Paspalum dilatatum Poir.

Management Notes (for the Swan NRM Region)

Alternative Names. Dallis grass.

General Biology. Growth form. Grass. Life form. Perennial, caespitose/shortly rhizomatous. Reproduction. Seed, short rhizomes. Dispersal. Seed spread by animals, clothing, shoes, water, wind, machinery. Vegetative spread by earth-moving, cultivation, inappropriate planting. Photosynthetic Pathway. C4. Toxicity. Not toxic itself however fungus-infected seedheads pose a threat to animal health. Fire response. Will quickly resprout from rootstock when conditions become favourable.

Notes. Widely naturalised particularly in sub-tropical and warm temperate climates, especially those with summer rainfall. Common in all Australian states in pastures, roadsides, gardens or lawns. A major weed of wetland edges, wet native grasslands and road drains. Susceptible to frost, however winter dormancy may enable it to survive frost in some areas. For active growth requires high temperatures, irrigation and high soil nitrogen levels. Has low salintiy tolerance however a deep root system confers significant drought tolerance once established. Flowering commences in early to mid summer, coinciding with a marked slowing in vegetative growth. Flowering continues through autumn, with little foliage produced until the following spring. Seed production is inhibited at temperatures below 13°C. Viability is often low and affected by ergot infection. Seed is sticky and is easily unintentionally dispersed. Disturbance events that create gaps (such as flooding and heavy grazing) promote recruitment. Vegetative spread is extremely slow. There are at least 5 different cultivars and 8 biotypes, with significant variation in seed production, quality and growth rates between genotypes. Can form hybids with Paspalum urvillei.

Additional information. Origin. South America. History of use/introduction. Summer pasture, erosion control particularly where there is water movement. Similar exotic species. Paspalum urvillei.

Suggested method of management and control. Cut out small populations and isolated plants, ensure rhizome removal. Remove seed heads for safe disposal. At early head stage spray with glyphosate 10 ml/L. For established actively growing adult plants spray with Fusilade® Forte 16 ml /L + wetting agent or for generic fluazifop-p (212g/L active ingredient) 8ml/L+ wetting agent. Older stands can also be controlled with 1% glyphosate, preferably pre- or early flowering. Alternatively, cut near ground level and immediately wipe with 10% glyphosate. A repeat application may be required for well established plants. Follow-up control of seedlings with 2 ml/L Fusilade® Forte + wetting agent or for generic fluazifop-p (212g/L active ingredient) 1.2ml/L+ wetting agent. Use hygiene practices - clean machinery and footwear after working in infested areas. Mowing and slashing will remove flowering heads but will not control established plants and can spread seed. Strategic use of fire may be useful in suppressing this species. Following any fire event is an optimal time to undertake control. Read the manufacturers' labels and material safety data sheets before using herbicides. For further information consult the Australian Pesticides and Veterinary Medicines Authority to determine the status of permits for your situation or state.

Management Calendar

Legend: Y = Yes, regularly, O = Occasionally, U = Uncertain, referred by others but not confirmed.

References

• Brown, K. & Brooks, K. (2002) Bushland Weeds: A Practical Guide to their Management. Environmental Weeds Action Network, Greenwood.
• Burson, B.L. (1992) Cytology and reproductive behaviour of hybrids between Paspalum urvillei and two hexaploid P. dilatatum biotypes. Genome, 35: 1002-1006.
• Chu, J.K.Y. (2007) Paspalum dilatatum. International Environmental Weed Foundation, Sydney, NSW. URL: http://www.iewf.org/weedid/Paspalum_dilatatum.htm - Accessed January 2010.
• Cook, B.G., Pengelly, B.C., Brown, S.D., Donnelly, J.L., Eagles, D.A., Franco, M.A., Hanson, J., Mullen, B.F., Partridge, I.J., Peters, M. & Schultze-Kraft, R. (2005) Tropical Forages: an interactive selection tool, Factsheet - Paspalum dilatatum. CSIRO, DPI&F(Qld), CIAT and ILRI, Brisbane, Australia. URL: http://www.tropicalforages.info/key/Forages/Media/Html/Paspalum_dilatatum.htm - Accessed January 2010.
• Cornaglia, P.S., Schrauf, G.E. & Deregibus, V.A. (2009) Flooding and grazing promote germination and seedling establishment in the perennial grass Paspalum dilatatum. Austral Ecology, 34: 343-350.
• Hussey, B.M.J., Keighery, G.J., Dodd, J., Lloyd, S.G. & Cousens, R.D. (2007) Western Weeds. A guide to the weeds of Western Australia. 2nd Edition. The Plant Protection Society of Western Australia, Victoria Park.
• Insausti, P., Grimoldi, A.A., Chaneton, E.J. & Vasellati, V. (2005) Flooding induces a suite of adaptive plastic responses in the grass Paspalum dilatatum. New Phytologist, 152 (2): 291 - 299.
• Moore, C.B. & Moore, J.H. (2002) Herbiguide, the pesticide expert on a disk. Herbiguide, PO Box 44 Albany, Western Australia, 6330.
• Muyt, A. (2001) Bush invaders of South-East Australia: A guide to the identification and control of environmental weeds found in South-East Australia. R.G. & F.J. Richardson, Melbourne.
• Nazer, C. & Carder, J. (1999) Evaluation of selective herbicides for control of exotic grasses in remnant native grasslands in southern Australia. In 12th Australian Weeds Conference, Papers and Proceedings, Hobart, Tasmania, Australia, 12-16 September 1999: Weed management into the 21st century: do we know where we're going.
• Pacific Island Ecosystems at Risk (2008) Plant threats to Pacific ecosystems. URL: http://www.hear.org/pier/scinames.htm - Accessed January 2010.
• Parsons, J.M. (ed.) (1995) The Australian weed control handbook. 10th Edition. Inkata Press, Melbourne.
• Pearson, C.J. & Shah, S.G. (1981) Effects of temperature on seed production, seed quality and growth of Paspalum dilatatum. Journal of Applied Ecology, 18: 897-905.
• Prober, S., Taylor, S., Edwards, R. & Mills, B. (2009) Effectiveness of repeated autumn and spring fires for understorey restoration in weed-invaded temperate Eucalypt woodlands. Applied Vegetation Science, 12: 440-450.
• Vasellati, V., Oesterheld, M., Medan, D. & Loreti, J. (2001) Effects of flooding and drought on the anatomy of Paspalum dilatatum. Annals of Botany, 88: 355-360.