Recent research highlights the alarming potential spread and economic impact of Chilean needle grass in New Zealand. Published in the science journal PLOS One, the study by Dr. Graeme Bourdȏt and Dr. Chris Buddenhagen from AgResearch reveals that if left unchecked, this invasive species could infest up to 3.96 million hectares across the country, leading to losses ranging from $192 million to $1.16 billion in the pastoral sector.
The research employed climate niche modelling and a spread model to predict the weed’s potential range and the economic fallout of a “do nothing” scenario. Depending on the spread rate, which could see the weed occupying 90% of its suitable range in 100 to 201 years, the financial impact on farming is substantial. This justifies an annual expenditure of $5.3 million to $34 million to prevent its spread.
AgResearch senior scientist Dr. Buddenhagen emphasises the need for a nationally coordinated management strategy. This strategy would involve surveillance in susceptible regions and control measures where the grass is already established.
Chilean needle grass, scientifically known as Nassella neesiana, has already affected areas in Hawke’s Bay, Canterbury, and Marlborough. Its sharp seeds not only cause harm to livestock, leading to blindness and carcass damage but also reduce pasture quality and grazing access, impacting farm production financially.
New Zealand is home to around 22,000 species of introduced plants, and identifying those that pose economic or environmental threats is a significant scientific challenge. Effective management of these ‘sleeper weeds’ is crucial for regional councils, the Department of Conservation, and other authorities.
Dr. Bourdȏt highlights the progress in research, noting the development of models and tools to identify and predict the spread of such weeds, especially in the context of a changing climate.
Collaborative efforts with Manaaki Whenua – Landcare Research and ongoing work with regional councils, the Department of Conservation, and the Ministry of Primary Industries aim to develop a web-based tool. This tool will facilitate informed decisions regarding investment in the management of sleeper weed programmes, marking a significant step in safeguarding New Zealand’s pastoral sector from invasive species like Chilean needle grass.
