An Improved Method to Track Changes of Candidatus Liberibacter asiaticus Titer in HLB-affected Citrus Trees

in HortScience

Monitoring the health of Huanglongbing-affected citrus trees by following changes in leaf Candidatus Liberibacter asiaticus (CLas) titer has an inherent element of imprecision because CLas titer varies considerably within the tree canopy and with calendar seasons. In addition, the destructive sampling method used to determine CLas titer entails a different set of leaves per sampling period adding to the inconsistency and inexactitude of the results. To overcome these ambiguities and to reduce the numerical variability between samples, we developed an experimental method that analyzes portions of the same treated leaves for up to four sampling periods. By assaying subsamples of adjacent locations of the same leaf, random variability was significantly reduced, and comparative analysis can be carried out with greater precision.

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Corresponding author. E-mail: eetxeber@ufl.edu.

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    Diagramatic depiction of a citrus leaf demonstrating the location of tissue excision. Discs were taken from the midrib to ensure consistent phloem tissue sampled throughout. First leaf disc sample was excised toward the center of the leaf, leaving sufficient space for the basipetal removal of subsequent disc samples.

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