Hygrophila (Hygrophila costata)

WEED ALERT: REGIONALLY PROHIBITED WEED
If you see this plant contact your council weeds officer, the NSW Invasive Plants & Animals Enquiry Line 1800 680 244 or email weeds@dpi.nsw.gov.au

Profile

Impact

Hygrophila is a highly invasive aquatic weed. It grows up to 1.5 m high in shallow water, forming mats of dense growth around the margins of freshwater lakes, rivers and watercourses where it can dominate and out-compete other vegetation. It grows all year round but most rapidly during the warmer months.

Dense infestations are likely to displace native flora and fauna by destroying their natural habitat. Hygrophila can also interfere with recreational activities such as boating and access to the water’s edge.

Distribution

Hygrophila is native to the Americas from southern Mexico to Argentina, and has naturalised in many tropical and subtropical areas around the world.

In New South Wales (NSW), hygrophila has become invasive in the far north coast, central coast and greater Sydney regions. Infestations are also occurring in southeast Queensland.

Distribution map

Spread

Reproduction is by either seed or stem fragments. Spread occurs when seeds and plant fragments attach to animals, machinery or watercraft, or are dispersed by wind or water.

Spreading stems sprout new roots from their nodes when they come in contact with the soil, enabling a new plant to form.

Description

Hygrophila is an erect emergent herb which grows to 1.5 m in height.

Key identification features

  • Leaves are hairy, up to 18 cm long and 3 cm wide, in opposite pairs and tapering at their base. They have prominent veins and a distinct midrib.
  • Upper stems are 4-angled, erect and rarely branched; lower stems are prostrate and root at nodes; the stems may have a red to purplish colour.
  • Flowers have white petals and are about 10 mm long. They occur in whorls just above the junction between leaves and the stem.
  • Fruit capsules are about 7 mm long, spindle-shaped and inconspicuous. Seeds are pale brown, flattened, round, about 0.3 mm wide and become sticky when wet.

Acknowledgements

Authors: Peter Gorham, John Hosking; Reviewers: Melissa Freeman, Birgitte Verbeek; Editors: Annie Johnson, Elissa van Oosterhout.

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Control

Control of hygrophila is very difficult as new infestations can form from any remaining pieces of the plant. Contact your local council weeds officer for assistance if you suspect you have found hygrophila.

Herbicide options

WARNING - ALWAYS READ THE LABEL
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au

See Using herbicides for more information.


PERMIT 14729 Expires 30/06/2019
Glyphosate 360 g/L (Only products registered for aquatic use)
Rate: 1.0 L per 100 L of water
Comments: Spray when plants are actively growing, re-treatments may be necessary. Do not spray directly onto waters surface or non-target species.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate


PERMIT 14729 Expires 30/06/2019
Metsulfuron-methyl 600 g/kg (Brush-off®)
Rate: 5–10g per 100 L of water
Comments: Minimise off target damage and water pollution by spraying towards the bank. Do not apply more than 3 times a year.
Withholding period: Nil (recommended not to graze for 7 days before treatment and for 7 days after treatment to allow adequate chemical uptake in target weeds).
Herbicide group: B, Inhibitors of acetolactate synthase (ALS inhibitors)
Resistance risk: High


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Legal requirements

The content provided here is for information purposes only and is taken from the Noxious Weeds (Weed Control) Order 2014 published in the NSW Government Gazette, detailing weeds declared noxious in New South Wales, Australia, under the Noxious Weeds Act 1993. The Order lists the weed names, the control class and the control requirements for each species declared in a Local Control Authority area.

Area Class Legal requirements
Bayside 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Bellingen 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Blue Mountains 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Burwood 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Camden 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Campbelltown 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Canada Bay 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Canterbury-Bankstown 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Central Coast 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Cessnock 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Clarence Valley 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Coffs Harbour 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Cumblerland 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Dungog 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Fairfield 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Georges River 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Hawkesbury River County Council 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Hornsby 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Hunters Hill 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Inner West 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Kempsey 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Ku-ring-gai 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Lake Macquarie 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Lane Cove 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Liverpool 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Maitland 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Mid-Coast 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Mosman 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Nambucca 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Newcastle 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
North Sydney 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Northern Beaches 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Parramatta 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Port Macquarie-Hastings 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Port Stephens 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Randwick 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Rous County Council 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Ryde 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Strathfield 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Sutherland 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Sydney 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Upper Hunter County Council 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Waverley 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Willoughby 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Wollondilly 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Woollahra 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant

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Reviewed 2014