An economic evaluation of the benefits of research into biological control of Clematis vitalba

Abstract

Clematis vitalba, or Old Man's Beard is a weed which is invading New Zealand's native bush. Introduced as a garden species, it has now spread into native bush in many areas of the country and is regarded as a very serious threat to native forests. The plant, a deciduous vine, climbs existing vegetation, smothering and eventually killing the trees below it. Present control measures include chemical application and hand~cutting or pulling, but the weed is still spreading in many areas. Consequently scientists are considering implementation of a research program with the aim of identifying and introducing biological agents which would control Clematis vitalba. An economic evaluation, undertaken to determine whether such research is justified, is the subject of this report.