ISHS Acta Horticulturae 276: II International Symposium on Computer Modelling in Fruit Research and Orchard Management
DEVELOPMENT OF A FORECAST MODEL OF GRAPE DOWNY MILDEW ON A MICROCOMPUTER |
| Authors: | Ph. Blaise, C. Gessler |
| Abstract:
Grape downy mildew caused by Plasmopara viticola is an explosive disease which, in Switzerland, causes severe damages in only 20 % of the years. A forecast system is therefore particularly profitable. A model based on biological data of the pathogen and weather data is presented. It is composed of three parts: A mechanistic model describing the asexual phase of the pathogen's life cycle, a linear, temperature-driven host growth model and a synthetic progeny/parent ratio model using the output of the two other parts. The required input consists in hourly temperature, relative humidity and rainfall values. The output of the first part of the model is a risk factor for infections without consideration of the actual state of the epidemic. The output of the third part is the simulated epidemic development calculated as the proportion of diseased host surface. The model parameters were taken from literature, our own data or were estimated. A feedback feature allows adaptation of the initial inoculum to the current epidemic. The "Vinemild" program is an implementation of the model on a microcomputer and provides the necessary interface with the user. It is menu driven and allows interactive input of data as well as biological parameters. All output is displayed graphically. Epidemiological data collected in 1988 and 1989 is presented and compared to the output of the model. | |
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