REMOTE SENSING FOR THE MANAGEMENT OF VERTICILLIUM WILT OF OLIVE

Verticillium wilt (VW) is a major disease in all the olive producing countries and leads to extensive losses of production and olive trees. There is not chemical treatment available currently for this pathogen and only preventive cultivation measures can be applied. In Greece, the most sensitive cultivars to VW infection are Chondrolia (Chalkidiki) and Amfissa (Fthiotida, Central Greece). Previous studies showed that remote sensing can be used to assess VW infection levels using spectral indices, such as the Carotenoid Reflectance Index 2 (CRI2) and Normalized Difference Vegetation Index (NDVI), which depict the non-visible and visible stages of the infection, respectively, suggesting a timely and area wide method to map the status and spread of the pathogen in fields grown with Chondrolia cultivar in Chalkidiki. In the same area, experimental and also commercial applications of a new Plant Growth Enhancer Formulation (PGEF) comprising of natural minerals and biological control agents provided clear visual field evidence that infected trees can be brought back in full productivity. The present work assessed the effect of the application of the PGEF on the spectral properties of the trees. The results showed that the application had a significant effect on the recovery of the olive trees, as expressed by the change in the NDVI rate of the treated trees compared to the untreated in two successive years. Furthermore, the use of CRI2 and NDVI for the second most important table olive cultivar in Greece (Amfissa) was validated for the detection of the early and advanced infection symptoms, respectively.