The Gulf Citrus Growers Association recently hosted a grower panel at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Southwest Florida Research and Education Center in Immokalee to discuss experiences and results of trunk injection of oxytetracycline (OTC) to treat HLB. Participating in the panel were Ron English, Florida’s Natural Growers/Ranch 1; David Wheeler, Wheeler Farms; and Joby Sherrod, Alico Inc. Ute Albrecht, UF/IFAS associate professor of plant physiology, moderated the panel. She has been a lead researcher on the OTC treatment.
All three growers acknowledged there was a large learning curve with initial trunk-injection applications last season, and there still is more to learn as the second applications are being made now. But they are getting a better handle on the process and moving the injection devices through groves as efficiently as possible.
Sherrod discussed how Alico’s plans for treatments evolved last season based on what made logistical sense.
“We ended up covering about 30% of Alico acreage last year. The target this year is to cover at least double that,” Sherrod said. “We started treatments in the second week of January. We are progressing nicely, benefiting from the lessons learned last year.”
Overall, the growers believe the treatments have been positive. But expectations have come back down to earth somewhat after trees initially responded vigorously soon after treatments. Moving forward, determining the age at which a tree might be too old to benefit from trunk injection will be important.
“The age of trees we treated last season ranged from about 4 years old to about 20 to 21 years old,” English said. “Anything older than that we just didn’t feel like it was viable to do.”
Wheeler observed a similar pattern in his groves. “After last season, on early varieties, we are leaning toward injecting trees 6- and 8-feet in size (and younger). I don’t think I want to inject 20- and 30-year-old trees.” he said. “It just doesn’t seem to be helping, particularly if those trees have blight.”
There also was discussion that the early varieties didn’t seem to respond as well as later varieties like Valencia. Wheeler shared observations on his groves, which were very dry in Polk County and very wet in Southwest Florida.
“All through the summer, we felt good about what we were seeing,” he said. “When fall came, we still felt good. We did not see drop. The drop was about a month late. When it came, it came as usual, unfortunately. We are struggling right now to determine what to do this year. We had 4.5 pounds solids in early fruit picking at 100 boxes per acre.”
The growers did acknowledge that some of the fruit drop problems this season are attributable to canker. There are also unknowns caused by the effects of the hurricanes and the trees’ recovery process. Wheeler reported that a recently harvested Vernia block picked out well, which was encouraging. He said he’s hopeful that trend will continue as harvest of later-season varieties continues.
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