|Production threat||Environmental threat||Public threat|
Australian sedge is a densely tufted, deep-rooted, perennial plant which can grow almost 1m tall. Unlike most sedges, which prefer swampy areas, Australian sedge grows in land which is seasonably dry. 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.
Australian sedge forms dense tussock infestations 30-90cm high in pasture areas. It is unpalatable to stock and reduces farm production by crowding out pasture. In open grassland areas, Australian sedge is also a threat to native species as it competes with seedlings.
It establishes and spreads most rapidly on disturbed and exposed soil where pasture doesn’t thrive 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 30cm of the plant. This creates an ever-increasing ‘mattress’ of Australian sedge.
All landowners/occupiers in the Waikato, on complaint from an adjoining neighbour, are responsible for controlling Australian sedge within 20m of their property boundaries and are required to work with Waikato Regional Council in areas where control programmes are in place. Australian sedge is also banned from being sold, propagated, distributed or included in commercial displays.
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 reinfested. Australian sedge will regenerate from fragments, so all root stock must be collected and disposed of. It is necessary to recheck the site regularly for seedlings and regrowth.
Glyphosate is an effective herbicide against Australian sedge. The area should be checked and resprayed each year to kill new seedlings and regrowth. The optimum time for spraying is November through to March. The best protection against reinfestation from seed still in the soil is a dense pasture cover.
|Herbicide rules will apply. You may need to notify neighbours if spraying. The Waikato Regional Plan explains the agrichemical (herbicides) use rule in section 6.2 in the Waikato Regional Plan.|
After initial control, it’s important to: