In the late nineteenth and early twentieth century, biosecurity measures were implemented by many governments to protect agricultural industries from disease. These measures were informed by developments in the understanding of disease, as the science of bacteriology began to influence both public health and agricultural policy. Localized understandings of outbreaks of disease began to be supplanted by global disease ecologies. This article examines these developments in the context of outbreaks of anthrax in New Zealand at the turn of the century. As an agricultural nation whose economic viability was dependent on international trade, New Zealand relied heavily on its reputation for pastoral purity. There was therefore a strong impetus for New Zealand agricultural officials to develop stringent biosecurity measures. However, increased state control often brought officials into conflict with farming communities. This article highlights the importance of historians developing more nuanced understandings of farmers’ responses to scientific agriculture.