Clover Root Weevil found in the South Island

16 February 2006

Clover root weevil has been detected in the South Island near Christchurch airport by AgResearch during a trap testing programme.

Clover root weevil, which causes significant pasture degradation, is already very widely spread in the North Island.

Biosecurity New Zealand has commissioned an assessment into the economic impacts of Clover Root Weevil from the New Zealand Institute of Economic Research.

It looks at a variety of scenarios and concludes that clover damage caused by Clover Root Weevil could cost the economy between $0.2 billion and $1 billion annually if it was to spread nationwide. Currently, annual clover production is estimated to add $3 billion to the national economy.

CRW was first detected on a Waikato dairy farm in 1996, but is thought to have been in the country much longer. It has since been found in the Bay of Plenty, Northland, Hawkes Bay, some parts of Taranaki and the Wairarapa. It is likely to have been in the South Island for some time before discovery. No eradication tools exist, and were they available, constant re-invasion from the North Island would be likely and make eradication impractical. Affected farmers have so far been able to mitigate the impacts principally by supplementary application of nitrogen.

The Ministry of Agriculture Sustainable Farming Fund is providing $347,000 and other funders $327,000 over the next three years to improve information and farmer knowledge about CRW. The project will focus on how farmers can maintain pasture and profitability in the presence of CRW. It will use key people in the pastoral sector to transfer research findings and solutions developed on-farm.

Research into understanding the impacts of CRW and methods for mitigating the impacts has been ongoing for some time. That research has established the biology of CRW in New Zealand, provided an assessment of impacts on pasture, and assessed the resistance of CRW to a variety of cultivars. It has also resulted in the identification and release of a promising biopesticide – the tiny parasitic Irish wasp.

Media contact: Tina Nixon, Senior Communications Adviser, Biosecurity New Zealand, 027 223 2789.



Last Updated: 23 September 2010

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