Benefit cost analysis is a tried and tested analytical framework that can clearly communicate likely net changes in social welfare from investment decisions to diverse stakeholder audiences. However, in a plant biosecurity context, it is often difficult to predict policy benefits over time due to complex biophysical interaction between invasive species and their hosts. In this paper, we demonstrate how benefit cost analysis remains highly relevant to biosecurity decision-makers using the example of a plant pathogen targeted for eradication from banana growing regions of Australia, banana bunchy top virus. We develop a partial budgeting approach using a stratified diffusion spread model to simulate the likely benefits of eradication to the banana industry over time relative to a status quo policy. Using Monte Carlo simulation to generate a range of possible future incursion scenarios, we predict that eradicating the disease will generate $12.5-23.6 million increased annual revenue for the banana industry. To reduce these benefits to zero would require a bunchy top re-establishment event three years in every four. Sensitivity analysis indicates that eradication benefits can be greatly improved through improvements in disease surveillance and incursion response.