Evaluation of the use of Sentinel-2 satellite images for the classification of areas affected by OQDS (Olive Quick Decline Syndrome) and for the monitoring of control measures against Xylella fastidiosa in Apulia
The fast and wide spread of the bacterium Xylella fastidiosa in EU territory, Italy in particular, and the rise of the number of host species urged to introduce strict emergency measures and mandatory surveys, inspections and diagnostic tests. The use of remote sensing to monitor the distribution of plant diseases has been widely used. Detecting spatial changes, mapping the spread of the disease, helps to take the right decision at the right timing. To this end, from July 2015 until July 2020, olive plantations were analysed using Sentinel-2 (Copernicus mission) satellite images of two municipalities in the region of Puglia: Maruggio (Taranto province) and Ugento (Lecce province), with respectively less and more severe presence of Xf symptoms (Olive Quick Decline Sindrome - OQDS).
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The images have provided their usefulness in the detection of the spatial and temporal evolution of Xf infected areas with the use of "ad hoc" combination of vegetation Indices (VIs): MCI-RI-Slope. Similarly, images elaborated in the winter-spring period of the same areas (2018-2020) helped to conclude that the combination of mYI, MCI and Slope indices gives a representative idea of the ground-situation of the application of agronomical practices e.g. removal of weeds, which are the control measures against Xf vectors. Based on the VIs used, two possible global ecological indicators have been defined for the identification and control of Xylella in the Apulia territory.
