The epidemic models for Phytophthora infestans and Pseudocercosporella herpotrichoides and their regional adaptation in Germany 1

The computer-aided models SIMPHYT I and II simulate the start and further progress of epidemics of Phytophthora infestans depending on weather, initial infection pressure, resistance of cultivars and application of fungicides. The model SIMCERC simulates epidemic progress (infected plants and growth of mycelium through the leaf sheaths) of Pseudocercosporella herpotrichoides on winter wheat and winter barley depending on weather factors. To use the models for prognostic purposes, an adaptation to regional conditions was necessary. For this adaptation, specific model parameters (regional factors) were defined. Their quantitative values were related to the region and a first data set was obtained by simulation experiments. The relation of these parameters to regional climatic factors was investigated and described by regression functions. Appropriate regional factors were calculated on this basis for each meteorological station used in the project. The regional factors may be interpreted as a characteristic of the different‘infection pressure’in the regions of Germany.