Evaluation of treatment strategies of the late blight Phytophthora infestans in Nepal by population dynamics modelling

The late blight disease caused by the fungus Phytophthora infestans is a serious pest of solanaceous crops capable of destroying a complete harvest. Therefore it is heavily treated with fungicides, especially in areas where the knowledge among farmers about application and impacts of fungicides is generally low, as it is the case in Nepal. In order to derive efficient treatment strategies with a minimum of fungicide use, a model describing the population dynamics of the disease on potato was established. The model is based on a universal epidemiological theory with further specification for P. infestans. The parameter estimation for the model was accomplished with field data of an uncontrolled epidemic in the Mid-Hills of Nepal. Using this model, different treatment strategies were evaluated by introducing fungicide treatment effects of different fungicide types into the model. Based on both field trials and population dynamics simulation recommendations for an optimised conventional treatment strategy were elaborated. Additionally the modelling tool PhytMod was developed, which simulates population dynamics and treatments and can be used to evaluate treatment strategies for other regions or even for general diseases without the P. infestans specification. (C) 2003 Elsevier Science Ltd. All rights reserved.