Italy: Remote sensing and GIS techiniques to study Psa
Aerial infra-red image of kiwi fruit areas affected by Psa.
The project, based on the electromagnetic spectrum and infra-red, investigats the reflectance curves emitted by the canopy of healthy and diseased kiwi fruit plants with the aim of developing computerized maps and to gain an overview of the spread/outbreak of the disease and to support strategies for containing the disease and be a valuable technological support, updated in real time, for plant protection services and more.
Reflectance curves of a healthy plant (left) and a diseased plant (right.). Click here to enlarge.
Investigating large areas from the ground requires considerable financial resources, operational units have difficulty covering all the territory and are based on subjectivity and the operator. Through remote sensing, however, it is possible to analyse large areas in a very short time, covering the entire territory and then returning to geo-referenced maps in high detail at short notice.
Above: study area (15 km2) investigated, south of Cisterna (Latina - Italy). Below: calibration on the ground to acquire spectroradiometric data.
The project specifically analysed the possibility of using innovative technologies and non-invasive monitoring of kiwifruit bacterial canker, using aircraft-satellite multi-spectral data, spatial analysis and geo-statistics.
During the study (season 2011), kiwifruit orchards were selected and individual plants of different kiwi fruit (A. chinensis and A. deliciosa) affected by Psa were screened. Then 2 flights were carried out over the area of investigation, 4 spectroradiometric samplings on plants with Psa, 6 assessments of the degree of illness, 2 samplings of reality on the ground, 1 year on plants with spectroradiometric woody decay, 1 spectroradiometric sampling of plants with chlorosis due to mineral deficencies.
The instruments used specially fitted to an ultralight plane. Click here to enlarge.
Following the acquisition of data, a complex elaboration and statistical validation was done of those which provided a comparison with all the vegetation index from those known in the literature (66) calculated on data spectroradiometric dataset, in order to show a significant correlation between the degree of illness and the same vegetation index.
The elaboration highlighted that, for different indexes of vegetation, both in plants of A. chinensis (cv. Soreli) and of A. deliciosa (cv. Hayward), it had a high statistical significance in correlating the measurements from flight, compared to the degree of disease assigned with the findings on the ground. Similarly, it was clear and statistically significant that also an analysis of "false positives" (wood decay, mineral deficiencies) could be clearly distinguished.
Geo-referenced map of the study compared the degree of disease previously developed.
In addition, after developing a geo-referenced map of the spread and intensity (incidence) of disease for the entire study area for July, it was possible to develop a further map, this time an estimate for the month of September, which then has demonstrated compliance with the terms it was found/verified in the field.
"This study," said Dr. Giorgio M. Balestra, coordinator of the study "is the first application at the international level on kiwifruit bacterial canker, by non-invasive monitoring techniques using multi-spectral remote sensing data".
"This pilot project (SIMBAKI), even improved in many ways," continues the researcher of the University of Tuscia "it has highlighted the considerable potential in the analysis of detail as to be an important forecasting tool".
"To geo-reference large areas and study for the entire season with an overall view, represent a highly computerized database accessible for public and private services. Data production of any significance, would be investigated simultaneously and different aspects can contribute to understanding the spread of disease or, alert in time of the presence of new outbreaks and, repeating over the years, would allow identification of areas at particular risk, such as totally Psa free. It is quick, with low costs, updating and managing the whole thing, as shown during the Conference of LT, using multimedia platforms have been already successfully tested in other contexts of public and private enjoyment".
Further info:
Dr Giorgio M. Balestra - Researcher
DAFNE department - Uni Tuscia
Via S. Camillo de Lellis
01100 Viterbo - Italy
Phone: +39 0761 357474
Fax: +39 0761 357473
Email: balestra@unitus.it
Web: www.unitus.it