Name: Lagarosiphon

                    Lagarosiphon major

Description

• A submerged perennial freshwater herb found in shallow water margins to depths of 6 m. 
• Leaves - Are curved backwards or downwards and arranged sprially around the stem.  Size is 16 mm long x 2 mm wide.
• Flowers - Tiny and pinkish.  Only female plants are found in NZ and seed is not produced here.

Why is this plant a problem?

• Lagarosiphon forms extensive monoculture stands excluding smaller aquatic vegetation.
• Large clumps dislodge that can affect recreational use and cause flooding.
• Rotting vegetation turns water stagnant, killing aquatic flora fauna.
• New plants can establish from small fragments making control difficult.

How do I get rid of it?

• Lagarosiphon is difficult to eradicate once it is established in a waterway. Small patches may be controlled by mechanical or chemical methods.
• For larger patches, lower the water level (if possible) and remove the plant material. The bottom should be lined with black polythene to prevent regrowth. Keep in place for up to 2 years and check regularly.
• The herbicide Diquat is registered for use on lagarosiphon. This can provide some control, but follow-up work will be necesary.

Status Under RPMS

• Lagarosiphon is a Total Control Pest Plant throughout Southland.  We know it is found in waterways around Invercargill and as from April 2005 is now known to occur in the Oreti River near Josephville.  We would like to know if it occurs in other waterways in Southland.