Speaker
Description
Black Sigatoka disease is an airborne fungal infection caused by \textit{Pseudocercospora fijiensis} that severely impacts global banana and plantain production. Its persistence and resistance to eradication make it one of the most challenging plant diseases to manage. We develop a deterministic host–pathogen model that captures BSD dynamics through dual transmission pathways and mate limitation in sexual reproduction. The model exhibits a backward bifurcation, where a stable endemic equilibrium coexists with the disease-free equilibrium even when $\mathcal{R}_0<1$. This result explains why control strategies based solely on reducing $\mathcal{R}_0$ may fail. We analyze the backward bifurcation regime using normalized forward sensitivity indices, Latin Hypercube Sampling, and Partial Rank Correlation Coefficients. The results show that host recruitment and susceptibility strongly drive endemic infection, while sanitation is a key control mechanism. A stochastic formulation using the Gillespie SSA captures variability in transmission dynamics. Simulations reveal that stochastic effects are significant near low-density thresholds, where extinction may occur despite deterministic persistence. Sobol sensitivity analysis further shows that variability in the endemic state is dominated by a few parameters, particularly $\kappa$, but also shaped by nonlinear interactions. These findings highlight the need for integrated control strategies combining sanitation and resistant plants.
