For the first time, scientists at AgResearch have developed a model that simulates population growth of the thistle. It has just been published in the online publication, Ecology and Evolution.
Californian thistle was recently estimated to cost almost $700 million each year in lost agricultural productivity in New Zealand.
Based on substantial experimental data gathered by New Zealand and overseas scientists over many years, the model allows scientists to compare different defoliation strategies, whether that be through use of herbicide, mowing or biological control like the green thistle beetle (Cassida rubiginosa) which is currently established in several parts of New Zealand.
Principal Scientist Graeme Bourdôt says defoliation of the thistle is widely regarded as the most effective way to halt its population growth in a pasture.