Dallis grass (Paspalum dilatatum) is an invasive plant of the grass family (Poaceae). The species is a serious weed in pastures and crops. Its dense growth can smother low-growing species. Dallis grass is also problematic in golf courses, sports fields and lawns. Herbicides are used to control this pest when mowing and digging it out of the soil are not sufficient to manage the weed.
Report a dallis grass sighting
Where it's found
Dallis grass has not been found in Canada. It is native to South America and has naturalized in tropical and southern Africa, Asia, southern Europe, Australia, New Zealand and across the southern United States. Its introduction elsewhere has mainly resulted from intentional planting as a forage grass. Habitats of dallis grass include wetlands, shrublands, pastures, lawns, turf grass, roadsides and irrigation ditches.
How to spot it
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Plant -
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Seeds
Dallis grass is a clump-forming perennial grass that can grow to over 1 m in height. The plant's roots are thick and fibrous and its stems arise from a knotted base of short rhizomes. Its stems are hollow, and either green or lavender coloured. The leaf blades are simple, green or burgundy, smooth, long and slender, and have a prominent mid-vein. Dallis grass inflorescences are made up of 2 to 7 spikes. Each spike has 4 rows of spikelets. Spikelets are oval, compressed and 3-4 mm long by 2-3 mm wide. The seeds are enclosed in the spikelets and are white to brown and 2-2.3 mm long.
How it spreads
Dallis grass plants produce many seeds that can be spread by water, lawn mowers, humans and pets. The species has been intentionally planted as a forage grass which has facilitated its spread around the world. It is also commonly spread to new areas through contaminated turf grass seed.
What you can do
- Maintain healthy and diverse pastures
- Use clean, high quality seed that is certified if possible
- Ensure machinery, vehicles and tools are free of soil and plant parts before moving them from one area to another
- Do not dump garden waste in parks, fields, forests or other natural areas
- Brush off clothing and clean footwear and camping gear to avoid spreading seeds and plant material
- If you think you've spotted it in Canada, report a dallis grass sighting to the Canadian Food Inspection Agency. We will follow up and determine if further action is needed.
What we are doing
Dallis grass is regulated as a pest in Canada under the Plant Protection Act. It is also listed as a prohibited noxious weed in the Weed Seeds Order, 2016 under the Seeds Act. Importation and domestic movement of regulated plants and their propagative parts is prohibited.
- RMD-13-04: Consolidated Pest Risk Management Document for pest plants regulated by Canada
- D-12-01: Phytosanitary Requirements to Prevent the Introduction of Plants Regulated as Pests in Canada
More information
- Weed seed: Dallis grass
- Invasive plants field guide
- Learn more about invasive species