Reasons to Believe HLB Is Beatable

Growers gathered in Bonita Springs in mid-June for the Florida Citrus Industry Annual Conference. The event hosted by Florida Citrus Mutual drew a good crowd. The mood of growers was mixed.

While there was hope that HLB trunk-injection therapies might have resulted in more dramatic improvements to this year’s crop, there also was recognition that these therapies represent one of the best opportunities to date for the state’s citrus industry to bounce back.

The educational program presented during the conference reflected positive industry developments. Rick Dantzler, chief operating officer of the Citrus Research and Development Foundation, moderated the seminars and said the program was meant to give growers faith that better days are ahead. This is backed up by evidence that science and new approaches might be finally catching up to HLB. He said he believed it is possible, between new breakthroughs and those to come, that Florida citrus growers could return to producing 90 million boxes per season — a number that could also be successfully sold on the market.

OTC TOPS AGENGA

As for the mixed results of the oxytetracycline (OTC) therapies, Dantzler related an antidote that was shared by grower Morgan Porter during a recent public meeting.

“She said that if you and I or a couple of other people join the gym tomorrow and started working out, in a year we all would not look the same. What she is saying is true that we are all not starting out at the same spot,” Dantzler said. “Some trees have been affected by the hurricanes, there are soil differences, whatever variable it may be (impacting treatment results). So, we recognize not everyone’s experience has been the same, but we do really believe we are on the right track (with these therapies).”

Ute Albrecht, associate professor of plant physiology with the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), presented her latest research results from OTC field trials. She said the treatment continues to show significant improvement in tree health and yield.

Albrecht also addressed whether it is beneficial to inject both sides of the trunk to better distribute OTC throughout the tree. Growers have noticed sectoring effects. For illustration, she showed photos of a tree where the right side of the trunk was injected. The visual differences were clear. There also was phytotoxicity and leaf yellowing on the right side, but it didn’t appear to negatively impact yields.

“You can see this clear sectoring. The right side is very dense and has a much bigger canopy than the left side. This is the side we injected,” she said. “And this is the side where we saw the phytotoxicity and yellowing of the leaves.

“At harvest, the right had more fruit, and they were also orange and much better looking than the left side. We collected fruit separately from each side for analysis. On the right, the fruit had good color and had a Brix of 11.2%. On the left, fruit had only 9.3% Brix. But the opposite side of the injected tree was still better than the non-injected (control) tree, which was 8.5%.

“The best way to avoid this sectoring is to do a double-sided injection. Also, when we have done the double injection, we have not seen the phytotoxicity because the material is better distributed.”

Albrecht acknowledged double-sided injection would represent more costs and labor considerations, but added if growers can do it, there is evidence it would be beneficial.

GROVE FIRST PROJECT

Michelle Heck, a molecular biologist with the U.S. Department of Agriculture (USDA), and Randy Niedz, USDA geneticist, gave an update on their research injecting compounds into trees in the grove and looking for big visual effects to more quickly identify new materials aimed at improving tree health.

Last year, the USDA research team injected 88 materials into trees to identify plant health responses. This year, another 200 compounds have been injected. The compounds that produced visible improvements in tree health and yields are now being moved into grower-validation trials for proof they can work in a real-world environment.

Heck said the goal is giving growers options for trunk injection. She added that if these materials appear to work, research will be done on how they perform through foliar applications, which would be a cheaper option for growers.

“Growers’ groves are living laboratories. The resources you have, your groves and your partnerships with us — there is nothing like this in the United States or in the world,” Heck said. “You are in a position to be a part of finding a sustainable solution for citrus.”

ARRESTING HLB

Bob Turgeon, a professor of plant science biology at Cornell University, presented research on utilizing anchored antibodies to arrest the HLB bacteria in trees. While it is complicated science, in simple terms he said antibodies could be programmed to target HLB bacteria and stop it in its tracks from the point where it enters the tree from psyllid feeding sites and other sites. It would essentially make the disease non-functional in citrus trees.

KEEP ON DIGGING

At the end of the educational session, Dantzler closed by showing a cartoon illustrating two characters digging a tunnel just inches away from a diamond treasure. One character had given up and was walking away, while the other continued to dig toward the treasure.

“I show you this because we are getting close to finding solutions to make this industry viable and able to thrive again,” he said. “Unfortunately, some have not made it. Getting to the other side of this is not going to be easy, but if you can, hang in there because I believe we truly are close to finding answers.”

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