Can Finger Limes Help ‘Valencia’ Trees be More Tolerant of Huanglongbing?
Posted August 2025
Researchers: Ozgur Batuman, Nabil Killiny, Lauren Diepenbrock, Jude Grosser, Manjul Dutt
Contact: Ozgur Batuman, UF/IFAS SWFREC obatuman@ufl.edu
Summary:
To evaluate the ability of huanglongbing (HLB)-tolerant finger limes to protect susceptible scions such as ‘Valencia’ (and ‘Hamlin’) against HLB, we utilized the interstock grafting technique. The idea is to assess whether antimicrobial peptides (and potentially other molecules) naturally found in finger limes are graft-transmissible and can provide HLB tolerance to citrus tree cultivars grown in Florida. For this, we established numerous ‘Valencia’ plants interstock-grafted with various finger lime types in the greenhouse at the UF/IFAS Southwest Florida Research and Education Center in Immokalee. We challenged these plants with Asian citrus psyllids carrying the HLB-causing bacterium. We determined that UF-SL and R1T98 interstock grafted scions (‘Valencia’ grafted on finger lime, which was grafted on Swingle rootstock) accumulated HLB bacterium significantly less than regularly grafted scions (‘Valencia’ grafted directly on Swingle rootstock). We are now continuing to monitor the HLB infection rate and the amount of bacteria accumulating in these plants in the grove with monthly visual observations for symptoms and qPCR tests. This study will allow us to better understand the mechanism of HLB tolerance in these graft combinations and to determine whether this method could be another practical tool for the integrated pest management (IPM) strategy for HLB management in citrus groves.
Take Home Message:
- The interstock graft technique may help with transferring HLB tolerance from finger limes to ‘Valencia’ and ‘Hamlin’.
- Preliminary results indicate that interstocked ‘Valencia’ plants protected from HLB and bacterial build up were delayed.
- A similar idea could be achieved by inarching the trees in the grove, and we will be testing this in 2025.
