Modelling the interaction between early blight epidemics and host dynamics of tomato

A model describing an early blight epidemic and the growth dynamics of tomato interacting together is developed. The model is formulated as a set of differential equations for the rate of change in the amount of healthy H, diseased Y and defoliated D area in the disease situation, and healthy H DF and defoliated D DF in the disease-free situation. Model parameters were estimated through fitting the model to experimental data obtained from glasshouse experiments which comprised tomato plants inoculated with A. solani at three inoculation times; early (t INOC = 23 days after transplanting (DAT)), intermediate (33 DAT) and late (43 DAT) in experiment 1 and t INOC = 22, 30 and 38 DAT in experiment 2. Defoliation rates were 2.5 times higher for late inoculated (older) plants compared with the early inoculated (younger) plants. Values of the logistic rate parameter for disease increase were about three-fold higher in the late inoculations (0.380, 0.305 day−1) when compared with the early inoculations (0.151, 0.095 day−1). Based on the good fit of the model outputs to observed data with R 2 > 0.995, the model can be considered as offering a good description of the dynamic interaction between the early blight epidemic and growth of tomato.