Pacific Island Ecosystems at Risk (PIER)


Dioscoria bulbifera


RISK ASSESSMENT RESULTS: High risk, score: 13


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

Dioscorea bulbifera L. Family - Dioscoreaceae Common Names(s) -cheeky yam, potato yam, air-potato, aerial yam, bitter yam. Synonym(s) - Dioscerea sativa Thumb., Dioscerea latifolia Benth., Dioscerea anthropophagorum A. Chev., Helmia bulbifera (L.) Kunth.,Dioscerea crispata Roxb., Dioscerea dicranandra Donn. Sm., Dioscerea heterophylla Roxb., Dioscerea hoffa Cordem., Dioscerea pulchella Roxb, Dioscerea tamnifolia Salisb., Dioscerea tenuflora Salisb., Smilax decipens Spreng., Dioscerea oppositifolia Campbell, Dioscerea papilaris Blanco, Dioscerea tunga Hamilton

Answer

Score

1.01

Is the species highly domesticated?

y=-3, n=0

n

0

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

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

0

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

y

2

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

2

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

3.04

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

n=0

y

4

3.05

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

n=0

y

2

4.01

Produces spines, thorns or burrs

y=1, n=0

n

0

4.02

Allelopathic

y=1, n=0

4.03

Parasitic

y=1, n=0

n

0

4.04

Unpalatable to grazing animals

y=1, n=-1

4.05

Toxic to animals

y=1, n=0

y

1

4.06

Host for recognized pests and pathogens

y=1, n=0

4.07

Causes allergies or is otherwise toxic to humans

y=1, n=0

y

1

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

n

0

4.09

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

y=1, n=0

y

1

4.10

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

y=1, n=0

y

1

4.11

Climbing or smothering growth habit

y=1, n=0

y

1

4.12

Forms dense thickets

y=1, n=0

n

0

5.01

Aquatic

y=5, n=0

n

0

5.02

Grass

y=1, n=0

n

0

5.03

Nitrogen fixing woody plant

y=1, n=0

n

0

5.04

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

y=1, n=0

y

1

6.01

Evidence of substantial reproductive failure in native habitat

y=1, n=0

n

0

6.02

Produces viable seed.

y=1, n=-1

n

-1

6.03

Hybridizes naturally

y=1, n=-1

6.04

Self-compatible or apomictic

y=1, n=-1

n

0

6.05

Requires specialist pollinators

y=-1, n=0

n

0

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

y

1

6.07

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

See left

1

1

7.01

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

y=1, n=-1

y

1

7.02

Propagules dispersed intentionally by people

y=1, n=-1

y

1

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

n

-1

7.04

Propagules adapted to wind dispersal

y=1, n=-1

n

-1

7.05

Propagules water dispersed

y=1, n=-1

7.06

Propagules bird dispersed

y=1, n=-1

n

-1

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

n

-1

7.08

Propagules survive passage through the gut

y=1, n=-1

n

-1

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

8.02

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

y=1, n=-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

-1

8.05

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

y=-1, n=1

n

1

Total score:

13

Supporting data:

Notes

Source

1.01

(1) Dioscorea bulbifera has been in cultivation for several millennia in both Asia and Africa. There are numerous edible cultivars in Asia and Africa.

(1) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15].

1.02

1.03

2.01

(1) Native range: AFRICA - Tanzania; Uganda; Cameroon; Burkina Faso; Cote D'Ivoire; Ghana; Guinea; Liberia; Nigeria; Senegal; Sierra Leone; Madagascar; Mauritius; Reunion; ASIA-TEMPERATE - China; ASIA-TROPICAL - Bhutan; India; Nepal; Sri Lanka; Cambodia; Laos; Myanmar; Thailand; Vietnam; Indonesia; Malaysia; Papua New Guinea; Philippines; AUSTRALASIA - Australia

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?14186 [Cited 2009 October 15].

2.02

(1) Native range: AFRICA - Tanzania; Uganda; Cameroon; Burkina Faso; Cote D'Ivoire; Ghana; Guinea; Liberia; Nigeria; Senegal; Sierra Leone; Madagascar; Mauritius; Reunion; ASIA-TEMPERATE - China; ASIA-TROPICAL - Bhutan; India; Nepal; Sri Lanka; Cambodia; Laos; Myanmar; Thailand; Vietnam; Indonesia; Malaysia; Papua New Guinea; Philippines; AUSTRALASIA - Australia

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?14186 [Cited 2009 October 15].

2.03

(1) D. bulbifera is confined to areas with tropical to subtropical climates. It can survive in areas with an average annual minimum temperature range of -12.2 to -9.5 °C (10-15°F) USDA hardiness zone 8b. In Florida , D. bulbifera is found in disturbed uplands, floodplain forests, maritime hammocks, pine rocklands, prairie hammocks, rockland hammocks, scrub, scrubby flatwoods, shell mounds, sink holes and xeric hammocks. (2) Naturalized in mesic areas in Hawaii 5-670 m.

(1) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15]. (2) Wagner, W.L., Herbst, D.R., Sohmer, S.H., 1999. Manual of the Flowering Plants of Hawaii. Bishop Museum Press, Honolulu.

2.04

(1) Native range: AFRICA - Tanzania; Uganda; Cameroon; Burkina Faso; Cote D'Ivoire; Ghana; Guinea; Liberia; Nigeria; Senegal; Sierra Leone; Madagascar; Mauritius; Reunion; ASIA-TEMPERATE - China; ASIA-TROPICAL - Bhutan; India; Nepal; Sri Lanka; Cambodia; Laos; Myanmar; Thailand; Vietnam; Indonesia; Malaysia; Papua New Guinea; Philippines; AUSTRALASIA - Australia

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?14186 [Cited 2009 October 15].

2.05

(1) Dioscorea bulbifera is widely cultivated and spread from the Atlantic coast of Africa throughout the Pacific and recently to the Neotropics, in Hawaii, a Polynesian introduction. (2) "D. bulbifera has been widely distributed through human activities and has become naturalized in many tropical and sub-tropical regions of the world."

(1) Wagner, W.L., Herbst, D.R., Sohmer, S.H., 1999. Manual of the Flowering Plants of Hawaii. Bishop Museum Press, Honolulu. (2) http://www.imapinvasives.org/GIST/ESA/esapages/documnts/diosbul.pdf [Cited 2009 October 19].

3.01

(1) Widely naturalized in the tropics and subtropics of the West Indies, Central and South America. D. bulbifera is also naturalized in Mississippi, Louisiana, Texas, Hawaii, and Mexico. (2) Naturalized in mesic areas, especially shaded mesic valleys and disturbed mesic forest 5-670 m on Kauai, Oahu, Molokai, Maui and Hawaii.

(1) Wheeler, G.S., Pemberton, R.W., Raz, L., 2007. A Biological Control Feasibility Study of the Invasive Weed-Air Potato, Dioscorea bulbifera L. (Dioscoreaceae): an Effort to Increase Biological Control Transparency and Safety. Natural Areas Journal 27, 269-279. (2) Wagner, W.L., Herbst, D.R., Sohmer, S.H., 1999. Manual of the Flowering Plants of Hawaii. Bishop Museum Press, Honolulu.

3.02

(1) Numerous individuals mention the weediness of D. bulbifera in their gardens on this blog site. Control efforts were not always successful.

(1) http://davesgarden.com/guides/pf/go/32235/ [Cited 2009 October 15]

3.03

(1) A common weed in orchards in Florida. [no economic impact or control methods mentioned]

(1) http://www.agmarketing.ifas.ufl.edu/dlfiles/AppE_Weeds.pdf [Cited 2009 October 15].

3.04

(1) Dioscorea oppositifoliais classified as a category I weed by the Florida Exotic Pest Plant Council. "Category I plants are those that alter native plant communities by displacing native species, change community structures or ecological functions, or hybridize with natives." D. bulbifera is very common and overwhelming in some areas. It occurs along hammock edges and roadsides. (2) Dioscorea bulbifera is one of the more common natural area weeds in central and south Florida. It occurs in tropical and subtropical hummocks and also invades disturbed uplands, scrub, sinkholes, alluvial flood plain forests, and urban lots. D. bulbifera can infest disturbed areas, such as forest canopies damaged by hurricanes. D. bulbifera impacts community structure by invading sights after natural disturbances (hurricanes).

(1) Morgan, E.C., Overholt, W.A., 2005. New Records of Invasive Exotic Plant Species in St. Lucie County, Florida. Castanea 70, 59-62. (2) Wheeler, G.S., Pemberton, R.W., Raz, L., 2007. A Biological Control Feasibility Study of the Invasive Weed-Air Potato, Dioscorea bulbifera L. (Dioscoreaceae): an Effort to Increase Biological Control Transparency and Safety. Natural Areas Journal 27, 269-279.

3.05

(1) Dioscorea oppositifolia is a perennial weed that out competes native plant species. Its control is a priority in the Great Smoky Mountains National Park, USA. D. oppositifolia has a prolific growth habitat and rapid spread threaten naturally occurring vegetation throughout temperate regions of the USA. (2) Dioscorea oppositifolia is an invasive riparian plant in the United States. It is a serious threat to native plant species richness and abundance.

(1) Mueller, T.C., Robinson, D.K., Beeler, J.E., Main, C.L., Soehn, D., Johnson, K., 2003. Dioscorea oppositifolia L. Phenotypic Evaluations and Comparison of Control Strategies. Weed Technology 17, 705-710. (2)Thomas, J.R., Gibson, D.J., Middleton, B.A., 2005. Water dispersal of vegetative bulbils of the invasive exotic Dioscorea oppositifolia L. in Southern Illinois. Journal of the Torrey Botanical Society 132, 187-196.

4.01

(1) No spines, thorns or burrs.

(1) http://aquat1.ifas.ufl.edu/misc/pdfs/diobul.pdf [Cited 2009 October 15].

4.02

Unknown

4.03

(1) Not parasitic.

(1) http://aquat1.ifas.ufl.edu/misc/pdfs/diobul.pdf [Cited 2009 October 15].

4.04

(1)" Raccoons, wild hogs and other animals do not seem to feed upon the bulbils."

(1) http://www.issg.org/database/species/ecology.asp?si=1220&fr=1&sts=&ver=print&prtflag=false [Cited 2009 October 19].

4.05

(1) Consumption of the underground tuber has been fatal to pigs.

(1) http://books.google.com/books?id=C8xJE2NfQpIC&pg=PA163&lpg=PA163&dq=dioscorea+bulbifera+
%2B+%22cattle%22&source=bl&ots=Cuc2Ep15_p&sig=4oDrEoaM84-89NnNRg6kuCtMhVw&hl=en&ei=GUziStXDFIjoM-vgnLkB&sa=X&oi=book_result&ct=result&resnum=5&ved=0CBcQ6AEwBA#v=onepage&q=
dioscorea%20bulbifera%20%2B%20%22cattle%22&f=false [2009 October 19].

4.06

Unknown (1) Possible host for Goplana diosoreae the fungal cause of yam rust disease in Pohnpei. (2) Host of a Cercospora sp. In American Samoa.

(1) http://www.ctahr.hawaii.edu/adap2/Publications/ADAP_pubs/banana.pdf [2009 October 15]. (2) http://www.ctahr.hawaii.edu/adap2/ascc_landgrant/dr_brooks/techrepno32.pdf [Cited 2009 October 19].

4.07

(1) The aerial tuber contains unnamed alkaloid and oxalates. It is toxic when immature. Some cultivars may be eaten after it has been peeled and cooked. (2) There are edible and toxic varieties of D. bulbifera. Some varieties are used as medicinals, while the unpalatable varieties may be used to create poisons. Poisons are derived from alkaloids, saponins, sapogenins and/or tannins present in the tubers.

(1) Morton, J.F. Plants Poisonous to People in Florida and Other Warm Areas. Miami, Florida. Southeastern Printing Company Inc. (2) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15].

4.08

(1) Dioscera bulbifera may create a moist barrier that impedes fire movement into invaded areas.

(1) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15].

4.09

(1) D. bulbifera grows rapidly in full sun. (2) In its native range, D. bulbifera grows in partially to fully shaded areas.

(1) http://www.imapinvasives.org/GIST/ESA/esapages/documnts/diosbul.pdf [Cited 2009 October 19]. (2) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15].

4.10

(1) In its native range D. bulbifera grows in loamy soils and soils of loose clay. In Florida, it grows in Spodosols, Entisols, Histosols, Entisols underlain by limestone, and an

(1) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15].

4.11

(1) Vigorously twining herbaceous vine, with small or absent underground tubers.

(1) http://aquat1.ifas.ufl.edu/misc/pdfs/diobul.pdf [Cited 2009 October 15].

4.12

(1) Vigorously twining herbaceous vine, with small or absent underground tubers.

(1) http://aquat1.ifas.ufl.edu/misc/pdfs/diobul.pdf [Cited 2009 October 15].

5.01

(1) Vigorously twining herbaceous vine, with small or absent underground tubers.

(1) http://aquat1.ifas.ufl.edu/misc/pdfs/diobul.pdf [Cited 2009 October 15].

5.02

(1) Vigorously twining herbaceous vine, with small or absent underground tubers. Dioscoreaceae.

(1) http://aquat1.ifas.ufl.edu/misc/pdfs/diobul.pdf [Cited 2009 October 15].

5.03

(1) Vigorously twining herbaceous vine, with small or absent underground tubers. Dioscoreaceae.

(1) http://aquat1.ifas.ufl.edu/misc/pdfs/diobul.pdf [Cited 2009 October 15].

5.04

(1) Vigorously twining herbaceous vine, with small or absent underground tubers.

(1) http://aquat1.ifas.ufl.edu/misc/pdfs/diobul.pdf [Cited 2009 October 15].

6.01

No evidence.

 

6.02

No evidence of seed production in Hawaii. (1) In Florida, D. bulbifera rarely produces flowers, the seeds are considered sterile. The primary means of spread is through human movement of bulbils. (2) D. bulbifera has been reported to produce flowers and fruits in Florida in contrast to earlier reports. (3) In its native range, Dioscorea bulbifera produces a dry dehiscent capsule that range from 1.802.8 cm in length and from 1-1.5 cm in width. Seeds range frp, 12-22 mm in length. Seeds are unilaterally winged, elongated and are slightly curved at the point of attachment. "The unilaterally winged seed of D. bulbifera found growing in less densely vegetated areas of the plant's native range has evolved into its present shape to allow for whirling flight in windy conditions."

(1) Wheeler, G.S., Pemberton, R.W., Raz, L., 2007. A Biological Control Feasibility Study of the Invasive Weed-Air Potato, Dioscorea bulbifera L. (Dioscoreaceae): an Effort to Increase Biological Control Transparency and Safety. Natural Areas Journal 27, 269-279. (2) http://aquat1.ifas.ufl.edu/misc/pdfs/diobul.pdf [Cited 2009 October 15]. (3) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15].

6.03

Unknown

6.04

(1) Dioscorea bulbifera is dioecious. In its native range, Dioscorea reproduces sexually by seed, and clonally through the production of aerial tubers (bulbils).

(1) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [Cited 2009 October 15].

6.05

(1) In its native range, all flowers of the genus Dioscorea are pollinated by night flying insects. Nothing is known about the pollinators of D. bulbifera. (2) Pollination is by insects, commonly by thrips.

(1) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15]. (2) http://www.sms.si.edu/irlSpec/Dioscorea_bulbifera.htm [Cited 2009 October 15]

6.06

(1) Dioscorea bulbifera is dioecious. In its native range, Dioscorea reproduces sexually by seed, and clonally through the production of aerial tubers (bulbils).

(1) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [Cited 2009 October 15].

6.07

(1) The bulbils of D.bulbifera go through a dormant stage that is specific to the variety. Bulbils may germinate within a few weeks of dropping or may remain dormant until the following growing season.

(1) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15].

7.01

(1) Can be dispersed as garden waste.

(1) http://www.issg.org/database/species/ecology.asp?si=1220&fr=1&sts=&lang=EN [Cited 2009 October 19].

7.02

(1) Dioscorea bulbifera is widely cultivated and spread from the Atlantic coast of Africa throughout the Pacific and recently to the Neotropics, in Hawaii, a Polynesian introduction. (2) "D. bulbifera has been widely distributed through human activities and has become naturalized in many tropical and sub-tropical regions of the world." It is one of the most common and widespread food yams. Wild forms are usually bitter and often poisonous. Cultivars do not survive in the wild for long periods.

(1) Wagner, W.L., Herbst, D.R., Sohmer, S.H., 1999. Manual of the Flowering Plants of Hawaii. Bishop Museum Press, Honolulu. (2) http://www.imapinvasives.org/GIST/ESA/esapages/documnts/diosbul.pdf [Cited 2009 October 19].

7.03

(1) In its native range, Dioscorea bulbifera produces a dry dehiscent capsule that range from 1.802.8 cm in length and from 1-1.5 cm in width. Seeds range from, 12-22 mm in length. Seeds are unilaterally winged, elongated and are slightlycurved at the point of attachment.

(1) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15].

7.04

[No evidence of seed production in Hawaii].(1) In its native range, Dioscorea bulbifera produces a dry dehiscent capsule that range from 1.802.8 cm in length and from 1-1.5 cm in width. Seeds range from, 12-22 mm in length. Seeds are unilaterally winged, elongated and are slightly curved at the point of attachment. "The unilaterally winged seed of D. bulbifera found growing in less densely vegetated areas of the plant's native range has evolved into its present shape to allow for whirling flight in windy conditions." D. bulbifera reproduces vegetatively through bulbils.

(1) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15].

7.05

(1) Tubers are known to float, aiding in dispersal. (2) Recent evidence suggests that tubers do not float. However the bulbils may become less dense after they fall of the vine and eventually float.

(1) http://aquat1.ifas.ufl.edu/misc/pdfs/diobul.pdf [Cited 2009 October 15]. (2) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15].

7.06

(1) In its native range, Dioscorea bulbifera produces a dry dehiscent capsule that range from 1.802.8 cm in length and from 1-1.5 cm in width. Seeds range from, 12-22 mm in length. Seeds are unilaterally winged, elongated and are slightly curved at the point of attachment. "The unilaterally winged seed of D. bulbifera found growing in less densely vegetated areas of the plant's native range has evolved into its present shape to allow for whirling flight in windy conditions." D. bulbifera reproduces vegetatively through bulbils.

(1) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15].

7.07

[No external means of attachment] (1) In its native range, Dioscorea bulbifera produces a dry dehiscent capsule that range from 1.802.8 cm in length and from 1-1.5 cm in width. Seeds range from, 12-22 mm in length. Seeds are unilaterally winged, elongated and are slightly curved at the point of attachment. "The unilaterally winged seed of D. bulbifera found growing in less densely vegetated areas of the plant's native range has evolved into its present shape to allow for whirling flight in windy conditions." D. bulbifera reproduces vegetatively through bulbils.

(1) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15].

7.08

[No evidence of seed production in Hawaii].(1) In its native range, Dioscorea bulbifera produces a dry dehiscent capsule that range from 1.802.8 cm in length and from 1-1.5 cm in width. Seeds range from, 12-22 mm in length. Seeds are unilaterally winged, elongated and are slightly curved at the point of attachment. "The unilaterally winged seed of D. bulbifera found growing in less densely vegetated areas of the plant's native range has evolved into its present shape to allow for whirling flight in windy conditions." D. bulbifera reproduces vegetatively through bulbils. (2) The squirrels carried the bulbils all over the property and on to the neighbor's land.

(1) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15]. (21) http://davesgarden.com/guides/pf/go/32235/ [Cited 2009 October 15]

8.01

Unknown

8.02

(1) The bulbils of D. bulbifera go through a dormant stage that is specific to the variety. Bulbils may germinate within a few weeks of dropping or may remain dormant until the following growing season.

(1) http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15].

8.03

(1) Repeated basal application of Herbicide (e.g., Roundup, Remedy or 50% Garlon 3A) over a 2-3 year period is necessary for control. A biologist at the Fern Forest, Florida estimated that herbicidal control (with Roundup and Rodeo) of heavily infested areas would require 5 years of treatments and monitoring. (2) Triclopyr ester has been used to achieve 100% control. Glyphosate has also been used to achieve control and is most effective if used later in the year (Roundup Pro at 1-1.5% applied when vines are well-developed and are beginning to produce bulbils). The bulbils have been effectively killed by temperatures as warm as 32° C for one week and by freezing for 8 hours.

(1) Wheeler, G.S., Pemberton, R.W., Raz, L., 2007. A Biological Control Feasibility Study of the Invasive Weed-Air Potato, Dioscorea bulbifera L. (Dioscoreaceae): an Effort to Increase Biological Control Transparency and Safety. Natural Areas Journal 27, 269-279. http://www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf [2009 October 15].

8.04

(1) Controlled burns can kill stem growth and bulbils on the ground. Some control of vine stems can be obtained by physically cutting the vines. Clipping should be done before new aerial bulbils form in the spring to weaken the underground rhizome.

(1) http://www.imapinvasives.org/GIST/ESA/esapages/documnts/diosbul.pdf [Cited 2009 October 15]

8.05

(1) Wheeler and Pembertons (2007) did a feasibility study for the possibility of biocontrol for D. bulbifera. Several herbivorous insects were found in Nepal and Africa that were highly damaging to D. bulbifera. The article summarizes current searches for classical biological control for D. bulbifera. (2) There are no approved biological control agents for Dioscorea bulbifera in the U.S.

(1) Wheeler, G.S., Pemberton, R.W., Raz, L., 2007. A Biological Control Feasibility Study of the Invasive Weed-Air Potato, Dioscorea bulbifera L. (Dioscoreaceae): an Effort to Increase Biological Control Transparency and Safety. Natural Areas Journal 27, 269-279. (2) http://www.imapinvasives.org/GIST/ESA/esapages/documnts/diosbul.pdf [Cited 2009 October 19].


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