Lagarosiphon

Lagarosiphon is a bottom-rooted, submerged, perennial aquatic herb. It alters habitat availability for native fish and invertebrates and affects dissolved oxygen levels.

Description

• Stems are less than 2m long and branching.
• Leaves are less than 16x2mm, curved downwards and arranged spirally around the stem.
• Flowers are small and pink.
• Vegetative spread from stem fragments, dispersed by water movement.
• Human-mediated dispersal through contamination of boats, fishing gear and machinery and deliberate plantings.
• Habitats include static to moderately fast-flowing freshwater bodies less than 6.5m deep.

What you need to know

Forms dense stands, displacing native aquatic herb species, altering habitat availability for fish and invertebrates, and affecting dissolved oxygen levels. Can impede recreational water access to water bodies.

Management approach

This is a declared pest managed under the Canterbury Regional Management Plan 2018 – 2038 (PDF file, 10.6MB) within the site led programme.

Site led

Exclude, eradicate, contain, reduce or control a pest within a specific place to the extent that doing so protects the values of that place.

Lagarosiphon that occurs outside site led areas designated under the Canterbury Regional Pest Management Plan 2018 – 2038 is a land occupier's responsibility and is to be managed via a community led approach.

Lagarosiphon is also declared an unwanted organism by the Ministry for Primary Industries (MPI) because it is capable of causing harm to the natural environment, physical resources or human health in Aotearoa/New Zealand.

These species pose a high risk to our environment, economy, recreation, and cultural values.

Rules

Any species declared a pest cannot be sold or be in a place where plants are being sold. Pest plants cannot be propagated, bred, multiplied, communicated, released, caused to be released, or otherwise spread.

Be aware when buying oxygen weed for your aquarium or pond. Lagarosiphon can mistakenly be confused with elodea (a common oxygen weed).

Control

If you see lagarosiphon, don't attempt to remove it, instead leave it where you found it and follow the Check, Clean, Dry method.

If you've been in a waterway and plan to move to another within 48 hours, you must clean all your gear that has been wet using the Check, Clean, Dry method.

It's vital that everyone uses the Check, Clean, Dry method on all equipment and vessels to stop freshwater pests.