Of the various crop pests and pathogens which blight our harvests, it is the fungi and oomycetes which are the most widely-dispersed groups and which lead the global invasion of agriculture. Here, we highlight the rapid growth in fungal and oomycete disease incidence and spread across the globe. We draw attention to the need for improved disease surveillance and for more sustainable agricultural intensification and consider the economic and humanitarian costs of fungal and oomycete diseases.