Detection of powdery midiou in grapevine using remotely-sensed UV-induced fluorescence
Résumé
Powdery mildiou is caused by Erysiphe Necator, an acomycete fungus. It can induce severe damages to a vineyard including yield loss and depreciation of wine sensory charcateristics. This disease as other fungal diseases is throroughly controlled by pesticides. In order to reduce the use of pesticides and to improve early detection for these diseases, we studied the potential of UV-induced imaging fluorescence to detect and quantify the colonization of a leaf by E. necator. Cuttings of grapewines were grown in a greenhouse. Twenty four leaves were collected and fourteen were innoculated with the fungus on their adaxial side, the remaining leaves were used as control. Images of fluorescence were taken in a lab at six combinations of emission/excitation wavelengths (F440/UV, F520/UV, F690/UV, F740/UV and F690/blue F740/blue). Data treatments include propoer image correction, interest area selection, fluorescence ratio computation and edge detection. Using the spatial average of F440/F520 for the whole leaf area it was possible to detect the fungus starting at three days after innoculation (DAI). using the edge detection algorithm it was possible to detect and quantify the colonization of the leaf starting at three DAI, with a lower coeeficient of variation compared to leaf spatial average.
Domaines
Ingénierie de l'environnement
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