Plant disease epidemiologists desire tools that use the results of their research. However disappointment results from the expectation that the forecast will work perfectly when introduced. In general, farmers have found forecasts less helpful than hoped. Therefore adoption of forecasts by farmers has been less than desired by epidemiologists, and reductions in use of fungicide have been less than desired by environmentalists. These pessimistic views contrast with an alternative view.
Revision is an integral part of the modelling process.
New insight leads to an improved understanding of the pathosystem and better disease control - sometimes without use of the forecast system. Insight derived from previous effort in forecasting has identified new factors important to forecasts in some pathosystems. Examples of new factors in forecasting will be examined. Additionally, improvements in weather monitoring equipment and in computer technology enable the integration of spatial and temporal factors. From the time of its first appearance, attempts were made to control late blight with chemicals.