5 Plant Pests
5.2 Eradication (Service Delivery) Plant Pests
5.2.11 Senegal Tea (Gymnocoronis spilanthoides)
Description
Senegal tea is a perennial, semi-aquatic herb. When flowering, the plant may grow up to 1.5m in height.
Reasons for the Strategy
Senegal tea is an extremely aggressive freshwater weed and inhabits wetlands and still or flowing waters. It forms dense floating mats, which can quickly cover waterways or wetland areas causing a number of serious adverse effects. It has the ability to exclude submerged native flora species.
By modifying habitats and smothering other useful species, Senegal tea may displace traditional food sources of value to Maori. It may also impede the flow of water and interfere with water utilisation including navigation and recreational activities.
Objective
Achieve zero density of Senegal tea in the Waikato Region by June 30, 2007.
Means of Achievement |
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Statutory Obligation |
No person shall knowingly communicate, release, sell, offer to sell, display in a place where plants are offered for sale or exhibition, propagate or breed Senegal tea (Gymnocoronis spilanthoides). A breach of this obligation will create an offence under section 154(m) of the Act. |
Monitoring |
Environment Waikato will monitor Senegal tea in the Region, in accordance with section 5.7.2 of the Strategy. |
Information & Advice |
Provide advice and information on the threats of Senegal tea to affected land occupiers and other interested parties in accordance with section 5.7.1 of the Strategy. |
Direct Control |
Undertake direct control of Senegal tea, as appropriate, in accordance with section 5.7.4 of the Strategy. |
Cost Benefit Analysis
Two scenarios for control of Senegal tea have been considered:
- do nothing
- eradication.
The "do nothing" scenario results in identifiable damage to Regional conservation values over 7,920 hectares.
Eradication is the preferred option as it produces a positive net benefit and meets the requirements of Sections 72(1)(a) and (b) of the Act, protecting 9,999 hectares.
The full cost benefit analysis can be found in the report entitled “Cost Benefit Analysis and Assumptions, Animal and Plant Pest Species Considered for Inclusion in the Proposed Waikato Regional Pest Management Strategy, a supporting document to satisfy section 72 requirements of the Biosecurity Act 1993”.
Alternative measures to achieve eradication
The ‘do nothing’ option is not considered appropriate as relying on the voluntary control of the plant will not achieve the objective of zero density. The loss of biodiversity and conservation values is likely to be considerable.
Alternatively, Environment Waikato could look to the occupier of infested areas to treat infestations of Senegal tea. However, such an approach is equally unlikely to achieve the objective of zero density, nor is it considered reasonable, given the plant is difficult to identify and the occupier is generally neither the beneficiary of control nor the exacerbator of the problem.
Funding – exacerbators/beneficiaries
Exacerbators are the original importers and distributors of the pest, and land occupiers where the plant now grows.
Beneficiaries are the Regional community through protection of ecological values of importance to the Region. Additional beneficiaries are the Crown.
Because of the low incidence and high threat nature of the pest, it is appropriate for Strategy costs to be fully funded by the General Rate.
