Laser-induced fluorescence spectroscopy applied to early diagnosis of citrus Huanglongbing

• HLB and CVC diseases cause chemical changes in citrus trees captured by LIFS.
• Samples were obtained by trees in the field and measured without previous preparation.
• LIFS system can differentiate citrus diseases with similar symptoms.
• LIFS system was able to do early diagnosis of HLB.

Over the last few years, citrus production has been threatened by diseases and plagues, especially Huanglongbing (HLB). Due to the long asymptomatic period, the most important and efficient tool for HLB management is early detection, which enables fast decisions to protect the farm. In this sense, a new methodology using a portable laser-induced fluorescence spectroscopy (LIFS) system and statistical tools was developed. It is capable of identifying not only symptomatic HLB leaves in the field, but also asymptomatic HLB trees and symptomatic citrus variegated chlorosis (CVC) trees. The differentiation reaches accuracy better than 90% and provides the ability of detecting an asymptomatic diseased tree 21 months before the symptoms appear, results supported by quantitative polymerase chain reaction (qPCR) analysis.

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