Laser-induced fluorescence imaging method to monitor citrus greening disease

The potential use of laser-induced fluorescence imaging to monitor citrus greening disease in sweet orange (Citrus sinensis) plants was investigated. For this purpose, an experiment using healthy plants as the control and plants of the same variety inoculated with Candidatus Liberibacter asiaticus (CLas) was performed to verify the fluorescence response through 8 months after bacterial inoculation. A system using laser-induced fluorescence at 473 nm of wavelength excitation was configured. Color descriptors from the collected fluorescence images were determined using the average values for red (R); green (G); blue (B); hue (H); saturation (5); value (V, or Intensity); relative red (rR); relative green (rG); relative blue (rB) and luminosity (L). The data were analyzed using a paired Student's t-test by means of comparison between diseased and healthy plants. The results demonstrate a potential method to identify citrus greening at an early stage of the disease (first month), prior to the onset of visual symptoms at confidence level of 95%. (C) 2011 Elsevier B.V. All rights reserved.