According to a recent industry survey, 64% of Florida citrus growers have injected their trees for three consecutive years with oxytetracycline (OTC). This article reports the results from three research trials conducted by the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Plant Physiology Team at the Southwest Florida Research and Education Center (SWFREC). All trials were initiated in 2023 and are in Polk County. The main objectives were to determine the optimal OTC dose, the best month of injection, rootstock responses to OTC, and whether it is preferable to inject in the rootstock or the scion.
OPTIMAL DOSE
Two trials were conducted, one with Hamlin/Carrizo and the other with Valencia/Swingle trees. Trees had been planted in 2005. Four different doses — 0.55, 0.825, 1.1 and 1.65 grams (g) of OTC per tree — were tested. In years 1 and 2, the 0.55-1.1 g doses were administered on one side of the trunk, while the 1.65 g dose was administered by injecting 0.825 g on each of two opposite sides of the trunk. In year 3, all doses were administered two-sided.
Hamlin…