Pacific Island Ecosystems at Risk (PIER)


Manihot esculenta


RISK ASSESSMENT RESULTS: Low risk, score: 3 (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

Manihot esculenta (Manihot utilissima, Jatropha manihot; Common name: cassada, cassava, manioc, yuca, tapioca, mandioca, shushu, muk shue, cassave, maniok, tapioka, imanoka, maniba, kasaba, catela boodin.

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

y

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

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

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

y

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

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

y

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

n

6.07

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

See left

2

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

n

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

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:

3

Supporting data:

Source

Notes

1.01

(1) '...Manihot is not known in the wild state, but there are two centers of speciation, one in Central America from southern Mexico to Guatemala and another in northeastern Brazil. Sweet cassavas are more widely distributed in South America than bitter varieties, and were cultivated by older civilizations, as long as 4,000 years ago in Peru and 2,000 years ago in Mexico.' (2)There are innumerable cultivated varieties of manioc, 160 or more. They are divided into bitter and sweet. Bitter manioc is characterized by its erect stalk, almost red-colored leaves and early heavy yields, and since they contain between 0.02–0.003% prussic acid are used to make industrial starch. Sweet manioc containing 0.007% prussic acid with most of HCN in the skin and outer cortical layer is used to eat as food and for fodder. Some cvs now in use are: 'Baker', 'Copeland', 'Red Manila', 'Jolo White', 'Manioca Basiorao', 'Aipin Mangi', 'Aipin Valence', 'Aipin Maxteiga', 'Yellow Bell', 'Blue Beard', 'Pacho III', 'Singapore', 'Cons

(1)http://www.hort.purdue.edu/newcrop/duke_energy/Manihot_esculenta.html (2)http://www.hort.purdue.edu/newcrop/duke_energy/Manihot_esculenta.html

1.02

(1) '...Manihot is not known in the wild state, but there are two centers of speciation, one in Central America from southern Mexico to Guatemala and another in northeastern Brazil. Sweet cassavas are more widely distributed in South America than bitter varieties, and were cultivated by older civilizations, as long as 4,000 years ago in Peru and 2,000 years ago in Mexico.' (2)Naturalized in disturbed sites, Florida keys

(1)http://www.hort.purdue.edu/newcrop/duke_energy/Manihot_esculenta.html (2)Long, R.W. and O. Lakela. 1971. A flora of tropical Florida. University of Miami Press, Coral Gables.

1.03

They look great, make a very mottled, attractive shade.. but if you don't want a yard full of trees all over, then be careful about adding this one to your landscape. Now I have no more adult- hacked it down to the ground... but seem to be forever battling the new 'weed' problem. [weedy race evidence]

http://plantsdatabase.com/go/1827.html

2.01

(1)The casava is native to South America. (2)Origin: Brazil (3)Native to South America where it is extensively cultivated also. Cultivated in the tropics and sometimes in the subtropics of the Old and New World as an important food and a source of starch. It is the second most important root crop in India. Many countries have developed extensive programs to further the raising of this crop, e.g. (Mexico, Central America, Brazil, Colombia, Jamaica, Africa, Ghana, Madagascar, Indonesia, Federated Malay States, Thailand, India, Philippine Islands, Paraguay, Fiji, and Sri Lanka). Manihot is not known in the wild state, but there are two centers of speciation, one in Central America from southern Mexico to Guatemala and another in northeastern Brazil. Sweet cassavas are more widely distributed in South America than bitter varieties, and were cultivated by older civilizations, as long as 4,000 years ago in Peru and 2,000 years ago in Mexico.

(1)http://www.tropilab.com/manihot-esc.html (2)http://www.desert-tropicals.com/Plants/Euphorbiaceae/Manihot_esculenta.html (3)http://www.hort.purdue.edu/newcrop/duke_energy/Manihot_esculenta.html

2.02

Pantropical in cultivation.

http://www.uog.edu/cals/site/POG/manihot.html

2.03

(1)Hardiness: USDA zone 9 B - 11. (2)Manioc will grow in all well-drained tropical and subtropical areas of the world where there is a warm humid climate. It requires a fairly well-spaced rainfall of about 15 dm for optimum growth of the crop. It will not tolerate frost, and usually does not grow above 1,100 m altitude. It grows best in welldrained neutral to alkaline, quite permeable, sandy loams. The plants need a lot of water, but must not stand in water; in lowlands the plants are ridged. Ranging from Warm Temperate Dry to Moist through Tropical Very Dry to Wet Forest Life Zones, cassava is reported to tolerate annual precipitation of 6.4 to 40.3 dm (mean of 56 cases = 16.4), annual temperature of 14.7 to 27.8°C (mean of 23.8 cases = 56), and pH of 4.5 to 8.7 (mean of 42 cases = 6.2). (3)May not tolerate 7oC for prolonged periods

(1)http://www.tropilab.com/manihot-esc.html (2)http://www.hort.purdue.edu/newcrop/duke_energy/Manihot_esculenta.html (3)http://ecocrop.fao.org/

2.04

(1)Pantropical in cultivation. (2)Cassava is native to South America but is cultivated in tropical and subtropical zones throughout the world. It is one of the most important tropical food crops in the world.

(1)http://www.uog.edu/cals/site/POG/manihot.html (2)http://www.floridata.com/ref/M/mani_esc.cfm

2.05

(1)Pantropical in cultivation. (2)Cassava is native to South America but is cultivated in tropical and subtropical zones throughout the world. It is one of the most important tropical food crops in the world.

(1)http://www.uog.edu/cals/site/POG/manihot.html (2)http://www.floridata.com/ref/M/mani_esc.cfm

3.01

(1) '...Manihot is not known in the wild state, but there are two centers of speciation, one in Central America from southern Mexico to Guatemala and another in northeastern Brazil. Sweet cassavas are more widely distributed in South America than bitter varieties, and were cultivated by older civilizations, as long as 4,000 years ago in Peru and 2,000 years ago in Mexico.' (2)Naturalized in disturbed sites, Florida keys

(1)http://www.hort.purdue.edu/newcrop/duke_energy/Manihot_esculenta.html (2)Long, R.W. and O. Lakela. 1971. A flora of tropical Florida. University of Miami Press, Coral Gables.

3.02

They look great, make a very mottled, attractive shade.. but if you don't want a yard full of trees all over, then be careful about adding this one to your landscape. Now I have no more adult- hacked it down to the ground... but seem to be forever battling the new 'weed' problem. [suggests variegated for is a potential garden weed, don't know economic impact]

http://plantsdatabase.com/go/1827.html

3.03

No evidence

3.04

No evidence

3.05

" a large number of its wild relatives are weedy types; i.e they invade agitated habitats that is disturbed by man. " The progeny of this hybridization is a complex of cassava and wild (could be M.tipartita, M. anomala,M. zenerneri and M. grahamii) This species complex behaves as a weedy, and can be detected in the margens of cassava plantations if it grown near wild relatives. In the long run these hybrids being subjected to natural selection develop new weedy species.

http://www.geneconserve.pro.br/artigo_23.htm

4.01

No evidence of such structures.

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

4.02

No evidence

4.03

No evidence

4.04

Throughout the region cassava leaves are used for human or animal consumption

Veltkamp, H.J. & de Bruijn, G.H., 2003. Manihot esculenta Crantz. [Internet] Record number 3233 from TEXTFILE On-line. Flach, M. & Rumawas, F. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Sunday, 16 May 2004.

4.05

"Moore(1976) proposed that high yields of foliage may be obtained if cassava was managed as a semi-perennial crop with repeated harvesting of the foliage at 2-3 month intervals. This idea was taken up in Dominican Republic by Ffloulkes and Preston (1978) who showed that the fresh foliage could be used as the whole source of protein and for supplementing a liquid diet of molasses-urea for attending cattle."

http://www.geneconserve.pro.br/artigo_23.htm

4.06

(1) A laboratory study of food selection behaviour of pyrgomorphid grasshopper, Zonocerus variegatus L., a pest of cassava (Manihot esculenta Cranz) was investigated. Z. variegatus was offered M. esculenta Euphorbiaceae, pawpaw (Carica papaya) Caricaceae, neem (Azadirachta indica A. Juss) Meliaceae and Siam weed (Chromolaena odorata) Asteraceae, all of which were respectively suspended at the four top corners of a cage (66 x 36 cm). Of the four plant species, M. esculenta and C. papaya were readily accepted as food but the frequency of visit and comsumption time of M. esculenta was significantly higher. C. odorata was initially nibbled and later discarded. A. indica was totally rejected throughout the experiment. The results demonstrate that the presence of alternative palatable food in the vicinity of the preferred host plant, M. esculenta does not interfere with its selection as food plant of choice by Z. variegatus. [wide host range]
(2) Bemisia afer (Homoptera: Aleyrodidae), a small piercing sucking pest,

(1) Muse, W. A. Editor: Lale, N. E. S. Molta, N. B. Donli, P. O. (1998) Food selection behaviour of Zonocerus variegatus (Orthoptera: Pyrgomorphidae). Entomology in the Nigerian economy. Research focus in the 21st century, 1998, pp. 33-38, 9 ref.

(2) Fu JianWei Huang JiAn Zhen QiongHua (1998) Occurrence and damage caused by Bemisia afer (Homoptera: Aleyrodidae) on soyabeans in Fuzhou. Wuyi Science Journal, 1998, Vol. 14, pp. 68-72, 4 ref.

4.07

(1)There is a bitter, poisonous- and a sweet, nonpoisonous variety of cassava, however the skin stays poisonous and the sweet variety should be peeled. There are hydrocyanic glucosides (HCN) in all parts of the plant; these glucosides are removed by peeling and boiling in water. The peeled roots of the sweet variety are usually eaten cooked or baked. The root of the bitter varity is very poisonous when raw. Cooking destroys the hydrocyanic acid; the cooking water must be discarded. (2)The root should is extremely poisonous when raw. Cooking destroys the prussic acid it contains and makes it edible. (3)All parts of the cassava plant are poisonous and must be processed by peeling, pressing or cooking before eating. It is reported that the Caribbean Arawak Indians committed suicide be eating raw cassava rather than face slavery under the Spanish invaders. [some evidence of poisoning in humans]

(1)http://www.tropilab.com/manihot-esc.html (2)http://www.desert-tropicals.com/Plants/Euphorbiaceae/Manihot_esculenta.html

4.08

plant needs a lot of water and humidity for growth. [unlikely to grow in fire prone habitats]

(1)http://www.tropilab.com/manihot-esc.html (2)http://www.hort.purdue.edu/newcrop/duke_energy/Manihot_esculenta.html

4.09

(1)full sun / light shade, (2)Sun Exposure: Full sun to light shade...The Cassava needs full sun if it is planted to recover the roots. (3)Cassava grows best if it gets full sun in the morning and partial shade at midday. (4)Full Sun

(1)http://www.tropilab.com/manihot-esc.html (2)http://www.desert-tropicals.com/Plants/Euphorbiaceae/Manihot_esculenta.html (3)http://www.floridata.com/ref/M/mani_esc.cfm (4)http://plantsdatabase.com/go/1827.html

4.1

(1)sandy loam, should be constantly moist. (2)pH of 4.5 to 8.7 (3)Soil tolerance: heavy, medium, light, organic

(1)http://www.tropilab.com/manihot-esc.html (2)http://www.hort.purdue.edu/newcrop/duke_energy/Manihot_esculenta.html (3)http://ecocrop.fao.org/

4.11

Not a climber -a shrub

http://www.tropilab.com/manihot-esc.html

4.12

No evidence

5.01

A tropical perennial shrub of approximately 6 feet tall

http://www.tropilab.com/manihot-esc.html

5.02

Euphorbiaceae

5.03

Euphorbiaceae

5.04

Tapioca is a bushy herb with palmately divided leaves of 3-7 lobes, … The root system is composed of multiple, elongated tubers.

http://www.uog.edu/cals/site/POG/manihot.html

6.01

No evidence

6.02

For agricultural purposes, cassava is propagated exclusively by vegetative means from stem-cuttings. It is raised from seed only for the purpose of selection.

http://www.hort.purdue.edu/newcrop/duke_energy/Manihot_esculenta.htm

6.03

(1) "A population of M. reptans, characterized by erect vigorous stems and large ribbed fruits, two characteristics of cassava (M. esculenta) was found about 15 Km North of Corumbá de Goiás. Apparently, these two characteristics were acquired by M. reptans through introgressive hybridization with cassava. It seems that M. reptans became introgressed with germplasm from other species and was able to extend its ecotypic range and colonize new areas where the pure M. reptans had been previously unable to penetrate."
(2) "Because of weak barriers between cassava and wild relatives it tends to hybridize with them when it comes in close contact with these species. Since a large number of its wild relatives are weedy types; i.e they invade agitated habitats that is disturbed by man. The progeny of this hybridization is a complex of cassava and wild (could be M.tipartita, M. anomala,M. zenerneri and M. grahamii) This species complex behaves as a weedy, and can be detected in the margens of cassava plantations if i

(1) http://www.geneconserve.pro.br/reprints16.htm

(2) http://www.geneconserve.pro.br/artigo_23.htm

6.04

"In cassava, both cross-pollination and self-pollination occur naturally. Male and female flowers hardly ever open simultaneously in the same raceme; however, female and male flowers on different branches of the same plant commonly open simultaneously. Male sterility is frequent. Cross-incompatibility has not been found." (2) Apomixis has been reported in cassava by Nassar ( Nassar, 1994, Nassar, 1995).

(1) Veltkamp, H.J. & de Bruijn, G.H., 2003. Manihot esculenta Crantz. [Internet] Record number 3233 from TEXTFILE On-line. Flach, M. & Rumawas, F. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Sunday, 16 May 2004.
(2) http://www.geneconserve.pro.br/artigo_23.htm

6.05

"Pollination is by insects (entomophilus), From a survey made by Nassar and Carvalho (1990), they detected various Hymenoptera and Coleoptera, but the principal pollinator in about 70% of flores was honey bees (Apes mellifera). Other species of coleoptera such as Trigone sinipes were collected."

http://www.geneconserve.pro.br/artigo_23.htm

6.06

(1)Propagation: seeds and cuttings.
(2)For agricultural purposes, cassava is propagated exclusively by vegetative means from stem-cuttings. It is raised from seed only for the purpose of selection.

(1) http://www.tropilab.com/manihot-esc.html
(2) http://www.hort.purdue.edu/newcrop/duke_energy/Manihot_esculenta.html

6.07

(1)Cassava is a tropical root crop, requiring at least 8 months of warm weather to produce a crop. (2)Short-lived perennial (3)So I dug up a seedling and ...The following spring it produced a load of insignificant flowers. Later in the spring to mid summer, little ornamental fruiting bodies that look a lot like miniature basketballs (green with orange striping, just like a basketball except in color, with slightly rough texture about 1" in diameter) hung all over the tree. [minimum estimate for a 3m tall perennial]

(1)http://www.hort.purdue.edu/newcrop/cropfactsheets/cassava.html (2)http://ecocrop.fao.org/ (3)http://plantsdatabase.com/go/1827.html

7.01

Probably yes as it can propagate through tubers. ["In commercial production, cassava is propagated exclusively from stem cuttings. Propagation from storage roots is impossible as the roots have no buds."]

Veltkamp, H.J. & de Bruijn, G.H., 2003. Manihot esculenta Crantz. [Internet] Record number 3233 from TEXTFILE On-line. Flach, M. & Rumawas, F. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Sunday, 16 May 2004.

7.02

Cassava is grown for its enlarged starch-filled tuberous roots. … The young leaves are used as vegetable and contain a high amount of vitamin C and A.

http://www.tropilab.com/manihot-esc.html

7.03

widely cultivated and marketed - tubers could possibly be a contaminant(?) ["In commercial production, cassava is propagated exclusively from stem cuttings. Propagation from storage roots is impossible as the roots have no buds."]

Veltkamp, H.J. & de Bruijn, G.H., 2003. Manihot esculenta Crantz. [Internet] Record number 3233 from TEXTFILE On-line. Flach, M. & Rumawas, F. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Sunday, 16 May 2004.

7.04

(1)The fruit is round or oblong and winged; each fruit contain 3 seeds. (2)capsules globose, about 1.2 cm across, with 6 winged angles; seeds 3 per capsule. (3)If you were too close at the time of an explosion, you could get hit in the face by flying seed. And seed went everywhere. [explosive gravity dispersal]

(1)http://www.tropilab.com/manihot-esc.html (2)http://www.hort.purdue.edu/newcrop/duke_energy/Manihot_esculenta.html (3)http://plantsdatabase.com/go/1827.html

7.05

No evidence

7.06

No evidence

7.07

No evidence that the propagules have any means of attachment.

7.08

No evidence of ingestion. Fruit is capsule

8.01

(1)The fruit is round or oblong and winged; each fruit contain 3 seeds. (2)capsules globose, about 1.2 cm across, with 6 winged angles; seeds 3 per capsule.

(1)http://www.tropilab.com/manihot-esc.html (2)http://www.hort.purdue.edu/newcrop/duke_energy/Manihot_esculenta.html

8.02

"Seed when used for propagation be very slower, normally suffers a degree of dormancy. Scarifying the seed and filing the micropylar end does not break dormancy. The best treatment is by chermical means. Nassar and Pio used alternated temperature of 18 C for 16 hrs and 26 for 8 hours to reach a better conditions of seed germination (Nassar and Pio 1983). "

http://www.geneconserve.pro.br/artigo_23.htm

8.03

the formulated mixture of ametryn + clomazone caused visual symptoms of injury [no attempts to intentionally kill it]

Oliveira Junior, R. S., J. Constantin, A. I. F. M. Hernandes, M. H. Inoue, O. Marchiori Junior, and A. C. Ramires. 2001. Tolerance of five cassava (<i>Manihot esculenta</i>) cultivars to herbicides. Planta Daninha 19:119-125

8.04

"Moore(1976) proposed that high yields of foliage may be obtained if cassava was managed as a semi-perennial crop with repeated harvesting of the foliage at 2-3 month intervals." [probably yes; tolerate repeated harvesting of foliage, storage roots may provide energy for resprout]

http://www.geneconserve.pro.br/artigo_23.htm

8.05

Don’t know


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