Salvinia is a floating water weed with oval-shaped leaves that have many waxy hairs on the top of the leaf. It forms dense mats that take over waterways and reduces water quality.
This plant is a Weed of National Significance
This plant is a water weed
This plant must not be sold anywhere in NSW
Salvinia forms dense mats that can smother the surface of the water. It:
Salvinia is a fast growing floating water fern.
Leaves have three growth stages:
Spore sacs are on stalks among the root-like filaments but they do not produce spores in Australia.
Similar looking plants
Salvinia looks similar to red root floater (Phyllanthus fluitans), which is a flowering plant with small white flowers and produces sixs-eeded capsules. Its leaves only grow up to 1.7 cm long.
At the primary growth stage salvinia looks like:
Salvinia grows along the NSW coast from the North Coast to the South East. It is common in the Tweed, Richmond, Clarence, and Macleay catchments on the North Coast. In Greater Sydney it is common on the central coast and in metropolitan areas and there are heavy infestations in the Hawkesbury–Nepean system. In the Hunter there is a heavy infestation in Woolombi Brook near Cessnock.
It has not naturalised west of the Great Dividing Range but has been sold illegally as an aquarium plant and sometimes found in aquariums and fishponds.
Salvinia is a perennial plant that is very adaptable and survives in many climates and nutrient levels. It grows best in warm fresh water that is still or slow-flowing and has high nutrient levels.
It can double in size in less than 3 days in ideal conditions. Rain can also stimulate growth by washing nutrients into the water.
Salvinia can survive:
Salvinia can produce by plant parts in two ways:
Salvinia spreads to new areas by:
Once in a waterway the plants can be spread by water flows especially floods and wind.
The spores are not viable in Australia
Successful weed control relies on follow up after the initial efforts. This means looking for and killing regrowth or new plants. Using a combination of control methods is usually more successful.
To tackle salvinia:
Floating booms or nets on waterways can help contain salvinia and limit spread to other areas. The plants that have been collected behind the booms are then easily controlled with chemicals or mechanically removed.
Reduce nutrient levels in waterways by:
Remove all plant parts to prevent rapid re-growth. Contact your local council for advice on how to dispose of this weed.
Mechanical removal is expensive and only an option for small infestations.
Salvinia can be effectively controlled with the Salvinia weevil (Cyrtobagous salviniae). The adult salvinia weevil is a small, black insect which grows to about 2 mm long. Adult weevils feed on the growing tips, suppressing growth. Larvae tunnel through the horizontal stems, particularly in younger parts of the plant causing the weed to break apart, sink and decompose on the bottom of the waterway.
The level of control depends on the local climate and the condition of the salvinia plants. When conditions are ideal the weevil can complete its life cycle in six weeks. On the North Coast of NSW in nutrient rich water it has controlled infestations within six months. Though in other areas it may take 2-3 years for weevil populations to establish.
The weevil does most damage when salvinia is healthy and green and the temperature is around 30°C. Weevils breed very slowly at temperatures less than 20 °C and ceases breeding below about 17 °C.
The best time to introduce the weevil is early spring. The warmer weather helps populations establish. If an infestation is multi-layered or old, pull out some of the weed or strip spray with herbicide.
Contact your local weeds officer to find out more about introducing salvinia beetle in your area.
Chemical control requires good access to the weed in waterways. It is best to control the infestation early. Dense, mature infestations are difficult to control with herbicides. The densely-folded and compact leaves make it difficult to get good herbicide contact.
Reedy banks and swampy backwater areas protect the plant from herbicides. Salvinia can rapidly reinfest these sites.
See Using herbicides for more information.
PERMIT 92971 Expires 31/03/2028
Metsulfuron-methyl 600 g/kg
(LYNX WG herbicide)
Rate: 10 g / 100 L water (plus wetter at 200 mL per 100 L)
Comments: Only for enclosed water bodies. Areas within 400 m of potable water supply uptakes are excluded. ONLY apply as a foliar spot spray during non-frost periods using a high volume sprayer/knapsack fitted with calibrated spray equipment. Apply a maximum of 3 applications per year at minimum intervals of 90 days. WARNING: Very toxic to aquatic plants and algae. See permit for more restraints and critical use comments.
Withholding period: A nil withholding period is applicable. However, it is recommended not to graze treated areas for 3 days to ensure product efficacy.
Herbicide group: 2 (previously group B), Inhibition of acetolactate and/or acetohydroxyacid synthase (ALS, AHAS inhibitors)
Resistance risk: High
PERMIT 83083 Expires 30/04/2025
Carfentrazone-ethyl 240 g/L
(Shark™ Aquatic Herbicide)
Rate: 933 mL of product per ha
Comments: For nonflowing water bodies. DO NOT apply more than two (2) applications per year with a minimum re-treatment interval of 90 days between consecutive treatments. See permit for further critical use comments.
Withholding period: Not required when used as directed.
Herbicide group: 14 (previously group G), Inhibition of protoporphyrinogen oxidase (PPO inhibitors)
Resistance risk: Moderate
PERMIT 14327 Expires 31/07/2026
Glyphosate 360 g/L
(Only products registered for aquatic use)
Rate: 1 L in 100 L of water OR 6 - 9 L / Ha
Comments: Hand gun application. Use of this permit is limited to staff and contractors of NPWS and agencies/ organisations represented by Regional Weed Committees. See permit for further critical use comments.
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate
Diquat 200 g/L
(Reglone®)
Rate: 400 mL per 100 L of water plus 150 mL Agral / 100 L water
Comments: Spray to wet all foliage thoroughly. About 1 mL of product should be sufficient to treat 1 metre squared of weeds.
Withholding period: Do not use treated water for human consumption, livestock watering or irrigation purposes for 10 days after application. Do not graze or cut sprayed vegetation for stock food for 1 day after application. See label for harvest withholding periods.
Herbicide group: 22 (previously group L), Inhibition of photosynthesis at photosystem I via electron diversion (PSI electron diversion)
Resistance risk: Moderate
Diquat 200 g/L
(Reglone®)
Rate: 5.0–10.0 L/ha
Comments: Apply as overall spray wetting foliage thoroughly. Use higher rates for heavy infestations or for deep or dirty water. Oxygen depletion of decaying weeds may occur therefore do not spray more than a quarter of the area at any one time.
Withholding period: Do not use treated water for human consumption, livestock watering or irrigation purposes for 10 days after application. Do not graze or cut sprayed vegetation for stock food for 1 day after application. See label for harvest withholding periods.
Herbicide group: 22 (previously group L), Inhibition of photosynthesis at photosystem I via electron diversion (PSI electron diversion)
Resistance risk: Moderate
Flumioxazin 15 grams /tablet
(Clipper herbicide®)
Rate: 1 tablet for every 37.5 cubic metres of water to achieve 400 parts per billion.
Comments: For use on dense or established weed populations in enclosed water bodies, deeper than 0.5 m and larger than 37.5 cubic metres, or margins of larger, still water bodies. Throw tablets directly into the water to achieve uniform distribution of the herbicide. See label for further instructions and restrictions.
Withholding period: 14 days before using treated water to irrigate food crops. See label for withholding periods for other uses of treated water.
Herbicide group: 14 (previously group G), Inhibition of protoporphyrinogen oxidase (PPO inhibitors)
Resistance risk: Moderate
Flumioxazin 15 grams /tablet
(Clipper herbicide®)
Rate: Inject solution into water body. 1 tablet per 37.5 cubic metres. Each tablet dissolved in at least 20 L of water + 0.5-1.0% adjuvant/surfactant
Comments: For use on dense or established weeds in water bodies less than 0.5 m deep or with a volume less than 37.5 cubic metres. Dissolve tablets in water (at least 20L per tablet) mix thoroughly and then inject the solution directly into the water body.
Withholding period: 14 days before using treated water to irrigate food crops. See label for withholding periods for other uses of treated water.
Herbicide group: 14 (previously group G), Inhibition of protoporphyrinogen oxidase (PPO inhibitors)
Resistance risk: Moderate
Flumioxazin 15 grams /tablet
(Clipper herbicide®)
Rate: Spray 12 - 15 L of solution per 100 m2. Solution = 1 tablet per 100 L water + 0.5-1.0% adjuvant/surfactant.
Comments: Spray on low density, establishing or re-establishing weeds in enclosed water bodies, deeper than 0.5 m and larger than 37.5 cubic metres, or margins of larger still water bodies. See label for restrictions.
Withholding period: 14 days before using treated water to irrigate food crops. See label for withholding periods for other uses of treated water.
Herbicide group: 14 (previously group G), Inhibition of protoporphyrinogen oxidase (PPO inhibitors)
Resistance risk: Moderate
Orange oil 55.2 g/kg
(Water Clear®)
Rate: 1.0 L per 100 L of water
Comments: Spray on free-floating plants lightly, just enough to change their colour. For non-potable water in artificial and enclosed water bodies.
Withholding period: Nil.
Herbicide group: n/a
Resistance risk: n/a
The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.
Area | Duty |
---|---|
All of NSW | General Biosecurity Duty All pest plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable. |
All of NSW |
Prohibition on certain dealings
Must not be imported into the state, sold, bartered, exchanged or offered for sale. |
Central West |
Regional Recommended Measure* (for Regional Priority - Prevention)
Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found. |
Greater Sydney |
Regional Recommended Measure* (for Regional Priority - Asset Protection)
Land managers should mitigate the risk of the plant being introduced to their land. Land managers should mitigate spread of the plant from their land. A person should not buy, sell, move, carry or release the plant into the environment. |
Hunter
An exclusion zone is established for all land in the region, except the core infestation which includes parts of: Lake Macquarie Local Government Area, MidCoast Local Government Area, Port Stephens Local Government Area. |
Regional Recommended Measure* (for Regional Priority - Containment)
Entire Hunter Local Land Services region: Land managers should mitigate the risk of the plant being introduced to their land. Exclusion zone: Notify local control authority if found. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Core infestation: Land managers should mitigate spread of the plant from their land. A person should not buy, sell, move, carry or release the plant into the environment. Land managers should reduce the impact of the plant on assets of high economic, environmental and/or social value. This Regional Recommended Measure applies to Salvinia molesta and Salvinia minima |
North West |
Regional Recommended Measure* (for Regional Priority - Eradication)
Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found. |
Riverina |
Regional Recommended Measure* (for Regional Priority - Eradication)
Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found. Your local biosecurity weeds officer can help to identify, advise on control, and how to remove this weed. |
South East |
Regional Recommended Measure* (for Regional Priority - Eradication)
Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found. |
*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfil the general biosecurity duty for this weed click here |
Reviewed 2023