New modelling tools to design efficient methods to control black sigatoka of bananas

Black Sigatoka (BS) is considered as the most destructive foliar disease of bananas and plantains. Due to important damages on yield, the integrated management particularly by using resistant varieties appears essential. To advance our knowledge of pathogen dynamics and to design control method, two mechanistic models were developed. At plant scale, the model simulates under optimal epidemiological conditions the BS development by describing the disease severity within time at leaf and plant scale. It describes the lesions development during several crop cycles with two sub-models, one defining simply the banana growth, the second describing the complete epidemic cycle. The model was calibrated on plantain and it was evaluated by using an independent data set, highlighting the good quality of model predictions. The sensitivity analyses performed for this model enabled to identify the main influence of five epidemic and plant parameters. Simulations allowed in evaluating the impact of host resistance components, the disease auto-infection and the leaf emission rate on BS severity. At plot scale, we've developed a spatio-temporal model describing the epidemiological state of plant in five compartments (healthy, exposed, latent, infectious and sporulating). Some differential equations describe the transition rate between each compartment. The parametrization of this model is under going to allow realistic simulations of varietal mixtures at different spatial scale (within plot, within farm, production area). These two models allowed to better understand BS epidemics and allowed to design virtually some efficient control practices at banana scale (resistance component, plant growth component) and plot scale (varietal mixtures).