Analytical and Bioanalytical Chemistry

, Volume 411, Issue 14, pp 3125–3133 | Cite as

Rapid and noninvasive diagnostics of Huanglongbing and nutrient deficits on citrus trees with a handheld Raman spectrometer

  • Lee Sanchez
  • Shankar Pant
  • Zhongliang Xing
  • Kranthi Mandadi
  • Dmitry KurouskiEmail author
Research Paper


Huanglongbing (HLB) or citrus greening is a devastating disease of citrus trees that is caused by the gram-negative Candidatus Liberibacter spp. bacteria. The bacteria are phloem limited and transmitted by the Asian citrus psyllid, Diaphorina citri, and the African citrus psyllid, Trioza erytreae, which allows for a wider dissemination of HLB. Infected trees exhibit yellowing of leaves, premature leaf and fruit drop, and ultimately the death of the entire plant. Polymerase chain reaction (PCR) and antibody-based assays (ELISA and/or immunoblot) are commonly used methods for HLB diagnostics. However, they are costly, time-consuming, and destructive to the sample and often not sensitive enough to detect the pathogen very early in the infection stage. Raman spectroscopy (RS) is a noninvasive, nondestructive, analytical technique which provides insight into the chemical structures of a specimen. In this study, by using a handheld Raman system in combination with chemometric analyses, we can readily distinguish between healthy and HLB (early and late stage)-infected citrus trees, as well as plants suffering from nutrient deficits. The detection rate of Raman-based diagnostics of healthy vs HLB infected vs nutrient deficit is ~ 98% for grapefruit and ~ 87% for orange trees, whereas the accuracy of early- vs late-stage HLB infected is 100% for grapefruits and ~94% for oranges. This analysis is portable and sample agnostic, suggesting that it could be utilized for other crops and conducted autonomously.

Graphical abstract


Raman spectroscopy Plant diseases Huanglongbing Chemometrics Nutrient deficiency 



The authors thank Texas A&M University-Kingsville, Citrus Center, and Riofarms, TX, for access to the citrus orchards.

Funding information

This study was supported by funds from Texas A&M AgriLife Research, Texas A&M University Governor’s University Research Initiative (GURI) grant program (12-2016/M1700437) to DK, and USDA-NIFA-AFRI (2018-70016-28198) to KKM.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no competing interests.

Supplementary material

216_2019_1776_MOESM1_ESM.pdf (6.5 mb)
ESM 1 (PDF 789 kb)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Lee Sanchez
    • 1
  • Shankar Pant
    • 2
  • Zhongliang Xing
    • 1
  • Kranthi Mandadi
    • 2
    • 3
  • Dmitry Kurouski
    • 1
    • 4
    Email author
  1. 1.Department of Biochemistry and BiophysicsTexas A&M UniversityCollege StationUSA
  2. 2.Texas A&M AgriLife Research and Extension Center at WeslacoWeslacoUSA
  3. 3.Department of Plant Pathology and MicrobiologyTexas A&M UniversityCollege StationUSA
  4. 4.The Institute for Quantum Science and EngineeringTexas A&M UniversityCollege StationUSA

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