Coordinating the Spatial and Temporal Deployment of Crop Resistance Genes to Reduce Pathogen Epidemics in a Dynamic...

Deploying cultivars containing resistance genes is an economical and effective method for managing pathogen outbreaks but is subject to a trade-off in which more effective control often accelerates the emergence of virulent, resistance-breaking pathogen strains (durability-effectiveness trade-off). Coordinating the deployment of resistance genes spatially and temporally could mitigate this trade-off. Using a novel spatiotemporal model, we explored whether coordinating the deployment of four resistant crop cultivars, each carrying a different resistance gene, spatially and temporally within a landscape could improve epidemic management and resistance durability. We also examined how the efficacy of different deployment strategies varied based on initial pathogen load, virulence allele frequency, pathogen source location and dispersal characteristics, and the frequency of non-host crops in the landscape. Even with landscape-level coordination, a durability-effectiveness trade-off remained, in which the strategies that most effectively reduced outbreaks resulted in a greater prevalence of virulent pathogen strains, especially when initial virulence frequencies were high. Rotating resistant cultivars every 5 years was the most effective strategy for resistance durability. However, the control effectiveness of this strategy was heavily influenced by the spatial arrangement of the cultivars within each rotation, with coordination across the whole landscape providing the best balance between durability and effectiveness. Combining non-host crops with resistance gene rotation strategies consistently reduced disease incidence and enhanced durability, proving extremely effective even when deployed across as little as 25% of the landscape. Our study highlights the potential benefit of coordinated spatial and temporal planning at the landscape level when using resistant cultivars for crop disease management.