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

Paspalum dilatatum (Paspalum, Dallis grass, Watergrass)

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

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

y

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

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

n

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

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

n

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

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

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

y

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

8.05

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

y=-1, n=1

Total score:

12

Source

Notes

1.01

No evidence.

1.02

Widely naturalized including Hawaii. (2)A problem species in Hawai‘i and New Zealand.
(3)Naturalized in California (4)naturalized in the subtropics.

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.hear.org/pier3/padil.htm (3)http://elib.cs.berkeley.edu/cgi/calflora_query?special=calflora&where-calrecnum=6083&one=T (4)http://www.dpi.qld.gov.au/pastures/4564.html

1.03

No evidence.

2.01

Native to South America, 'Common dallisgrass is a warm-season forage grass…'

http://www.nal.usda.gov/ttic/tektran/data/000008/32/0000083299.html

2.02

2.03

1)Elevation: between 0 and 1312 feet (400m) 2)It can be found at elevations between sea level and 2000 m within the latitudinal range 28°N-35°S. However, fails to produce seeds if temperature falls below 13 C.

http://elib.cs.berkeley.edu/cgi/calflora_query?special=calflora&where-calrecnum=6083&one=T 2)http://pppis.fao.org/

2.04

Native to South America and widely naturalized including Hawaii. A problem species in Hawai‘i and New Zealand. (3)Naturalized in California (4)naturalized in the subtropics.

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.hear.org/pier3/padil.htm (3)http://elib.cs.berkeley.edu/cgi/calflora_query?special=calflora&where-calr (4)http://www.dpi.qld.gov.au/pastures/4564.html

2.05

Native to South America and widely naturalize including Hawaii. A problem species in Hawai‘i and New Zealand. (3)Naturalized in California (4)naturalized in the subtropics.

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.hear.org/pier3/padil.htm (3)http://elib.cs.berkeley.edu/cgi/calflora_query?special=calflora&where-calr (4)http://www.dpi.qld.gov.au/pastures/4564.html

3.01

Native to South America and widely naturalized including Hawaii. A problem species in Hawai‘i and New Zealand. (3)Naturalized in California. (4)naturalized in the subtropics.

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.hear.org/pier3/padil.htm (3)http://elib.cs.berkeley.edu/cgi/calflora_query?special=calflora&where-calr (4)http://www.dpi.qld.gov.au/pastures/4564.html

3.02

'It is a problem weed in lawns because the flower stalk regrows rapidly after mowing giving the appearance of many defiant flags waving over the well, trimmed sod.'

Lorenzi, J. and Jeffery, L.S. 1987. Weeds of the United States and their control. Van Nostrand Reinhold company. New York.

3.03

Listed as a serious weed in Australia and Philippines and as a principal weed in Brazil, Columbia, Soviet Union and Taiwain. 2) weed of corn in subtropics

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. 2)Broome-Malcolm-L {a}; Triplett-Glover-B-Jr; Watson-Clarence-E-Jr2000. Vegetation control for no-tillage corn planted into warm-season perennial species. Agronomy-Journal. 92 (6): 1248-1255..

3.04

No evidence.

3.05

Paspalum conjugatum and P. distichum are listed as serious weeds 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

No evidence.

4.03

No evidence.

4.04

High palatability to grazing animals.

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

4.05

Slightly toxic?. (2)It is toxic when infected by the fungus Claviceps paspali - which causes ergotism in cattle. No evidence of healthy paspalum being toxic.

http://plants.usda.gov/cgi_bin/topics.cgi (2)Brownie, C. F. 1987. Suspected convulsive ergotism in beef calves on overgrown dalis grass (Paspalum dilatatum). Veterinary and human toxicology. Vol 29(3): 257-258

4.06

Lists 65 fungal species to be found on this grass. (2)Paspalum striate mosaic monogeminivirus which affects P. dilatum also affects Zea mays and Triticum aestivum.

http://nt.ars-grin.gov/fungaldatabases/all/FindRecOneFungusFrame.cfm (2)http://image.fs.uidaho.edu/vide/descr559.htm

4.07

No evidence.

4.08

Not fire resistant. High fire tolerance.

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

4.09

1)Intermediate shade tolerance. 2)It does not grow well in shade.

1) http://plants.usda.gov/cgi_bin/topics.cgi 2)http://www.ecoport.org/EP.exe$EntPage?ID=1623

4.1

pH range: 4.9 to 7.5 (2)Paspalum grows best on heavier textured alluvial soils or red loams with high fertility 3)fertile soils

http://plants.usda.gov/cgi_bin/topics.cgi (2)http://www.dpi.qld.gov.au/pastures/4564.html 3)http://www.rlq.dcilgp.qld.gov.au/beef/3304.html

4.11

It is a creeping grass. No evidence of climbing or smothering habit.

http://www.dpi.qld.gov.au/pastures/4564.html

4.12

No evidence.

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.

5.03

5.04

6.01

No evidence.

6.02

' However, dallisgrass seed is usually of poor quality, and germination is very low.'

http://www.nal.usda.gov/ttic/tektran/data/000008/32/0000083299.html

6.03

No information regarding natural hybridization although artificial hybrids have been made.

Burson-Byron-L 1992 Cytology and reproductive behavior of hybrids between Paspalum urvillei and two hexaploid Paspalum dilatatum biotypes. Genome-. ; 35 (6) 1002-1006..

6.04

'Because of its unusual method of reproduction (called apomixis), dallisgrass seed quality cannot be improved by normal breeding methods.' (2)Common dallisgrass (Paspalum dilatatum) is an apomictic pentaploid. (3)Reproduction occurs both by self fertilization and by cross fertilization

http://www.nal.usda.gov/ttic/tektran/data/000008/32/0000083299.html (2) Espinoza-F; Quarin-C-L. 2000. 2n + n hybridization of apomictic Paspalum dilatatum with diploid Paspalum species. International-Journal-of-Plant-Sciences. 161 (2): 221-225. (3)HICKENBICK-M-C-M. FLORES-A-I-P; CAVALLI-MOLINA-S; WEBER-L-H; KERSTING-A-C-O; COSTA-L-S; SOUZA-CHIES-T-T-D; ALBARUS-M-H. 1992. MODE OF REPRODUCTION AND SEED PRODUCTION IN PASPALUM-DILATATUM POIR VIRASORO BIOTYPE DILATATA GROUP GRAMINEAE. Revista-Brasileira-de-Genetica. 15 (1): 85-102.

6.05

'Several floral characters of P. dilatatum indicate that this perennial grass may be both entomophilous and anemophilous….plants pollinated by both bees and wind had a significantly higher seed set than plants pollinated by wind alone.'

Adams, D. E.; Perkins, W. E.; Estes, J. R.. 1981. Pollination systems in Paspalum dilatatum (Poaceae): an example of insect pollination in a temperate grass. American Journal of Botany Vol.68, No.3, pp.389-394

6.06

Propagation by seed. Vegetative spread slow. Does not spread by cuttings, sod and sprigs. (2)It spreads by short root-stocks

http://plants.usda.gov/cgi_bin/topics.cgi (2)http://www.dpi.qld.gov.au/pastures/4564.html

6.07

No information. But probably one year since it is a fast growing grass speceies.

7.01

Propagules do not have any means of attachment.

7.02

The species is not valued as an ornamental nor does it produce edible fruits.

7.03

Seeds are small and could easily be transported with grass clippings (pasture).

7.04

No obvious adaptation to wind

7.05

7.06

7.07

Propagules do not have any means of attachment.

7.08

Probably dispersed incidentally by grazers (hard seeds) but no direct evidence.

8.01

Caryposis reddish brown, elliptical, about 2mm X 1.5 mm. (2) 220,000 seeds per pound.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu. (2)http://plants.usda.gov/cgi_bin/topics.cgi

8.02

seeds viable > 2 years

Tischler-C-RBurson-B-L. 1999. Seed dormancy and germination of dallisgrass, Paspalum dilatatum, stored under differing conditions.Seed-Science-and-Technology. 27 (1): 263-271.

8.03

(1) 'MSMA at 3 lb/acre, applied in July was the most economic and effective treatment against P. dilatatum in Bermuda grass. ' (2)Results are given of trials in which P. dilatatum, which is resistant to most herbicides used in Citrus, was well controlled with Roundup (glyphosate) at 200 ml in 20 litres spray vol/dunam [= 1000 m2], provided the weed was slashed when almost at the flowering stage, two weeks before spraying. This rate is much lower than that required to control the unslashed weed. Additional spot treatment was sometimes necessary, 2 to 4 months after the initial spraying, in order to achieve season-long control; the quantity used was 12-33 ml/dunam.
(3)Repeated spot application of DSMA, MSMA or glyphosate may be used to destroy established plants ... Many herbicides used to prevent germination of crabgrass in turf will also prevent dallisgrass germination.'

(1) Batten, S. M.; Menn, W. 1981. Dallisgrass (Paspalum dilatatum) control studies in Bermudagrass and St. Augustinegrass. Consolidated Progress Report, Texas Agricultural Experiment Station, No.PR-3831-3851: Texas turfgrass research 1979-80, pp.85-88
(2)Oren, Y.; Beeri, M. 1978. Improving and reducing control costs of Paspalum dilatatum in citrus with Roundup. Proceedings, Roundup Seminar, Madrid., 1978, pp.19-23
(3)Lorenzi, J. and Jeffery, L.S. 1987. Weeds of the United States and their control. Van Nostrand Reinhold company. New York.

8.04

1)No resprout ability. 2)regrows after moderate grazing

1)http://plants.usda.gov/cgi_bin/topics.cgi 2)ITO-K ; IKEGAMI-Y; ISHII-Y 1991. EFFECT OF DEFOLIATION FROM MIDDLE AUTUMN TO EARLY WINTER ON THE REGROWTH IN NEXT SPRING OF DALLISGRASS PASPALUM-DILATATUM POIR. IN THE LOWLANDS OF SOUTHERN KYUSHU JAPAN. Grassland-Science. 37 (1): 55-63..

8.05

Don’t know