Oxytetracycline Trunk Injection Tips
Posted August 2025
Researchers: Ute Albrecht, Larissa Nunes, Gabriel Pugina, Caroline Tardivo, Jasmine Freitas, Gerardo Moreno, Igor Rodrigues, Deived Carvalho
Contact: Ute Albrecht, UF/IFAS SWFREC ualbrecht@ufl.edu
Summary:
Injection Timing
- Inject at least 180 days before harvest.
- Injections are best performed during spring and early summer.
- Injections performed later in the year result in a higher Brix, but…
- … injections performed later than July result in high fruit residues.
- Inject when leaves are fully expanded and during the morning.
- Trees should be well-hydrated at the time of injection.
Performing the Injections
- Follow label instructions to determine the correct oxytetracycline (OTC) dose.
- Ensure the OTC solution is acidified correctly.
- Use only freshly prepared OTC solution. The solution should be yellow and clear.
- Use a smaller drill bit and applicator tip for smaller trees to reduce trunk injury.
- Both rootstock and scion injection are effective, but young trees and trees with a short trunk are better injected into the rootstock.
- Subsequent injections should be performed opposite to the previous injection or spaced apart by several inches.
- Do not inject right next to, or into a previous injection site.
Phytotoxicity and Sectoring
- Moderate phytotoxicity (leaf yellowing, bronzing) to severe phytotoxicity (leaf drop, twig die-back, fruit drop) may occur after injection.
- To reduce phytotoxicity and sectoring, try injecting half of the desired OTC dose each on two different sides of the trunk.
- Consider using a smaller applicator tip when performing two-sided injections.
- Do not inject directly underneath a main scaffold branch when performing one-sided injections.
Aftercare
- Good tree care is important for tree recovery.
- Continue to manage psyllids. OTC injections are no replacement for psyllid control.
Take Home Message:
- OTC injections are effective.
- Injections must be performed properly to maximize the beneficial effects.
- OTC injections are no replacement for psyllid control and other good tree care practices.
