Sea spurge (Euphorbiaparalias): using plant development to inform the eradication programme in New Zealand

摘要

Sea spurge (Euphorbiaparalias L.) is a serious weed of coastal sand dunes in Australia and has the potential to establish along much of the New Zealand coastline. It was first detected in February 2012 on the west coast of the North Island. This is the only known site in New Zealand and the propagule pressure from additional seed floating on coastal waters is likely to be extremely low. Therefore the eradication programme is based on maintaining a zero population density to prevent further seed production at the detection site, and will continue until the seed reserve at the site is exhausted. The Ministry for Primary Industries is the lead agency for the programme and is working in collaboration with the Waikato Regional Council and the Departmentof Conservation.This paper presents the results of two years of observations on plant growth at the detection site. Germination occurred throughout the year, and some seedlings reached maturity in less than five months. Flowers were present between December and June. Plant height and branching were not reliable indicators of plant maturity.