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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Citrus and Other Subtropical Products Research » Research » Publications at this Location » Publication #422003
Research Project: Determination of Flavor and Healthful Benefits of Florida-Grown Fruits and Vegetables and Development of Postharvest Treatments to Optimize Shelf Life an Quality for Their Fresh and Processed Products

Location: Citrus and Other Subtropical Products Research

Title: Managing endemic Huanglongbing in commercial citrus production through vascular delivery of oxytetracycline

Author
item ALBRECHT, UTE - University Of Florida
item TARDIVO, CAROLINE - University Of Florida
item MORENO, GERARDO - University Of Florida
item DE FREITAS, JASMINE - University Of Florida
item SINGERMAN, ARIEL - University Of Florida
item Plotto, Anne
item Bai, Jinhe

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/16/2025
Publication Date: 4/16/2025
Citation: Albrecht, U., Tardivo, C., Moreno, G., De Freitas, J., Singerman, A., Plotto, A., Bai, J. Managing endemic Huanglongbing in commercial citrus production through vascular delivery of oxytetracycline. Crop Protection. 195:107250. 2025. https://doi.org/10.1016/j.cropro.2025.107250.
DOI: https://doi.org/10.1016/j.cropro.2025.107250

Interpretive Summary: The antibiotic oxytetracycline (OTC) has been identified as one of the most effective treatments to fight the devastating citrus greening disease, a.k.a. Huanglongbing (HLB). Trees injected with OTC have seen the bacterial titer in leaves decrease, and health and productivity temporarily restored. This study reports on OTC treatments at several doses and modes of application in mature trees over a period of two years. OTC significantly increased fruit yield, especially after the second year of application. Fruit and juice quality were improved. Residual OTC in fruit from treated trees was below the maximum level allowed. An economic analysis indicated that the effects were substantial enough to offset the cost of injections.

Technical Abstract: The bacterial disease huanglongbing (HLB) is devastating citrus industries around the world. Trunk injection of oxytetracycline (OTC) has been identified as one of the most effective ways to reduce pathogen titers and restore citrus tree health and productivity. This technology was recently approved for the management of HLB in commercial citrus production in Florida. Here we assess the efficacy of OTC injections to mitigate HLB in a commercial citrus grove in Florida over two production cycles. Nine-year-old ‘Valencia’ orange (Citrus sinensis) trees were injected with two different rates of OTC in May 2022 and 2023 using two different injection methods and compared against non-injected trees. Regardless of the method, OTC injection significantly improved fruit yield and juice quality. At the lower rate (0.55 g OTC/tree) fruit yield increased by up to 66% in year 1 and 95% in year 2. At the higher rate (1.1 g OTC/tree) fruit yield increased by up to 70% in year 1 and 121% in year 2. Significant increases were also measured for fruit size, fruit weight, juice color, and soluble solidsBrix, and the Brix/acid ratio, regardless of the OTC rate although the higher rate generally produced better results. Juice sensory analysis confirmed the superiority of the juice from injected trees over non-injected trees. OTC residues in the fruits collected at harvest were below the maximum allowed level, regardless of the rate. Leaf bacterial titers measured one year after each injection were not different between injected and non-injected trees, suggesting that reinfection occurred and that repeated injections are necessary to maintain the beneficial effects of this therapy. The economic analysis showed that the cumulative result of OTC treatments over two seasons is positive, denoting that their benefit outweighed their cost.