Abstract: Wheat foliar diseases such as Zymoseptoria tritici and Pyrenophora triticirepentis pose significant threats to yield under Mediterranean conditions. We developed a biologically informed SEIR (Susceptible–Exposed–Infectious–Removed) model to quantify epidemic dynamics during the critical BBCH 37 growth stage and to evaluate the impact of fungicide strategies on the instantaneous epidemic growth rate r(t). The model integrates pathogenspecific traits, environmental modulation of transmission, and fungicide decay to simulate daily infection pressure over a 10day period. Scenario A (seed treatment with Systiva®) resulted in transient positive r(t) values for Z. tritici and nearzero or slightly negative values for P. triticirepentis, indicating partial suppression. Scenario B (seed treatment plus foliar propiconazole) produced consistently negative r(t) for both pathogens, reflecting stronger and sustained epidemic decline. These findings align with field data from Thessaly, Greece, and demonstrate that combining systemic seed protection with a BBCH 37timed foliar application enhances disease suppression by reducing transmission and increasing removal rates. The SEIR framework provides a practical and interpretable tool for assessing fungicide efficacy, supporting integrated disease management decisions in Mediterranean wheat systems.

Keywords: SEIR epidemiological modeling, Wheat leaf diseases, Pyrenophora tritici-repentis, Zymoseptoria tritici, Fungicide management strategies, Εpidemic growth rate r(t), BBCH 37, Mediterranean wheat systems

Pages: 35-53

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