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

Panicum maximum (Guinea grass, buffalo grass)

Answer

1.01

Is the species highly domesticated?

y=-3, n=0

n

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

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

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

y

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

y

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

n

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

y

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

y

5.01

Aquatic

y=5, n=0

n

5.02

Grass

y=1, n=0

y

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

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

y

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

y

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

n

8.03

Well controlled by herbicides

y=-1, n=1

y

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

n

Total score:

17

Source

Notes

1.01

No evidence.

1.02

Native to Africa, widely cultivated and naturalized throughout the tropics including Hawaii.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

1.03

No evidence.

2.01

Indigenous to Africa; introduced, cultivated, and now naturalized in many tropical and subtropical areas of the world. (2)A grass for wet tropics and subtropics

http://www.hort.purdue.edu/newcrop/duke_energy/Panicum_maximum.html#Uses (2)http://www.dpi.qld.gov.au/pastures/4513.html

2.02

2.03

It grows in dry areas between sea level and 1,200 m (2)Ranging from Warm Temperate Dry to Moist through Tropical Very Dry to Wet Forest Life Zones

http://www.hear.org/pier3/pamax.htm (2)http://www.hort.purdue.edu/newcrop/duke_energy/Panicum_maximum.html#Uses

2.04

Native to Africa, widely cultivated and naturalized throughout the tropics including Hawaii.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

2.05

Native to Africa, widely cultivated and naturalized throughout the tropics including Hawaii.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

3.01

Native to Africa, widely cultivated and naturalized throughout the tropics including Hawaii.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

3.02

fields and on waste lands

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

3.03

(1)Considered a major problem weed in cultivated areas. (2)Listed as a serious weed in several countries including Hawaii and Australia.

(1)Hasselwood, E.L. and G.G. Motter. 1983.Handbook of Hawaiian Weeds. University of Hawai‘i Press. (2)Holm, L, Pancho, J.V.,Herberger,J.P. and Plucknett, D.L. 1979. A geogrpahical atlas of world weeds. John Wiley and sons. New York.

3.04

No evidence (primarily colonizes disturbed wastelands (see 3.02 above))

3.05

P. fasciculatum and P. repens are listed as a serious weed in several countries.

Holm, L, Pancho, J.V.,Herberger,J.P. and Plucknett, D.L. 1979. A geogrpahical atlas of world weeds. John Wiley and sons. New York.

4.01

No evidence.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

4.02

It has a strong allelopathic activity

http://www.hear.org/pier3/pamax.htm

4.03

No evidence.

4.04

High palatability to browsing animals and medium palatability to grazing animals. (2)Especially palatable in the younger stages, tending to become coarser and less readily eaten by cattle as it matures. High quality forage.

http://plants.usda.gov/cgi_bin/topics.cgi (2)http://www.hort.purdue.edu/newcrop/duke_energy/Panicum_maximum.html#Uses

4.05

A high quality forage.

http://www.hort.purdue.edu/newcrop/duke_energy/Panicum_maximum.html#Uses

4.06

Lists 140 fungal species to be found on this grass but no specific serious pests.

http://nt.ars-grin.gov/fungaldatabases/all/FindRecOneFungusFrame.cfm

4.07

Reported to be diuretic and preventative, guineagrass is a folk remedy for tympanitis

http://www.hort.purdue.edu/newcrop/duke_energy/Panicum_maximum.html#Uses

4.08

Not fire resistant, high fire tolerance. (2) Fire will sweep through stands of this grass but it regenerates rapidly from underground rhizomes. (3). Its resistance to drought also means it builds up a dangerous mass of plant material so when fires occur, the blaze is fiercer and native plants which have not built up fire-tolerance are wiped out. As Guinea Grass can survive fires, it dominates the ground after a fire.

http://plants.usda.gov/cgi_bin/topics.cgi (2)http://www.hear.org/pier3/pamax.htm (3)http://www.naturia.per.sg/buloh/plants/guinea_grass.htm

4.09

Shade intolerant. (2)Somewhat tolerant to shade and grows under trees or in stands of low bush

http://plants.usda.gov/cgi_bin/topics.cgi (2)http://www.hort.purdue.edu/newcrop/duke_energy/Panicum_maximum.html#Uses

4.1

pH range from 5.2 -6.9 (2)Grows well on a wide variety of well-drained soils. Does

http://plants.usda.gov/cgi_bin/topics.cgi (2)http://www.hort.purdue.edu/newcrop/duke_energy/Panicum_maximum.html#Uses

4.11

It is not a vine. No evidence of climbing or smothering habit.

4.12

plants grow extremely rapidly, providing much biomass. forming (dense) colonies

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

5.01

5.02

Perennial bunch grass

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu. http://plants.usda.gov/cgi_bin/topics.cgi

5.03

5.04

6.01

No evidence.

6.02

No evidence of non-viability.

6.03

No information.

6.04

It is a facultative apomict in which both apospory and pseudogamy occur (Warmke, 1954, quoted by Javier, 1970). The amount of sexual reproduction varies from 1-5 percent depending on the variety.

http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000278.htm

6.05

Probably not as it is a grass species and may be pollinated by wind.

6.06

Propagated by seed. Vegetative spread rate none. (2)By seed and underground stems.

http://plants.usda.gov/cgi_bin/topics.cgi (2)Haselwood, E.L. and Motter, G.G. 1983. Handbook of Hawaiian weeds. University of Hawaii Press.

6.07

personal observation CCD

7.01

Propagules do not have any means of attachment.

7.02

For cattle grazing.

7.03

Probably yes as the seeds are very small.

7.04

The seeds are dispersed by wind

http://www.hear.org/pier3/pamax.htm

7.05

7.06

"The seeds are dispersed by birds". (occasionally- role of birds is questionable since the birds are granivorous and do not cache) Well developed pappus indicates wind dispersal.

http://www.naturia.per.sg/buloh/plants/guinea_grass.htm

7.07

7.08

According to above reference the seeds are dispersed by birds but it is not clear whether they eat the seeds or use pieces of the flowering stalks as nest material.

8.01

1,106,000 seeds per pound. (2)Seeds profusely (3)Seeds 1.7–3.1 million/kg.

http://plants.usda.gov/cgi_bin/topics.cgi (2)http://www.hear.org/pier3/pamax.htm (3)http://www.hort.purdue.edu/newcrop/duke_energy/Panicum_maximum.html#Uses

8.02

Seed viability under natural conditions is short-lived.

http://www.hort.purdue.edu/newcrop/duke_energy/Panicum_maximum.html#Uses

8.03

Several herbicides have been mentioned for the control of this grass. 2)It can be killed by a pre-emergent spray of 2,4-D sodium salt at 4.5 kg/ha of an 840 g AI/kg product (e.g. Hormicide). No wetting agent is required when used as a pre-emergent spray. Use a minimum of 340 litres of water per hectare. For seedlings in the five-leaf stage, use Diuron at 2.5 kg/ha of an 800 g AI/kg product (Karmex, Diuron) applied in a minimum of 340 litres of water per hectare. For mature plants use 2,2-DPA at 2.3 kg of a 740 g AI/kg product (Shirpon, Dowpon) plus paraquat at 85 ml of a 200 g AI/litre product (e.g. Gramoxone) plus wetting agent at 250 ml per 200 litres of water. Spray to the point of runoff (Tilley, 1977).

Swarbick, J. T. 1982. The Australian weed control handbook. Plant press. Toowoomba. 2)http://www.fao.org/ag/AGP/AGPC/doc/Gbase/DATA/Pf000278.htm

8.04

No resprout ability. (2)Fire will sweep through stands of this grass but it regenerates rapidly from underground rhizomes.

http://plants.usda.gov/cgi_bin/topics.cgi (2)http://www.hear.org/pier3/pamax.htm

8.05

Forms thickets on wastelands in Hawai‘i.