity.ummz.umich.edu/site/accounts/information/Pteropus_conspicillatus.html

7.07

no known means of external attachment

7.08

(1) "In the West Indies, the seeds are mainly dispersed by gravity and humans. There are undoubtedly animal vectors in the original native habitat." [juicy fruit, animal dispersal syndrome]
[domesticated by humans; green fruit, thin seed coat, don't know if it is consumed or if it would survive]

(1) http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf
(2) http://animaldiversity.ummz.umich.edu/site/accounts/information/Pteropus_conspicillatus.html

8.01

(1) In India trees are expected to bear 600—1500 fruits per year.
(2) Fruits in one collection in Puerto Rico ranged from 3.0 to 4.5 cm in diameter and weighed from 19 to 51 g. Air-dried seeds separated from them averaged 0.0702 + 0.0037 g/seed or 14,000 seeds/kg. [unlikely, large fruit and relatively large seeds]

(1) Ravie Sethpakdee, 2003. Citrus aurantifolia (Christm. & Panzer) Swingle. [Internet] Record number 1490 from TEXTFILE On-line. Verheij, E.W.M. and Coronel, R.E. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Monday, 17 May 2004.
(2) http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf

8.02

"Placed on moist blotter paper, 84 percent germinated between 15 and 49 day after sowing." [no evidence of aparent dormancy]

http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf

8.03

no evidence of being controlled for

8.04

"Plants are top-killed by fires and hard frosts, but will sprout and survive if the disturbance is not repeated frequently."

http://www.fs.fed.us/global/iitf/pdf/shrubs/Citrus%20aurantiifolia.pdf

8.05

(1) "In Hawaii, heavy infestations of the whitefly have been observed on the foliage of various citrus trees such as pummelo, lemon, and orange. Damage. The greatest injury is caused by the sucking of plant sap, which removes water and nutrients. Additional damage is caused by the excretion of tiny droplets of sticky honeydew from the whitefly upon which grows sooty mold fungus, usually on the upper surfaces of leaves. A heavy growth of sooty mold on leaves results in reduced respiration and photosynthesis. The combination of direct feeding of high numbers of whiteflies with large amounts of sooty mold growth being produced causes a decline in the general health of the tree and a reduction in fruiting." [domesticated Citrus trees require human protection from insects] (2)Phytophthora foot rot appeared in the Azores in 1842 and later in other parts of the world, which stimulated a search for resistant stocks. [Lime is not listed as a resistant root stock - they are typically grafted]

(1)http://www.hawaiiag.org/hdoa/npa/npa99-03_citrusbf.pdf (2)http://www.uga.edu/fruit/citrus.htm


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