MOLECULAR AND SATELLITE SPECTRAL IMAGING DETECTION OF Avocado Sunblotch Viroid (ASBVd)

Abstract

The objective of this work was to determine if spectral images form the QuickBird satellite can differentiate avocado (Persea americana Mill.) trees infected with Avocado sunblotch viroid (ASBVd) from healthy or asymptomatic trees, and also from other tree species. Differentiation between healthy and ASBVd symptomatic trees was approached with the classification of maximum likelihood. Nine symptomatic avocado trees, verified by RT-PCR 20 d before the satellite image capture, were positively detected by the image. Detection precision lowered to 70.4 % when the study was made 14 and 24 months after the image capture of 112 symptomatic and asymptomatic avocado trees. The satellite technique would be more efficient if the tree sampling, RT-PCR analysis and image capture, are simultaneously made. This is the first report for the detection of ASBVd symptomatic avocado trees with high spatial and spectral resolution satellite images. Digital analysis of remotely sensed imagery allowed differentiation of avocado from oak trees, and from plant free soil, and could be used to estimate the avocado cropped area in a region.