Spartina, Cord Grass

(Spartina spp.)

Total Control Pest

Spartina is an aquatic, perennial grass, growing 60–80 cm high, which inhabits estuaries and other coastal areas. It has short rhizomes and forms dense mats in intertidal zones. It was originally planted to assist reclamation of tidal flats through its ability to trap sediment. Dispersal and establishment occurs mainly from vegetative fragments and rhizomes in seawater, and infrequently by seed.

Reasons for the Strategy

Spartina, or Cord Grass, growing in a dry, brown field.

Sedimentation trapped by Spartina can lead to flooding and the restriction of bird and flatfish habitat. Spartina can alter the hydrodynamics of important fish spawning and nursery areas and change the scenic and recreational values of foreshores. Raising silt levels can alter drainage on adjacent flats and leads to deterioration of their native plant cover. There are substantial areas of sheltered beaches throughout the Tasman-Nelson region that are vulnerable to invasion.

Spartina is assessed at “2” on the infestation curve. It was widely distributed through a number of estuaries, but it is only active on numerous sites along the edges of the Waimea Inlet and Westhaven Inlet. Control of Spartina started in the 1970s and was greatly assisted in the 1990s by the introduction of a new salt-tolerant herbicide. As a result, the area of Spartina has been greatly reduced; it appears to have been eradicated from the Moutere Inlet, Riwaka, Kaiteriteri, Ngaio Bay, and Farewell Spit. The benefit of maintaining a low incidence of Spartina far outweighs the cost. Spartina occurs on publicly owned land. Control will therefore be undertaken by the Management Agency and the Department of Conservation, and this forms the basis of the Strategy rule. If Spartina is found on private land, the Management Agency will arrange to carry out control. The low incidence of Spartina in the Tasman-Nelson region, extensive areas of suitable habitat, and the potential for it to cause significant adverse effects, mean the benefits of total control far outweigh the costs.

Objective

To contribute to the eradication of Spartina by ensuring that all known sites in the Tasman-Nelson region are inspected annually and all live plants are destroyed during the term of the Strategy.

Alternative Measures

The alternative option of “do nothing” or relying on voluntary control will not achieve the objective of eradication, and will result in significant additional costs to the community with respect to lost natural values and the increased cost of control in the future. The Management Agency will arrange and carry out control.

Strategy Rule for Spartina

The Management Agency and the Department of Conservation shall destroy all adult and juvenile plants.

Biosecurity Act Requirement

No person shall knowingly sell, propagate, breed, release, or commercially display Spartina, under Sections 52 and 53 of the Act.