Project: 2004-03. Report - Biological control agents for weeds in New Zealand: A Field Guide
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Date: 2005 Author: Compiled by Lynley Hayes Publication: Field Guide Project reference: 2004-03 This report is available for purchase from: |
Executive summary:
Alien weeds, including exotic grasses, shrubs, vines and trees, pose a serious and increasing threat to all of New Zealand’s ecosystems. Unless current control is improved more than 575 000 ha of high priority conservation land will soon be threatened by weeds. In the longer term, the ecosystem-altering effects of invasive plants will have serious impacts on New Zealand’s indigenous biodiversity and productive sectors, by altering hydrological regimes, disturbing the flow of energy and nutrients, and changing the structure and composition of native communities.
The financial cost of weeds is also huge. For example, in 1982 the cost of pastoral weeds alone (in terms of production losses plus weed control expenditure) was estimated to be $393 million per annum, which equates to about $1.1 billion today.
Biological control is increasingly being recognised as an important tool for managing New Zealand’s serious weed problems. Successful biological control for mist flower (Ageratina riparia), St John’s wort (Hypericum perforatum), and ragwort (Senecio jacobaea) means it is now uncommon for other control methods to be required. The need for control measures against alligator weed (Alternanthera philoxeroides), Mexican devil weed (Ageratina adenophora), and nodding thistle (Carduus nutans) has also been substantially reduced.
This field guide explains how to find and recognise biocontrol agents that have been deliberately and successfully introduced to attack weeds in New Zealand. The most significant of the self-introduced and native species that commonly attack weeds in New Zealand are also covered. Species currently under development are not included but we hope to produce additional pages for them in the future.
This report is available for purchase from:
Forest Research
Private bag 3020
Rotorua
New Zealand
