Salvinia: declared pest

Page last updated: Monday, 20 July 2020 - 2:45pm

Please note: This content may be out of date and is currently under review.

Salvinia (Salvinia molesta) is a declared pest in Western Australia (WA). This article describes the nature of the plant with links to requirements land owners/occupiers must adhere to and pest control methods.

Form: aquatic

Status: present in WA

Native to South America, this weed was introduced to Australia as an aquarium plant. Salvinia is a Weed of National Significance (WoNS).


Salvinia is a free-floating perennial aquatic fern made up of pairs of oval, green to brown leaves connected by a horizontal stem. The top of each leaf has many tiny, hairlike structures that split then rejoin at the tips to form an eggbeater-like structure. Under the water, each plant produces other leaves that look like a small bunch of brown roots.

Stems: Slender jointed and much branched to 30 centimetres long to one to two millimetres diameter. Length of leaf nodes varies inversely with density of the plants.

Leaves: Two kinds: a submerged leaf which is brown and deeply divided into a group of unbranched root-like filaments 2-25 centimetres long. Emergent leaves are green, roughly circular, two lobed, with a smooth edge. Upper surface covered in rows of waxy, eggbeater-shaped hairs one millimetre long.

Agricultural and economic impact

An environmental water weed. Salvinia grows quickly to form thick mats covering lakes, slow-moving rivers and other waterways. It can cover the entire surface of small and medium-sized waterbodies with a thick mat of vegetation. These mats severely interfere with the use of water bodies for irrigation, flood mitigation and conservation of wildlife. It helps accumulate litter, shades out any submerged plant life and promotes water stagnation that encourages breeding of mosquitoes.

Salvinia infestations can affect commercial and recreational fishing by blocking nets and impeding the passage of boats. It can block irrigation channels.

Declared pest category

The Western Australian Organism List (WAOL) contains information on the area(s) in which this pest is declared and the control and keeping categories to which it has been assigned in Western Australia (WA). Search for salvinia in the WAOL using the scientific name Salvinia molesta.

Requirements for land owners/occupiers and other persons

Requirements for land owners/occupiers and other persons if this pest is found can be sourced through the declared plant requirements link.

Search > detect > report

MyPestGuide™ Reporter
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(Select 'Send report to MyWeedWatcher' from menu)

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080

Control method

Report the presence of this organism before undertaking a control measure. Control methods for this declared plant can be found through the salvinia control link.

Contact information

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080
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