Find 10 tips for citrus trunk injections from a UF/IFAS Tip of the Week to help Florida citrus growers to get the best results.

Florida citrus growers were granted a 24(c) special local need label to use oxytetracycline administered by trunk injection to combat citrus greening in 2022, with final clearance coming in January 2023, according to a UF/IFAS Tip of the Week article. While there is a lot of hope for citrus trunk injections, administering oxytetracycline via injections is not a simple process. The article shares 10 tips, or ‘Best Practices,’ for using trunk injections in citrus. See them below.

Best Practices for Citrus Trunk Injections

The following tips for citrus trunk injections are from the article:

  1. “Follow label directions.
  2. Inject after the main flowering period to prevent exposure of pollinators.
  3. Uptake and distribution of injected materials is driven by transpiration. Transpiration is the process of evaporation of water vapor on the leaf surface through the stomata. The loss of water vapor pulls water (and therefore injected materials) from the stem and roots upwards. Therefore: A) Inject when leaves are fully expanded (not during flush) to ensure efficient uptake and distribution. B) As much as possible, inject during mid- to late morning when trees are actively transpiring. Injections in the afternoon are likely to be less effective and may also increase the risk for phytotoxicity.
  4. Avoid injecting during the hottest time of the day and season. There have been reports of phytotoxicity (leaf bronzing) when injections were conducted in August.
  5. Use a sharp brad-point drill bit to minimize injury.
  6. Drill the hole no deeper than necessary. The inner (older) wood of the trunk is metabolically less active, and drilling results in more internal damage and dysfunction.
  7. Do not use any wound sealants or plugs/stoppers to seal the injection hole. These inhibit the tree’s ability to effectively compartmentalize (heal) the wound.
  8. Remember that trees can become reinfected. Oxytetracycline injection is not a replacement for psyllid control.
  9. Although the label allows it, it is not advised to inject trees with a trunk diameter of less than 2.5 inches.
  10. Inject trees only once annually and leave a preharvest interval of at least 180 days.”

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