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Tavelures du pommier et de l’olivier : réalisation de modèles épidémiologiques par des méthodes exploitant des observations biologiques acquises au verger

Abstract : Apple scab, caused by Venturia inaequalis, and peacoq leaf spot, cause by Fusicladium oleagineum, are key diseases respectively for apple and olive growers. These disease usually require a large number of treatments. Adequate protection need a good evaluation of quantitative disponibility of inoculum, and estimation of infection conditions. In this thesis, these two problems were studied using only field data. This is an original aprroach to obtain knowledge about biology of fungi : most previous works were realised by regression of laboratory data obtained under controled conditions. In the case of Venturia inaequalis, primary inoculum consists of pseudothecia present in leaf litter. Treatments agains ascospore release period is the cornerstone of the strategy against apple scab. However, the existing forecasting models are not reliable, and are all based on degree-day time scale, proposed in 1982. Here, using a corpus of data acquired between 1996 and 2013, including observations of ascospore release and weather data, we assessed the daily rate of development of primary inoculum by fitting generic new time scale functions. Further improvements were then studied to take into account elements reported in litterature about the incidence of rain or wetness.Different methods were tested and adapted for the parameterisation of models by numerical optimisation. Some forcasting models were proposed and adapted to the area where the study was conducted, with parameters including rain and temperature. The validity was tested, and further developements of the forecasting tool was then proposed. In the case of Fusicladium oleagineum, a field-operational model predicting disease outbreaks was established as a function of temperature and relative humidity. First with the help of points selected by experts, Secondly automaticaly using a neural network. A model defining latent period as a function of average temperature after contamination was then realised.
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  • HAL Id : tel-02788163, version 1
  • PRODINRA : 409591

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Christophe Roubal. Tavelures du pommier et de l’olivier : réalisation de modèles épidémiologiques par des méthodes exploitant des observations biologiques acquises au verger. Phytopathologie et phytopharmacie. Université d'Avignon et des Pays de Vaucluse, 2017. Français. ⟨tel-02788163v1⟩

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