Combining single-gene-resistant and pyramided cultivars in agricultural landscape compromises the benefits of pyramiding in most, but not all, productions situations

Abstract

ContextWhile resistant cultivars are valuable in safeguarding crops against diseases, they can be rapidly overcome by pathogens. Numerous strategies have been proposed to delay pathogen adaptation (evolutionary control), while still ensuring effective protection (epidemiological control). Resistance genes can be deployed in 1) single-gene-resistant cultivars sown in the same field (mixture strategy) or in different fields (mosaic strategy), 2) a pyramided cultivar (pyramiding strategy) or 3) hybrid strategies that combine the three previous strategies. In addition, the spatial scale at which resistant cultivars are deployed can affect the plant-pathogens interaction: small fields are thought to reduce pest density and disease transmission. ObjectivesWe aim to compare these strategies, focusing on the effects of the simultaneous deployment of single-gene-resistant and pyramided cultivars sharing resistance genes in an agricultural landscape. We also investigate the impact of field size. MethodsWe used the spatially-explicit stochastic model landsepi to compare the evolutionary and epidemiological control across spatial scales and deployment strategies for two major resistance genes. ResultsThe evolutionary control provided by the pyramiding strategy is at risk when single-gene-resistant cultivars are concurrently planted in the landscape (hybrid strategies). The probabilities of pathogen mutation and the corresponding fitness costs play a crucial role in determining the feasibility of planting pyramided cultivars alongside single-gene-resistant ones. Instead, field size did not affect strategies recommendation. ConclusionsPlanting pyramided cultivars alongside single-gene-resistant ones should be avoided. Socio-economic perspectives for the adoption of resistance management strategies are discussed.