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Uptake, Translocation, and Persistence of Oxytetracycline in Coconut Palm. Randolph E. McCoy, Assistant Professor, University of Florida, Agricultural Research Center, 3205 S. W. 70th Avenue, Ft. Lauderdale 33314; Phytopathology 66:1039-1042. Accepted for publication 12 November 1975. Copyright © 1976 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-66-1038.

Oxytetracycline-HCl (OTC) residues were measured in coconut palm (Cocos nucifera) by microbiological assay of aqueous extracts of freeze-dried or fresh tissue samples. Detectable uptake of OTC was obtained only through the injection of aqueous solutions directly into the trunk of the palms. Soil drenches, foliar sprays, and implantation of solid tablets produced no detectable foliar residues. Residues of OTC as high as 20 µg/g fresh weight were found in foliage within 2 days of trunk injection of 6 g of antibiotic. Most of this material accumulated in the middle and upper fronds of the treated trees. Lower concentrations were found in roots, trunk, unopened spear or bud leaves, older senescing fronds, and in fruit. The half-life of OTC in foliage was about 2 weeks.

Additional keywords: lethal yellowing, antibiotic assay.