Fungicide use patterns in South African barley production

Fungicide resistance is an escalating threat to barley (Hordeum vulgare L.) production worldwide. To evaluate use patterns and potential resistance risks, fungicide application data from the South African national barley production traceability and compliance platform, called the Barley Passport (2021–2024) were analysed. Program intensity was consistently high, with three-application regimes dominating and two-application programs declining over time. Single-application programs were rare. Combinations of Succinate Dehydrogenase Inhibitors (SDHI) and Demethylation Inhibitors (DMI) represented the most common spray type (22–25% of fields), while mixtures of DMI, SDHI and Quinone outside Inhibitors (QoI) contributed an additional 15–22%. Together, SDHI-containing programs accounted for approximately 40–45% of all sprays annually. Spatial analysis revealed notable regional variation in fungicide application practices. Certain production regions consistently accounted for the highest number of treated barley fields, while other regions demonstrated a growing shift toward integrated fungicide programmes, particularly those combining SDHI + DMI and QoI chemistries. These patterns suggest differential responses to disease pressure, agronomic conditions, and resistance management awareness across the barley-growing landscape. Barley-on-barley cropping persisted on 20–21% of hectares, reinforcing conditions of elevated disease pressure. These findings show that South African barley production relies heavily on fungicide chemistries with a high risk of resistance development. This underscores the urgent need for integrated disease management and stewardship to preserve fungicide efficacy and ensure the long-term sustainability of the malting barley sector. Given barley’s global importance, insights into regional resistance dynamics and management responses in South Africa offer valuable lessons for international production systems facing similar challenges.