A variety of treatments Florida citrus growers are using for HLB have so far produced mixed results, according to observations reported by Highlands County Citrus Growers Association (HCCGA) President Aaron Nelson.
In a recent association newsletter, Nelson wrote that many are anxious to see harvest data showing what effects the treatments have had over the past year. The treatments he referred to include oxytetracycline (OTC) and heavier use of plant growth regulators (PGRs) such as gibberellic acid and 2,4-D.
“The answers to the questions many of us are asking will ultimately come once the groves have been picked,” Nelson stated. “With that being said, what I have seen with these different treatments on a purely observational level has been a mixed bag of results. While OTC has had an overall positive effect on tree health and thus far fruit drop, it has not performed consistently in every block. Canopy density and fruit retention are often very different in comparable groves. The differences have been hard to correlate to something concrete such as a rate or time of year.
“Learning what we can do better in year two of trunk injections is important but is complicated by the inconsistent results from block to block. Plant growth regulators are even more inconsistent and difficult to evaluate. Gibberellic acid seems to keep fruit green, trigger a flush and reduce drop, but again the results in every grove are so inconsistent.
“Adding another layer of complexity to evaluating PGRs is the potential for unintended consequences such as delaying maturation and affecting flowering in the spring. To complicate evaluation of these therapies even further is the fact that this is the first crop post-Hurricane Ian in 2022. How much was our tree’s ability to grow a healthy crop impacted by last year’s storm?
“These treatments are no doubt useful tools for growers. However, learning to use them in conjunction with one another is still something we need to figure out … As usual, there are more questions than answers, but I am optimistic that we are building some momentum that we can carry into the future.”
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