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Managing fungicide resistance using the principles of population biology: insights from mathematical modeling and field experiments

Alexey Mikaberidze: Epidemiology of Plant Diseases, ETH Zurich

<div>To preserve efficacy of fungicides, we first need to understand the ecological and evolutionary principles that govern pathogen adaptation to fungicides. Fungicide resistance develops in two phases. First, resistant mutants arise through mutation and invade the pathogen population (emergence phase). After successful emergence, the frequency of resistance increases due to selection imposed by a fungicide in a deterministic fashion (selection phase). Fungicide dose can be adjusted to suppress emergence of resistance. To investigate this possibility, we combined a population dynamical model with dose-response field data for <i>Zymoseptoria tritici</i>, an important wheat pathogen. To reduce selection for resistance, one can optimize the proportion of fungicides in the mixture as our modeling study indicates. However, this requires that substantial fitness costs are associated with mutations conferring fungicide resistance.</p> <p>I will discuss further possibilities to suppress fungicide resistance by (i) optimizing spatial scales of fungicide applications and (ii) combining fungicides with host resistances. To find optimal strategies, we need to better characterize pathogen's epidemiological parameters such as infection efficiencies, transmission rates and dispersal kernels. This knowledge would inform modeling studies with the aim to propose best candidate strategies, which will need to be tested in the field. I will review our work in progress in this area.</div>