Pacific Island Ecosystems at Risk (PIER)


Citrus maxima


RISK ASSESSMENT RESULTS: Low risk, score: 0


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 maxima (Burm.) Merr.; Citrus grandis, Citrus decumana, shaddock, pummelo, pomelo

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

1

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

y

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

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

n

6.07

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

See left

6

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

n

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:

0

Supporting data:

Notes

Source

1.01

The pummelo is native to southeastern Asia and all of Malaysia; grows wild on river banks in the Fiji and Friendly Islands. It may have been introduced into China around 100 B.C. It is much cultivated in southern China (Kwang-tung, Kwangsi and Fukien Provinces) and especially in southern Thailand on the banks to the Tha Chine River; also in Taiwan and southernmost Japan, southern India, Malaya, Indonesia, New Guinea and Tahiti. [longhistory of cultivation, wild population in native range unknown; fruit dramatically altered by humans]

http://www.hort.purdue.edu/newcrop/morton/pummelo.html

1.02

(1)"The pummelo is native to southeastern Asia and all of Malaysia; grows wild on river banks in the Fiji and Friendly Islands." (2)Occasional in garden areas, mature fallow forests, and secondary forests, where it seems to be naturalized [Fiji]

(1)http://www.hort.purdue.edu/newcrop/morton/pummelo.html (2)http://payson.tulane.edu:8085/cgi-bin/gw?e=t1c11home-envl-1-T.1.B.6.1-500-50-10e&q=&d=T.1.B.6.14&a=t

1.03

no evidence of being weedy

2.01

Origin and geographic distribution The origin of the pummelo is uncertain. There is little doubt that the species is indigenous in Malesia. It has spread to Indo-China, southern China and the southernmost part of Japan and westwards to India, the Mediterranean and tropical America. However, it remains a fruit of the Orient; neither in India nor further west has it become popular. The best match of cultivars, environmental niches and growing skills appears to be found in Thailand.

Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

2.02

2.03

(1) The pummelo thrives in the lowland tropics. In the production centres of Thailand mean monthly temperatures are about 25—30°C with a few cooler (and dry) months; the dry season lasts for 3—4(—5) months and annual rainfall is about 1500—1800 mm. The crop is not grown commercially above elevations of 400 m.
(2) The pummelo is tropical or near-tropical and flourishes naturally at low altitudes close to the sea. It has never performed well in New Zealand because of insufficient heat.

(1) Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

(2) http://www.hort.purdue.edu/newcrop/morton/pummelo.html

2.04

Origin and geographic distribution The origin of the pummelo is uncertain. There is little doubt that the species is indigenous in Malesia. It has spread to Indo-China, southern China and the southernmost part of Japan and westwards to India, the Mediterranean and tropical America. However, it remains a fruit of the Orient; neither in India nor further west has it become popular. The best match of cultivars, environmental niches and growing skills appears to be found in Thailand.

Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

2.05

Origin and geographic distribution The origin of the pummelo is uncertain. There is little doubt that the species is indigenous in Malesia. It has spread to Indo-China, southern China and the southernmost part of Japan and westwards to India, the Mediterranean and tropical America. However, it remains a fruit of the Orient; neither in India nor further west has it become popular. The best match of cultivars, environmental niches and growing skills appears to be found in Thailand.

Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

3.01

(1)"The pummelo is native to southeastern Asia and all of Malaysia; grows wild on river banks in the Fiji and Friendly Islands." (2)Occasional in garden areas, mature fallow forests, and secondary forests, where it seems to be naturalized [Fiji]

(1)http://www.hort.purdue.edu/newcrop/morton/pummelo.html (2)http://payson.tulane.edu:8085/cgi-bin/gw?e=t1c11home-envl-1-T.1.B.6.1-500-50-10e&q=&d=T.1.B.6.14&a=t

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

"branches spreading, spiny (seed propagation) or spineless (vegetative propagation)"

Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

4.02

no evidence

4.03

no evidence

4.04

not recognized as a fodder plant

http://ecocrop.fao.org/

4.05

Today, oranges are primarily eaten fresh or prepared as frozen juice concentrate. The byproducts of juice making (the pulp, rind and seed) are utilized for cattle feed and molasses (for alcohol or feed) … ' [refers to oranges but no records of poisoning by pumelo]

http://www.aquapulse.net/knowledge/orange.html

4.06

AB: "Of 6 Citrus spp. studied lemon was highly susceptible to E. tetranychus, followed by Kaghzi lime (C. aurantifolia), chakotra (C. decumana) and grapefruit. Sweet orange and mandarin were most resistant to attack."

Sadana, G. L. Kanta, V. (1972) Susceptibility of different varieties of citrus to the citrus mite, Eutetranychus orientalis (Klein). Science and Culture, 1972, Vol. 38, No. 12, pp. 525-526, 3 ref.

4.07

Toxicity
Like that of other citrus fruits, the peel of the pummelo contains skin irritants, mainly limonene and terpene, also citral, aldehydes, geraniol, cadinene and linalool, which may cause dermatitis in individuals having excessive contact with the oil of the outer peel. Harvesters, workers in processing factories, and housewives may develop chronic conditions on the fingers and hands. [applies only to "excessive contact"]

http://www.hort.purdue.edu/newcrop/morton/pummelo.html

4.08

no evidence [evergreen]

4.09

(1) Trunk strangulation (ringing) was performed under artificial shading (80% shade) and unshaded conditions from mid-July to harvest time to determine whether strangulation treatment could overcome the negative effect of heavy shading on fruit development and quality in 6-year-old Tosa Buntan pummelo budded on Poncirus trifoliata. Steel wires of diameter 1.6 mm were sunk flush into the trunk bark. The wire rings were removed 2 months later. Chlorophyll content of 80% shade leaves decreased after exposure to full sun and increased after reimposing shading; the shaded first flush leaves retained more chlorophyll than unshaded ones. Specific leaf weight of the first flush leaves, shoot growth of second flush and fruit size significantly decreased in strangled trees with 80% shade. However, either trunk strangulation with full sun or trunk strangulation with shade hastened the degreening of the fruit rind and increased the sugar and citric acid contents in fruit juice. Thus, although strangulation was effective

(1) Yamanishi, O. K. Hasegawa, K. (1995) Trunk strangulation responses to the detrimental effect of heavy shade on fruit shade and quality of 'Tosa Buntan' pummelo. Journal of Horticultural Science, 1995, Vol. 70, No. 6, pp. 875-887, 36 ref.

(2) http://www.hort.purdue.edu/newcrop/morton/pummelo.html

4.1

Pummelo tolerates a wide range of soils from coarse sand to heavy clay.

Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

4.11

Tree, 5—10(—15) m tall

Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

4.12

no evidence

5.01

The pummelo thrives in the lowland tropics.

Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

5.02

tree, Rutaceae

5.03

no evidence

5.04

tree

6.01

The fleshy seed with its thin coat dries out easily and needs near-ideal conditions to germinate; spontaneous seedlings are rare. [the plant is domesticate' wild populations in native habitat are unkown]

Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

6.02

The fleshy seed with its thin coat dries out easily and needs near-ideal conditions to germinate; spontaneous seedlings are rare.

Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

6.03

"About 1948, citrus specialists began to suggest that the grapefruit was not a sport of the pummelo but an accidental hybrid between the pummelo and the orange. The botanical name has been altered to reflect this view, and it is now generally accepted as Citrus X paradisi."

http://www.hort.purdue.edu/newcrop/morton/grapefruit.html

6.04

Nevertheless most cultivars are self-sterile to a high degree. In the presence of pollinators most cultivars produce seeded fruit. It has been suggested that seediness may also be the result of selfing, provided favourable conditions prevail, e.g. a temperature (25—30°C) high enough for fast pollen tube growth and low enough to delay wilting of the pistils.

Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

6.05

"pollination is entomophilous, mainly by bees and butterflies. "

Lim, A. L. Editor: Wong, K. M. Lee, S. S. Saari, G. (2001) Citrus and citroids: recent biological findings. Malayan Nature Journal, 2001, Vol. 55, No. 1/2, pp. 221-229, 35 ref.

6.06

no evidence

6.07

(1)A seedling progeny consists largely of tall slender trees with long spines, coming into bearing 6—8 years after sowing. (2)First fruits may be harvested after 2-8 years [lower number seems to refer to vegetative propagation]

(1)Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004. (2)http://ecocrop.fao.org/

7.01

unlikely, large fruit

7.02

In South-East Asia pummelo is grown in home gardens, in mixed citrus orchards and in pure pummelo orchards, the latter for instance in Thailand and the Philippines.

Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

7.03

seeds discarded after consuming fruit

7.04

Fruit a subglobose to pyriform berry, 10—20(—30) cm in diameter, greenish-yellow, densely glandular dotted; peel 1—3(—4) cm thick; segments with large, pale yellow or pink pulp-vesicles, filled with sweetish juice. Seeds usually few, large, plump, ridged, yellowish, monoembryonic.
[large juicy fruit with few seeds]

Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

7.05

no evidence

7.06

(1) "Fruit a subglobose to pyriform berry, 10—20(—30) cm in diameter, greenish-yellow, densely glandular dotted; peel 1—3(—4) cm thick; segments with large, pale yellow or pink pulp-vesicles, filled with sweetish juice." [juicy fruit, animal dispersal syndrome but no direct evidence of bird consumption - the rind is too thick!]
(2) "Common fruits eaten include citrus, mango, Northern Bloomwood, and Apple Box." [unspecified citrus fruit used by fruit eating bat]

(1) Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

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

7.07

no known means of attachment

7.08

The fleshy seed with its thin [domesticated plant]

Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

8.01

Fruit a subglobose to pyriform berry, 10—20(—30) cm in diameter, greenish-yellow, densely glandular dotted; peel 1—3(—4) cm thick; segments with large, pale yellow or pink pulp-vesicles, filled with sweetish juice. Seeds usually few, large, plump, ridged, yellowish, monoembryonic.
[unlikely, large fruit with few seeds]

Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.

8.02

(1) The fleshy seed with its thin coat dries out easily and needs near-ideal conditions to germinate; spontaneous seedlings are rare.
(2) The seeds can be stored for 80 days at 41º F(5º C) and 56-58% relative humidity.

(1) Niyomdham, C., 2003. Citrus maxima (Burm.) Merr.. [Internet] Record number 1491 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: Wednesday, 19 May 2004.
(2) http://www.hort.purdue.edu/newcrop/morton/pummelo.html

8.03

no evidence of being controlled for

8.04

Vigorous growth requires management [=frequent pruning] to prevent the boughs from becoming too leggy to support the fruit.

http://www.echonet.org/eln&herbs/fruittrees.htm

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. [Pumelo 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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