Australian sedge is unpalatable to stock and reduces farm production. It is also a threat to native species as it competes with seedlings. Find out how to recognise this plant and check out our tips for control.
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Why Australian sedge is a pest
Australian sedge forms dense infestations in pasture areas. It is unpalatable to stock and reduces farm production. In open grassland areas, Australian sedge is also a threat to native species as it completes with seedlings.
It establishes and spreads most rapidly on disturbed and exposed soil where pasture is not thriving due to low soil fertility, drought, overgrazing or insect damage.
Australian sedge produces many seeds, which remain viable for three to five years. Once established, it can spread rapidly throughout the farm via livestock. The seed is quite heavy and most falls within 30 cm of the plant. This creates an ever-increasing 'mattress' of Australian sedge.
Identifying features
- Leaves are about 5 mm wide, Y-shaped in cross section (with gradually tapering tips), often exceeding the flowering stems in length.
- Leaf edges are harsh and will cut if you pull your fingers through the leaves.
- Basal sheath is dark brown.
- Flowering stems are triangular in cross section and sharply angled.
- Flowers are very small and grouped in catkin-like spikes, most of which are female and hang at the end of long thin nodding stalks.
- Seeds are small smooth triangular nuts, enclosed within a long beaked covering about 5 mm long.
- Deep rooted.
How to recognise Australian sedge
Australian sedge is a densely tufted, deep-rooted, perennial plant which grows to one metre tall. Look for the triangular shape of the flower stem, which is characteristic of all sedges. Unlike most sedges, which prefer swampy areas, Australian sedge grows in land which is seasonably dry. The plant normally flowers and seeds from October to February.
Larger infestations are eye-catching as they form a large dense colony. Australian sedge is distinguished in New Zealand by its distinctive flower/seed head.
Responsibility for control
Land occupiers within the Waikato region are required to control all Australian sedge plants located within 20 m of the boundary. Environment Waikato encourages all land occupiers to control Australian sedge across their entire property.
Australian sedge is banned from sale, propagation, distribution or commercial display.
If you think you have seen Australian sedge, please call 0800 BIOSECURITY (0800 246 732) to report it to your local Biosecuirty Plant Pest Contractor.
Controlling Australian sedge
Physical control
Grubbing should only be used to deal with scattered isolated plants. It is a costly and ineffective method of control for large infestations. Breaking up the plant encourages seeds to germinate and the ground becomes re-infested. Australian sedge will regenerate from fragments, so all root stock must be collected and disposed of. It is necessary to re-check the site regularly for seedlings and re-growth.
Herbicide control
Roundup® is an effective herbicide against Australian sedge. The area should be checked and re-sprayed each year to kill new seedlings and re-growth. The optimum time for spraying is November through to March. The best protection against re-infestations from seed still in the soil is a dense pasture cover. 1
When using herbicides:
- read the instructions on the manufacturer's lable closely
- always wear protective clothing
- always minimise the risk to desirable plants
- contact the supplier for further advice.
Further information
Useful contacts
For further information and advice contact your local Biosecurity Plant Pest Contractor.
For enquired on policy and procedural matters call Environment Waikato's Freephone 0800 800 401
For more information on plant pests, please visit the Weedbusters website.
Related publications
Visit our Waikato Regional Pest Management Strategy.
'What makes a pest a pest? - A guide to Waikato's pest management future' download (730 kb, 104 seconds to download, 56k modem), order or pick up for free from our offices.
Pick up or order 'Plant me instead - Plants to use in place of common pest plants' for free from our offices.
Download the National Pest Plant Accord.
Pick up or order 'Poisonous plants and fungi in New Zealand - A guide for parents, schools and child minders' for $15 from our offices.
Disclaimer
Although this content has been prepared in good faith from a number of sources believed to be reliable, Environment Waikato does not give any warranty that all information contained is accurate or complete, or that advice given will be appropriate in all circumstances. Mention of product trade names implies neither endorsement of those products nor criticisms of similar products not mentioned.