Geodaysit 2023

Monitoring and surveillance of plant pathogens and pests are essential steps in integrated pest management. However, conventional field monitoring of diseases and pests is time-consuming, labor-intensive, and generally not very effective. Remote sensing (RS) techniques could play a crucial role in large-scale monitoring of plant diseases and pests. Citrus Tristeza Virus (CTV) is the most important citrus virus globally. In 2002, two outbreaks of the virus were reported in the Apulia region, Italy.
To examine the epidemic effects of the virus in the Apulia region, a remote sensing approach based on time series analysis was applied. Time series of the Normalized Difference Vegetation Index (NDVI) obtained from MODIS-Terra satellite and Sentinel-2 multispectral imagery were used to study fluctuations related to the infection in nine citrus fields monitored by MODIS-Terra for a period of 21 years and in four citrus orchards observed with Sentinel-2 for a period of 5 years.
Phonological parameters were extracted from MODIS-Terra and Sentinel-2 NDVI by applying asymmetric curve fitting methods. Subsequently, their evolution was analyzed using linear regression. The evaluated approach demonstrated high potential in monitoring infected citrus fields.
MODIS-Terra, with its medium spectral resolution, allowed for the assessment of infection's temporal trend over a long period and identifying long-term trends. Sentinel-2, thanks to its high spectral resolution, enabled the monitoring of small orchards and greater precision in the spatial analysis of infected areas.
Statistical analysis revealed a correlation between the incidence of infection and the trends of seasonal parameters, particularly the peak value, seasonal amplitude, and seasonal integral in the summer period. These results suggest that integrating MODIS-Terra and Sentinel-2 data could constitute an effective strategy for monitoring and assessing the effects of CTV in the Apulia region.