The economic impact of failures in plant protection to New Zealand

Plant weeds, pests and diseases comprise significant threats to pastoral agriculture in New Zealand. The extent of damage incurred by New Zealand’s agricultural industry from these weed and pest threats varies significantly depending on the response implemented, and the technologies available. This paper assesses the projected economic impact of three individual potential failures in plant protection, specifically the spread of clover root weevil, giant buttercup and glassy-winged sharpshooter across New Zealand, and the potential mitigation of economic loss caused by these failures through various response methods. This assessment is carried out with the use of a national-level agricultural production and value model, based on data from the Ministry for Primary Industries farm models and the Lincoln Trade and Environment Model, an international trade and environment model. The model projects economic impact on agriculture until 2030, comparing the differences in economic impact between business as usual without the advent of each threat and then with the advent of each threat alongside various potential responses. The modelled responses cover firstly the most probable responses, and secondly the use of biological control agents, in the form of a parasitoid or bio-herbicide control. The results show that biological controls offer the most effective and feasible responses to the modelled threats to pastoral agriculture compared with other responses.