University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) multi-county citrus Extension agent Ajia Paolillo recently provided information about two commercial oxytetracycline hydrochloride products approved for use against HLB.
TJ Biotech LLC was the first company to receive approval from the Environmental Protection Agency (EPA) for trunk injection of this formulation. EPA granted TJ Biotech a Federal Insecticide, Fungicide, and Rodenticide Act 24(c) special local needs label in October 2022 for the product ReMedium TI.
AgroSource, Inc. in January 2023 received EPA approval for a 24(c) label for its product Rectify.
Both formulations are 95% (by volume) oxytetracycline hydrochloride.
TJ Biotech has released its trunk-injection device, FLexInject, to deliver ReMedium TI into the tree. AgroSource does not list a specific injection device on its product label.
The depth of the hole to be drilled for injection is dependent on trunk diameter.
Product concentration is measured in parts per million, and volume rate is measured in milliliters. Concentration and volume rate are determined by the tree’s bearing or non-bearing status (mature vs. young), HLB symptom severity, canopy density and trunk diameter.
Both products are recommended to be added to a solution which has been buffered by muriatic acid to lower the pH of the injection solution to a range of 1.8 to 2.0.
The amount of time needed to empty the injection device varies by tree. Factors contributing to this variation are rate applied, tree canopy volume, HLB severity, tree transpiration rate and air temperature.
Crews available for hire are being trained in the injection process and growers may also be training their own employees to do the injections.
Growers will need to determine which trees will receive the specified concentration and volume rate. It may be beneficial to have one or two people who will determine this. This will allow their determination to be consistent from tree to tree and block to block.
Growers also may find it beneficial to map out each block and mark the respective concentrations and rates. This may make filling the injection devices easier if a specific concentration and volume rate was delivered to selected trees during a certain time. For example, a grower may choose to inject all non-bearing trees in one week and then move to bearing trees the next.
More advice on applying oxytetracycline hydrochloride can be found here.
See the product labels for ReMedium TI and Rectify. Contact the chemical company representatives for additional information.
Source: UF/IFAS
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