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

Brachiaria mutica (California or para 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

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

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

y

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

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

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

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

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

n

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

7.05

Propagules water dispersed

y=1, n=-1

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

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

y

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

n

Total score:

12

Source

Notes

1.01

The species is widely cultivated as a pasture grass but did not find any evidence that it is a cultivar. Cultivated species similar to wild.

1.02

The species is naturalized in 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

Did not find any evidence of weedy sub-species, cultivars or varieties.

2.01

(1) 'Native range unknown, now pantropical... ' (2) & (3) Native to Africa and introduced in Hawaii, Florida, Texas in the US and in Samoa, Tonga and Fiji.

(1) Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu. (2) Whistler, W. A. 1983. Weed handbook of western polynesia. Germany.Whistler, W. A. 1983. Weed handbook of western polynesia. Germany. (3) Haselwood E. L. & R. T. Hirano. 1983. Handbook of Hawaiian weeds. University of Hawaii Press. Honolulu

2.02

(1) 'Native range unknown, now pantropical … '(2) Native to Africa (South America) and introduced in tropics like Hawaii, Fiji, Guam, Cuba and continental U.S. of Florida and gulf of Texas.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu. (2) Huges, H. D., M. E. Heath & D. S. Metcalfe. 1962. Forages. Iowa state uniersity press. (3)Huges, H. D., M. E. Heath & D. S. Metcalfe. 1985. Forages. Iowa state uniersity press.

2.03

Low elevation, wet or highly disturbed mesic conditions for establishment. It can grow in a wide range of moisture conditions. It grows luxuriantly in wet -swampy habitats but it can withstand severe drought too. it is a severe weed in cultivated areas, wastelands and along roadsides.

Haselwood E. L. & R. T. Hirano. 1983. Handbook of Hawaiian weeds. University of Hawaii Press. Honolulu

2.04

1)The species is naturalized in Hawaii. 2) It is a weed of roadsides and waste places in Samoa.

1)Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu. 2)Whistler, W. A. 1983. Weed handbook of western polynesia. Germany.

2.05

Native to Africa and introduced to Hawaii, Fiji, Guam, Continental U.S. (Florida and gulf of Texas) and Cuba.

(1)Huges, H. D., M. E. Heath & D. S. Metcalfe. 1962. Forages. Iowa state uniersity press. (2)Huges, H. D., M. E. Heath & D. S. Metcalfe. 1985. Forages. Iowa state uniersity press.

3.01

1)The species is naturalized in Hawaii. 2) It is a weed of roadsides and waste places in Samoa.

1)Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu. 2)Whistler, W. A. 1983. Weed handbook of western polynesia. Germany.

3.02

It is a weed of roadsides and waste places in Samoa. Answer left blank because this species meets the more serious criteria of 3.03 and 3.04

Whistler, W. A. 1983. Weed handbook of western polynesia. Germany.

3.03

(1) '…can become a pest in croplands converted to pasture.' (2) In Cuba it has become a pest in sugarcane fields. (3) '… it is a pest in sugarcane fields in the tropics.'

(1) Whistler, W. A. 1983. Weed handbook of western polynesia. Germany. (2) Huges, H. D., M. E. Heath & D. S. Metcalfe. 1962. Forages. Iowa state uniersity press. (3)Huges, H. D., M. E. Heath & D. S. Metcalfe. 1985. Forages. Iowa state uniersity press.

3.04

(1)It is one of Australia's worst environmental weeds. Estimated to invade 100,000 ha of swamp land in Queensland, 40,000 in Townswille - displaces water chestnut - attempts to control it with spray, burning and mechanical extraction have been unsuccessful. (2)This perennial grass can reach heights of 2 m. It forms dense monotypic stands by layering from trailing stems. It will overgrow most shrubs and trees in its habitat. The species grows in wet habitats between sea level and 700 m. Open marshy areas, such as Kawainui Swamp, O'ahu, are the principal habitat. (3)naturalized and usually forming dense mats in areas of high soil moisture or nearby open water, such as along stream banks (4)Interferes with stream flow and poses a nuisance to marine navigation when rafts of the grass float out to sea. Forms monotypic stands in forest openings and marshes, displacing native plants and destroying bird habitats

(1)Low, T. 1997. Tropical pasture plants as weeds. Tropical Grasslands. Vol 31(4) : 337-343. (2)http://www.botany.hawaii.edu/faculty/cw_smith/bra_mut.htm (3)Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu. (4)Motooka, P., L. Castro, D. Nelson, G. Nagai and L. Ching . 2002. Weeds of pastures and natural areas of Hawaii and their management.UHCTAHR, Honolulu.

3.05

B. subquadripara is a weed in Samoa and Tonga. Also B. paspaloides and B. reptans are recognized as weeds.

Whistler, W. A. 1983. Weed handbook of western polynesia. Germany.

4.01

The species does not have any spines,, burrs or thorns.

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

4.02

Did not find any evidence of it being allelopathic.

4.03

Did not find any evidence on it being parasitic.

4.04

It is considered a valuable pasture grass.

Whistler, W. A. 1983. Weed handbook of western polynesia. Germany.

4.05

'… para grass caused osteoporosis, a bone disorder in horses. This disorder occurred by eating para grass as sole diet but was not observed with cattle.' Did not find any other evidence of it being toxic to cattle.

Ranacau, E. Review of research and observations on pastures in Fiji (1920 - 1985). 1986. Fiji Agricultural Journal. Vol 48: 12- 18.

4.06

Piricularia oryzae, Pythium arrhenomanes, Pythium artotrogus, Pythium rostratum, Sclerospora graminicola and Thaia oryziphon

Word's Worst Weeds

4.07

Did not find any evidence of it being toxic to humans.

4.08

Probably not since this species particularly inhabits wet areas., but dried/dead culms are flamable.

Whistler, W. A. 1983. Weed handbook of western polynesia. Germany.

4.09

Don’t know.

4.1

'It is adapted to moist soil rich in organic matter.' Grows well in heavy soils without irrigation - grows extremely well along margins of lakes and streams, marshes. (does not clearly indicate a wide range of soil conditions, seems to prefer rich, wet, heavy soil)

Huges, H. D., M. E. Heath & D. S. Metcalfe. 1962. Forages. Iowa state university press.

4.11

It is not a climber and did not find any evidence of it having a smothering habit although with the support of shrubs it can grow to a height of about 15 m.

4.12

'…in Hawaii naturalized and usually forming dense mats in areas of high soil moisture or nearby open water, … '

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

5.01

5.02

It’s a perennial grass.

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

5.03

5.04

6.01

Did not find any evidence on reproductive failure in native habitat.

6.02

(1) 'Paragrass will produce seed but the germination usually is extremely low.' (2) Although para grass produces flower heads quite profusely it is a poor seed producer'. 'In Northern Territory It rarely set viable seed and so planting …"

(1)Huges, H. D., M. E. Heath & D. S. Metcalfe. 1962. Forages. Iowa state uniersity press. (2) Smith, R. N. W. 1973. Para grass in Northern Territory -parantage and propogation. Tropical Grasslands Vol 7, no 2, Pg 249-250.

6.03

Don’t know.

6.04

No direct evidence that this species is apomict except - 'The selection and release of superior apomictic ecotypes as cultivars is common for several … Brachiara species and others.'

Sotomayor-Rio, A & W. D. Antonio. 2001. Tropical forage plants development and use. CRC press. London

6.05

No evidence that it requires specialist pollinators. It is a grass and probably wind pollinated.

6.06

'It forms dense monotypic stands by layering from trailing stems.'

Smith, C.W. 1985. Impact of alien plants on Hawaii's native biota. In Hawaii's terrestrial ecosystems preservation and management. Eds. C. P. Stone & J. M. Scott. University of Hawaii.

6.07

R. Criley, UH Department of Horticulture, personal communication

7.01

It is a poor seed producer and the underground stems by means of which it generally spreads are less likely to be dispersed unintentionally.

7.02

No evidence of it being a species of any ornamental value.

7.03

Species is a poor seed producer. Even commercially cultivated pastures of this grass depend on vegetative means of propagation and not on seed.

7.04

Probably gravity dispersed - it is a grass and the seeds do not have any mechanism of attachment but does not have a clear adaptation to wind either.

7.05

It is known to grow near lakes and rivers and can grown in standing water too. But I did not come across any evidence of dispersal by water. Seeds probably float.

7.06

No evidence, grains may be consumed by birds

7.07

Propagules do not have any means of attachment.

7.08

Probably not. It rarely produces seeds so cattle probably eat the vegetative parts only.

8.01

(1) 'Rarely flowers' (2) 'The seed of para-grass is not very satisfactory as it shatters very readily, is seldom gathered.' (3) Seed yield is reported to range from nil to moderate.

(1) Haselwood E. L. & R. T. Hirano. 1983. Handbook of Hawaiian weeds. University of Hawaii Press. Honolulu (2) Piper, C. V. 1920. Forage plants and their culture. The Macmillan company. (3)Crowder, L. V. & H. R. Chheda. 1982. Tropical Grassland and Husbandary.Longman. London.

8.02

The seed of para-grass is not very satisfactory as it shatters very readily, is seldom gathered.' Wetland grasses generally have short-lived seeds.

Piper, C. V. 1920. Forage plants and their culture. The Macmillan company.

8.03

Few herbicides have been listed for the control of this species. (1)Basfapson grass killer as foliage spray. (2) HYVAR x Bromacil weedkiller (3) HYVAR X-L Weedkiller liquid (4)Lane Agripon herbicide (5) Roundup herbicide. 2)According to Brown (1975) Roundup at 2.5–5 kg/ha gives good control of paragrass.

Swarbrick, J. T. 1982. The Australian weed control handbook. Plant press Toowoomba.

8.04

Don’t know about fire. The cut stems can reproduce vegetatively. Grows back after cutting (personal observation)

8.05

Forms dense populations in Hawaii