Plant pests and diseases are a real concern for the global agriculture industry and to food security. Early warning systems are essential to preparing for and combatting plant pests, and rapid diagnostic tools are pivotal to this. However, current procedures for strain-level fungal disease diagnosis are lengthy and not straightforward. Dave Hodson and Diane Saunders discuss their development of the Mobile And Real-time PLant disEase (MARPLE) system and how it has made possible an in-field gene-based rapid diagnosis of fungal diseases, specifically wheat rust disease, to the strain level. Their study is published in BMC Biology today.