Use of Systemic Acquired Resistance Inducers to Protect New Flushes from Huanglongbing and Citrus Canker
Posted August 2025
Researchers: Ozgur Batuman, Bayer Crop Science: Denise Manker, Jeremy Dufour, Thomas Knobloch, Stephane Brunet
Contact: Ozgur Batuman, UF/IFAS SWFREC obatuman@ufl.edu
Summary:
A therapeutic screening pipeline for huanglongbing (HLB) management was established, where we identified compounds of interest that include a class of synthetic systemic acquired resistance (SAR) inducers in citrus trees. These SARs have been tested for their efficacy in preventing HLB infection of young shoots (in the greenhouse) and slowing HLB infection of new trees (in the field). By spraying SAR treatments on young flushes before Asian citrus psyllid (ACP) colonization to activate plant defense (priming) and prevent bacterial infection, we observed that young flushes could be protected from reinfections of the HLB-causing bacterium due to ACP feeding. Some preliminary field experimental results were encouraging, providing a substantial delay in HLB infection (~3-7 months) after 2-3 applications. Moreover, some SARs were also significantly effective in citrus canker control. We are currently testing some of these compounds on newly established citrus trees across 4 grove sites in Florida. We propose that emerging young flushes, particularly after OTC injection or IPC removal from young trees, could be sprayed with SARs to protect them from HLB in the grove.
Take Home Message:
- New flushes must be protected from ACP feeding and HLB reinfections.
- Spray of plant defense inducers can protect young flushes from HLB, citrus canker, and ACP feeding.
- SARs can be used after OTC efficacy starts declining and after IPC removal to protect young flushes.
