Age-structured modeling of pathogen invasion and host resistance in fungal plant diseases

This study develops an age-structured integro-differential model to analyze the epidemiological and evolutionary dynamics of fungal leaf pathogens within a homogeneous host population. The model incorporates key factors such as plant tissue age, time since infection, and pathogen phenotypic variation, focusing on pathogen adaptation to quantitative resistance. A key focus of our analysis is the invasion and persistence of fungal strains in heterogeneous landscapes, which we characterize using a reproductive number formulation derived from the spectral properties of a linear integral operator. We establish conditions for pathogen persistence and study the evolutionary dynamics shaping strain adaptation to host resistance. Our results highlight the critical role of host age in modulating infection risk and evolutionary pressures on pathogen populations, offering new insights into sustainable plant disease management strategies. These findings contribute to the growing body of research integrating epidemiology and evolution in mathematical modeling and provide a theoretical framework for predicting pathogen adaptation to quantitative resistance in plant populations.