By Frank Giles
During the Florida Citrus Industry Annual Conference, Ute Albrecht, a plant physiologist with the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), provided an update on her research on the use of oxytetracycline hydrochloride (OTC-HCl) to treat HLB.
She began her presentation with some history of OTC-HCl. The compound has been in use since the 1940s. It was tested in citrus dating back to the 1970s but was not pursued until more recently as a treatment for HLB via trunk injection.
Albrecht has conducted trials in different citrus growing regions of the state. While trials have variable results based on the overall health of the tree and its age, her results have been positive thus far. She provided an example of one such trial in Southwest Florida.
“We found a significant difference in the yield and the differences were not affected by the month when the injections were made (April or June). We had an improvement of yield of 30% to 50% over the control,” Albrecht said. “Interestingly in this trial, the lower concentration of OTC-HCl was a little bit better. But again, we can see variability in these results.”
The pounds solids of the OTC-HCl treated trees also were improved over the control. The injected trees had a 7.5 to 7.8 pounds solids versus 6.5 in the control. And there was no statistical difference between rates of OTC-HCl applied.
Albrecht also discussed research looking at differences between injecting the rootstock versus the scion. There has been some discussion that injection via the scion may result in improved uptake of OTC-HCl. Albrecht has conducted trials testing that theory. “We took measurements and saw no significant differences in the uptake whether we injected in the rootstock or scion of the tree,” she said.
She also has been observing the potential damage to the tree resulting from the process of trunk injection. “We have injected trees multiple times over several years. The trees we injected are still standing and are looking better than the other trees,” she said. “So, I am kind of optimistic it will work for at least a few years.”
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