Pest weed has department on alert

Callum HunterSouth Western Times
Camera IconSalvinia. Credit: Photographer Simon Eyres Copyrig

South West green-thumbs have been urged to stay vigilant after the aquatic weed salvinia was discovered in a Bunbury backyard.

The discovery was made earlier this month in a backyard pond and prompted warnings region wide from the Department of Primary Industries and Regional Development.

“Salvinia was discovered in a Bunbury garden approximately a week ago and was reported by a member of the public using the MyPestGuide Reporter app,” DPIRD priority weed response manager Andrew Reeves said.

“A member of the public saw the salvinia and recognised it shouldn’t be free in WA ... it’s actually a species we’re trying to eradicate.”

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The free-floating aquatic fern is made up of oval shaped leaves connected by a horizontal stem and has the ability to double in size every 20 days during summer.

“If left unmanaged it would eventually cover the entire water surface, killing any fish by de-oxygenating the water,” Mr Reeves said.

“It is quite an attractive pond plant ... but unfortunately some people do like to spread it and give it as gifts or when they hand over a goldfish or something and it’s previously been available at things like car boot sales.”

Once the surface is covered, the weed can continue to grow on top of itself to eventually be inches thick in places, as was the case in several Perth waterways in the early and mid 2000s.

According to the Department of Envionment and Energy’s Weed Management Guide, a salvinia infestation can reach up to 400 tonnes of wet weight per hectare.

Mr Reeves said when removing salvinia, every piece, leaf or stem had to be accounted for given its rapid growth and regeneration.

“Anyone who suspects they have salvinia in their garden should report this weed so that it can be properly disposed of,” he said.

DPIRD officers are continuing to monitor the affected pond and urge gardeners to remain vigilant.

Any suspected sightings of salvinia should be reported to the Pest and Disease Information Service on 9368 3080 while digital reports can be made using the MyPestGuide Reporter app and selecting the project MyWeedWatcher.

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