This axis integrates the knowledge obtained in the three previous topics (1, 2, 3) to identify and assess the efficacy and the sustainability of different resistance deployment strategies. This means answering questions such as: "How an effective level of functional diversity can be reintroduced into crops at field and landscape scales?" and "How different types of resistance can be combined to make multi-scale deployment strategies more sustainable?" Our ambition is to evaluate the relevance of different management principles, themselves declined into different concrete agroecological solutions. We would like to assess by statistical inference and modelling the efficacy and the sustainability of resistance deployment taking into account molecular specificities associated with resistance genes and other environmental constraints.

The modelling work of Julien Papaïx during his PhD thesis had made it possible to assess the theoretical influence of wheat variety deployment strategies in a landscape, whose heterogeneity, fragmentation and connectivity could be optimized to reduce the intensity of epidemics and slow down the breakdown of resistance genes. Model validation and implementation now require a better knowledge of multi-year epidemiological processes but also of demogenetic and phenotypic data that must be available at the landscape scale over relatively long periods of time. This type of data has been acquired over the past 20 years on stripe and leaf rust (see Topic 1) but are not adapted for landscape-scale studies. The objective is now to design and manage surveys and collections of rust populations at the landscape scale in some relevant reference areas.