5 May 2014

Public support needed to keep water free of banned weeds

The Ministry for Primary Industries (MPI) and Auckland Council are asking residents to report any fresh sightings of two banned and highly destructive weeds - water hyacinth and salvinia.

Both weeds are present in the Auckland region and are known for growing rapidly to form large dense floating mats on ponds, drains, lakes and still waters in swamps.

“Water hyacinth and salvinia are among the world’s worst weeds,” says MPI Response Manager Emmanuel Yamoah.

Both plants grow very quickly. Water hyacinth is able to double its population size in as little as 12 days, while salvinia only needs about a week.

“These weeds have the potential to cause huge damage to our waterways, native aquatic plants and fish. They can clog waterways, making almost all water activities impossible and increasing the danger of drowning to humans and livestock. The weeds also have adverse impacts on hydro-electricity generation and irrigation.”

Dr Yamoah says MPI and the Auckland Council have an eradication programme in place for water hyacinth and salvinia.

“We need to know where these weeds are so we can wipe them out, so the assistance of the general public is crucial to the success of the eradication programme.”

He says many home and farm ponds around Auckland have been cleared of the noxious weeds, thanks to calls from concerned owners and residents.

“Anyone who sees any of these weeds, or suspects they may be present, should report it to us on 0800 80 99 66. MPI contractors will visit the site and remove the weeds free of charge if they find them.”

It is illegal under the Biosecurity Act 1993 to share, grow or sell unwanted and notifiable organisms.

Background information about salvinia and water hyacinth
Salvinia is a small, free-floating aquatic fern with branched, horizontal stems that lie just below the water surface. The upper surface of the leaf is covered with distinct white hairs. It has a root-like structure underneath each leaf pair and as the plant matures, these ‘roots’ resemble wet hair. The plant grows usually up to 30cm long.

Water hyacinth is a floating aquatic perennial, with distinctive bladder-like swollen leaf petioles giving buoyancy. It has shiny rounded leaves with thick masses of feathery dark roots that can reach 2.5m in length. A single flowering stalk with a cluster of mauve-blue flowers, each with a yellow spot, is produced above the foliage. Plants produce floating horizontal stems from which new plants arise.

Water hyacinth was first declared as a Class A noxious weed in 1981 under the Noxious Plants Act. Salvina was first declared in 1983.

Visit www.biosecurity.govt.nz/pests/salvinia for more information.

ENDS

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