Sharing banned pest plants illegal

17 May 2012

Pond owners are being asked not to propagate or share the banned aquatic pest plants Salvinia and Water hyacinth.

Salvinia (Salvinia molesta) and Water hyacinth (Eichhornia crassipes) are rapidly growing freshwater plants that form large dense floating mats that can completely cover entire waterbodies affecting water quality, drainage, recreational use, and increase the risk of drowning and flooding. They are among the world's most invasive weeds and have the potential to cause huge damage to our waterways and fish that live in them.

The Ministry for Primary Industries (MPI) and the Northland Regional Council (NRC) are working together to eradicate Salvinia and Water hyacinth from Northland.  Both plants have been declared unwanted and notifiable organisms under the Biosecurity Act 1993, which makes it illegal to sell, propagate or distribute them. They are also banned under the Northland Regional Council's Regional Pest Management Strategy.

In March, Northland Regional Council biosecurity staff found Salvinia in the Hikurangi area, near Whangarei, and near Okaihau in the Far North District. Most of these finds were in home ponds.

More finds of Salvinia have been reported to the Ministry for Primary Industries in recent weeks, raising concerns that the plant is being distributed, especially amongst pond owners.

"We are concerned at the extent of the spread of these aquatic weeds," says MPI response manager Emmanuel Yamoah.

"Anyone who sees any of these weeds in Northland – or suspects they may be present – should report it to either the Northland Regional Council on 0800 002 004 or Ministry for Primary Industries on 0800 80 99 66.

"Regional council biosecurity staff or MPI contractors will visit the site and remove the weeds free of charge if they find them."

Dr Yamoah says people need to be aware that distributing Salvinia and Water hyacinth really undermines efforts to eradicate these serious weeds.

Salvinia is a small, free-floating aquatic fern with branched, horizontal stems that lie just below the water surface.

Plants are usually up to 30 cm long, and have green to bronze spongy leaves that occur in pairs, while leaf shape varies with the age and environment of the plant. Young leaves are oval, about 12 mm across and lie flat on the water, often resembling duckweed and as the plant matures, leaves become thick and fold at the mid-rib.

The upper surface of the leaf is water repellent and covered with distinct white hairs with an egg beater-like tip.  Salvinia has no true roots, but has a root-like structure underneath each leaf pair and as the plant matures, these 'roots' resemble wet hair.

Water hyacinth plants consist of a free-floating rosette of shiny rounded leaves with thick masses of feathery roots which hang in the water. The roots are dark in colour and can reach 2.5 m in length. A single flowering stalk with a cluster of mauve-blue flowers, each with a yellow spot, is produced from the rosette. The stalk grows up to 50 cm above the leaf canopy. Plants produce floating horizontal stems from which new plants arise. Mature mats of this plant are held together by these stems.

More information about Salvinia and Water hyacinth is available on the National Interest Pests Response section of the MPI website www.biosecurity.govt.nz or via the 'pest plants' section of the Northland Regional Council's website www.nrc.govt.nz/nasties

Salvinia and Water hyacinth are among the pests being eradicated under the National Interest Pest Response programme led and funded by the Ministry for Primary Industries in partnership with regional councils and the Department of Conservation.

For more information, please contact:

Judith Hamblyn, Senior Communications Adviser, Ministry for Primary Industries
Phone: 04 894 0161

OR

Ross Johnson, Biosecurity Officer, Northland Regional Council
Phone: 09 438 4639