Pacific Island Ecosystems at Risk (PIER)


Cajanus cajan


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

Cajanus cajan (C. indicus; pigeon pea)

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

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

y

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

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

n

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

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

4.09

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

y=1, n=0

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

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

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

y

8.02

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

y=1, n=-1

8.03

Well controlled by herbicides

y=-1, n=1

8.04

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

y=1, n=-1

n

8.05

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

y=-1, n=1

Total score:

0

Supporting data:

Source

Notes

1.01

(1)Truly wild Cajanus has never been found; they exist mostly as remnants of cultivations. In several places Cajanus persists in the forest. (2)Pigeonpea probably evolved in South Asia and appeared about 2000 BC in West Africa, which is considered a second major center of origin. The slave trade took it to the West Indies, where its use as bird feed led to the name "pigeonpea" in 1692 (van der Maesen 1986). Pigeonpea is best known as a human food.

(1)http://www.hort.purdue.edu/newcrop/duke_energy/Cajanus_cajun.html (2)http://www.winrock.org/forestry/factpub/FACTSH/C_cajanbckup.html

1.02

(1)"apparently naturalized in Hawaii" - restricted to roadsides, pastures, sugar can fields (2)recorded as growing naturally in Kruger National Park, South Africa (3)Rare escape from cultivation in Florida

(1)Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu. (2)http://www.parks-sa.co.za/conservation/scientific_services/Biota/villageplantspolicy.htm (3) Wunderlin. 1998. Guide to the vascular plants of Florida. University press of Florida, Gainesville.

1.03

Many cvs differ in height, habit of growth, color of flower, time of maturity, color, and shape of pods, and color, size, and shape of seed. No evidence that these any of the cultivars is weedy.

2.01

(1) 'List of countrieswith natural population: India, Bangladesh, Indonesia, Cambodia, Laos, Malaysia, Philippines, Sri Lanka, Thailand, Vietnam and Africa. (2)Probably native to India, pigeon pea was brought millennia ago to Africa where different strains developed. These were brought to the new world in post-Columbian times. Truly wild Cajanus has never been found; they exist mostly as remnants of cultivations. In several places Cajanus persists in the forest.

(1)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://www.hort.purdue.edu/newcrop/duke_energy/Cajanus_cajun.html

2.02

2.03

(1)Approximate limits north to south: 28°N to 15°S Altitude range: 200 - 2000 m (2)Various cultivars are grown from sea level to 3,000 m (3)tropical wet & dry (Aw), tropical wet (Ar), steppe or semiarid (Bs), subtropical humid (Cf), subtropical dry summer (Cs), subtropical dry winter (Cw) (4)In Hawaii they failed to set seed at 1,000 meters.

(1)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://www.winrock.org/forestry/factpub/FACTSH/C_cajanbckup.html (3)http://ecocrop.fao.org/ (4)http://www.tropical-seeds.com/tech_forum/veg_herbs/pigeon_pea.html

2.04

(1) 'List of countrieswith natural population: India, Bangladesh, Indonesia, Cambodia, Laos, Malaysia, Philippines, Sri Lanka, Thailand, Vietnam and Africa. (2)Probably native to India, pigeon pea was brought millennia ago to Africa where different strains developed. These were brought to the new world in post-Columbian times. Truly wild Cajanus has never been found; they exist mostly as remnants of cultivations. In several places Cajanus persists in the forest.

(1)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://www.hort.purdue.edu/newcrop/duke_energy/Cajanus_cajun.html

2.05

Introduced to several countries in Central America, South America, Zimbabwe, Cuba and the Caribbean.

3.01

(1)"apparently naturalized in Hawaii" - restricted to roadsides, pastures, sugar can fields (2)recorded as growing naturally in Kruger National Park, South Africa (3)Rare escape from cultivation in Florida

(1)Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu. (2)http://www.parks-sa.co.za/conservation/scientific_services/Biota/villageplantspolicy.htm (3) Wunderlin. 1998. Guide to the vascular plants of Florida. University press of Florida, Gainesville.

3.02

No evidence

3.03

No evidence

3.04

No evidence

3.05

No evidence

4.01

No evidence

CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

4.02

(1) Not allelopathic
(2) AB: "Two field experiments were conducted at Lajas and Juana Díaz, Puerto Rico, to evaluate 7 pigeon pea (Cajanus cajan ) cultivars for yields, weed suppression and impact on subsequent tomato (Lycopersicon lycopersicum ) [Lycopersicon esculentum ] and pepper (Capsicum annuum ) plantings."; "Compared with control plots, pigeon pea did not affect weed densities at Lajas, but all cultivars reduced weed densities in tomato and pepper grown in 1994 and 1995 at Juana Díaz. The greatest reduction in density was from 219 to 78 weeds per 0.5 m2 with Line 84. The weed species suppressed by pigeon pea in the tomato crop were Amaranthus dubius , Cyperus rotundus , Echinochloa colona [E. colonum ] and Trianthema portulacastrum . It is concluded that pigeon pea had allelopathic effects upon these weed species. " [field but did not test allelopathy versus other posiblilities]
(3) AB: " pigeon peas have been used in Guatemala to control Cyperus rotundus"
(4) AB: "A phytotoxic compound was iden

(1) http://plants.usda.gov/cgi_bin/topics.cgi
(2) Semidey, N.; Bosques-Vega, A. (1999)Yield and weed suppression by pigeon pea cultivars in rotation with tomato and pepper. Journal of Agriculture of the University of Puerto Rico, 1999, Vol.83, No.1/2, pp.55-64, 10 ref.
(3) Hepperly, P.; Aguilar-Erazo, H.; Perez, R.; Diaz, M.; Reyes, C. (1992) Pigeon pea and velvet bean allelopathy.Editors: Rizvi, S. J. H.; Rizvi, V. Allelopathy: basic and applied aspects., 1992, pp.357-370, 14 ref.
(4) Ohwaki, Y.; Ogino, J.; Shibano, K. (1993) 3-Hydroxy-5-methoxystilbene-2-carboxylic acid, a phytotoxic compound isolated from methanolic extracts of pigeonpea (Cajanus cajan Millsp.) leaves. Soil Science and Plant Nutrition, 1993, Vol.39, No.1, pp.55-61, 13 ref. (5)http://www.tropical-seeds.com/tech_forum/.../pigeon_pea.html

4.03

No evidence

4.04

High palatability for browsing and grazing animals.

http://plants.usda.gov/cgi_bin/topics.cgi

4.05

Not toxic

http://plants.usda.gov/cgi_bin/topics.cgi

4.06

(1)Pests recorded: Insect pests:
Exelastis atomosa
Helicoverpa armigera (This is a serious pest is Australia on several crops including Cotton, Tomatoes and Maize-
http://www.usyd.edu.au/su/macleay/larvae/noct/armi.html )
Melanagromyza obtusa
Fungus diseases:
Gibberella indica
Heterodera cajani
(2)Many fungal diseases (31), involving 45 pathogens, are known; the most serious is wilt disease (Fusarium udum), favored by soil temperatures of 17°–20°C. The fungus enters the plant through the roots and may persist in soilborne stubble for a long time. The only effective control measure is development of resistant cvs (e.g., 'C-ll,' 'C-36,' 'NP-15,' 'NP-38,' and 'T-17'). Rotation with tobacco and intercropping with sorghum is said to decrease the wilt problem. Other fungi include: Cercospora spp., Colletotrichum cajanae, Corticium solani, Diploidia cajani, Leveillula taurica, Macrophomina phaseoli, Phaeolus manihotis, Phoma cajani, Phyllosticta cajani, Phytophthora sp., Rhizoctonia bataticola, Rosellinia sp., Scl

(1)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International. (4)http://ecocrop.fao.org/

4.07

(1)Not toxic (2)the young green seeds are eaten as vegetables and the ripe dry seeds as a pulse. Ripe dry seeds can be split and made into dhal.

(1)http://plants.usda.gov/cgi_bin/topics.cgi (2)http://ecocrop.fao.org/

4.08

Drought tolerant shrub - if grown at high density, could be fire risk in dry areas

4.09

(1)Tolerates shade (2)light tolerance - very bright sun to clear skies (3)Too much shading causes the plant to make spindly growth and to bear thin, pale green foliage and few pods (Krause, 1932) (4)Full sun

(1)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://ecocrop.fao.org/ (3)http://www.fao.org/WAICENT/FAOINFO/AGRICULT/AGP/AGPC/doc/GBASE/data/Pf000150.HTM (4)http://edis.ifas.ufl.edu/EP107

4.1

(1)It will grow in all types of soils, varying from sand to heavy clay loams, well-drained medium heavy loams being best. (2)It grows on acid sands in the Sahel and alkali clays in India.

(1)http://www.hort.purdue.edu/newcrop/duke_energy/Cajanus_cajun.html (2)http://www.winrock.org/forestry/factpub/FACTSH/C_cajanbckup.html

4.11

Probably not - not a vine.

4.12

No evidence

5.01

Terestrial

5.02

5.03

C. cajan is a woody, short-lived (1-5 years), perennial shrub, often grown as an annual. It is a nitrogen-fixing species

CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

5.04

6.01

(1)Flowers multi-colored with yellow predominant, red, purple, orange occur in streaks or fully cover the dorsal side of the flag, zygomorphic. (2)'…chiefly grown for its pods and seeds which are used as food all over the tropics, but especially in the Indian subcontinent and East Africa.'

(1)http://www.hort.purdue.edu/newcrop/duke_energy/Cajanus_cajun.html(2)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

6.02

(1)Germination cryptocotylar. Seed germinate in about 2 weeks (2)Its propagation is generally done by seed; stem cuttings rarely succeed.

(1)http://www.hort.purdue.edu/newcrop/duke_energy/Cajanus_cajun.html(2)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

6.03

No evidence of hybridization in the wild. 'Male sterile lines have been developed and are used in hybridization programs. One ICRISAT hybrid, ICPH8, consistently yielded 25% more grain than the best control in 15 trials in India (Wallis et al. 1986). Interspecific hybrids with species of the congeneric genus Atylosia have shown promise as fodder and cover crops.'

http://www.winrock.org/forestry/factpub/FACTSH/C_cajanbckup.html

6.04

'Pigeonpea (2n=22) is mostly self-pollinating, but a range of 3 - 95% outcrossing has been reported. This is probably a function of environment and populations of pollinating insects.'

http://www.winrock.org/forestry/factpub/FACTSH/C_cajanbckup.html

6.05

Pollinated by insects.

http://www.winrock.org/forestry/factpub/FACTSH/C_cajanbckup.html

6.06

(1)Its propagation is generally done by seed; stem cuttings rarely succeed. (2) No vegetative spread.

(1)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://plants.usda.gov/cgi_bin/topics.cgi

6.07

(1)Early cvs start podding in 12 weeks but maturation requires 5–6 months. Late cvs require 9–12 mos. (2)Half of the plants begin to flower within 56-210 days after sowing. Maturity ranges from 95 to 256 days.

(1)http://www2.ctahr.hawaii.edu/sustainag/SustainableAg/GreenManures/pigeonpea.asp (2)http://www.hort.purdue.edu/newcrop/duke_energy/Cajanus_cajun.html

7.01

no evidence that the propagules have any means of attachment.

7.02

Land use, environmental and service aspects: Descriptors: agroforestry; soil improvement; land reclamation; erosion control; windbreaks; hedges

CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

7.03

'Quite frequently (in India) pigeon pea is grown mixed with other crops or grown in alternate rows with rows of sorghum, groundnuts, sesame, cotton, pineapples, millets or maize.'

7.04

No evidence tha the seeds have any mechanism of dispersal by wind. 'pods not shattering in the field.'

http://www.hort.purdue.edu/newcrop/duke_energy/Cajanus_cajun.html

7.05

no evidence that the species inhabits coastal or riverine areas.

7.06

The slave trade took it to the West Indies, where its use as bird feed led to the name "pigeonpea" in 1692 (van der Maesen 1986). [dpn't know if it is naturally dispersed by birds from pods on a plant; presumably, the seeds serve as a source of protein and are ground in the pigeon gizzard, killing the seeds]

http://www.winrock.org/forestry/factpub/FACTSH/C_cajanbckup.html

7.07

Probably not - no evidence that the propagules have any means of attachment.

7.08

Don’t know [pods are probably swallowed by cattle, but seeds apparently do not have a hard coat or dormancy]

8.01

(1)Pods compressed, 2–9-seeded, not shattering in the field. Seeds lenticular to ovoid, to 8 mm in diameter, about 10 seeds per gram, separated from each other in the pod by slight depressions. ... Green-pod yields vary from 1,000 to 9,000 kg/ha. Dried seed yields may reach 2,500 kg/ha in pure stands, but average yields are closer to 600 kg/ha. (2)weigh 4-25 g/100 seed [If I calculate using the 600 kg dryseed per hectare and 4 g / 100 seeds, then production is 1500 seeds per m2

(1)http://www.hort.purdue.edu/newcrop/duke_energy/Cajanus_cajun.html (2)http://www.winrock.org/forestry/factpub/FACTSH/C_cajanbckup.html

8.02

No pre-germination treatment of seeds is needed.

http://www.winrock.org/forestry/factpub/FACTSH/C_cajanbckup.html

8.03

The FAO reports that pigeon pea is fairly tolerant of herbicides. [vague]

http://www2.ctahr.hawaii.edu/sustainag/SustainableAg/GreenManures/pigeonpea.asp

8.04

(1)Has resprout ability. No coppice potential. (2)It does not persist if heavily grazed (Ripperton and Hosaka, 1942). For cut forage, it should be topped at a height of about 0.8 m. Under grazing conditions, it makes vigorous growth during the first year and then declines and ordinarily requires replanting every four to five years. Grazing management : Allow the plants to develop well before grazing and then lightly graze to a hedge at the desired height. The plant stems are brittle and easily broken, so grazing should not be continuous. Easily destroyed by fire (Downes, 1966). [tolerance of light grazing/pruning only] (3)"No regrowth occurs when plants are cut off at ground level

(1)http://plants.usda.gov/cgi_bin/topics.cgi (2)http://www.fao.org/WAICENT/FAOINFO/AGRICULT/AGP/AGPC/doc/GBASE/data/Pf000150.HTM (3)http://www.tropical-seeds.com/tech_forum/veg_herbs/pigeon_pea.html

8.05

Don’t know


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