Panel Discussions Highlight Florida Citrus Show Seminars

Daniel CooperBreeding, HLB Management

A pair of panel discussions during the citrus seminars at the Florida Citrus Show gave growers the opportunity to engage with experts on top-of-mind topics.


The citrus seminar program started with a discussion among citrus breeders moderated by Flavia Zambon, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) assistant professor at the Indian River Research and Education Center (IRREC). The breeder panel was composed of Jude Grosser and John Chater of the UF/IFAS Citrus Research and Education Center and Kim Bowman and Matt Mattia of the U.S. Department of Agriculture-Agricultural Research Service U.S. Horticultural Research Laboratory.

The breeder panel included John Chater, Jude Grosser, Kim Bowman and Matt Mattia.
Photos by Robin Koestoyo, UF/IFAS

Bowman advised growers not to put too much stock in a single trial. He said multiple trials are needed over multiple years before a new variety or rootstock can be deemed a success. Bowman announced that SuperSour 6, a new dwarfing rootstock, will likely be commercially released next year.

When asked what grapefruit variety they would plant in the Indian River, Grosser and Chater’s picks both included UF 914, a pummelo-grapefruit hybrid. Chater recommended the X-639 rootstock for UF 914. Bowman said he wouldn’t plant a true grapefruit right now, only hybrids. Mattia advised growers to be selective but plant a diversity of varieties, including both old and new ones.

The breeders were also asked what varieties hold the most promise. Mattia mentioned SunDragon, a sweet orange-like hybrid producing 14 Brix across Florida. He noted that it can be blended into orange juice, comprising 10% of the juice. Another orange-like variety he likes is 53108, which has a tropical flavor and juices well. He is also excited about the Donaldson variety.

With Florida oranges currently producing low Brix due to HLB, Grosser stressed the need for blending in order to put high-quality orange juice (12 Brix) in the bottle at grocery stores that consumers will want to buy. To meet this goal, he said one grower had the idea of planting an orange-like variety (for blending) every 10th tree in a new orange grove.

Grosser noted that almost no fruit from Marathon mandarin trees is HLB symptomatic. He added that he is working to get two Vernia clones with high Brix commercially released. Grosser’s work also includes creating red grapefruit cybrids with kumquat that are showing better canker and HLB tolerance.

Chater likes 1859, a newly released sweet orange-like hybrid with good tree health and consumer acceptance.

A grower asked the breeders if they thought Florida citrus growers would ever get back to producing 600-plus boxes per acre again. All four breeders were optimistic that this could happen.

“It won’t happen in the next five years,” said Bowman. “It will take some time, but we can get there.”

Mattia added that growers can get back to high yields, but it will require a lot of inputs.


The citrus seminars concluded with a grower panel discussing HLB management tactics. Mark Ritenour, UF/IFAS IRREC professor, moderated the session. Participating on the panel were Daniel Scott of Scott Citrus Management, George Hamner Jr. of Indian River Exchange Packers and Matt Machata of Rolling Meadow Ranch.

Daniel Scott, George Hamner Jr. and Matt Machata served on the grower panel

The growers shared their experiences with trunk injection of oxytetracycline (OTC). Hamner reported his first-year results on red grapefruit, which included a 30% increase in yield, improved tree health and less drop.

Machata did not see a lot of results in year one of trunk injection, but strong flush and bloom are currently leading him to have higher expectations for year two. He noted that mature trees take longer to uptake OTC, so he urged growers to ensure that field workers do not remove injection devices until uptake is complete.

Scott said he has seen some modest improvement in fruit quality and yield in his first year of OTC treatment. He believes injecting both sides of a tree (split dose) with two injectors is beneficial because the OTC reaches a greater portion of the tree canopy.

Scott added that he is a big proponent of applying kaolin particle film on newly planted trees. He uses kaolin instead of individual protective covers to deter psyllids.

Hamner stressed the importance of spreading out fertilizer applications throughout the year and increasing the amounts of nutrients applied to keep trees alive.

Machata emphasized the need for proper irrigation and a balanced nutrition program to reduce tree stress. He added that it is essential to spend money on insecticides to protect flush.

Ritenour asked the growers what types of research projects are of most interest to them. Scott said plant development, including rootstocks and varieties, is crucial. “We also need to work to sustain what we have through soil health and stress reduction,” he added. “If we aren’t replanting, we’ll be out of business.”

Hamner pointed to the value of the Citrus Research and Field Trial (CRAFT) program. He encouraged growers to use CRAFT as a way to subsidize new plantings. “Look hard at the options and plant what you are interested in that you want to learn more about,” he advised.

Machata said that peptide research trials at his grove have been beneficial. Trees are showing excellent growth response and less stress.

When asked about managing increasing costs, the growers had no easy solutions. But all agreed that if you aren’t spending money to keep trees healthy, you won’t have any trees.

“The cost of saving the tree is worth it if you want to stay in the industry,” said Hamner. “If you don’t spend the money, you’ll be out.”

Machata agreed: “You have to commit to spending dollars if you want to keep trees alive. And carry good strong insurance.”

“If we can improve tree health and productivity, we can live with less return,” said Scott. “I do believe we are on the cusp. We have made huge leaps and bounds in managing HLB. I see the light at the end of the tunnel,” concluded Hamner.

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Tacy Callies

Editor of Citrus Industry magazine

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